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urn:nbn:nl:ui:32-410859 2026-03-31 urn:nbn:nl:ui:32-410859/mods Environmental variables, pesticide pollution and meiofaunal community structure in two contrasting temporarily open/closed false bay estuaries Bollmohr S. aut van den Brink P.J. 126862214 0000-0002-7241-4347 0000000398609633 aut Wade P.W. aut Day J.A. aut Schulz R. aut text info:eu-repo/semantics/article 2011 10.4314/wsa.v37i3.68490 2-s2.0-79960855098 000293341500014 en Environmental variables (including natural and anthropogenic stressors) and meiobenthic communities were sampled in a ‘natural’ (Rooiels) and a ‘disturbed’ (Lourens) estuary in the Western Cape, South Africa, bimonthly for 20 months. A primary aim of the study was to assess if the meiobenthic community structure is driven by different variables when comparing ‘natural’ versus ‘disturbed’ system. Due to the much smaller catchment of the Rooiels Estuary, many environmental variables were significantly different (p<0.001) from the variables in the Lourens Estuary, e.g. salinity, temperature, pH, total suspended solids, nitrate and depth. No pesticide concentrations were expected in the Rooiels Estuary due to the absence of agricultural development in the catchment. However, chlorpyrifos (8.9 µg/kg), prothiofos (22.0 µg/kg) and cypermethrin concentrations (0.42 µg/kg) were detected frequently, with the highest concentrations recorded during the summer months. Principal response curve analysis showed that temporal variability between sampling dates explained 42% of the variance in environmental variables and pesticide concentrations and spatial variability between the 2 estuaries explained 58%. Variables contributing most to the differences were higher concentrations of endosulfan, p,p-DDE and nitrate concentrations in the Lourens Estuary and larger grain size and higher salinity at the bottom in the Rooiels Estuary. In general the meiofaunal community in the Rooiels Estuary showed a significantly higher number of taxa (p<0.001), a significantly higher Shannon Wiener Diversity Index (p Wageningen Environmental Research WIMEK CWC - Environmental Risk Assessment Aquatic Ecology and Water Quality Management disturbance exposure lourens river principal response curves sediment south-africa spatial patterns warm-temperate water western-cape Wageningen Environmental Research WIMEK CWK - Environmental Risk Assessment Aquatische Ecologie en Waterkwaliteitsbeheer Water SA 37 391 400 03784738 urn:nbn:nl:ui:32-410859/obj 2026-03-31 http://purl.org/eprint/accessRights/OpenAccess