Simultaneous 'hotspots' and 'coldspots' of marine biodiversity and implications for global conservation

Global and smaller-scale assessments of biodiversity typically use only 'species' measures. Using a broader set of concepts, we show that different biodiversity elements can exhibit contrasting patterns within the same environment. The Arabian Gulf, estuaries and hydrothermal vents are stressful environments having low species richness yet high beta(turnover)-diversity, and around vents taxonomic distinctness is also marked. Similarly, in the Atlantic, beta-diversity of starfishes declines from the coasts to the deep sea, contrasting with patterns of species richness and taxonomic distinctness. Thus, environments can, unexpectedly, be both 'hotspots' and 'coldspots' of biodiversity. These results have major implications for international conservation programmes which use biodiversity as a major criterion for identifying priority regions. Unpicking and prioritizing biodiversity's different threads will help environmental organisations better define and target hotspot regions. Current applications of complementarity could theoretically be expanded from a regional to a global perspective, to determine areas in which biodiversity representation is maximal but concepts are not applicable to assemblage properties (e.g. taxonomic distinctness).