Short-term recovery of macroinvertebrate communities following a flash flood in an urban river: a case study of the Palmiet River in Durban, South Africa

Abstract

Extreme floods have become frequent in the urban Palmiet River due to exacerbating climate change. Therefore,  the current study aimed to explore a short-term recovery of macroinvertebrate communities following a flash flood in the Palmiet River, KwaZulu-Natal, South Africa. Different biotopes, i.e. stones, gravel sand and mud, and vegetation were sampled after the March-April heavy rain in 2018. Ephemeroptera, Odonatan, and Hemipteran have shown similar trends across weeks at all sites. Plecoptera and Coleoptera started recovering at week four However, the total abundance and taxa richness had significantly recovered during the fourth week at site 2 and 3, and fifth week at site 1. Communities have shown no significant difference for each site from weeks six to eight (ANOVA, p> 0.5), which implies that climax on macroinvertebrate communities was reached at week six. Hydrologic regime change has not influenced water quality parameters across all weeks (ANOVA, p > 0.5) and this was also reflected on the average score per taxon (ASPT), which has shown no significant difference (ANOVA, p > 0.5) across weeks at all sites. These findings provide a baseline for future studies on flood effect on urban streams and supplement the understanding of the effects of sudden hydrologic regime changes on macroinvertebrate communities.