The impact of climate change on marine ecosystems is still poorly understood. The distribution of marine populations in response to climate change could be a key clue to the future of marine ecosystems in our changing world. Sorte et al. (2011) studied the population-level variation of temperature tolerance in several populations of marine invertebrates. There were three separate case studies, all designed to better understand the lethality of rising water temperature. The authors identified the western Atlantic as a target zone for populations right at the edge of their temperature tolerance. They found both mussel and subtidal epibenthic (organisms living on the sea bed) species showed the highest susceptibility to temperature change. By compiling experimental data with current thermotolerance data and climate predictions the authors concluded that most populations of the intertidal Littorina snail were able to overcome geographic differences in temperature tolerance via acclamation. The authors concluded that particular species’ life history strategy and dispersal ability may determine their temperature adaptation abilities more than their overall geographical location.—Connor O’Boyle
Sorte, C., Jones, S., Miller, L., 2011. Geographic variation in temperature tolerance as an indicator of potential population responses to climate change. Journal of Experimental Marine Biology and Ecology 400, 209-217.
The relationship between ocean temperature changes and marine ecosystems is an important and relevant issue in the current changing climate. Sorte et al. studied multiple marine species and their physical and biological patterns to address how tolerances vary geographically and whether certain species have better ability to acclimate. They hoped to provide a starting point on which broader questions on the future of marine ecosystems could be based.
In their study they did three main experiments, the first was a trans-continental comparison using species that were geographically isolated, to test the impact of geographic location on a species survival. They collected four epibenthic species that grow on both the East and West coast of the United States and looked at their responses to their geographical independent temperature fluctuations. In their second experiment the authors compared mussel populations from France and the USA, in their abilities to cope with lab controlled marine temperature changes. The third experiment tested the long-term temperature acclimatization of Littorine snails from the same region of the western Atlantic.
The results of these experiments showed that the East Coast populations of epibenthic species were living closer to their tolerance levels than the West Coast ones, and that the higher temperature fluctuations on the East Coast of the United States create a greater risk for these species going forward. The authors concluded that if acclimatization is similar within species, individuals on the East Coast could experience dramatic population declines because of the current proximity of water temperatures to lethal levels. The authors found the mussels from France had a higher temperature tolerance than the US population, but both decreased in tolerance after multiple temperature exposures. These findings led the authors to believe that finding temperature history of a population’s habitat is essential in predicting the survivability of that population. The findings of the last experiment showed that temperature tolerance increased with lab acclamation but the response in geographic temperature tolerance differed between the species of snail. They concluded that in populations with low tolerance, survivability would depend on dispersal distance and the specific environmental behaviors (such as using tall eel grass to buffer temperature change).
The authors concluded that additional studies need to be made to analyze coping behaviors for species experiencing wide temperature changes in order to accurately predict population change. They found that in tunicates and bryozoans the temperature tolerance was related to habitat temperatures. The differences in tidal habitat zone could play a large part in a species’ ability to adapt and the authors established that populations with limited dispersal distances could be negatively impacted because of their inability to find suitable water conditions to recolonize. The organisms living in the western Atlantic could experience more drastic population change due to the heightened water temperature levels with species living in water very close to their lethal temperature.