Posts Tagged 'mammals'

Projected amplification of food web bioaccumulation of MeHg and PCBs under climate change in the Northeastern Pacific

Climate change increases exposure and bioaccumulation of pollutants in marine organisms, posing substantial ecophysiological and ecotoxicological risks. Here, we applied a trophodynamic ecosystem model to examine the bioaccumulation of organic mercury (MeHg) and polychlorinated biphenyls (PCBs) in a Northeastern Pacific marine food web under climate change. We found largely heterogeneous sensitivity in climate-pollution impacts between chemicals and trophic groups. Concentration of MeHg and PCBs in top predators, including resident killer whales, is projected to be amplified by 8 and 3%, respectively, by 2100 under a high carbon emission scenario (Representative Concentration Pathway 8.5) relative to a no-climate change control scenario. However, the level of amplification increases with higher carbon emission scenario for MeHg, but decreases for PCBs. Such idiosyncratic responses are shaped by the differences in bioaccumulation pathways between MeHg and PCBs, and the modifications of food web dynamics between different levels of climate change. Climate-induced pollutant amplification in mid-trophic level predators (Chinook salmon) are projected to be higher (~10%) than killer whales. Overall, the predicted trophic magnification factor is ten-fold higher in MeHg than in PCBs under high CO2 emissions. This contribution highlights the importance of understanding the interactions with anthropogenic organic pollutants in assessing climate risks on marine ecosystems.

Continue reading ‘Projected amplification of food web bioaccumulation of MeHg and PCBs under climate change in the Northeastern Pacific’

Assessing the vulnerability of marine mammal subsistence species in the Bering Sea to climate change

The Bering Sea is a highly productive region of the Pacific Arctic. Native Alaskan communities rely heavily on the marine resources of the Bering Sea for survival. The timing of the formation and thaw of sea ice each year has a significant impact on the structure of the Bering Sea ecosystem. In its current state, the northern Bering Sea is a benthic-dominated ecosystem that supports many species of marine invertebrates, fish, birds, and mammals. Eight of these mammal species are relied on heavily by Native Alaskans for subsistence. However, this region is already experiencing the effects of climate change in ways that threaten the persistence of these communities as a result of changes in the timing of sea ice advance and retreat. As these changes progress, understanding the ways in which the ecosystem is vulnerable to climate change will be essential for resource managers and local communities to prepare to adapt. Climate change vulnerability analyses (CCVAs) provide a framework for quantifying vulnerability that can be useful for developing, implementing, and monitoring management solutions to reduce vulnerability. This study uses a CCVA to quantify the vulnerability of eight species of marine mammals in the Bering Sea as a first step in understanding how the communities that rely on them for subsistence are also vulnerable. Although some species are more vulnerable than others, this method allows managers to pinpoint sources of vulnerability for each one to develop strategies for reducing their vulnerability.

Continue reading ‘Assessing the vulnerability of marine mammal subsistence species in the Bering Sea to climate change’


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