Changes in distribution of marine species

April 2020: Increasing ocean temperatures may be a significant contributor to latitudinal changes in population distribution, abundance, and seasonality of marine species. Marine species migrating away from the equator towards cooler poleward waters present significant risks to food security for coastal communities and may cause knock-on effects on local marine ecosystems.

Information

Climate change is increasing ocean temperatures across the globe which may significantly contribute to changes in population distribution, abundance, and seasonality of marine species. New evidence shows a general pattern of population increases towards the poles and decreases near the equator. These global distribution trends are identifiable across all groups of marine life such as plankton, marine invertebrates, fish, and seabirds. The results suggest that many marine species prefer colder conditions and have been unsuccessful in adapting to warmer conditions. Instead, many marine species are migrating poleward into more productive cooler regions. Many marine species are adapted to narrower ranges of temperatures than their terrestrial counter parts with fewer available microhabitats, particularly in the tropics where fish are already operating at upper temperature tolerance levels.

Implications and opportunities

Climate change induced increases in sea temperature may continue to drive latitudinal abundance shifts in marine species. This could impact local species abundance with high-impact knock-on effects for coastal communities and marine biodiversity hotspots. Changing distributions of marine species can have cascading effects on local ecosystems and people, which could include significant economic impact on local fisheries, reduced parasite control for open water fish farming, and reduced food and nutrition security for coastal communities and predator species. This will most likely have a severe impact on food security in the developing world and regions that rely on fish as their primary source for protein. In addition, species that unable to adapt to warming conditions or migrate will most likely face extinction. The researchers call for increased climate change mitigation efforts and to pair such efforts with increased habitat conservation programmes and decreased fishing quotas to reduce stressors for marine life.

Limitations

The study focuses on well-studied species and regions of the world and its results should be seen within the study’s geographic context. Additional long-term research will be needed to arrive at recommendations for less explored species and regions such as the high seas. Moreover, future research will have to account for underlying processes such as water oscillation impacting species movement to arrive at conclusive results pointing towards climate change as primary trigger for migration.

Sources

Daley, J., (2020). Ocean species are shifting toward the poles. Retrieved from https://www.scientificamerican.com/article/ocean-species-are-shifting-toward-the-poles/

Hastings, R. A., et.al. (2020). Climate Change Drives Poleward Increases and Equatorward Declines in Marine Species. Current Biology, 30, 1-6.  doi:10.1016/j.cub.2020.02.043