Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module
Specialist Report
Country: Namibia
Discipline: Aquatic Macroinvertebrates
Shishani Namutenya Nakanwe
June 2009


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EFA Namibia Aquatic Macroinvertebrates





Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module



Specialist Report

Country: Namibia

Discipline: Aquatic macroinvertebrates

Author: Shishani Namutenya Nakanwe

Date: 30 June 2009


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EFA Namibia Aquatic Macroinvertebrates

EXECUTIVE SUMMARY
When the OBSC noted that there was inadequate information about the physico-chemical,
ecological and socio-economic effects of such possible developments in the Okavango river; it
proposed that a preliminary Environmental Flow Assessment (EFA) be carried out to predict
possible development-driven changes in the flow regime of the Okavango River system, the
related ecosystem changes, and the consequent impacts on people using the river's
resources. One of the study's specific objectives is: to ascertain at different points along the
Okavango River system, including the Delta, the existing relationships between the flow
regime and the ecological nature and functioning of the river ecosystem. Aquatic
macroinvertebrates are among the multidisciplinary specialties EFA study comprises.

Delineation of the Okavango basin into different integrated units of analysis was done using
different criteria during the preparation workshop that took place in Maun Botswana. The end
results were three sites in Angola, two in Namibia and three in Botswana. The Namibian sites
are EFA Site 4 at Kapako (in the floodplain area) and Site 5 at Popa rapids. Indicators for the
aquatic macroinvertebrates were chosen and agreed upon by specialists from all three
countries. For each site, applicable indicators were identified. For each indicator,
representative families were identified to act as guidance during the sampling depending on
the linkage to flow regime and social importance

Data were collected in dry low-flow and wet high-flow season. Aquatic macroinvertebrates
collected were identified to the family level. It was found that the number of families such as
Caenidae and Unionidae found at Kapako in the dry season was low compared to those found
in the wet season, with some representative families such Dytiscidae and Planorbidae not
recorded at all. At Popa rapids, although most of the representative families and more were
found in the dry season, abundance doubled in the wet season e.g. Simuliidae,
Hydropsychidae and Tricorythidae. This somehow shows the linkage of the aquatic
macroinvertebrates to the water level and flow.

Prediction on what will happen to each indicator during different flow regime categories would
be worked out at the Knowledge Capture workshop to be held in Windhoek in April 2009.
Scenario development will take place in the workshop to be held in June 2009 in Cape Town,
South Africa.




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EFA Namibia Aquatic Macroinvertebrates

TABLE OF CONTENTS

EXECUTIVE SUMMARY ................................................................................................ 3
ABBREVIATIONS ........................................................................................................... 7
ACKNOWLEDGEMENTS ............................................................................................... 7
1.INTRODUCTION ......................................................................................................... 8
1.1 Background ..................................................................................................... 8
1.2 Okavango River Basin EFA Objectives and Workplan .................................... 8
1.2.1 Project objectives ...................................................................................... 8
1.3 Layout of this report ......................................................................................... 9
2.STUDY AREA ............................................................................................................ 10
Description of the Okavango Basin ......................................................................... 10
Delineation of the Okavango Basin into Integrated Units of Analysis ...................... 11
Overview of sites ..................................................................................................... 12
2.3.1 Site 4: Okavango River at Kapako.............................................................. 12
2.3.2 Site 5: Okavango River at Popa Falls ......................................................... 13
Discipline-specific description of Namibia sites ....................................................... 13
2.4.1 Site 4: Kapako ............................................................................................ 13
2.4.2 Site 5: Popa Rapids .................................................................................... 14
3.IDENTIFICATION OF INDICATORS AND FLOW CATEGORIES ............................. 15
3.1 Indicators .......................................................................................................... 15
3.1.1 Introduction ................................................................................................. 15
3.1.2 Indicator list for Aquatic macroinvertebrates ............................................... 15
3.1.3 Description and location of indicators ......................................................... 16
3.2 Flow categories ­ river sites .............................................................................. 19
4.LITERATURE REVIEW ............................................................................................. 21
4.1 Introduction ....................................................................................................... 21
4.2 Indicator 2: Channel dwellers in Marginal Vegetation (Ephemeroptera
/Odonata /Gastropoda). ....................................................................................... 23
4.2.1 Main characteristics of Indicator 2: Channel dwellers in Marginal Vegetation
(Ephemeroptera/Odonata/Gastropoda) .............................................................................. 24
4.3 Indicator 3: Channel dwellers in fine sediment (Bivalves/Pill clams: Unionidae
and Sphaeridae) .................................................................................................. 25
4.4 Indicator 4: Channel dwellers in Rapids or fast flowing water
(Diptera/Simulium/Blackflies) ............................................................................... 26
4.5 Indicator 5: Channel dwellers on stones and rocks (Trichoptera:
Hydropsychidae and Ecnomidae) ........................................................................ 27
4.6 Indicator 6: Floodplain dwellers in Marginal Vegetation (Odonata/Gastropoda)
............................................................................................................................ 27
4.7 Indicator 7: Floodplain dwellers in pools (Coleoptera) ................................... 29

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EFA Namibia Aquatic Macroinvertebrates

4.8 Summary ........................................................................................................... 29
5.DATA COLLECTION AND ANALYSIS ...................................................................... 31
5.1 Methods for data collection and analysis .......................................................... 31
5.2 Results ............................................................................................................. 32
Channel dwellers in Marginal Vegetation ............................................................ 33
Channel dwellers in Fine sediments .................................................................... 34
Channel dwellers in Rapids or fast flowing waters .............................................. 34
Channel dwellers in stones and rocks ................................................................. 34
Floodplain dwellers in marginal vegetation .......................................................... 35
Floodplain dwellers in Pools ................................................................................ 35
5.3 Summary ....................................................................................................... 35
5.3.1 Indicator 2 (Channel dwellers in marginal vegetation) ................................ 36
5.3.2 Indicator 3 (Channel dwellers in fine sediments) ........................................ 37
5.3.3 Indicator 4 (Channel dwellers in rapids or fast flowing waters) ................... 38
5.3.4 Indicator 5 (Channel dwellers in stones and rocks) .................................... 39
5.3.5 Indicator 6 (Floodplain Marginal vegetation) ............................................... 40
5.3.6 Indicator 7 (floodplain dwellers in pools) ..................................................... 41
5.4 Conclusion ..................................................................................................... 42
5.5 Flow-response relationships for use in the Okavango EF-DSS ..................... 42
6.REFERENCES .......................................................................................................... 43
APPENDIX A: FULL DESCRIPTIONS OF INDICATORS ................................................. 46
APPENDIX B: RAW DATA .............................................................................................. 47

LIST OF FIGURES

Figure 2. 1: Upper Okavango River Basin from sources to the northern end of the Delta10

Figure 3. 1: Three representative years for Site 4: Okavango River @ Kapako (hydrological
data from Rundu), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 19
Figure 3. 2: Three representative years for Site 5: Okavango River @ Popa (hydrological
data from Mukwe), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 20

Figure 3. 1: Three representative years for Site 4: Okavango River @ Kapako (hydrological
data from Rundu), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 19
Figure 3. 2: Three representative years for Site 5: Okavango River @ Popa (hydrological
data from Mukwe), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 20

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EFA Namibia Aquatic Macroinvertebrates

Figure 5. 1:Location of Namibia in southern Africa, the Okavango River (lower map) and
the habitats sampled for aquatic invertebrates at EFA site 4,
Kapako. .................................................................................... 32

TABLE OF TABLES

Table 2.1: Location of the eight EFA sites ..................................................................... 12
Table 3.1: List of indicators for aquatic macroinvertebrates and those chosen to represent
each site ................................................................................... 15
Table 3.2: Questions to be addressed at the Knowledge capture Workshop, per indicator
per site. In all cases, 'natural' embraces the full range of natural
variability .................................................................................. 20
Table 4.1: List of families and chosen representative families for aquatic invertebrate
indicators. ................................................................................. 22
Table 5.1: Predicted response to possible changes in the flow regime of Channel dwellers
in marginal vegetation in the Okavango River ecosystem. ...... 36
Table 5.2: Predicted response to possible changes in the flow regime of Channel dwellers
in fine sediments in the Okavango River ecosystem. ............... 37
Table 5.3: Predicted response to possible changes in the flow regime of Channel dwellers
in rapids or fast flowing waters in the Okavango River ecosystem.
................................................................................................. 38
Table 5.4: Predicted response to possible changes in the flow regime of Channel dwellers
in stones and rocks in the Okavango River ecosystem. ........... 39
Table 5.5: Predicted response to possible changes in the flow regime of floodplain dwellers
in marginal vegetation in the Okavango River ecosystem ....... 40
Table 5.6: Predicted response to possible changes in the flow regime of floodplain dwellers
in pools in the Okavango River ecosystem. ............................. 41



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EFA Namibia Aquatic Macroinvertebrates

ABBREVIATIONS
ABBREVIATION
MEANING
DTM
Digital Terrain Model
EFA
Environmental Flow Assessment
EF-DSS
Environmental Flow ­ Diagnostic Support System
EPSMO
Environmental Protection and Sustainable Management of the Okavango River
Basin Project
NASS
Namibian Scoring System
OBSC
Okavango Basin Steering Committee
OKACOM
Okavango River Basin Water Commission
SASS
South African Scoring System
TDA
Transboundary Diagnostic Analysis
UN-FAO
Food and Agriculture Organisation for the United Nations

ACKNOWLEDGEMENTS

Thanks to the following people. Shirley Bethune, Kevin Roberts, Cynthia Ortmann and
Ndinomwaameni Nashipili for their valuable support during the EFA work. I also want to thank
Drs Jackie King, Cate Brown and Mrs. Belda Mosepele for the guidance in producing this
report and Mrs. Mosepele and Mrs. Bethune for editing this report.

Mrs. Mosepele, Dr King, Ms Bethune, Mr. Roberts, Ms Nashipili for assistance with my
literature search and sampling, Dr Brown for assistance and guidance with sampling. And
finally Mrs. Hermine Iinana at the National Museum of Namibia for assisting with identification
of snails.
.




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1. INTRODUCTION
1.1 Background
An Environmental Protection and Sustainable Management of the Okavango River Basin
(EPSMO) Project is being implemented under the auspices of the Food and Agriculture
Organization of the United Nations (UN-FAO). One of the activities is to complete a
transboundary diagnostic assessment (TDA) for the purpose of developing a Strategic Action
Plan for the basin. The TDA is an analysis of current and future possible causes of
transboundary issues between the three countries of the basin: Angola, Namibia and
Botswana. The Okavango Basin Steering Committee (OBSC) of the Okavango River Basin
Water Commission (OKACOM) noted during a March 2008 meeting in Windhoek, Namibia,
that future transboundary issues within the Okavango River basin are likely to occur due to
developments that would modify flow regimes. The OBSC also noted that there was
inadequate information about the physico-chemical, ecological and socio-economic effects of
such possible developments. OBSC recommended at this meeting that a preliminary
Environmental Flow Assessment (EFA) be carried out to predict possible development-driven
changes in the flow regime of the Okavango River system, the related ecosystem changes,
and the consequent impacts on people using the river's resources.

This preliminary EFA is a joint project of EPSMO and the Biokavango Project. One
component of the preliminary EFA is a series of country-specific specialist studies, of which
this is the Aquatic Macroinvertebrates Report for Namibia.

1.2
Okavango River Basin EFA Objectives and Workplan
1.2.1 Project
objectives
The goals of the preliminary EFA are:
· To summarise all relevant information on the Okavango River system and its users, and
collect new data as appropriate within the constraints of this preliminary EFA
· to use these to provide scenarios of possible development pathways into the future for
consideration by decision makers, enabling them to discuss and negotiate on sustainable
development of the Okavango River Basin;
· to include in each scenario the major positive and negative ecological, resource-economic
and social impacts of the relevant developments;
· to complete this suite of activities as a preliminary EFA, due to time constraints, as input to
the TDA and to a future comprehensive EFA.

The specific objectives at a preliminary level are:
· to ascertain at different points along the Okavango River system, including the Delta, the
existing relationships between the flow regime and the ecological nature and functioning of
the river ecosystem;
· to ascertain the existing relationships between the river ecosystem and peoples'
livelihoods;
· to predict possible development-driven changes to the flow regime and thus to the river
ecosystem;
· to predict the impacts of such river ecosystem changes on people's livelihoods.
· To use these preliminary EFA outputs to enhance biodiversity management of the Delta.
· To develop skills for conducting EFAs in Angola, Botswana, and Namibia.


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1.3
Layout of this report
Chapter 1 gives a brief introduction, to the background of the project and lists project
objectives. Chapter 2 describes the broad study area of the Okavango River Basin and gives
more detail on the two specific sites chosen for this preliminary EFA within the Namibian
section of the river- Kapako and Popa rapids. Chapter 3 highlights the agreed aquatic
invertebrates indicators and flow categories. Literature pertinent to aquatic invertebrate work in
the Okavango River and other similar systems is reviewed in Chapter 4 and the indicators are
listed. The field survey work undertaken for the aquatic invertebrate investigation within
Namibia in both the dry season (October 2008) and wet season (February 2009); together with
data collection, analysis and results are outlined in Chapter 5. Chapter 6 is a first attempt to
link aquatic invertebrates to flow and provide information on the flow-response relationships
for use in the Okavango EF-DSS. References are found in Chapter 7. Appendix A gives a full
description of indicators and Appendix B contains my raw field data.


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2. STUDY AREA
Description of the Okavango Basin
The Okavango River Basin consists of the areas drained by the Cubango, Cutato, Cuchi,
Cuelei, Cuebe, and Cuito rivers in Angola, the Okavango River in Namibia and Botswana, and
the Okavango Delta (Error! Reference source not found.). This basin topographically
includes the inactive drainage are of the Omatako Omuramba. Although this ephemeral river
still regularly floods along its southern portion, it has not contributed any flow to the Okavango
River. Outflows from the Okavango Delta are drained through the Thamalakane and then
Boteti Rivers, the latter eventually joining the Makgadikgadi Pans. The Nata River, which
drains the western part of Zimbabwe, also joins the Makgadikgadi Pans. On the basis of
topography, the Okavango River Basin thus includes the Makgadikgadi Pans and Nata River
Basin (Error! Reference source not found.). This study, however, focuses on the active
drainage parts of the basin in Angola and Namibia, and the Okavango delta in Botswana. The
Omatako Omuramba, Makgadikgadi Pans and Nata River are not included.

Upper Okavango River Basin
N
W
E
S
Cu
t
Cu
a
#
t
o
ch
i
#
C
C
u
u
#
it
a
o
nava
#
le
Cu
#
C
Menongue
ba
u
n
c
g
h
#
Major settlement
o
i
# Cuito Cuanavale
River
C
#
ue
Fossil river
be
C
Panhandle
ANGOLA
uiri
Permanent swamps
ri
#
Seasonal swamps
Cubango
Cuito
NAMIBIA
Okavango
#
Rundu
#
#
#
0
300 Kilometers
#

Figure 2. 1: Upper Okavango River Basin from sources to the northern end of the Delta




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EFA Namibia Aquatic Macroinvertebrates
Okavango River Basin
N
W
E
S
C
u
ta
Cu
#
to
c
h
i#
C
C
ui
ua
#
t
o
nava
#
l
e
C
# Menongue
ub
C
a
u
n
c
g
h
o
i
# Cuito Cuanavale
# Cuebe
C
ANGOLA
uiri
#
ri
Cubango
Cuito
NAMIBIA
Okavango
#
Rundu
#
# #
#
##
#
#
#
Maun
#
Makgadikgadi Pans
# Ghanzi
#
Major settlement
River
Fossil river
Panhandle
0
600 Kilometers
Permanent swamps
Seasonal swamps

Figure 2. 2: The Okavango River Basin, showing drainage into the Okavango Delta and the
Makgadikgadi Pans

Delineation of the Okavango Basin into Integrated Units of Analysis
Within the Okavango River Basin, no study could address every kilometre stretch of the river,
or every person living within the area, particularly a pilot study such as this one. These
representative areas that are reasonably homogeneous in their ecological characteristics and
can be delineated and used to choose several sites in which focus for data-collection and
monitoring can be done. The results from each representative site can then be extrapolated
over the respective wider areas.

Using this approach, the Basin was delineated into Integrated Units of Analysis
(EPSMO/Biokavango Report Number 2; Delineation Report) by: dividing the river into
relatively homogeneous longitudinal zones in terms of:
· hydrology;
· geomorphology;
· water
chemistry;
· fish;
· aquatic
macroinvertebrates;
· vegetation;
· wildlife
harmonising the results from each discipline into one set of biophysical river zones;
dividing the basin into relatively homogeneous areas in terms of social systems;

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EFA Namibia Aquatic Macroinvertebrates

harmonising the biophysical river zones and the social areas into one set of Integrated Units of
Analysis (IUAs). See delineation report for details

The 19 recognised IUAs were then considered by each national team as candidates for the
location of the allocated number of study sites:
· Angola:
three
sites
· Namibia:
two
sites
· Botswana:
three
sites.

The sites chosen by the national teams are given in table 2.1.

Table 2.1: Location of the eight EFA sites
EFA Site No
Country
River
Location
1
Angola
Cuebe
Capico
2
Angola
Cubango
Mucundi
3
Angola
Cuito
Cuito Cuanavale
4
Namibia
Okavango
Kapako
5
Namibia
Okavango
Popa Rapids
6
Botswana
Okavango
Upper Panhandle
around Shakawe
7
Botswana
Xakanaka lagoon
Xakanaka in Delta
and Khwai River
8
Botswana
Boteti Rivers
Maun and Chanoga

Overview of sites
In the Namibian section of the Okavango River, the majority of the human population lives
along the river and the main road, with several hot spots such as Rundu, Divundu and
Nkurenkuru which have a high population density. The river can be divided into four clear
units of analysis, the longest section that extends from where the river enters Namibia at
Katwitwi to the Cuito confluence that is typified by the meandering mainstream and large
seasonally-flooded floodplains on either side to the river (Kapako site 4, was chosen as a
typical floodplain and mainstream site within this section); the section immediately
downstream of the Cuito confluence that has permanently swamped areas and large islands
(not included in the preliminary survey but essential to include in a later more detailed EFA
study); the southward flowing rocky, braided section from Mukwe to just below the Popa
Rapids where the river is largely confined to the mainstream and flows around several sand
and rock based islands (Popa rapids Site 5, was chosen as a typical rocky river site within this
section) and the protected section of the river downstream of Popa to the border with
Botswana at Mohembo that lies within the newly declared Bwabwata National Park which as
two of its core conservation areas on either side of the river, the Buffalo core area on the west
bank and the Muhango core area on the east bank.

2.3.1 Site 4: Okavango River at Kapako
The river is at the heart and core of the Okavango Basin, and a variety of aquatic plants
animals live in and near it and make good use of the river, its water and other wetland
resources. In Namibia most of the river often has broad margins of floodplains on either side
beyond which there are drier, deciduous woodlands. A variety of organisms are specialised
inhabitants of the floodplains.



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The fish communities can be divided into two groups based on their food preference and
specialization, those that feed on plant material and those that prey on other fish. Secondly
they can be divided according to the habitats where the different fish occur, some preferring
the mainstream, others the rocky areas and rapids, other groups in the backwaters or
permanent swamps and a distinct community found in the floodplains. The floodplains are of
greatest value as places in which most fish breed.

Local people have recognised that the quality of water and fish resources is decreasing in the
Okavango River. Fish and fishing remain a significant feature in the lives of people at Kapako,
who fish for food or to earn incomes by selling their catches as well as by providing trips for
tourists. Fish stocks in the floodplains are estimated to be four times higher than in the main
channel.

The riverine landscape comprises the main Okavango River channel; annually flooded
floodplains with braided channels, the higher fluvial terrace with alluvial deposits are flooded
less regularly (Mendelsohn and el Obeid 2004).

2.3.2 Site 5: Okavango River at Popa Falls
The southward flowing section from Mukwe to the Popa rapids is rocky without floodplains and
has many sand and rock based islands set in the braided rocky channels. The shore is
wooded with the exception of settled areas mainly on the western bank that have been largely
cleared for settlements and crops. The islands remain well forested and several are used as
burial areas for chiefs.

Popa rapids are where the river cascades down several meters before resuming its normal
slow and leisurely flow. The rocks were formed from sediments deposited in rift valleys about
900 million years ago, (el Obeid, S., Mendelsohn date). During the focus group discussion by
the socio-economic team, it was mentioned that due to the Popa rapids and rocky areas, it's
difficult for the local fishermen to catch fish as desired. Therefore, only a few individuals
owning local mukoros, hook and line, and gill fish nets have access to fish catches in the main
channel.

Papyrus cyperus, papyrus dominates the deepest water margins alongside the main channels.
Water can seep through the walls of papyrus to the reedbeds behind the papyrus and in
places it exits into backwaters and side channels. The sandy sediments are confined to the
channels. These are flanked by reed beds of Phragmites, Typha capensis or bulrushes and
the sedge Miscanthus junceus in the shallower waters. The residents do not experience floods
as there are no floodplains in this area. They depend on the main channel for their water and
wetland resources (Mendelsohn and el Obeid 2004).

Discipline-specific description of Namibia sites
2.4.1 Site 4: Kapako
This site comprises the main channel and floodplain areas with seasonal rain fed pools and
inundated backwaters on the Okavango River. The site is situated about 30km upstream of
Rundu, the biggest and most populated town in the Namibian part of Okavango River. It has
different habitats. The main one is aquatic with marginal vegetation found in both the main
channel stream and floodplains. Although the

families found in these two similar habitats do not differ very much, different families may
dominate. Marginal vegetation in the channel is dominated by ephemeropterans such as

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caenids and baetids, while for floodplains the marginal vegetation is dominated by Odonata
such Libellulidae and Coenagrionidae. Aquatic vegetation biodiversity is rich, dominated by
Phragmites spp, oxygen weed Lagarasiphen spp, grasses (e.g. hippo grass Vossia
cuspidata), River Rhus, Rhus quartiana and Myriophyllum spp in wet season; and trees on the
edge of both the channel and floodplain.

2.4.2 Site 5: Popa Rapids
This site is typical of the rockier, confined section of the Okavango River in Namibia. It is
characterised by shallow, rocky rapids and braided side channels. Habitats include cobbles in
and out of current, aquatic and marginal vegetation as well as embedded (in fine sediment)
and unembedded stones. Papyrus, Cyperus spp and Phragmites dominate the marginal
vegetation found at this site. Invertebrate families such as Simuliidae, Hydropsychidae and
Ecnomidae, Perlidae and Heptageniidae dominate habitats at this site. This is a protected
area as part of the Namibia Wildlife Resort Popa Falls area and the community camp site on
the opposite bank minimized local communities' activities. There are several large islands in
the river with limited access due to deep channels around the islands. However, the banks
immediately upstream and downstream of the site are being rapidly cleared of both reeds and
trees.


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3. IDENTIFICATION OF INDICATORS AND FLOW
CATEGORIES
3.1 Indicators
3.1.1 Introduction
Biophysical indicators are discipline-specific attributes of the river system that respond to a
change in river flow by changing in their:
· abundance;
· concentration;
or
· extent
(area).

Social indicators are attributes of the social structures linked to the river that respond to
changes in the availability of riverine resources (as described by the biophysical indicators).

The indicators are used to characterise the current situation and changes that could occur with
development-driven flow changes.

Within any one biophysical discipline, key attributes can be grouped if they are expected to
respond in the same way to the flow regime of the river. By example, fish species that all
move on to floodplains at about the same time and for the same kinds of breeding or feeding
reasons could be grouped as Fish Guild X.

3.1.2 Indicator list for Aquatic macroinvertebrates
In order to cover the major characteristics of the river system and its users many indicators
may be deemed necessary. For each of the EF site, however, the number of indicators is
limited to ten (or fewer) in order to make the process manageable. The full list of aquatic
invertebrate indicators was developed collaboratively by the country representatives for this
discipline ­ Belda Mosepele and Hillary Masundire from Botswana, Shishani Nakanwe in
Namibia and Maria de Fátima Livramento from Angola and is provided in table 2. Further
details of each indicator, including the representative families of each biological one, are given
in Appendix A, and discussed fully in Chapter 4.

Table 3.1: List of indicators for aquatic macroinvertebrates and those chosen to represent each
site

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EFA Namibia Aquatic Macroinvertebrates
Indicato
Sites represented ­ no more than ten
r
Indicator name
indicators per site
Number
1 2 3 4 5 6 7 8





1
Channel dwellers in submerged aquatic



vegetation
2
Channel dwellers in marginal vegetation



X
X



3
Dwellers in fine sediments



X
X



4
Channel dwellers in rapids pools




X



5
Channel dwellers on stones and rocks




X



6
Floodplain dwellers in marginal vegetation



X




7
Floodplain dwellers in pools



X




8
Delta dwel ers in pools and backwaters)








9
Delta dwellers on aquatic macrophyte









3.1.3 Description and location of indicators
3.1.3.1 Aquatic macroinvertebrates Indicator 2
Name: Channel dwellers in Marginal Vegetation


Description: Invertebrates found on the marginal vegetation in the main channel at Kapako
and Popa rapids, on the edge of permanent water

Representative family:
Ephemeroptera (Mayflies): Family Caenidae, Tricorythidae

Other characteristic families: Odonata (dragonflies and damselflies): Family Aeshnidae and
Gastropoda (snails): Family Planorbidae

Known water needs: This habitat requires certain level of inundation in all seasons to maintain
the biodiversity of macroinvertebrates that prefer this habitat.

Flow-related location: Invertebrate community found in vegetated edge of the wetted surface
in the channel in dry and wet season. Therefore, sustained flows
at this level to sustain the marginal vegetation community.


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3.1.3.2 Aquatic macroinvertebrates Indicator 3
Name: Channel dwellers in fine Sediments
Description: Invertebrates found in the fine sediments of the main channel at both Sites
Kapako and Popa rapids.
Representative family: Bivalves (Families Unionidae and Sphaeridae)
Other characteristic family: Ephemeroptera: Family Polymitarcyidae and Gastropoda: Family
Thiaridae

Known water needs: They need to be submerged in mud or wet sand with constant and
moderate flow.

Flow-related location: Situated in the wet sand or submerged mud and gravel in the main
channel. Invertebrates will not survive, either permanent or
intermittent, drying out of these sandy sediments. Reduction in
wet or submerged sand beds will reduce habitat size and thus
productivity.
3.1.3.3 Aquatic macroinvertebrates Indicator 4
Name: Channel dwellers in Rapids or fast flowing waters

Description: Invertebrates found in shallow rocky rapids at site 5, Popa rapids

Representative family: Diptera (Family Simuliidae or blackflies)
Other characteristic family: Trichoptera: Family Hydropsychidae; Odonata: Family Libellulidae.
Known water needs: They need constant fast flowing oxygenated water with organic materials.
Larvae need rapidly flowing water and need submerged rocks to
attach to.

Flow-related location: Situated in the rapids on rocks, vegetation and on fairly sparse.

3.1.3.4 Aquatic macroinvertebrates Indicator 5
Name: Channel dwellers in stones and rocks (These are stones as such but may be classified
as cobbles because of the size).

Description: Invertebrates found in stones and rocks at site 5, Popa rapids

Representative family: Trichoptera: Hydropsychidae and Ecnomidae

Other characteristic family: Odonata
Known water needs: this indicator has stones and or rocks and needs to be on the edge of the

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EFA Namibia Aquatic Macroinvertebrates
surface open water with moderate to strong flows. It is
permanently inundated. Total area inundated may increase
slightly in flood season.

Flow-related location: Not known. However, this site is situated immediately downstream of
the rapids, therefore there is always flow of water.
3.1.3.5 Aquatic macroinvertebrates Indicator 6
Name: Floodplain dwellers in marginal vegetation

Description: Invertebrates found in the marginal vegetation in the floodplain at site 4, Kapako

Representative family: Odonata: Coenagrionidae and Gastropoda: Physidae

Other characteristic family: Ephemeroptera: Baetidae

Known water needs: vegetation needs to be on the edge of the surface open water. It can be
inundated for about four months per year during flood season.

Flow-related location: At the edge of the wetted surface of the floodplain during wet season
low and high flow.
3.1.3.6 Aquatic macroinvertebrates Indicator 7
Name: Floodplain dwellers in pools

Description: Invertebrates found in the pools in the floodplain at site 4.

Representative family: Coleoptera/Beetles: Dytiscidae

Other characteristic family: Hemiptera: Naucoridae

Known water needs: Needs to retain water in the dry-low flow season and have some open
surface water.

Flow-related location: Not known. But pools fill either with water from the main channel in high
flows or with rain water (or both). These pools require inundation
during certain times of the year for the macroinvertebrates to
complete their life cycles. Although, situated within or at the edge
of the floodplain during wet and dry seasons.



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EFA Namibia Aquatic Macroinvertebrates

3.2 Flow categories ­ river sites
One of the main assumptions underlying the EFA process to be used in the TDA is that it is
possible to identify parts of the flow regime that are ecologically relevant in different ways and
to describe their nature using the historical hydrological record. Thus, one of the first steps in
the EFA process, for any river, is to consult with local river ecologists to identify these
ecologically most important flow categories. This process was followed at the Preparation
Workshop in September 2008 and four flow categories were agreed on for the Okavango
Basin river sites:
· Dry
season
· Transitional
Season
1
· Flood
Season
· Transitional
Season
2.
Tentative seasonal divisions for river Sites 4 and 5 are shown in Figure 3 to Error!
Reference source not found.4. These seasonal divisions will be formalised by the project
hydrological team in the form of hydrological rules in the hydrological model. In the interim
they provide useful insights into the flow regime of the river system suggesting a higher year-
on-year variability of the Cubango River, than the Cuito River.

1000
900
Wet
We
800
Dry
Dr
Tra
Tr n
a s
n 1
s
Tra
Tr n
a s
n 2
s
Dry
Dr
700
600
Year 1
500
Year 2
400
Year 3
300
200
100
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S

Figure 3. 1: Three representative years for Site 4: Okavango River @ Kapako (hydrological data
from Rundu), illustrating the approximate division of the flow regime into four flow
seasons



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EFA Namibia Aquatic Macroinvertebrates
1800
1600
Wet
1400
Dry
Trans
n 1
Trans 2
Dry
1200
1000
Year 3
00
Year 2
800
Year 1
600
400
200
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S

Figure 3. 2: Three representative years for Site 5: Okavango River @ Popa (hydrological data
from Mukwe), illustrating the approximate division of the flow regime into four flow
seasons
Table 3.2: Questions to be addressed at the Knowledge capture Workshop, per indicator per
site. In all cases, 'natural' embraces the full range of natural variability
Question
Season
Response of indicator if:
number
1
Onset is earlier or later than natural mode/average
2
Dry Season
Water levels are higher or lower than natural mode/average
3
Extends longer than natural mode/average
Duration is longer or shorter than natural mode/average - i.e. hydrograph is
4
Transition 1
steeper or shallower
5
Flows are more or less variable than natural mode/average and range
Onset is earlier or later than natural mode/average ­ synchronisation with
6
Flood season
rain may be changed
7
Natural proportion of different types of flood year changed
8
Onset is earlier or later than natural mode/average
Transition 2
Duration is longer or shorter than natural mode/average ­ i.e. hydrograph is
9
steeper or shallower



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EFA Namibia Aquatic Macroinvertebrates

4. LITERATURE REVIEW
4.1 Introduction
Macroinvertebrates are animals without backbones that can be seen with a naked eye,
although some larval forms require a microscope for identification (Dallas and Mosepele,
2007). They are essential components in the functioning of the aquatic ecosystems.

Aquatic invertebrates' assemblages and communities offer a good reflection of the prevailing
flow regime and water quality (Thirion 2007). They also form an essential component of the
riverine ecosystem (O'Keeffe and Dickens 2000 in Thirion 2007). Aquatic invertebrates are
important for processing organic matter, purifying the water, and acting as food to larger
animals within and outside the system (Skorozjewski and De Moor 1999 in Thirion 2007).
They are sensitive to changes in water quality and therefore are used as good indicators of
ecosystem health (Dallas and Day, 2007, Dallas and Mosepele, 2007).
Aquatic macro-invertebrates form a major component of the biota of aquatic ecosystems and
are associated with one or other aquatic habitat (Palmer 1991, Dallas 1997, 2002; Dallas and
Day 2007) such as stony beds, floating vegetation, marginal and instream vegetation, gravel,
sand and mud. According to Dallas and Mosepele (2007), they are mostly primary feeders
(feeding on plant material), secondary feeders (feeding on planktonic or benthic organisms) as
well as consumers (near the base of the food chain). Some macroinvertebrates help maintain
the health of the water ecosystem by eating bacteria and dead, decaying plants and animals
(Wallace 1996). They include insects, annelids, molluscs, crustaceans and others ranging in
size from about 0.125 mm to several centimetres.

The overall health and ecological condition of a stream can be determined by looking at the
invertebrates living in that particular stream; since aquatic animals are good indicators of the
health of streams (Fore 1998). All over the world studies have been undertaken to look at the
animals found in rivers, streams, wetlands, lakes, and the seas, springs and pools , including
South Africa (Gerber and Gabriel 2002) and Botswana (Dallas and Mosepele 2007). In
Namibia, particularly in the Okavango River, such studies were conducted in the 1980s and
early 90s by Curtis and Appleton (1987 in Bethune 1991), Curtis (1991) and Bethune (1991).
Most attention was given to human interactions with aquatic invertebrates such as the
medically important mollusc families (Curtis and Appleton 1987), that transmit water-borne
diseases and those that are edible (Bethune 1991), although, all invertebrates found in aquatic
systems play important roles in their functionality. Aquatic invertebrates are useful for
monitoring because of their diversity, survival strategies and adaptations to changing
environments (Fore 1998). However, some macroinvertebrates also are transmitters or
vectors of disease such as bilharzias (Allonson and Nordin, 2003).
In South Africa, a system called SASS has been developed (Chutter 1994), deduced from a
British system to use macroinvertebrates to assess the quality of water (Chutter 1994). The
system uses scores allocated to each invertebrate family depending on tolerance of water
quality. The same Scoring system was tested in the Okavango, Kwando, Zambezi and
Kunene Rivers in Namibia (Chutter 1997, Taylor 1999). It was found that, with a few
modifications, the system can be applied to assess water quality in Namibian rivers; because
some invertebrates are found either in Namibian rivers or South African rivers and not in both
(Chutter 1997, Taylor 1999). The Namibian version is called Namibian Scoring System
version 2 (NASS2) (Palmer and Taylor 2004), and was derived from SASS4. Since this work
was done, South African river specialists have developed SASS5; hence adjustments need to
be done to revise NASS2, which has not been used since it was developed in 2004.

The macroinvertebrates found in the Okavango River include Ephemeroptera (Mayflies),
Plecoptera (Stones flies), Simuliidae (Black flies), Chironomidae (midges), Gastropoda (snails)
and Pelecypoda (bivalves), crustaceans, Hemiptera (true bugs), Trichoptera (caddisflies),

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EFA Namibia Aquatic Macroinvertebrates
Coleoptera (beetles), Odonata (dragonflies and damselflies), Culicidae (mosquitoes) and
Annelida (aquatic earthworms) (Bethune, 1991, Curtis 1991, Palmer and Taylor 2004; and
Gerber and Gabriel 2002). The gastropods are the best studied group in Namibian wetlands
and rivers (Brown et. al 1992, Brown 1994 in Curtis et. al 1998) followed by the aquatic
Coleoptera (Curtis 1991). The gastropods of the Okavango River are similar to those of the
Zambezi River but this is not the case with other invertebrates (Curtis et. al. 1998). However,
more work needs to be done on the aquatic invertebrates in Namibian rivers, particularly on
the Okavango, Kunene, Kwando, Chobe and Linyanti Rivers.

Aquatic invertebrates are an essential component of the river's food web and are responsible
for the secondary production occurring in rivers and wetlands; and their long life cycles,
compared to other groups, give clues to temporal changes caused by environmental impacts
(Davies and Day 1998).

Nationally, apart from the information in Bethune (1991) and Curtis (1991) that these taxa
were recorded from Okavango River, no other detailed studies have been conducted on this
group. Gastropods such Pila occidentalis are considered to be edible and may be food to the
local communities (Curtis 1991), although, no-one interviewed by the social team admitted to
eating them along the Okavango. Bulinus species such as Bulinus globosus that causes
Bilharzia in humans that come in contact with them and Bulinus tropicus, host to schistosomes
in livestock and game (Curtis 1991), and are medically important. The studies done in Namibia
on these molluscs do not point out the specific habitat in the river zone preferred by these
invertebrates. There are records that they were found in Northern Rivers (Okavango and
Kwando, Zambezi Rivers) and that some, e.g. B. globosus are found throughout the country.
The ecological functioning of the dynamic Okavango River system depends on seasonal
floods (Bethune 1991). Seasonal floodplains, for instance EFA site 4 at Kapako, alternate
between annual dry (September to November) and wet (February to May) periods (Mostert
pers. comm.).

The periodic inundation (during high flow in the wet season) and desiccation (during low flow
in the dry season) of riverine and floodplain substrata can leave large areas unavailable for
colonisation by aquatic macroinvertebrates for some part of the year (De Moor 1997).
Physical habitat and water quality changes during low flows can adversely affect aquatic biota
in the short-term (Caruso 2001).
Table 4.1: List of families and chosen representative families for aquatic invertebrate indicators.
Indicator
List of Order
Representative
Why this family?
family
Channel dwellers in
Ephemeroptera
Caenidae sp.
Diverse and it is food
marginal vegetation

Tricorythidae
for fish.



Odonata
Aeshnidae
Food for birds



Gastropoda
Planorbidae
Bilharzia vector
Channel dwellers in
Bivalves/Pill clams
Unionidae,
Water Quality
fine sediment
Sphaeriidae
indicators
Channel dwellers in
Diptera
Simuliidae- Simulium
Reduced flow lowers
rapids or fast flowing
sp.
its abundance, and it
waters
is a river blindness
disease vector.
Although disease
does not occur in
Namibia, some
species in this family
cause livestock
irritation (black fly in

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EFA Namibia Aquatic Macroinvertebrates
sleep)
Channel dwellers in
Trichoptera
Hydropsychidae and
Abundance affected
stones and rocks
Ecnomidae
by fluctuating flow
Floodplain dwellers
Odonata
Coenagrionidae

in marginal
Gastropoda
Physidae, Planorbidae Abundance. Also food
vegetation
for fish and birds
Floodplain dwellers
Coleoptera
Dytiscidae
Food for fish and
in pools
affected by
fluctuations in flow
4.2 Indicator 2: Channel dwellers in Marginal Vegetation (Ephemeroptera /Odonata
/Gastropoda).



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EFA Namibia Aquatic Macroinvertebrates

4.2.1 Main characteristics of Indicator 2: Channel dwellers in Marginal Vegetation
(Ephemeroptera/Odonata/Gastropoda)
This habitat is a predominant habitat at site 4 and these aquatic invertebrates, mainly
ephemeropterans e.g. caenids and baetids and gastropods e.g. Thiaridae, Ampuraliidae and
Planorbidae, spend most of their lives in rivers and streams (Fore 1998); and are most likely to
be affected by any drastic flow change. These groups require unpolluted, well-oxygenated,
cool water to survive. This makes them useful indicators of ecosystem health (Fore 1998). In
many habitats they are important fish food due to their diversity. The marginal vegetation at
Site 4 serves as a habitat to a large number of mayflies, damselflies and dragonflies, and
snails. This habitat is under threat from humans and livestock, through overgrazing and
overharvesting of reeds and grass. Since there is a decline in this habitat especially during the
dry season, when it is easily accessible to livestock, any change in flow is a challenge to the
invertebrates.
4.2.2 Life cycle attributes of Indicator 2: Channel dwellers in Marginal Vegetation
(Ephemeroptera/Odonata/Gastropoda)
Ephemeroptera:
The sub-imagos (stage between nymphs and adults of mayflies) are poor fliers and vulnerable
to predation. They are often found resting in areas, separated from contacts with others,
among vegetation near water bodies from which they emerged. This group needs moderate
flow, because their reproduction and developmental life cycle is very short. In dry periods,
mating does not take place and females may reproduce parthenogenetically (de Moor et al.
2003).

Odonata
Odonata are hemimetabolous as they only have three developmental stages including egg,
nymph and adults. Unlike other insects like Coleopterans, mosquitoes and butterflies,
Odonata lack pupa stage. Adults, although not fully aquatic, spend their lifetime next to water
(Suhling and Martens 2007). In dry seasons, odonates are able to survive in soft sand and
mud where they wait for rain and complete their life cycles (De Moor et. al. 2003)

Gastropoda

During the dry season, some planorbids aestivate in sand or mud and perform self-
fertilization after the worse environmental condition (Brown 1980 and Appleton 1996) when
their habitat is re-filled with rainwater.
4.2.3 Links to flow
Habitat
Ephemeropterans such as Baetids, one of the most common families in this Order, are found
climbing on the stems of submerged vegetation on the margins or instream. The larvae are
aquatic and each family has preferences for a different type of habitat, which is influenced by
factors such as water temperature, flow rate, chemical composition and light
(http://www.ento.csiro.au/education/insects/ephemeroptera.html).

Tricorythidae tend to be found among solid submerged substrata/plants in fast flowing
streams, whilst caenids and planorbids are found in muddy or vegetated areas, in aquatic
vegetation or on gravel beds in flowing waters respectively (de Moor et. al. 2003).
Odonata in the family Aeshnidae are found in different habitats but prefer aquatic submerged
vegetation (Suhling and Martens 2007).

Gastropods such as Planorbidae are mostly associated with aquatic plants, thus preferring to
live among marginal or submerged vegetation (Appleton 1996).

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EFA Namibia Aquatic Macroinvertebrates

Breeding of ephemeropteran
Generally, since adults are semi-aquatic, after mating, females fly back to the nearest
waterbody to oviposit, (lay eggs), or enter the water and lay eggs on the substratum before the
females die (De Moor et. al 2003). Eggs are laid on the water surface, where they sink,
scattering along the substratum and amongst aquatic plants and debris, immediately after
mating before the adults die. This requires continuous and relatively slow flow. The life span
for these taxa is very short, lasting from a few hours to a few
(http://www.ento.csiro.au/education/insects/ephemeroptera.html).

Odonates, after mating on land, the female adults move to nearby water bodies to dip their
eggs in the water among the vegetation on the edge of the backwater or simply on the surface
of the water, by lowering their abdomens into the water (De Moor et al. 2003).

Feeding
Although adult mayflies do not feed, nymphs feed on aquatic plants and other associated
organisms by scraping algae and detritus from underwater stones and vegetation
(http://www.ento.csiro.au/education/insects/ephemeroptera.html); nymphs are deposit feeders
or grazers, with some filter-feeder and a few predators (De Moor et. al 2003).

Odonata are opportunist predators by catching a wide variety of prey (De Moor et. al. 2003).
See indicator 6 more information on feeding in Odonata and Gastropoda.

4.3 Indicator 3: Channel dwellers in fine sediment (Bivalves/Pill clams: Unionidae and
Sphaeridae)
4.3.1 Main characteristics of Indicator: Channel dwellers in fine sediment (Bivalves/Pill
clams)
The main aquatic inhabitants of the fine sediments in the river channels are bivalves and pill-
clams. These inactive macro-invertebrates are good water quality indicators as they are
intolerant of polluted water or low quality water (Gerber and Gabriel 2002).

4.3.2 Life cycle attributes of Indicator Channel dwellers in fine sediment (Bivalves/Pill
clams: Unionidae and Sphaeridae)
4.3.3 Links to flow
Habitat
Unionidae prefer perennial waters as compared with the Sphaeridae, which are also found in
many types of waterbodies including temporary ones (Appleton 1996). They are free-living
burrowers that lie partly in fine sediments with their inhalant and exhalant raised above the
sediment.

Breeding
Unionidae and Sphaeridae reproduce hermaphroditically. Their eggs are fertilised internally
immediately after copulation (Appleton 1996).

Feeding
Unionidae and Sphaeridae are collectors, using the large gills to filter organic particles from
the moderate water flow. By opening their inhalants, bivalves are able to take food and
dissolved oxygen in the passing current. Since they are capable of filtering large volumes of
water in the river system (Appleton 1990), they are known as "cleansers" of water from

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EFA Namibia Aquatic Macroinvertebrates
pollutants and excessive nutrients. However, Sphaeridae is more sensitive to polluted water;
making them very good indicators of water quality.

4.4 Indicator 4: Channel dwellers in Rapids or fast flowing water
(Diptera/Simulium/Blackflies)
4.4.1 Main characteristics of Indicator 4: Channel dwellers in Rapids or fast flowing
waters (Diptera/Simulium/Blackflies)
The typical aquatic invertebrates living in the rapids in river channels are Simulium species.
Simuliids require flowing water for them to become established and are found mostly in rapids,
waterfalls and cascades (de Moor 1997), which is an uncommon feature in the Okavango
River. Although common at site 5 Popa rapids- specifically chosen to indicate this family.
This family includes many species of veterinary and medical importance such as Simulium
damnosum, a vector for the nematode worm (Onchocerca volvulus) that causes
Onchocerciasis known as River Blindness in humans (Davies and Day 1998 and Day et al
2002). In West Africa, this family is better studied than in Southern Africa as the disease is
more common than in Southern Africa (Day et al 2002). Apart from being medically important,
they are also ecologically important because of their ability to filter large volumes of water by
processing dissolved organic matter and avail it in the food chain. It is a good water quality
indicator as their larvae are unable to survive polluted waters
(http://blackflies.info/en/content/information).

4.4.2 Life cycle attributes of Indicator Channel dwellers in Rapids (Diptera,
Simulium/Blackflies)
Females deposit eggs on vegetation just below the water surface. Larvae emerge from eggs
and attach themselves to aquatic or emergent vegetation as well as rocks (Butler and
Hogsette 1998).

4.4.3 Links to flow
Habitat
Since adults are terrestrial, larvae of Simuliids are found in shallow rapids, attached to stones
plants or solid surface (Gerber and Gabriel 2002), well-oxygenated in fast flowing freshwater
(Davies and Day 1998 and Day et al. 2002).

Breeding
Dipterans are dioecious, meaning they have both sexes. They need blood in their systems in
order to produce eggs; hence biting humans and livestock (Davies and Day 1998 and Day et
al. 2002. Egg incubation takes from a few hours to a few days, depending on the temperature
and other factors (Day et al. 2002).

Feeding
Simulium sp. Most black fly larvae are filter feeders, with the larvae feeding on nutrients in the
water as it flows by (Butler and Hogsette 1998b) in slow-moving stream, but most species
prefer rapidly flowing water (Robinson 1997). Lower flows will result in an increase in the
occurrence of riffles and rapids and the populations of Simulium sp. is likely to rise with
possible negative economic consequences.
· channel features, e.g., rocks in current and riffle in between.


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EFA Namibia Aquatic Macroinvertebrates


4.5 Indicator 5: Channel dwellers on stones and rocks (Trichoptera: Hydropsychidae
and Ecnomidae)
4.5.1 Main characteristics of Indicator 5: Channel dwellers on stones and rocks
(Trichoptera: Hydropsychidae and Ecnomidae)
Trichoptera are characteristic of river channel reaches with loose stones or cobbles. This
habitat is fairly rare in the Okavango River in Namibia and found only immediately downstream
of Popa rapids.

These macroinvertebrates are found under stones in fast flowing waters, slow streams or
sometimes in quiet pools (Gerber and Gabriel 2002). According to de Moor (1997),
Hydropsychidae plays an important role in controlling population sizes for Simuliids in medium
to large rivers. It is good water quality indicator; some genera are sensitive to pollution
contaminants and suffer decline or even death if their environment has drastic changes
(http://zipcodezoo.com/Key/Animalia/Hydropsychidae_Family.asp).
4.5.2 Life cycle attributes of Indicator 5: Channel dwellers on stones and rocks
(Trichoptera: Hydropsychidae and Ecnomidae)
The Hydropsychid larvae spend their entire life in freshwater.
4.5.3 Links to flow
Habitat
Hydropsychids are found under stones, living in shelters made of sand grains, in fast flowing
waters (Gerber and Gabriel 2002). Whilst, Ecnomids are found under stones or in submerged
vegetation in slow streams (Gerber and Gabriel 2002).

Breeding
They are hermaphroditic and self-fertile. Breeding happens when the flow is constant and the
temperature is optimal in the main channel.

Feeding
Hydropsychids are predators that feed on a variety of prey and ecnomids are deposit feeders
(King and Schael 2001). Hydropsychidae construct dwellings called "retreats", which are fixed
to the sides of rocks; composed of collected plant and mineral fragments. The nets or sieves
that form at the entrance of the "retreats" catch algae, detritus, and smaller invertebrates. Due
to this technique of collecting food, Hydropsychids require flowing water in order to trap prey
items in these nets (Stuijfzand 1999).
· channel features : Sand and loose stones

4.6 Indicator 6: Floodplain dwellers in Marginal Vegetation (Odonata/Gastropoda)
4.6.1 Main characteristics of Indicator 6: Floodplain dwellers in Marginal Vegetation
(Odonata/Gastropoda)
Odonata and some gastropods are typical of the marginal vegetated sections found in and
alongside seasonal floodplains. Permanent floodplain pools serve as refuge for these families
in dry season.


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EFA Namibia Aquatic Macroinvertebrates
The Odonata are semi-aquatic as only growing larval stages inhabit water (De Moor et al.
2003) during low flow (October to December).

4.6.2 Life cycle attributes of Indicator Floodplain dwellers in Marginal Vegetation
(Odonata/Gastropoda)
This group is typified by the Odonata: dragonflies and damselflies. Odonata are
hemimetabolous as they only have three developmental stages including egg, larva and
adults. Unlike other insects like Coleopterans, mosquitoes and butterflies, Odonata lack pupa
stage. Adults, although not fully aquatic, spend their lifetime next to water (Suhling and
Martens 2007). Some Odonata species survive in soft mud and wait for the return of flow/rains
to complete their development (De Moor et al. 2003). That means if no flow is experienced or
floodplain pools dry out, their development may be affected and hence their reproduction and
abundance. Their egg development and growth is temperature depended (Suhling and
Martens 2007).
4.6.3 Links to flow
Habitat
Odonata are found among vegetation on the edges of slow streams or backwaters as they
slowly move among vegetation (Gerber and Gabriel 2002). In Southern Africa, many families
prefer well-lit, weedy margins of pools, streams and rivers (De Moor et al. 2003).

Gastropods are generally associated with aquatic plants, often among marginal and
submerged vegetation (Appleton 1996).

Breeding
After mating on land, the female adults move to nearby water bodies to dip their eggs in the
water among the vegetation on the edge of the backwater or simply on the surface of the
water, by lowering their abdomens into the water (De Moor et al. 2003).

Gastropods, pulmonates breed hermaphroditically. This is a useful strategy since their habitats
are sometimes unstable, may dry out and are also subject to floods.

Feeding
Dragonfly larvae are voracious feeders. They will eat an entire specimen sample if not killed
immediately (Bethune pers. observ). Some of them are strong enough to catch and eat insects
as large as butterflies and other dragonflies (Suhling and Martens 2007).

They feed on various preys both smaller and larger invertebrates, that is why they are
considered opportunist predators or generalists. Odonata use two distinct strategies to get its
prey, `sit-and-ambush' or `active searching'. The former is used in the rivers where predation
from fish is high and the latter in temporary waters when predation from fish is low (De Moor
et. al. 2003). Some Odonates grasp their prey while in flight (Suhling and Martens 2007).

According to Appleton (1996), Gastropods feed on dead and decaying organic matters and on
periphyton growing on submerged surfaces which maybe include fungi, algae, protozoans and
bacteria.

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EFA Namibia Aquatic Macroinvertebrates

4.7 Indicator 7: Floodplain dwellers in pools (Coleoptera)
4.7.1 Main characteristics of Indicator 7: Floodplain dwellers in pools (Coleoptera)
These floodplain pools' dwelling aquatic macroinvertebrates can be typified by the taxon
Coleoptera or water beetles. Some can fly and so move between pools.
For this taxon, both larvae and adults are aquatic (King and Schael 2001) and found in pools
in the floodplains (de Moor 1997), and need water for survival; affected by alternating flooding
periods and drought. Because their habitat is determined by the presence of water in the
floodplains when the river overflows and feed the floodplains. Dytiscids generally prefer slow
moving or stagnant water, such as ponds, lakes, pans or oshanas, dams, and pools at the
edges of streams (http://www.anbg.gov.au/cpbr/WfHC/Dytiscidae/index.html).
4.7.2 Life cycle attributes of Indicator Floodplain dwellers in pools (Coleoptera)
Macroinvertebrates such as Coleoptera take refuge in floodplain pools during the dry season
(July/August and November/December) as their preferred habitat, and some move back to the
mainstream during wet season (February to May). But they die when they become stranded
and isolated from the main flow for too long during the dry season or when the pools dry up.
Although they can fly to reach new pools (Bethune pers. observ); and where there is lack of
deeper pools for refuge (Caruso 2001).

4.7.3 Links to flow
Habitat
Coleoptera prefer stagnant or quiet water in pools or at the edge of streams. The strong flying
ability of adults allows recolonization of aquatic habitats after drought periods (Caruso 2001).

Breeding
Coleopterans breed amongst plants found on the edges of pools in the floodplains that are
inundated during the high-flow in the wet season (de Moor 1997) in (February to May).

Feeding
Coleoptera are active hunters (King and Schael 2001) and therefore prefers stagnant or slow
moving water. They need stable water flow to ambush its prey.
· channel features, Good and regular floodwaters need to spill from the main channel to
inundate the pools in the floodplain.

4.8 Summary
There is huge a gap in the information available on the aquatic invertebrates found in
Okavango River, and their specific water flow requirements. There is good information
available on the occurrence of aquatic macroinvertebrates in the Okavango River, particularly
for the Namibian section e.g. Bethune (1991, Curtis 1991). There is also a wealth of literature
available worldwide and even in southern Africa on the main orders and families of aquatic
macroinvertebrates known to occur in the Okavango River system, which includes useful
information on their lifecycles, feeding and habitat preferences. Yet, there is more to be done
in order to understand the aquatic biota of Okavango with respect to their habitats, behaviour
and responses to flows.

For the Okavango River, the list of families found in the system is available, but in most cases
with little detailed information on when these macroinvertebrates breed or the effects of flow
changes on them. This made the comparison with other river systems with better information
difficult, especially with literature from Australia and America. Most of the general information

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EFA Namibia Aquatic Macroinvertebrates
used was downloaded from the Internet through Google searches. Southern African
information was obtained from guide books on aquatic invertebrates for South Africa and
Southern Africa (Gerber and Gabriel 2001 and 2002, Day et al 2002, De Moor et. al 2003,
Suhling and Martens 2007).

Previous research on aquatic macroinvertebrates in Namibia and particularly on the Okavango
River was found in reports and articles on the work of Bethune and Curtis in the 1980s to
1990s (Bethune 1991 and Curtis 1990). One group, the Odonata, has since been studied in
detail in detail in Namibia and a book produced as part of BIOTA Project (Suhling and Martens
2007).


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EFA Namibia Aquatic Macroinvertebrates


5. DATA COLLECTION AND ANALYSIS
5.1 Methods for data collection and analysis
The first field trip to Site 4 Kapako floodplain and Site 5 Popa rapids was undertaken between
the 18 and 22 October 2008. Site 4 Kapako was visited on the 20th of October 2008, whereby
the marginal vegetation in the mainstream of the Okavango River, and a floodplain pool were
sampled. A NASS/SASS net was used to sweep the vegetation on the margins of the stream
and also of the floodplain pool. This was done according to the SASS 4/NASS 2 method. The
collected specimens were emptied into a white tray for identification of the invertebrates. The
macroinvertebrates were identified to family level and recorded on the NASS scoring sheet.
This method was repeated thrice. See figure 5 for habitats/sites sampled at Site 4 Kapako.

At Site 5 Popa rapids, the same net was used to collect invertebrates from unembedded
stones-in- current; marginal vegetation and embedded stones-in-current. Here stones were
thoroughly kicked, turned and washed into the net, facing upstream. Collected debris was
emptied into the white tray for identification. Identified macroinvertebrates families were
recorded in the NASS scoring sheet. Invertebrates from site 5 were further grouped in
functional feeding groups for better understanding. See figure 6 for habitats/sites sampled at
Site 5 Popa rapids.

The second field trip to the two Namibian sites was undertaken between the 05th and 13th
February 2009 at the onset of the wet or high flow season. Site 5 Popa rapids, was sampled
on the 5th February 2009. Three different habitats as per this discipline's indicators were
sampled; namely marginal vegetation, sediment (sand), and stones-in-current. Indicators
number 2, 3 and 5 were also sampled in the side channel immediately downstream in the
rocky rapids at Popa.

Site 4 Kapako was sampled on the 8th and 9th February 2009. This is the floodplain area
where marginal vegetation and deeper lily-filled pools in the flood plain were sampled. The
marginal vegetation of the main channel was also sampled as many times as possible to get
the overview of macroinvertebrates found in this habitat. Due to high flow and the depth of
water, no sampling could be done in the sediments of the main channel.

As time was limited on both field survey trips, no light traps or any other specific collecting
methods were used e.g. to collect snails. It is assumed that given more time, more intensive
collecting could be done in subsequent studies.

During the wet season, the site was accessed by boat with 25hp engine and mukoros
(wooden canoes used in the river to transport people and goods across and along the river).

The macroinvertebrates collected were identified using the field guide "South African Rivers'
invertebrates" (Gerber and Gabriel 2001 and 2002) and entered in the NASS 2 scoring sheet.
Specimens that could not be identified on site were preserved in 70% ethanol and were
brought to the DWAF laboratory in Windhoek for identification. Snails collected were taken to
the National Museum entomology division in Windhoek for further identification.

The data collected were analyzed according to the water quality standards as described in the
SASS/NASS methods and then linked to the flow depending on the type of habitat the
invertebrates were found in.


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EFA Namibia Aquatic Macroinvertebrates
In parallel with this EFA work, ten other sites within the Namibia section of the river are
sampled regularly, every 3rd month, using SASS/NASS method. This project was initiated in
July 2008 and will run until July 2009.

5.2 Results
See Appendix B for the raw data incurred from sampling in both the dry and wet season for
site 4 and 5.


Figure 5. 1:Location of Namibia in southern Africa, the Okavango River (lower map) and the
habitats sampled for aquatic invertebrates at EFA site 4, Kapako.


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EFA Namibia Aquatic Macroinvertebrates

Figure 5. 2: Location of Namibia in southern Africa, the Okavango River (lower map) and the
habitats sampled for aquatic invertebrates at EFA site 5, Popa rapids
Channel dwellers in Marginal Vegetation
Ephemeropterans such as Caenidae were abundant, about i.e. five to ten per scoop compared
to other invertebrates especially in the wet season. Tricorythidae were rare as only two or
fewer organisms were found. Aeshnidae were present but their abundance was low. For other
invertebrates found at this habitat, see Appendix B. Habitats samples for Kapako and Popa
are shown in figure 5 and figure 6 respectively; with known water depth specifically during wet
season.

Most Ephemeroptera were found in larval stages, which is common during the early periods of
wet seasons.


Social importance:
Invertebrate communities play an important role in the food web, as a food source for fish,
birds, frogs and other macroinvertebrates. They also contribute significantly to the fisheries
production in the river system. Unfortunately, there are no direct benefits recorded for local
communities, hence the social benefit is best categorised as `economic non-use value'.

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EFA Namibia Aquatic Macroinvertebrates
Although P. occidentalis is believed to be edible no evidence was found showing this. Maybe
it is a small-scale or even individual food source, although not found in the SASS/NASS
samples. In the case of medically important macroinvertebrates such as molluscs,
Planorbidae, which affect people through schistosomiasis (Bilharzia) by Schistosoma spp., are
likely to occur and can be considered harmful. There is a high incidence of bilharzia especially
amongst the school children

No information on the impressions of local communities on what happens in years when there
are good rains/wet season flows, and in years when there are poor rains/wet season flows; in
terms of aquatic macroinvertebrates.

One can assume that remnant/vegetated pools that remain on the floodplain in the dry season
could harbour bilharzias and pose a health risk.

Channel dwellers in Fine sediments
Bivalves are not too common, although Unionidae were rarely found in the dry season. They
were mainly found in adult form with growth rings and eroded patches clearly visible.
Sphaeridae were very rare and not recorded from this habitat during either season. High water
levels at the start of the wet season made it impossible to sample the sediments in the
channel.

Like Gastropoda, their importance to local communities is insignificant. No information is
available of the impressions of local communities on what happens in years when there are
good rains/wet season flows, and in years when there are poor rains/wet season flows in
terms of aquatic invertebrates.

Channel dwellers in Rapids or fast flowing waters
Simuliidae was recorded as much more abundant in wet season than in the dry season at
different habitats within the rapids, such marginal vegetation and cobbles and boulders. See
Appendix B for other invertebrates found at this habitat. See figure 6.

However, human interference, such as building of weirs and flood manipulation, can lead to
the development of vast populations of a single family that cause a nuisance when adults
emerge in mass. They may pose health problems to humans and animals. These include
simuliids and other biting midges.
No information was gathered by the social team on the impressions of local communities on
what happens in years when there are good rains/wet season flows, and in years when there
are poor rains/wet season flows in terms of aquatic invertebrates.
Channel dwellers in stones and rocks
As representative family for this indicator, Hydropsychidae were abundant at Site 5 Popa
rapids in both seasons, although wet season numbers were higher of about ten organisms per
scooping. Ecnomidae were common.

They were all found in their larval stages. See figure 6

No information on the impressions was gathered of local communities on what happens in
years when there are good rains/wet season flows, and in years when there are poor rains/wet
season flows; in terms of aquatic invertebrates.


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EFA Namibia Aquatic Macroinvertebrates
Floodplain dwellers in marginal vegetation
Odonata was dominated by Coenagrionids followed by Libellulidae (although not an
indicator/representative family for this study); in both seasons.

Social importance:
Apart from being a very important source of food to other invertebrates and vertebrates such
as fish, reptiles, birds and frogs, this order does not have direct benefits to the local
communities.

Its high abundance in both dry and wet seasons tells us little about the effect of changes in
flow.

No information of the impressions of local communities on what happens in years when there
are good rains/wet season flows, and in years when there are poor rains/wet season flows; in
terms of aquatic invertebrates.

Floodplain dwellers in Pools
As a representative family for this indicator, Dytiscidae was not recorded from this habitat in
either seasons. See Appendix B for invertebrates that were instead found. See figure 5 for this
habitat/site

No information on the impressions of local communities on what happens in years when there
are good rains/wet season flows, and in years when there are poor rains/wet season flows; in
terms of aquatic invertebrates.


a. Summary
A summary of present understanding of the predicted responses of all (Aquatic vegetation)
indicators to potential changes in the flow regime.

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EFA Namibia Aquatic Macroinvertebrates
5.3.1 Indicator 2 (Channel dwellers in marginal vegetation)
Table 5.1: Predicted response to possible changes in the flow regime of Channel dwellers in marginal vegetation in the Okavango River ecosystem.
Confidence in
Question
number
Season
Possible flow change
Predicted response of indicator (Both Kapako and Popa rapids)
prediction (very low,
low, medium, high)
Onset is earlier or later than
Unlikely to affect
1
Medium
natural
Water level lower, limited organic material transportation, accumulation of silts and low water
Water levels are higher or lower
2
Dry Season
than natural
quality. The indicator species will drastically reduce in numbers and if this persist for long, it can
Medium
lead to the species perishing
Low flow or no flow at all, exposing vegetation and limit the habitat, drastic reduction in number
3
Extends longer than natural
medium
of the indicator species
Duration is longer or shorter than
Little effect
4
natural - i.e. hydrograph is
Low
Transition 1
steeper or shallower
Flows are more or less variable
Little effect if flows are more variable. Less variation is unlikely to affect
5
than natural
Low
Onset is earlier or later than
Unlikely to affect
6
natural ­ synchronisation with
Low
Flood season
rain may be changed
Natural proportion of different
Possibly if larger floods are less frequent. the indicator species will be confined to the little
7
types of flood year changed
available habitat and get more abundant as those individuals that can not survive will die
Medium
Onset is earlier or later than
Nil
8
natural
Low
Transition 2
Duration is longer or shorter than
Little effect
9
natural ­ i.e. hydrograph is
Low
steeper or shallower











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EFA Namibia Aquatic Macroinvertebrates
5.3.2 Indicator 3 (Channel dwellers in fine sediments)
Table 5.2: Predicted response to possible changes in the flow regime of Channel dwellers in fine sediments in the Okavango River ecosystem.
Confidence in
Question
number
Season
Possible flow change
Predicted response of indicator (both Kapako and Popa rapids)
prediction (very low,
low, medium, high)
Onset is earlier or later than
Nil
1
Low
natural
Water levels are higher or lower
Little effect. Unless the river dries out
2
Dry Season
Low
than natural
Low flow or no flow at all, exposing sand banks and limit the habitat, it will reduce the
3
Extends longer than natural
indicator species population sizes.
Medium
Duration is longer or shorter than
Nil
4
natural - i.e. hydrograph is
Low
Transition 1
steeper or shallower
Flows are more or less variable
Reduced transportation of sediments, resulting in accumulation of silts
5
than natural
Medium
Onset is earlier or later than
Nil
6
natural ­ synchronisation with
Low
Flood season
rain may be changed
7
Natural proportion of different
Little effect. If no larger floods experienced, there will be short in nutrients supply.
Medium
types of flood year changed
8
Onset is earlier or later than
Nil
Low
natural
Transition 2
Duration is longer or shorter than
Little effect. Benthos could be smothered by sand banks collapse if hydrograph is steep
9
natural ­ i.e. hydrograph is
Low
steeper or shallower











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EFA Namibia Aquatic Macroinvertebrates
5.3.3 Indicator 4 (Channel dwellers in rapids or fast flowing waters)
Table 5.3: Predicted response to possible changes in the flow regime of Channel dwellers in rapids or fast flowing waters in the Okavango River
ecosystem.
Confidence in
Question
Predicted response of indicator (Popa rapids only)
prediction (very low,
number
Season
Possible flow change
low, medium, high)


Onset is earlier or later than
Nil
1
natural
Low
Water levels are higher or lower
If lower, it could affect the rapids and limit the habitat of the indicator species. The
2
Dry Season
than natural
population will be less abundant
Medium
3
Extends longer than natural
Could limit the habitat, if dry for longer period, hence reducing the indicator species
Medium
abundance
Duration is longer or shorter than
Nil
4
natural - i.e. hydrograph is
Low
Transition 1
steeper or shallower
5
Flows are more or less variable
Could affect if more variable
Low
than natural
Onset is earlier or later than
Nil
6
natural ­ synchronisation with
Low
Flood season
rain may be changed
7
Natural proportion of different
Little effect, if larger floods are less frequent
Medium
types of flood year changed
Onset is earlier or later than
Nil
8
Low
natural
Transition 2
Duration is longer or shorter than
Nil
9
natural ­ i.e. hydrograph is
Low
steeper or shallower











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EFA Namibia Aquatic Macroinvertebrates
5.3.4 Indicator 5 (Channel dwellers in stones and rocks)
Table 5.4: Predicted response to possible changes in the flow regime of Channel dwellers in stones and rocks in the Okavango River ecosystem.
Confidence in
Question
Predicted response of indicator (Popa rapids only)
prediction (very low,
Season
Possible flow change
number
low, medium, high)


Onset is earlier or later than
Nil
1
natural
Low
2
Dry Season
Water levels are higher or lower
Lower, when rocks are exposed there is minimal habitat for the Simuliids to attach, limited
Medium
than natural
food supply, indicator species will be less abundant
3
Extends longer than natural
Limit habitat area, competition for food from other invertebrates, leads to reduction in
Medium
numbers of indicator species
Duration is longer or shorter than
Nil
4
natural - i.e. hydrograph is
Low
Transition 1
steeper or shallower
5
Flows are more or less variable
Nil
Low
than natural
Onset is earlier or later than
Little effect
6
natural ­ synchronisation with
Low
Flood season
rain may be changed
Natural proportion of different
Little effect
7
Low
types of flood year changed
Onset is earlier or later than
Nil
8
natural
Low
Transition 2
Duration is longer or shorter than
Nil
9
natural ­ i.e. hydrograph is
Low
steeper or shallower











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EFA Namibia Aquatic Macroinvertebrates
5.3.5 Indicator 6 (Floodplain Marginal vegetation)
Table 5.5: Predicted response to possible changes in the flow regime of floodplain dwellers in marginal vegetation in the Okavango River
ecosystem
Question
Confidence in
number
Season
Possible flow change
Predicted response of indicator (Kapako only)
prediction (very low,
low, medium, high)
1
Onset is earlier or later than
Unlikely to affect
Low
natural
Dry Season
Water levels are higher or lower
When lower, loss of available habitat area, hence reduction in the population of the indicator species
2
Medium
than natural
3
Extends longer than natural
Affected it only dries out
Low
Duration is longer or shorter than
Little effect
4
natural - i.e. hydrograph is
Low
Transition 1
steeper or shallower
5
Flows are more or less variable
Little effect
Low
than natural
Onset is earlier or later than
Nil
6
natural ­ synchronisation with
Low
Flood season
rain may be changed
7
Natural proportion of different
Abundance affected when there are too small flood and too big floods that cause washing away of
Low
types of flood year changed
indicator species from vegetation.
8
Onset is earlier or later than
Nil
Low
natural
Transition 2
Duration is longer or shorter than
Little effect
9
natural ­ i.e. hydrograph is
Low
steeper or shallower











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EFA Namibia Aquatic Macroinvertebrates
5.3.6 Indicator 7 (floodplain dwellers in pools)
Table 5.6: Predicted response to possible changes in the flow regime of floodplain dwellers in pools in the Okavango River ecosystem.
Confidence in
Question
number
Season
Possible flow change
Predicted response of indicator (Kapako only)
prediction (very low,
low, medium, high)
Onset is earlier or later than
Little effect
1
Low
natural
Dry Season
Water levels are higher or lower
If low, it could affect the pools that the indicator species will have limited habitat, Exposure
2
Medium
than natural
to predators and reduces the number of the species
3
Extends longer than natural
If longer, the pools may dry up and that means no habitat for this indicator species
Medium
Duration is longer or shorter than
Little effect
4
natural - i.e. hydrograph is
Low
Transition 1
steeper or shallower
5
Flows are more or less variable
When flows are more variable
Low
than natural
Onset is earlier or later than
When later, the pools may not hold water until the floods
6
natural ­ synchronisation with
Medium
Flood season
rain may be changed
7
Natural proportion of different
Little effect, when larger floods are less common
Low
types of flood year changed
Onset is earlier or later than
Unlikely to affect
8
Low
natural
Transition 2
Duration is longer or shorter than
Little effect, drying out too fast if duration is longer
9
natural ­ i.e. hydrograph is
Medium
steeper or shallower









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EFA Namibia Aquatic Macroinvertebrates
5.4
Conclusion
More detailed data on the distribution of the macroinvertebrates and their life cycles in the
Okavango River and other perennial rivers in Namibia and Southern Africa would have been
of great help. Most of the information was for South African rivers and sometimes the
habitats where certain macroinvertebrates are found differ from the Namibian ones. For
example, the Caenidae found on stones and muddy areas in South Africa were found in
marginal vegetation of both the channel and floodplain areas alongside the Okavango River.
One can therefore speculate that their response to changes in flow would be different.

In Namibia, river ecologists have lots of regional or international examples to follow when it
comes to Environmental Flow Assessment, but have no or little practical experience. Poor
detailed knowledge of the aquatic biota and ecological functions specific to our rivers makes
it difficult to carry out this kind of work. But there is a will to learn from experts, hence this
study.

I would like to specialize in the ecological functions of rivers in Namibia and their aquatic
biota. I also would like to be trained further in aquatic macroinvertebrates identification
because I am keen to continue monitoring the ecology of macroinvertebrates with the other
two countries, even after the EFA project.

5.5
Flow-response relationships for use in the Okavango EF-DSS

The flow-response curves were drawn at the Knowledge Capture Workshop in Windhoek
from 30th April ­ 4th April 2009 and will be included in a CD that accompanies the project
Final Report.




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EFA Namibia Aquatic Macroinvertebrates
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Stuijfzand, S.C. 1999. Caddisflies (Trichoptera: Hydropsychidae) Used for Evaluating Water
Quality of Large European Rivers. Archives of Environmental Contamination and Toxicology
36: 186-192. doi:10.1007/s002449900459.


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EFA Namibia Aquatic Macroinvertebrates
Suhling F. and Martens A. 2007. Dragonflies and damselflies of Namibia. Gamsberg
Macmillan Publishers. Windhoek.
Taylor E.D. 1999. A pilot study on the Biological monitoring of water quality in Namibia's
north-eastern perennial Rivers. Department of Water Affairs of the Ministry of Agriculture,
Water and Rural Development. Report no. RR/99/2
Thirion C. 2007. Module E: Macroinvertebrates Response Assessment Index in River
EcoClassification: Manual for EcoStatus Determination (version 2). Joint Water Research
Commission and Department of Water Affairs and Forestry Report. WRC Report No. TT
332/08
Wallace J. B. 1996. The role of macroinvertebrates in stream ecosystem function. Annual
Review Entomol. 41:115-39




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EFA Namibia Aquatic Macroinvertebrates
APPENDIX A: FULL DESCRIPTIONS OF INDICATORS
Table 7.1: List of species and the representative species for aquatic invertebrates indicators.
Indicator
List of Orders Representat
Why this order/family
ive Family
Channel dwellers Ephemeropter
Caenidae sp. Diversity, abundance and it is food for fish.
in Marginal
a
Tricorythidae
Vegetation

Aeshnidae
Food for vertebrates such birds, frogs and fish
Odonata



Planorbidae
Medically important Bulinus globosus is host for
Gastropoda
Schistosomes parasites that cause Bilharzia in
humans. While Bulinus tropicus is host for
livestock and game schistosomes.
Channel dwellers Bivalves/Pill
Unionidae,
Water Quality indicators. As filter-feeders, they are
in fine Sediment
clams
Sphaeriidae
affected by polluted water
Channel dwellers Diptera Simuliidae-
Medically important as River blindness disease
in Rapids
Simulium sp. vector
Channel dwellers Trichoptera Hydropsychi
Abundance affected by fluctuating flow
in cobbles and
dae and
boulders
Ecnomidae
Floodplain
Odonata
Coenagrionid Abundance. Also food for fish and birds
dwellers in
Gastropoda
ae
Marginal
Physidae,
Vegetation
Planorbidae
Floodplain
Coleoptera
Dytiscidae
Food for fish and affected by fluctuations in flow.
dwellers in pools
With limited habitat especially during the low-
flow/dry season, they become vulnerable to
predation.




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EFA Namibia Aquatic Macroinvertebrates
APPENDIX B: RAW DATA

Dry Season


EFA Site 4: Kapako
EFA Site 5: Popa
Representative
Found Species
Representative
Found Species
Species
Species
Channel MV
Channel MV
Channel MV
Channel MV
Caenidae Baetidae Caenidae Baetidae
Aeshnidae Caenidae Aeshnidae Libellulidae
Planorbidae Coenagrionidae
Planorbidae Gerridae
Nepidae
Veliidae/Mesoveliidae
Pleidae

Dytiscidae

Channel sediment
Channel sediment
Channel sediment
Channel sediment
Unionidae Unionidae Unionidae Oligochaeta
Sphaeridae Oligochaeta Sphaeridae Perlidae
Polymitarcyidae
Caenidae
Heptageniidae
Polymitarcyidae
Libellulidae
Ecnomidae
Certopogonidae
Chironomidae
Unionidae
Channel cobbles
Channel cobbles
Channel cobbles
Channel cobbles and
and boulders
and boulders
and boulders
boulders
Not Applicable
Not applicable
Hydropsychidae
Perlidae
Ecnomidae
Baetidae
Heptageniidae
Tricorythidae
Ecnomidae
Hydropsychidae
Leptoceridae
Hydraenidae
Chironomidae
Simuliidae




Channel Rapids
Channel Rapids
Channel Rapids
Channel Rapids
Not Applicable
Not Applicable
Simuliidae
Heptageniidae
Simuliidae
Hydropsychidae
Libellulidae
Ecnomidae
Tricorythidae
Perlidae
Floodplain MV
Floodplain MV
Floodplain MV
Floodplain MV
Coenagrionidae
Not sampled
Not Applicable
Not Applicable
Physidae


Planorbidae



Floodplain Pool
Floodplain Pool
Floodplain Pool
Floodplain Pool
Dytiscidae
Corixidae
Not Applicable
Not Applicable
Notonectidae


Chironomidae









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EFA Namibia Aquatic Macroinvertebrates

Wet Season


EFA Site 4: Kapako
EFA Site 5: Popa
Representative
Found Species
Representative
Found Species
Species
Species
Channel MV
Channel MV
Channel MV
Channel MV
Caenidae Baetidae Caenidae Baetidae
Aeshnidae Caenidae Aeshnidae Tricorythidae
Planorbidae Leptophlebiidae
Planorbidae Libellulidae
Oligoneuridae
Hydropsychidae
Tricorythidae
Chironomidae
Aeshnidae
Simuliidae
Libellulidae
Caenidae
Naucoridae
Ecnomidae
Veliidae
Hydroptilidae
Chironomidae
Leptoceridae
Ampulariidae

Thiaridae

Channel sediment
Channel Sediment
Channel sediment
Channel sediment
Unionidae Water
depth
was
Unionidae Oligochaeta
about 4m, not
sampled
Sphaeridae
Sphaeridae Ceratopogonidae
Chironomidae
Ancylidae
Channel cobbles
Channel cobbles
Channel cobbles
Channel cobbles and
and boulders
and boulders
and boulders
boulders
Not Applicable
Not applicable
Hydropsychidae
Hydroptilidae
Ecnomidae
Chironomidae
Oligochaeta
Libellulidae
Chlorocyphidae
Channel Rapids
Channel Rapids
Channel Rapids
Channel Rapids
Not Applicable
Not Applicable
Simuliidae
Heptageniidae
Simuliidae
Hydropsychidae
Libellulidae
Culicidae
Floodplain MV
Floodplain MV
Floodplain MV
Floodplain MV
Coenagrionidae
Hydracarina
Not Applicable
Not Applicable
Physidae Baetidae

Planorbidae
Coenagrionidae


Lestidae

Libellulidae

Ampulariidae

Lymnaeidae

Thiaridae

Gerridae

Chironomidae

Ostracoda

Caenidae

Floodplain Pool
Floodplain Pool
Floodplain Pool
Floodplain Pool
Dytiscidae
Corixidae
Not Applicable
Not Applicable
Oligochaeta


Baetidae





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EFA Namibia Aquatic Macroinvertebrates
The Okavango River Basin Transboundary Diagnostic Analysis Technical Reports

I
Diagnostic Analysis to establish a base of available
n 1994, the three riparian countries of the Okavango River
scientific evidence to guide future decision making. The
Basin ­ Angola, Botswana and Namibia ­ agreed to plan for
study, created from inputs from multi-disciplinary teams in
collaborative management of the natural resources of the
each country, with specialists in hydrology, hydraulics,
Okavango, forming the Permanent Okavango River Basin
channel form, water quality, vegetation, aquatic
Water Commission (OKACOM). In 2003, with funding from
invertebrates, fish, birds, river-dependent terrestrial
the Global Environment Facility, OKACOM launched the
wildlife, resource economics and socio-cultural issues, was
Environmental Protection and Sustainable Management of
coordinated and managed by a group of specialists from
the Okavango River Basin (EPSMO) Project to coordinate
the southern African region in 2008 and 2009.
development and to anticipate and address threats to the

river and the associated communities and environment.
The following specialist technical reports were produced as
Implemented by the United Nations Development Program
part of this process and form substantive background
and executed by the United Nations Food and Agriculture
content for the Okavango River Basin Trans-boundary
Organization, the project produced the Transboundary.
Diagnostic Analysis
Final Study
Reports integrating findings from all country and background reports, and covering the entire
Reports
basin.


Aylward, B.
Economic Valuation of Basin Resources: Final Report to
EPSMO Project of the UN Food & Agriculture Organization as
an Input to the Okavango River Basin Transboundary
Diagnostic Analysis


Barnes, J. et al.
Okavango River Basin Transboundary Diagnostic Analysis:
Socio-Economic Assessment Final Report


King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment Project
C.A.
Initiation Report (Report No: 01/2009)


King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment EFA
C.A.
Process Report (Report No: 02/2009)


King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Guidelines for Data Collection, Analysis and Scenario Creation
(Report No: 03/2009)

Bethune,
S.
Mazvimavi,
Okavango River Basin Environmental Flow Assessment
D. and Quintino, M.
Delineation Report (Report No: 04/2009)


Beuster, H.
Okavango River Basin Environmental Flow Assessment
Hydrology Report: Data And Models(Report No: 05/2009)

Beuster,
H. Okavango River Basin Environmental Flow Assessment
Scenario Report : Hydrology (Report No: 06/2009)


Jones, M.J.
The Groundwater Hydrology of The Okavango Basin (FAO
Internal Report, April 2010)


King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 1
of 4)(Report No. 07/2009)


King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 2
of 4: Indicator results) (Report No. 07/2009)


King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions: Climate
Change Scenarios (Volume 3 of 4) (Report No. 07/2009)


King, J., Brown, C.A.,
Okavango River Basin Environmental Flow Assessment
Joubert, A.R. and
Scenario Report: Biophysical Predictions (Volume 4 of 4:
Barnes, J.
Climate Change Indicator Results) (Report No: 07/2009)


King, J., Brown, C.A.
Okavango River Basin Environmental Flow Assessment Project
and Barnes, J.
Final Report (Report No: 08/2009)


Malzbender, D.
Environmental Protection And Sustainable Management Of The
Okavango River Basin (EPSMO): Governance Review


Vanderpost, C. and
Database and GIS design for an expanded Okavango Basin
Dhliwayo, M.
Information System (OBIS)


Veríssimo, Luis
GIS Database for the Environment Protection and Sustainable
Management of the Okavango River Basin Project

Wolski,
P.
Assessment of hydrological effects of climate change in the
Okavango Basin




Country Reports
Angola
Andrade e Sousa,
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Biophysical Series
Helder André de
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Sedimentologia &
Geomorfologia


Gomes, Amândio
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Vegetação


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EFA Namibia Aquatic Macroinvertebrates

Gomes,
Amândio
Análise Técnica, Biofísica e Socio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final:Vegetação da Parte Angolana da Bacia Hidrográfica Do
Rio Cubango


Livramento, Filomena
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina:Macroinvertebrados


Miguel, Gabriel Luís
Análise Técnica, Biofísica E Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango:
Subsídio Para o Conhecimento Hidrogeológico
Relatório de Hidrogeologia


Morais, Miguel
Análise Diagnóstica Transfronteiriça da Bacia do Análise Rio
Cubango (Okavango): Módulo da Avaliação do Caudal
Ambiental: Relatório do Especialista País: Angola Disciplina:
Ictiofauna

Morais,
Miguel
Análise Técnica, Biófisica e Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final: Peixes e Pesca Fluvial da Bacia do Okavango em Angola


Pereira, Maria João
Qualidade da Água, no Lado Angolano da Bacia Hidrográfica
do Rio Cubango

Santos,
Carmen
Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S. N.
Okavango: Módulo do Caudal Ambiental: Relatório de
Especialidade: Angola: Vida Selvagem


Santos, Carmen Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S.N.
Okavango:Módulo Avaliação do Caudal Ambiental: Relatório de
Especialidade: Angola: Aves

Botswana Bonyongo, M.C.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Wildlife


Hancock, P.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report: Country:
Botswana: Discipline: Birds

Mosepele,
K. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Fish


Mosepele, B. and
Okavango River Basin Technical Diagnostic Analysis:
Dallas, Helen
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Aquatic Macro Invertebrates

Namibia
Collin Christian &
Okavango River Basin: Transboundary Diagnostic Analysis
Associates CC
Project: Environmental Flow Assessment Module:
Geomorphology


Curtis, B.A.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report Country:
Namibia Discipline: Vegetation


Bethune, S.
Environmental Protection and Sustainable Management of the
Okavango River Basin (EPSMO): Transboundary Diagnostic
Analysis: Basin Ecosystems Report


Nakanwe, S.N.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Aquatic Macro Invertebrates

Paxton,
M. Okavango River Basin Transboundary Diagnostic Analysis:
Environmental Flow Module: Specialist
Report:Country:Namibia: Discipline: Birds (Avifauna)


Roberts, K.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Wildlife

Waal,
B.V. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia:Discipline: Fish Life
Country Reports
Angola
Gomes, Joaquim
Análise Técnica dos Aspectos Relacionados com o Potencial
Socioeconomic
Duarte
de Irrigação no Lado Angolano da Bacia Hidrográfica do Rio
Series
Cubango: Relatório Final

Mendelsohn,
.J.
Land use in Kavango: Past, Present and Future


Pereira, Maria João
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Qualidade da Água


Saraiva, Rute et al.
Diagnóstico Transfronteiriço Bacia do Okavango: Análise
Socioeconómica Angola

Botswana Chimbari, M. and
Okavango River Basin Trans-Boundary Diagnostic Assessment
Magole, Lapologang
(TDA): Botswana Component: Partial Report: Key Public Health
Issues in the Okavango Basin, Botswana

Magole,
Lapologang
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Land Use Planning


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EFA Namibia Aquatic Macroinvertebrates


Magole, Lapologang
Transboundary Diagnostic Analysis (TDA) of the Botswana p
Portion of the Okavango River Basin: Stakeholder Involvement
in the ODMP and its Relevance to the TDA Process

Masamba,
W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Output 4: Water Supply and
Sanitation


Masamba,W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Irrigation Development

Mbaiwa.J.E. Transboundary Diagnostic Analysis of the Okavango River
Basin: the Status of Tourism Development in the Okavango
Delta: Botswana


Mbaiwa.J.E. &
Assessing the Impact of Climate Change on Tourism Activities
Mmopelwa, G.
and their Economic Benefits in the Okavango Delta

Mmopelwa,
G.
Okavango River Basin Trans-boundary Diagnostic Assessment:
Botswana Component: Output 5: Socio-Economic Profile


Ngwenya, B.N.
Final Report: A Socio-Economic Profile of River Resources and
HIV and AIDS in the Okavango Basin: Botswana

Vanderpost,
C.
Assessment of Existing Social Services and Projected Growth
in the Context of the Transboundary Diagnostic Analysis of the
Botswana Portion of the Okavango River Basin

Namibia
Barnes, J and
Okavango River Basin Technical Diagnostic Analysis:
Wamunyima, D
Environmental Flow Module: Specialist Report:
Country: Namibia: Discipline: Socio-economics


Collin Christian &
Technical Report on Hydro-electric Power Development in the
Associates CC
Namibian Section of the Okavango River Basin


Liebenberg, J.P.
Technical Report on Irrigation Development in the Namibia
Section of the Okavango River Basin


Ortmann, Cynthia L.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report Country:
Namibia: discipline: Water Quality


Nashipili,
Okavango River Basin Technical Diagnostic Analysis: Specialist
Ndinomwaameni
Report: Country: Namibia: Discipline: Water Supply and
Sanitation

Paxton,
C.
Transboundary Diagnostic Analysis: Specialist Report:
Discipline: Water Quality Requirements For Human Health in
the Okavango River Basin: Country: Namibia


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