Impact of global climate change on fish growth, digestion and physiological status: developing a hypothesis for cause and effect relationships

Global climate change is impacting and will continue to impact on marine and estuarine fish and fisheries. Data trends show climate change effects ranging from fish growth, digestion physiology and performance in marine and freshwater ecosystems. The present study was designed to develop a concept for a cause and effect understanding with respect to climate-induced temperature and salinity changes and to explain ecological findings based on physiological processes. The concept is based on a wide comparison of fish species. The preliminary conclusion can be drawn that warming will cause a shift of distribution limits for fish species with a change in growth performance, gastric evacuation performance and physiology, or even extinction of the species in the world. In association with the elevated seawater temperature growth performance will also be changed with water quality parameters, for example, salinity. Our interpretations of evidence include many uncertainties about the future of affected fish species. Therefore, it is essential to conduct research on the physiology and ecology of marine, estuarine and freshwater fishes, particularly in the tropics where comparatively little research has been conducted and where temperature fluctuation is comparatively lower. As a broader and deeper information base accumulates, researchers will be able to make more accurate predictions and forge relevant solutions.