Biological monitoring: Zimbabwe

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21 Biological monitoring: Zimbabwe GENERAL INFORMATION Implementing institution: Zimbabwe National Water Authority Head: Sibekile Mtetwa Details of institution: Address: Zimbabwe National Water

1 21 Biological monitoring: Zimbabwe GENERAL INFORMATION Implementing institution: Zimbabwe National Water Authority Head: Sibekile Mtetwa Details of institution: Address: Zimbabwe National Water Authority, Water Quality Section, National Water Quality Laboratory, No. 6 off Pauling Drive, KG V1, P. Bag CY 617, Causeway, Harare Tel.: (+263) Fax: (+263) hydro@mweb.co.zw Implementation period: June 2000 to November Costs: US$22,000, funded by the Water Research Fund for Southern Africa. 247

2 248 V OLUME 11: SAFE D RINKING WATER S UMMARY The majority of people living in rural areas of Zimbabwe obtain their drinking water from rivers. Although chemical and microbiological water quality monitoring programmes are well established in Zimbabwe, the quality of the nation s rivers has been progressively deteriorating, partly because of various constraints on the monitoring programmes. Biological monitoring, which involves an assessment of the macroscopic life in the rivers, provides an alternative means of evaluating the quality of riverine environments and would complement chemical monitoring in an effective, countrywide water quality management system. The main objective of the project, therefore, was to undertake research to establish reference sites suitable for the long-term biomonitoring of water quality in Zimbabwean rivers. To achieve this, a methodology developed and applied in South Africa was adopted. This involved a desktop study aimed at establishing a spatial framework of the river systems in Zimbabwe. A pilot site, the Manyame catchment area in the north of the country, was subsequently chosen to assess whether the system developed in South Africa could be replicated in Zimbabwe. If so, the results of the pilot project would help to guide the implementation of a biomonitoring programme in Zimbabwe and ultimately throughout southern Africa. B ACKROUND AND J USTIFACTION Zimbabwe has suffered recurring water shortages over the last decade as a result of below-average rainfall. As a consequence, there has been a realization that the management of water resources in this water-scarce country is essential if national development is not to be constrained by water availability and if maximum benefits are to be gained from existing water resources. Along with chemical and microbiological monitoring, biological monitoring (or, more simply, biomonitoring) is a valid way of determining the quality of a body of water. It is based on the fact that different species of aquatic insect prefer different types of water. Species that live in fast-flowing streams, for example, will most likely not be found in muddy pools and vice versa. Any changes in the insect fauna of a river, therefore, can help to identify changes in water quality, whether it is changes in oxygen content, ph, or other parameters caused by pollution from agricultural run-off or wastewater dumping. Biomonitoring, therefore, can have applications in integrated catchment management and can help to ensure the sustainable utilization and management of water resources. It can also provide information that can be used to assess the potential effects of proposed water resource development plans, including, for example, the pumping of water from one catchment area where water is plentiful to another where it is scarce.

3 Biological monitoring: Zimbabwe 249 Information on the aquatic biodiversity in Zimbabwe was last assessed in the 1960s and biomonitoring as a tool to monitor water quality was used only as a research tool. The objective of this project was to use biomonitoring as a complementary tool to the existing practice of chemical water quality monitoring. However, although both chemical and microbiological water quality monitoring is well established in Zimbabwe, the quality of the nation s rivers has been progressively deteriorating due to constraints on the monitoring programmes. Against this background, a pilot biomonitoring project was conceived with the primary aim of initiating a nationwide biomonitoring programme to complement chemical monitoring. In this biomonitoring programme, the South African Scoring System version 4 (SASS4) was used. SASS4 is a rapid biological assessment method that was developed to evaluate the impact of changes in water quality using aquatic macro-invertebrates such as insect larvae as indicator organisms. One advantage of biomonitoring is that it is simple to carry out and requires no sophisticated equipment. In addition, people in rural areas can easily be trained to use biomonitoring principles themselves to determine whether their water is safe to drink or not. D ESCRIPTION This project was the first attempt of the Water Quality Section of the Zimbabwe National Water Authority to use biomonitoring. The project included four components: purchase of equipment for use in the biomonitoring by the Water Quality Section; capacity-building through the training of Water Quality Section staff to enable them to undertake biomonitoring to complement their present chemical and biological monitoring capabilities; a desktop survey of the whole country using geographical information systems (GISs) and various digital information overlays; and land classification based on its use or natural vegetation type. Training included providing staff of the Water Quality Section with the background to biomonitoring; a knowledge of the relationship between biomonitoring and chemical water quality; and the use of SASS4, including the correct ways to collect, sort, preserve and identify samples and to assess and score habitat types. D ESKTOP SURVEY Maps at a scale of 1:50,000 were prepared and the country was classified into bio-geographical regions based on broad historical patterns of catches of fish, studies of aquatic macro-invertebrates and the known riparian vegetation using the ecological land classification as described in the State of the Environment report for Zimbabwe. Considering both biotic and abiotic factors, the country was divided into six Level-I eco-regions,

250 V OLUME 11: SAFE D RINKING WATER namely, Central, Eastern Highlands, Kalahari, Save Limpopo, Zambezi and open water, each with its own characteristic features in terms of hydrology, landforms,

4 250 V OLUME 11: SAFE D RINKING WATER namely, Central, Eastern Highlands, Kalahari, Save Limpopo, Zambezi and open water, each with its own characteristic features in terms of hydrology, landforms, land use, rainfall patterns, relief and geology. The country s catchment boundaries were then used for dividing the Level-I eco-regions into smaller, more manageable units (fig. 1). The Manyame catchment area in the north of the country was selected as the project area. Rivers were then classified depending on their size and flow patterns and based on mean monthly flows determined at selected gauging stations owned by the Data and Research branch of the Zimbabwe National Water Authority. Using these data, reference sites within the Manyame catchment area were selected. The choice of the reference sites also depended on local knowledge, land-use coverage, representativeness, links with ongoing water quality monitoring projects, accessibility, diversity of biotopes represented and the area served by the site. B IOMONITORING FIELD WORK The South African Scoring System Version 4 (SASS4) is a rapid assessment method. It involves the collection of macro-invertebrates from selected reference or monitoring sites. Samples are divided into their respective taxonomic groups and counted. Each taxonomic group has a grade or ranking relative to its sensitivity to pollution. Families with a ranking of 1, for example, are very tolerant to pollution while those with a rank of 15 are more sensitive. Mayfly larvae in the family Leptophlebiidae, for example, have a rank of 13 and prefer clean water, while caddis fly larvae in the family Philopotamidae have a rank of 12 and can tolerate some deterioration in water quality. In contrast, midge larvae (Chironomidae) have a rank of 4 and mosquito larvae (Culicidae) have a rank of 1 and both can tolerate living in poor-quality water (table 1). The basic principle of SASS4 is that healthy rivers contain large numbers of different species with all levels of pollution tolerance, with no single species dominating. Figure 1. Zimbabwe. Catchment boundaries of The habitat assessment matrix (HAM), a simple, subjective method associated with stream and bank characteristics, was also used to allow sites to be compared. The assessment includes noting whether the stream bed is made of mud, gravel or rocks; whether the banks are subject to erosion; and the nature of the bankside vegetation. The combination of these riverine habitats gives a good idea of the aquatic diversity that can be expected as it relates the number of biotopes, or ecological niches, available to the invertebrates.

Biological monitoring: Zimbabwe 251 S AMPLING FOR THE MACRO-INVERTEBRATES Sampling for the macro-invertebrates was done as follows: a suitable site was selected; a fixed-point photograph was taken of

5 Biological monitoring: Zimbabwe 251 S AMPLING FOR THE MACRO-INVERTEBRATES Sampling for the macro-invertebrates was done as follows: a suitable site was selected; a fixed-point photograph was taken of the site; a global positioning system (GPS) reading was taken to enable the exact site to be revisited; ph, conductivity, dissolved oxygen and temperature readings were taken; an HAM was completed; water velocity was measured using floating objects timed over a known distance; macro-invertebrate samples were taken at 30-second intervals four times using the kick method (see below); debris and macro-invertebrate samples were placed in a bucket; invertebrates were sorted into a tray and identified to family level; the families were marked on the SASS4 scoring sheet; an average score per taxon (ASPT) was calculated from the sample score and the number of families identified. kick stones covering about one square metre out of the current; use a net to sweep marginal and aquatic vegetation with and against the current for 2 metres (fig. 2); stir sand and mud with feet then sweep net over disturbed area for 30 seconds; and sample gravel and any other biotope for 30 seconds. Note: surface animals must be collected as well as animals adhering strongly to rocks. If present, 30 seconds may be spent in a manual search of rocks and logs. Then: tip the contents of the net onto a tray and remove leaves, twigs and other trash; check taxa present for 15 minutes but stop if no new taxa are seen after 5 minutes (fig. 3); and estimate their abundance on the scale: A=1-9; B=10-99; C= ; D=1000+ The kick method for sampling for macro-invertebrates is carried out as follows: kick stones in the current for two up to a maximum of five minutes; Figure 2. Using a net to sample for macro-invertebrates along a stream.

252 V OLUME 11: SAFE D RINKING WATER preferred. Selected examples of the data collected from the 33 sites are shown in table 3. P ARTNERSHIPS Figure 3.

6 252 V OLUME 11: SAFE D RINKING WATER preferred. Selected examples of the data collected from the 33 sites are shown in table 3. P ARTNERSHIPS Figure 3. Assessing the contents of a net to identify and count the macro-invertebrates caught. R ESULTS In total, 33 reference sites were assessed and some fifty macro-invertebrate families were recorded. Among them are those highlighted in table 1. The biological condition of each of the 33 sites was rated based on the indices of average score per taxon (ASPT), habitat assessment matrix (HAM) and SASS4 score as well as variables such as electrical conductivity, ph and water flow rates. These data were analysed using multivariate statistics, performed using Minitab Version 13 software, to determine the most representative reference sites for each river type. Guideline values (Chutter, 1995) were also used to assess the biological condition of the selected sites (table 2). The results showed that there were few reference points, mainly because there were few unimpacted sites and site accessibility was difficult. A minimum number of 60 reference sites would have been The Institute of Water and Sanitation Development, a regional organization, and the Zimbabwe National Water Authority played significant roles in the project, especially in the provision of technical support. An external expert in biomonitoring, Helen Dallas of the Freshwater Research Unit, Zoology Department, University of Cape Town, South Africa, was contracted to review the work. She concluded that the project would provide a solid foundation upon which further biomonitoring initiatives could be based. Although the budget for the project meant that community participation was not taken into consideration when the project was initiated, if funds and resources become available, the objective of the Water Quality Section is to introduce the concept of biomonitoring to the public once all the catchments are covered. For this purpose, there are prospects of re-engaging stakeholders who were initially involved in the project such as the Institute of Water and Sanitation Development and the Water Research Fund for Southern Africa. The Water Quality Section is lobbying for funds from both the Zimbabwe National Water Authority and the private sector to carry out this exercise.

7 Biological monitoring: Zimbabwe 253 Table 1. Some of the macro-invertebrate taxa identified in this study. Order Family Common name Sensitivity / tolerance ranking TURBELLARIA Planarians Flatworms 5 ANNELIDA Oligochaeta Sludge worms 1 MOLLUSCA, Lymnaeidae Pond snails 3 GASTROPODA Planorbidae Orb / rams-horn snails 3 MOLLUSCA, Sphaeridae Clam, seed shells 3 PELECYPODA HYDRACARINA Hydrachnellae Water mites 8 EPHEMEROPTERA Baetidae Small minnow 4-12 (Mayflies) mayflies Caenidae Small square gills 6 Heptageniidae Flat-headed mayflies 10 Leptophlebiidae Prong-gills 13 HEMIPTERA Belostomatidae Giant water 3 (True bugs) bugs Corixidae Water boatmen 3 Gerridae Long-legged water striders 5 Nepidae Water scorpions 3 Notonectidae Backswimmers 3 ODONATA, Anisoptera Aeshnidae Dragonflies 8 (Dragonflies) Gomphidae Club tails 6 Libellulidae Common skimmers 4 ODONATA, Zygoptera Chlorocyphidae Damselflies 10 (Damselflies) Coenagrionidae Narrow-winged damselflies 4 Lestidae Spread-winged damselflies 8 PLECOPTERA Perlidae Common stoneflies 12 (Stoneflies) TRICHOPTERA Hydropsychidae Common net spinners 4-12 (Caddis flies) Philopotamidae Finger net caddis 12 Ecnomidae Case-less caddis 8 COLEOPTERA Dytiscidae Predaceous diving beetles 5 (Beetles) Gyrinidae Whirligig beetles 5 Helodidae Marsh beetles 12 DIPTERA Chironomidae Non-biting midges 2 (True flies) Ceratopogonidae Biting midges 5 Simulidae Blackflies 5 Tabanidae Horseflies 5 Tipulidae Crane flies 5

8 254 V OLUME 11: SAFE D RINKING WATER Table 2. Guideline values for rating biological condition of a body of water using SASS4 scores and average score per taxon (ASPT). SASS4 ASPT Biological water condition >100 >6 Water quality natural, biodiversity high <100 >6 Water quality natural, biodiversity reduced >100 <6 Borderline case between water quality natural and some deterioration in water quality. Interpretation should be based on the extent to which SASS4 exceeds 100 and ASPT is less than <6 Some deterioration in water quality <50 Variable Major deterioration in water quality Table 2. Results for selected reference sites used in the data analysis. Site No. ph Conductivity Average HAM ASPT SASS4 No. of Biological (µs/m) velocity score taxa condition (sec/10m) Poor Poor Poor Fair Fair Fair Good Good Good Excellent Excellent R EPLICABILITY The findings of this pilot project in the Manyame catchment area were meant to give guidance in the implementation of a countrywide biomonitoring programme in Zimbabwe and ultimately in the southern Africa region. The project, which demonstrated the feasibility of using the SASS4 monitoring scheme, has since been expanded to cover the whole of Zimbabwe. Scientists and technicians of the Water Quality Section on all seven catchment councils have now taken a training course in biomonitoring conducted at the National Water Quality Laboratory.

9 Biological monitoring: Zimbabwe 255 In addition, other southern African nations are now in the process of applying biomonitoring as a complementary tool for water quality monitoring. For example, biomonitoring is being carried out on the Komati River in Swaziland. There are recent initiatives to establish a regional water quality monitoring system in the Zambezi Basin and biomonitoring has been chosen as one of the main components of the project. The Zimbabwean experience in the use of biomonitoring in the Manyame project and other catchment areas would contribute significantly to this initiative. L ESSONS L EARNED Originally it was envisaged that the desktop survey would divide the country into various bio-geographical regions. However, owing to difficulties in obtaining comprehensive information on the distribution of macro-invertebrates in Zimbabwe, the term eco-region was used instead of bio-geographical region. There were also problems associated with accessing digital data from other government departments, much of which had to be re-digitized to be of use for determining the extent of each eco-region. P OLICY I MPLICATIONS I MPACT Although the project as such did not bring about any changes in legislation, it did reinforce existing legislation on water resource management and the environment. The Zimbabwe National Water Act of 1999, the Zimbabwe National Water Authority Act of 1999 and the recent Environmental Management Act of 2002 are strongly supported by the findings of the project. The project also provided information on the state of the aquatic environment and therefore provides a basis on which to work regarding water quality as well as enabling target levels to be determined if ever remedial action, for example cleaning up after a pollution event, is necessary. The impact of the project will be felt when other stakeholders, including rural communities, are brought on board once funding is obtained from either the private sector or other sources. It is hoped that the long-term implementation of a national biomonitoring programme will help to maintain the health of the country s rivers by alerting the authorities to potential problems. In terms of the rural population, the Water Quality Section of the Zimbabwe National Water Authority is planning to develop pamphlets written in English and the two main local languages Shona and Ndebele that describe a mini SASS. These pamphlets, designed for use in rural areas, will contain all the basic information and pictures required for nonspecialists to make a rapid assessment of

10 256 V OLUME 11: SAFE D RINKING WATER water quality. In this way, people living in rural areas can quickly make decisions as to whether their local source of water is suitable for drinking and if not, make sure that it is treated, for example by boiling, chlorination or even using solar disinfection (SODIS). F UTURE P LANS There are recent initiatives to establish water quality monitoring programmes in the shared watercourses in the Southern African Development Community (SADC). Biomonitoring can be used in the monitoring of transboundary rivers, such as in the Limpopo Basin. Plans are already in place to incorporate biomonitoring in the Zambezi River Basin. The experiences gained from this project should provide a valuable input to these initiatives. It was unfortunate that, during the inception and implementation of the project, no public awareness campaigns were carried out owing to funding limitations. However, there are plans by the Water Quality Section to produce pamphlets describing a mini SASS for use by rural communities. There are also plans to train primary and secondary schoolchildren in rural areas in the use and importance of the mini SASS. P UBLICATIONS Assessment of Reference Sites for a Biomonitoring Water Quality Assessment Network in Zimbabwe. Volume 1: Initiation of a Biomonitoring Programme in Zimbabwe. Assessment of Reference Sites for a Biomonitoring Water Quality Assessment Network in Zimbabwe. Volume 2: Biomonitoring Protocols and Registered Sampling Sites. Assessment of Reference Sites for a Biomonitoring Water Quality Assessment Network in Zimbabwe. Volume 3: Sampling Sites Results. Chutter, F.M. (1995). Research on the rapid biological assessment of water quality impacts in streams and rivers. Final project report to Division of Water Technology, Council for Scientific and Industrial Research, Pretoria, South Africa. Goetsh, P.A., Uys, M.C. and O Keeffe, J.H. (1996). National biomonitoring programme for riverine ecosystems: Ecological indicators, review and recommendations. NBP Report Series No. 4, Institute for Water Quality Studies, Department of Water Affairs and Forestry, Pretoria, South Africa. Mtetwa, S., Chipfunde, L. and Makwanise, R. (2003). Establishment of biomonitoring reference sites for Zimbabwe s rivers: A tool for effective integrated catchment management. Paper presented at the Fourth Waternet/WARFSA Symposium, October 2003, Dar es Salam, United Republic of Tanzania.

11 Biological monitoring: Zimbabwe 257 Case study prepared by: Zvikomborero Manyangadze Address: Ministry of Water Resources and Infrastructural Development P. Bag 7767, Causeway, Harare, Zimbabwe Tel.: (+263) / , ext Direct line: (+263) Fax: (+263) hydro@mweb.co.zw Project participants: The project team comprised: Sibekile Mtetwa: Principal investigator. Regis Makwanise: Field assistant. Christopher Topping and Lisben Chipfunde (research assistant): Conducted the initial training of biomonitoring practitioners. Hellen Dallas: Consultant contracted to review the project, especially on issues relating to the establishment of the reference sites.

Wetland versus Stream Macroinvertebrates

Wetland versus Stream Macroinvertebrates Purpose: Summary: To investigate various biomes through observation and comparison of the diversity of life, in particular, the specific number of species, biomass,