For over a decade, Prof. Ben Halpern, of the Univ. of California, Santa Barbara’s Bren School of Environmental Science and Management, has focused his research on the global consequences of human activities on marine species.
In the face of national and international efforts to combat climate change, Halpern’s interest shifted towards understanding how “one of the most pernicious threats to marine biodiversity” is likely to alter ocean life in the future.
According to a study published in Nature Climate Change, temperature shifts in the ocean will lead to greater marine migration towards the poles. Additionally, certain species may expand their range. But species with limited thermal tolerances may be threatened with extinction.
“We did a modeling study,” explains Halpern in an interview with R&D Magazine. “We had information and maps on what temperature species like and can tolerate, and the ranges of where they currently live. We then (modeled) changes to global ocean temperatures each year, moving forward to 2100, and tracked how species are expected to follow those shifts in ocean temperature. It was a huge ‘big data’ exercise.”
The team tracked the movements of nearly 13,000 species, including fish, corals, jellies, snails, seaweed and crabs, among others. Study co-authors David Schoeman and Jorge Garcia Molinos, writing in The Conversation, noted they modeled two scenarios: one where the temperatures increased by 2.5 C by 2100, and another where they increased by 1 C. The species’ shifts suggested marine ecosystems will become more homogenous, as certain species increase their footprint, leading to a lack of biodiversity in marine populations.
However, areas such as the Coral Triangle, which boasts an ample variety of marine life, from whale sharks to sea turtles, may be threatened. According to the researchers, more than 5,000 of the species studied are found in the Coral Triangle. “Species living in tropical seas already live close to their thermal optimum,” write the researchers in The Conversation. “As temperatures increase, they will exceed the upper thermal limits of some species. When this happens, some species will adapt, for instance, by seeking out micro-refuges, such as small patches of cool water caused by upwelling, or they might resort to living in deeper waters, if the water is clear enough.”
The study’s projections showed between 500 and 1,000 species from the area migrating to different waters.
“Many countries in these regions are highly dependent on marine species for food, tourism and their local economies,” says Halpern. “Such dramatic shifts in marine biodiversity in these regions could have profound consequences for people living there.”
Already, species are feeling the effects of climate change, according to Halpern. Rocky intertidal creatures, such as barnacles, in places around the world, and pelagic fish in the north Atlantic are a couple of examples.
“Climate change is a global challenge, so ultimately we need global solutions, like strong commitments and actions by countries to significantly (reduce) carbon emissions,” said Halpern. “But we can also build resilience into systems by reducing other threats, like overfishing and pollution, so that species have a bit more ‘breathing room’ to be able to deal with the pressures from climate change.”
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