Long Term Time-Series Data on Aquatic Macro-invertebrates Monitoring by Okavango Research Institute, Botswana

The Okavango Delta is one of the largest inland deltas in the world. The highly variable and complex aquatic ecosystem presents a variety of habits for macroinvertebrates, specifically in seasonal floodplains, that are highly productive and easily accessible for natural products and other ecosystem services . Meanwhile, aquatic macroinvertebrates in these highly interactive riparian zones can often be used as environmental indicators of ecosystem health because they are sensitive to variations in water quality and food availability. The Okavango Research Institute (ORI) conducts a monthly survey at three of four monitoring sites, to determine changes in relative abundances and diversity of macroinvertebrate taxa found in the lower SE Okavango Delta using the Okavavango Assessment System (OKASS) based approach. OKASS itself is a tool for bio-assessment, modified from the South African Scoring System (SASS) by Mosepele and Dallas (2007) for the Okavango Delta . It is a monthly rapid, field-based method that is largely based on family-level field identifications of aquatic macroinvertebrates (MI). It provides qualitative data on aquatic macroinvertebrates for the sampled habitat, e.g. marginal vegetation in current (i.e. in a flowing channel) or marginal vegetation out of current (i.e. a lagoon or slackwater). A sampling net (30 x 30 cm square frame, 1mm mesh) is used to sweep the vegetation to dislodge the attached organisms, which are then collected in the net. For this resource, several taxa have been identified to family level while others have been left at higher taxonomic levels, e.g families identified include Belostomatidae, Corixidae, Gerridae , Ceratopogonidae and Atyidae , while Coleoptera species largely remain identified at order level, safe for (Griniudae) The ongoing monitoring surveys provide baseline information and time series data on macroinvertebrate assemblages and environmental conditions at selected sites in the Delta. The data are useful for estimation of relative abundance and diversity of taxa found in the areas sampled , and other generalizations such as checklists for the Okavango Delta aquatic macroinvertebrates.