The main aim of the SAFRASS project was to develop a new river biomonitoring approach for pilot use initially in Zambia, so we collected benthic diatoms, benthic invertebrates and macrophytes at each site, as well as water physico-chemistry and habitat data.
With repeat-sampling at some sites the total number of individual samples in the dataset is 271. The pilot scheme was successfully developed and the outputs have been passed on to the appropriate agencies (DWA mostly, but quite a range of other organisations too) in Zambia, via a series of training days and workshops (in Lusaka and at Kasanka NP) which we held before the end of the project period.
The first-ever extensive macrophyte survey of Zambian rivers and associated floodplain waterbodies, conducted during 2006–2012, collected 271 samples from 28 sites, mainly located in five freshwater ecoregions of the world primarily represented in Zambia.
The results supported the hypothesis that variation in macrophyte community structure (measured as species composition and diversity) in southern tropical African river systems, using Zambia as a case study area, is driven primarily by geographical variation in water physico-chemical conditions. In total, 335 macrophyte taxa were recorded, and achronological cumulative species records curve for the dataset showed no sign of asymptoting: clearly many additional macrophyte species remain to be found in Zambian rivers.
Emergent macrophytes were predominant (236 taxa), together with 26 floating and 73 submerged taxa. Several species were rare in a regional or international context, including two IUCN Red Data List species:
Aponogeton rehmanii and
Nymphaea divaricata.
Ordination and classification analysis of the data found little evidence for temporal change in vegetation, at repeatedly-sampled sites, but strong evidence for the existence of seven groups of samples from geographically-varied study sites. These supported differing sets of vegetation(with eight species assemblages present in the sample-groups) and showed substantial inter-group differences in both macrophyte alpha-diversity, and geographically-varying physico-chemical parameters.
The evidence suggested that the main environmental drivers of macrophyte community composition and diversity were altitude, stream order, shade, pH, alkalinity, NO3-N, and underwater light availability,while PO4-P showed slightly lower, but still significant variation between sample-groups.
See literature references:
904,
905 and
1008