Sweep net and activity trap sampling were conducted and each evaluated for their effectiveness in collecting macroinvertebrates. The diversity and composition of taxa did not differ in activity traps placed at the four depth locations. Sixty-eight percent of taxa occurred more frequently in net sweep sampling compared to activity trap sampling.
The research described in this thesis was carried out at the Center for Environment and Development, University of KwaZulu-Natal, Pietermaritzburg, under the supervision of Or Nevil Quinn (Faculty of the Built Environment, University of the West of England, Bristol, U.K.) and Dr. Donovan Kotze (Center for Environment and Development, University of KwaZulu-Natal, Pietermaritzburg, South Africa). Where use has been made of the work of others, this is duly acknowledged in the text. Essak Abib, Senior Technician and Gertrude Nala, Technical Assistant, Department of Soil Science, University of KwaZulu-Natal, for their provision of expertise and time in the water quality analysis laboratory.
25 Table 2.9 Details of activity trap protocols used in selected case studies 26 Table 2.10 Details of the Gerking sampler used in the Mid-Atlantic Wetland Project and its . Shielding and its associated advantages and disadvantages (DiFranco and Stevenson Table 2.13 Details of heating pipe sampling used by the Maine Department of the Environment.
INTRODUCTION
Aquatic macroinvertebrates have been widely used internationally as water quality biomonitoring tools in streams and rivers (Wissinger 1999, Hicks 2000, Butcher 2003), and are the second most popular choice of bioindicator after plants for wetland bioassessment (DWAF 2004). SASS5 plays an important role in the South African National Rivers Health Program (Uys et al. 1996) and has been employed to assist in the determination of the ecological reserve as required by the South African National Water Act (1998) (Dickens and Graham) 2002). This study tests whether the current SASS5 tolerance scores are appropriate for assessing nutrient-enriched palustrine wetlands in South Africa.
However, the use of aquatic macroinvertebrate assemblages for rapid bioassessment has been most popular since 1989 (Sutherland and Stribling 1995). However, to date little work has been done on wetland health assessment in South Africa. The purpose of this research is to investigate the potential use of aquatic macroinvertebrates and the SASS5 assessment procedure for monitoring and assessing palustrine wetlands in South Africa, which will contribute to the development of a South African wetland water quality biomonitoring program .
Based on the survey results, an aquatic macroinvertebrate sampling technique was developed for use in KwaZulu-Natal palustrine wetlands. The second article fulfills objective three and documents the procedure undertaken to test the applicability of the SASS5 scoring procedure in nutrient-enriched palustrine wetlands.
LITERATURE REVIEW
Advantages and Disadvantages of Using Aquatic Macroinvertebrates as a Biomonitoring Tool
Case Studies
Hicks 2000) • The patchiness of biotope conditions in a single wetland will result in complex patterns of invertebrates. Details of the sweep net sampling method along with its advantages and disadvantages are given in Table 2.4. Long linear wetlands sites within a macrophyte- network is forced forward or may require subdivision and. wetland strongly from the base of plants to the edge separate assessment. water surface macrophytes Separate sampling of the submerged. sprouts and and emergent plant biotope is . reeds) is preferred.
Three to five collections collect most of the taxa present in a single wetland biotope (Reberet al. 2000). The volume of the trap and whether the trap is closed (glass, plastic) or open (screen). Pennits the calculation of the number of invertebrates per unit area of wetland soil (a quantitative estimate) (Karr and Chu 1999).
However, if there are large amounts of dirt in the sample, small amounts of the sample should be placed over the glass and diluted with water (H~~n20021. The statistical significance of the separation can be confirmed using standard statistical tests such as tests The higher the percentage of the three dominant taxa are, the greater the degree of water quality degradation.
For each of the wetlands sampled, the number of organisms within each family is multiplied by its given value.
METHODOLOGY
This was preferable as the need for a sample site biotope assessment metric would have complicated and potentially compromised the accuracy of the results. Starting at the surface, the sweep net is pulled forcefully through the water column at a 45 degree angle until the net arrives at the bottom of the wetland. Once in the lab, the contents of the jars were emptied into a white tray and any large pieces of debris were removed, ensuring that all organisms were removed first.
Twenty samples were taken at each of the four depths, for a total of 80 samples collected. Once in the laboratory, the contents of the jars were emptied into a white container and then left to stand for five minutes*. There was a large amount of dirt in some samples. Therefore, the glass bowl and light box were not used, as they are not effective under these conditions (Helgen 2002).
The entire sample was chosen because this study required the accurate detection of all organisms in a sample. Other authors who support choosing the entire sample include Courtemanch (1996), Doberstein et al. Non-metric Multi-Dimensional Scaling (NMDS) ordination (Ter Braak and Smilauer 2003) This method provided a visual representation that shows the degree of similarity within and between the taxon compositions of the different sweep intensities.
NMDS ordination (Ter Braak and Smilauer 2003) This method provided a visual representation that showed the degree of similarity within and between taxon compositions at different depth locations. MRPP This procedure was used to test whether the taxon composition of sweep net samples differed significantly from that of activity trap samples. ISA and Monte Carlo significance test. These procedures determined whether there were taxa favored by one or the other of the two methods.
In each of the three areas, the implemented method was carried out twice in two separate locations (Figure 3.1), so that a total of six samples were collected from each affected wetland. Six samples were also collected from each of the reference wetlands, but the only influence on sample location for these wetlands was the availability of suitable sampling biotope. For the five aspects, there is a list of features to be assessed at each site.
Features and Examples of a Palustrine System
SASS Version 5 Score sheet Taxon S Yes GSM TOTTaxon S Yen GSM TOT Taxon 5 Yes GSM TOT. Sweep marginal vegetation (IC & OOC) for 2m total and aquatic plants 1m2. Stir and sweep gravel, sand, mud for 1 minute total.
Tolerance Score Comparison Table
Pilot Study Activity Trap Data Sheet
Macrohabitat Score Sheet
Physico-chemical Data Sheet
Sample Biotope Detection Assessment (SBDA) Index
Melmoth Vlei is part of the Myamvubu Vlei system, which is located in the Thukela River basin (Figure 1). It is close to the source of the Myamvubu River which originates close to the mountain. Sampling for this study took place in emergent vegetation adjacent to an open water area of the wetland.
Minimum and maximum results for each parameter for each of the three locations were collected. The contents of the tray were then washed through a sieve (mesh size 1 mm) and placed in a. The overlap in the distribution of the samples from the different locations suggests that there is no consistent difference in the taxon composition collected at the four different depths (Figure 4).
Begg G (1989) Wetlands of Natal (Part 3): the location, status and function of the priority wetlands in Natal. Bowd R (in preparation) Testing the utility of the SASS5 scoring procedure for assessing wetland health: a case study in the KwaZulu-Natal midlands, South Africa. Chutter FM (1994) The rapid biological assessment of water quality in streams and rivers using the macroinvertebrate community in South Africa.
Testing the applicability of the SASS5 scoring procedure for assessing wetland health: a case study in KwaZulu-Natal. The purpose of the study was to test whether SASS5 could be used to determine the health of nutrient-enriched palustrine wetlands in South Africa. Potential RWs and IWs in the KwaZulu-Natal midlands were identified by examination of 1:50 000 topographic maps of the area.
The sweep net is dragged strongly from the surface through the water column (at a 45 degree angle) until the net reaches the bottom of the wetland. After extraction from the wetland, the contents of the net were placed in a white tray (250 mm x 350 mm). There was no apparent trend in 'pre-impact' samples with higher SASS5 scores compared to 'on' and 'downstream' samples of the same wetland.
It is therefore likely that the wetland has good physicochemical results and SASS5 scores due to the combination of the minimum still method and the availability of good sampling biotope. When considering the SASS5 site scores without reference to water quality guidelines, there appears to be a loose relationship between SASS5 scores, recorded physicochemical measurements, and macrohabitat assessment of the wetlands studied (Tables 10 and 11).
