Ingestion rates and grazing impact of the brackwater mussel Brachidontes virgiliae in Lake St Lucia, iSimangaliso Wetland Park, South Africa

Research reveals that the brackwater mussel Brachidontes virgiliae, dominant during wet phases in Lake St Lucia, iSimangaliso Wetland Park, exhibits significant grazing impact on phytoplankton biomass. Using an in situ gut fluorescence technique, scientists estimated ingestion rates of 5.78 µg pigment per individual per day during the wet season and 4.44 µg pigment per individual per day in the dry season, with higher rates likely due to increased water temperature and food availability. The study found that mussel aggregations could deplete up to 20 times the available phytoplankton biomass locally, particularly in northern reaches where densities are highest. These findings suggest that the ecological dynamics of Lake St Lucia may shift during flood events, necessitating integration into existing ecological models.

Nel, H., Perissinotto, R., & Carrasco, N. (2016). Ingestion rates and grazing impact of the brackwater mussel Brachidontes virgiliae in Lake St Lucia, iSimangaliso Wetland Park, South Africa. African Journal of Marine Science, 38(2), 241–248. https://doi.org/10.2989/1814232x.2016.1186733