Temporal turnover in marine assemblages in a rapidly changing world
Recent research highlights the potential of anthropogenic climate change to restructure marine communities. Range shifts have been documented for many species, but community responses are not well understood. Here we analyse a 29 year time series of marine fish communities, across a 670 km by 940 km area to the west of Scotland. We quantify both temporal alpha and temporal beta diversity.
Our analysis shows that species richness is maintained through time, but, consistent with the prediction that turnover is accelerating relative to baseline levels, we uncover marked changes in species composition. Beta diversity partitioning reveals that turnover in species identity is a consistently stronger driver of community reorganization than species richness. Temporal turnover rates are not constant across the assemblages. Northern localities increasingly resemble more southerly ones in terms of species identity; this trend mirrors the pattern of rising but less differentiated ocean temperatures over the same time scale.