Grey mullet (Mugilidae) as possible indicators of global warming in South African estuaries and coastal waters

The grey mullet usually occur in large numbers and biomass in the estuaries of all three South African biogeographic regions, thus making it an ideal family to use in terms of possibly acting as an environmental indicator of global warming. In this analysis the relative estuarine abundance of the dominant three groups of mugilids, namely tropical, warm-water and cool-water endemics, were related to sea surface coastal temperatures. The study suggests a strong link between temperature and the distribution and abundance of the three mullet groups within estuaries and indicates the potential of this family to act as an indicator for future climate change within these systems and adjacent coastal waters. •The distribution and abundance of mullet in South African estuaries is linked to temperature•The distribution of tropical mullet may expand by the end of the century. •The distribution of endemic temperate mullet will likely show little change by the end of the century. •Changes in the abundance of temperate mullet may be apparent by the end of the century.