In January 2019, we experienced a fish die off at the Capricorn Business Park Lake which forms part of the Muizenberg East Biodiversity Cluster, managed by Andrea von Gunten.

The cause of the die off is as a result of a blue-green algae (Cylindropermopsis sp) which was confirmed in the lab at the time. The algae is naturally occurring and poses no threat to humans if not ingested (as usual at this site, no person should drink or be in full contact with this water). Whilst the exact triggers which caused the die off event are not known at this stage, the build-up of nutrients over a number of years will certainly be a contributing factor. Algal blooms cause a depletion of oxygen in the water which as a result causes the fish die off.

However, there was a positive outcome from this algal bloom, when as a result of the fish die off, the conservation team was able to identify new species for the Muizenberg East Biodiversity Cluster: a Mozambican longfin eel.

Other species identified included Common carp, Mozambican tilapia, Banded tilapia, Southern mullet and Nile kurper.

Well done to all who were involved in the cleanup effort – in total, 4 tonnes of fish were collected from the Lake.