Spatial variations of microinvertebrates across different microhabitats of temporary floodplains of lower Okavango Delta, Botswana

Abstract

AbstractTemporary floodplains of the Okavango Delta have been suggested as important nursery sites for juvenile fish. Fish production in the Delta is dependent on how well temporary floodplains are maintained. A study was conducted to understand how floodplains function so as to put measures in place that will sustain temporary floodplains in a high productive state. During high floods, distinct microhabitats (open water, sedges and inundated terrestrial grasses) develop in which microinvertebrate community structure was assessed across such habitats during the 2009–2010 flooding season. Depth was highest (ANOVA, P < 0.05) in the open‐water microhabitat and lowest within inundated grasses. Conductivity, total phosphorus and chlorophyll a were all highest (ANOVA, P < 0.05) within inundated grasses than in other microhabitats. A total of 46 microinvertebrate taxa were identified, and they were most diverse within the sedges. The abundance of microinvertebrates was highest (ANOVA, P < 0.05) within the inundated grasses and lowest within the open‐water zone. Given that microinvertebrates are an important food source for juvenile fish, their presence in high densities within inundated terrestrial grasses is a key determinant of fish production. This suggests the need for serious consideration of the importance of temporary floodplains when formulating conservation strategies for the Okavango Delta.