What are the Climate Change Impacts on Marine Ecosystems?

The climate, also defined as "the regular pattern of weather conditions of a particular place" (Oxford Dictionary), has been identified through peer-reviewed and corroborated research to have warmed about 1 degree C since the pre-industrial era as a result of not only natural but as well anthropogenic causes.

This change in Earth's average temperature, aka global warming, has been registered to have a significant impact on several aspects of Earth's natural composition, one very important is the Sea. 

Organisms in the ocean are highly responsive to temperature as it affects their natural physiological and phenological cycle: each species has a specific range of temperature in which they tend to experience a stronger somatic growth, reproductive conditions and finally simple survival.

When global warming is inserted in the picture, these niches of survival are put into question. The only way for organisms to survive this event is for them to develop some sort of thermal adaptation which would cause a shift and change in the range of these niches. The natural response to environmental change for living organisms is to trigger an evolution of the species. However, evolution always happened throughout several centuries and it is therefore difficult to capture the possible future scenarios in laboratory experiments. 

"The net change in marine biodiversity at the local scale is a product of these counteracting temperature-dependent changes in immigration, phenology, physiology and interactions- and consequently extinctions" (Hillebrand, 2018).

Assuming temperature change as the most influential variable, the expectations towards population shifts in biodiversity may "lead to numerous local extinction in the sub-polar regions, the tropics and semi-enclosed seas. Simultaneously, species invasion is projected to be most intense in the Arctic and the Southern Ocean. Together, they result in dramatic species turnovers of over 60% of the present biodiversity, implying ecological disturbances that potentially disrupt ecosystem services" (Cheung et al, 2009).

However, other variables need to be considered. Ocean acidification is a major variable affecting biodiversity in the ocean considering that approximately one quarter of the carbon dioxide emitted to the atmosphere is absorbed by it, resulting in changes in the chemical balance of the sea water. This causes a reduced availability of carbonate minerals, such as corals, which represent a major source of feeding ground for organisms, thus forcing them to mobilitate to a new area or in the worst case to extinction. 

As a conclusion, considering the complexity of predicting changes in marine biodiversity and conservation, which will require well-resolved and long-term continuous observation, in order to optimize the mitigation of anthropogenic impacts we must consider public perceptions of the ocean, market forces and the sustainable blue economy. 

References:

Anne Strack et al, Plankton response to global warming is characterized by nonuniform shifts in assemblage composition since the last ice age, Nature Ecology & Evolution (2022).

Louthan AM, Morris W, Climate change impacts on population growth across a species' range differ due to nonlinear responses of populations to climate and variation in rates of climate change, PLoS One. 2021;16(3).

Schierenbeck KA. Population-level genetic variation and climate change in a biodiversity hotspot. Ann Bot. 2017;119(2):215-228.

Cheung WWL, Lam VWY, Sarmiento JL, Kearney K, Watson R, Pauly D. Projecting global marine biodiversity impacts under climate change scenarios. Fish and Fisheries. 2009;10(3):235–51.

Secretariat of the Convention on Biological Diversity (2009). Scienti c Synthesis of the Impacts of Ocean Acidi cation on Marine Biodiversity. Montreal, Technical Series No. 46, 61 pages.

Herbert-Read, J.E., Thornton, A., Amon, D.J. et al. A global horizon scan of issues impacting marine and coastal biodiversity conservation. Nat Ecol Evol 6, 1262–1270 (2022).