Aquatic macroinvertebrates can change their abundances, the number of ‘species’ and their presence in rivers because of environmental changes. The mud spill in the Paraopeba River is a major environmental change in this ecosystem. We observed that that mud spill might have reduced the number of ‘species’ of aquatic macroinvertebrates and induced the disappearance of a caddisfly ‘species’.

Estuaries that disconnect from the marine environment are vulnerable to human impacts and warrant special interventions to prevent ecosystem degradation. One such example is the mechanical opening of estuary mouths to prevent flooding of low-lying developments and facilitate periods of marine connectivity. This study has highlighted the importance of allocating sufficient freshwater to ensure that these practices successfully achieve management objectives.