A study that appeared recently in PLoS ONE, published by marine biologist Dr. Kristin Kaschner, shows that about half the species of marine mammals will experience a loss in their habitat and the ranges of the other half may increase by up to 40 percent due to climate change. Kaschner is a research affiliate at the Institute of Biology I of the University of Freiburg, and worked with researchers from the U.S., Canada and Brazil.
Marine mammal diversity “hotspots” are found in the temperate waters of the southern hemisphere, and it is predicted that the number of cetacean and pinniped species will stay quite high in these areas in the next 40 years, regardless of climate change. However, the predictions for individual species is quite different.
The research team made these predictions of patterns of global marine mammal biodiversity by using a species distribution model which incorporated oceanographic data such as depth, temperature, sea ice concentrations and data on marine mammal species occurrence.
They used an intermediate climate change scenario to investigate the effects of global warming on individual species’ distribution by the yearh 2050. Based on these results, the expected change in the distribution of marine mammals by 2050 was small, except in Antarctic and Arctic waters where only a few species currently reside; in these waters, up to an 80 percent loss of native species was predicted, while total biodiversity could increase by more than one order of magnitude due. The dramatic increase in biodiversity is due to climate change as the habitats of temperate and subpolar species expands. Tropical waters will also experience a minor loss in diversity.
Because they chose an intermediate climate change scenario, the results of this study are likely to be an underestimate of the true impacts of climate change. Their models were also unable to account for indirect effects like changes in prey distribution or breeding habitats.
Studies like this one are important in determining overall marine biodiversity. Marine mammals can be indicitive of this because they are key members of the food web. Identifying cetacean and pinniped hotspots can help scientists and policy makers determine areas that require conservation regulations. This is one of the primary goals of the Convention of Biological Diversity: to establish a network of marine protected areas covering at least ten percent of the global ocean surface by 2020. Sadly, with just over one percent protected, the Convention is far from reaching its goal. Hopefully, studies like this will make it easier to establish new MPAs across the ocean surface.
Copyright © 2011 by Marine Science Today, a publication of OceanLines LLC