Climate Change Disrupts The Distribution Of Marine Species

A new modeling study published in the journal Global Change Biology has found that, if climate change continues at the current pace, most of marine species will lose significant amounts of their suitable habitat ranges by 2100.

“Ocean’s biodiversity changes faster than in terrestrial ecosystems. To be able to protect marine species and with them all the marine resources that humans depend on, it is important to understand where and how marine species communities may change,” explained study co-lead author Irene Roca, a biologist at the Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB).

While many marine species have already started shifting their distributional ranges due to global warming, estimating what marine biodiversity will look like in the future is challenging, particularly since previous studies have focused solely on temperature as the main environmental factor leading to future changes in biodiversity.

Now, the scientists examined occurrence data of over 33,500 marine species and took into consideration seven environmental factors, including water depth, water temperature, salinity, and oxygen concentrations. Based on this data, they estimated whether and where these species are likely to occur in the future in the case of three different CO2 emissions scenarios.

The analysis revealed that species’ core habitat ranges – the marine areas in which chances are higher than 50 percent that a species occurs based on its preferred environmental conditions – may not only shift but also considerably decline in a high emissions scenario.

Besides habitat loss, the preferred habitat area of a variety of species will be disrupted. “Especially along the equator, our model projections revealed areas which are ill-suited for most marine species, for instance because of high temperatures,” Roca said.

According to the researchers, fragmented habitats will lead to diminished population sizes which can threaten many species with extinction (although new species could also develop in changed climatic conditions). Another significant problem is that different species can keep up with changing environmental conditions to varying degrees, thus leading to a restructuring of food webs and changes in the relationship between habitat-forming species such as coral and their inhabitants.

“Even though our model does not account for such interspecific interactions, the results provide valuable clues on how differently marine environments and communities are likely to change depending on the future CO2 emission scenarios,” said study co-lead author Dorothee Hodapp, a marine ecologist at HIFMB.

Understanding this high risk of critical reorganization of marine life will pose further challenges to conservation efforts. “We need to think ahead and work on effectively implementing the recent international agreements on biodiversity protection,” Hodapp concluded.