SYMP 4-4
Detecting and attributing recent local biodiversity gains and losses in coastal marine systems
The modern biodiversity crisis reflects global extinctions and local introductions, and human activities have dramatically altered the rates and scales of the processes that regulate local species diversity. Surprisingly, temporal trends in local biodiversity (quantified as species richness) of local assemblages have not universally reflected predictions of net loss, raising questions about the severity of the biodiversity crisis. Recent efforts to quantify local species richness temporal change have employed a wide range of methods for data selection and analysis, leaving open the possibility that biases in data availability, analytical approaches or other sources are contributing to the conclusions of how biodiversity has changed. We used hierarchical mixed effects models to analyze 439 time series, from 189 sites in coastal marine ecosystems in the context of ecologically relevant factors, including human impacts.
Results/Conclusions
We found that net species loss was associated with localized effects of anthropogenic impacts, but net species gain prevailed in the absence of documented impacts. In particular, communities with relatively low richness experienced the greatest gains and assemblages low in the food chain exhibited greater increases than consumers and predators. These patterns at local scales do not contradict evidence of accelerating global extinctions, and are consistent with local species loss in areas with direct human impacts, complemented by invasions and range expansions. Impacted sites were under-represented, suggesting caution in interpreting general biodiversity trends from analyses that represent a non-random sample of the planet. Sound application of basic ecological principles should aid in predicting future local biodiversity change in the Anthropocene.