Researchers analyzed the abundance of the most common types of marine organisms and found that their ranges shifted from the equator toward higher latitudes. The ongoing warming of waters will exacerbate this process, and would jeopardize the fishing zone depends on the food of three billion people. The results of a study published in the journal Current biology.
Climate change has led to the increase in the average temperature of the oceans by one degree Celsius compared to pre-industrial levels. Especially strong heating occurred in Equatorial latitudes. As a rule, marine organisms are stenothermy and poorly adapted to the increasing temperature.
The most pronounced heating of the surface waters of the oceans observed in the Equatorial latitudes. This process can lead to negative consequences for marine ecosystems, and the economy. The decrease and increase in the population of one species affects all species with which it interacts, and leads to a restructuring of food chains and the redistribution of ecological niches. For economic activity a key role is played by the Equatorial latitudes, where the main fishing zone. In the diet of three billion people on Earth protein comes from seafood, and 12 percent of jobs in the global labor market depends on fisheries.
Ruben Hastings (Reuben A. Hastings) from the University of Bristol and her colleagues conducted a meta-analysis of abundance data of marine animals, using works published between 1991 and 2016 in the Global database on biodiversity and the world registry of marine species. For review we selected only those types of population change which for 25 years was recorded at least 50 times. This approach allowed us to exclude poorly known marine life, the number of which has not yet been the subject of long-term observations. In the end, the authors studied 304 species and combined them into the following groups: phyto – and zooplankton, micro – and macroalgae, reptiles, mammals, seabirds, invertebrates, fish and their larvae.
The spatial scale of the study covered 540 ocean (the number of each species measured at least 50 times, but the number of plots where it occurred, was in the range of from 1 to 20). Data were processed using the tool ModestR, which allows you to integrate taxonomic and ecological characteristics of living organisms to map their distribution.
On the distribution of marine organisms is affected not only by the temperature of the upper water layers, but also changes its pH and salinity, and movement of sea ice and the presence of necessary for living biological resources. But even with these factors, researchers found a decrease in the number of species in those habitats that were closer to the equator, and increases toward the polar latitudes. The most active growth of species abundance observed in temperate latitudes on the continental shelves of Europe, North America and Japan. Strongest fluctuations in the number of affected fish, and the most resistant to warming turned out to be phytoplankton.