Changes in Marine Biodiversity as an Indicator of Climate Change

Ambient temperature is very likely the most important environmental factor determining the distribution and diversity of life in the oceans. Hence, climate change is expected to alter marine biodiversity on a global scale. Here we review observed and predicted effects of climate change on the diversity of marine species. Overall, an increasing number of studies demonstrate that effects of climate change on marine biodiversity are already apparent from local to global scales. So far, long-term fish and plankton monitoring data have provided the most compelling evidence for climate-driven changes in species distribution and diversity, but studies involving other groups such as corals, seaweeds, and mammals are increasing. As a general pattern, tropical regions often experience a loss of species due to elevated heat stress, whereas temperate regions increase in diversity, as species migrate polewards. Net increases in diversity are also expected in the polar regions, but so far there are few observations to support this. Complex patterns of change can emerge where ocean warming is accompanied by the effects of sea level rise, acidification, habitat change, changes in ocean circulation, stratification, and other aspects of global change. From a management perspective, the conservation of biological diversity will provide insurance and resilience in the face of rapid global change. Cumulative impacts of exploitation, habitat destruction and other threats to biodiversity need to be minimized to maintain the adaptive capacity of marine ecosystems in the present and coming centuries. This might be particularly pressing in tropical regions and developing countries, which will face exceptional socio-economic and climate-related pressures, as well as in the polar regions, which are faced with a multitude of emerging pressures.