WORKING GROUPS

Global change and the conservation of high latitude marine mammals

Overview

We are currently witnessing significant and rapid changes in high latitude ecosystems, manifested most noticeably by rapid declines in summer ice extents (Maslanik et al 1996), significant reductions in perennial ice cover (Comiso, 2002; 2006), and declines in sea ice thickness (Yu et al. 2004, Belchansky et al. 2008) in many areas of both the Arctic and Antarctic. Furthermore, some predictions indicate that circumpolar sea ice cover in the Arctic may decline by as much as 20% by 2050 (e.g. Vinnikov, et al., 1999).

Rapid changes in temperature regimes and ice conditions in arctic ecosystems pose significant challenges for marine mammal species with foraging strategies adapted to ice-associated productivity and those that use sea ice as a platform for breeding and social activity (Ragen et al. 2008). Some species are truly "arctic" in their habits, being inherently tied to sea ice for survival, and may be most sensitive to dramatic changes in temperature and ice conditions (Laidre et al. 2008). Some species, often described as "subarctic" are also of concern as they use sea ice as a platform for breeding or social activity, or rely on food-webs that originate from ice-associated productivity for some portion of their life cycle (Johnston et al. 2005, Laidre et al. 2008). The magnitude of the threat faced by these species is further complicated by the restricted range some exhibit (e.g. hooded seals are found only in the North Atlantic) and the narrow range of habitat needs they may require (e.g. bearded seals are benthic foragers requiring relatively shallow habitats). Finally, some of these species are commercially exploited (Johnston et al. 1995), or function as important food sources and cultural icons in high latitude communities (Hovelsrud et al. 2008) and their sustainability is important for the humans that rely on them (e.g. Metcalf and Robards 2008).

While many high latitude species have evolved with natural climate variability at decadal scales (e.g. the North Atlantic Oscillation), they may not be prepared for rapid and possibly unidirectional changes in climate that are occurring now (Johnston et al. 2005, Moore & Huntington 2008). While the mechanisms by which climate change and environmental variability affect polar regions are being investigated, how these changes cascade to other ecosystem components remain poorly understood at all spatial and temporal scales (Fraser and Hofmann 2003). Furthermore, we have little knowledge of how the ecological roles of marine mammals may change in high latitude ecosystems in the Northern Hemisphere if their populations are dramatically affected, as has been noted in Antarctic systems after the depletion of several mega-vertebrate predator populations. (e.g. Laws 1977, Clapham and Baker 2001). For Arctic species, among the best-studied are bowhead whales, polar bears, ringed seals and bearded seals, where regional (and to some extent larger scale) effects on their biology have been noted (Moore & Huntington, 2008). In some cases, expansions in habitat use may be occurring with warming at high latitudes. In the case of gray whales, acoustic detections throughout the winter in the Beaufort Sea suggest that these animals are overwintering farther north, ostensibly because of reductions in sea ice and warming temperatures (Stafford et al. 2007). In the case of polar bears the opposite appears to be occurring - landward shifts in den distributions have been linked to reductions in the availability of stable multi-year ice (Fishbach et al. 2007); some populations are declining due to increased mortality of both juvenile and adult bears, stemming from changes in the timing of spring sea ice breakup (e.g. Regehr et al. 2007). Where research effort has been directed at commercially exploited species - as in the case of harp seals - there is growing evidence that climate variability, in conjunction with other anthropogenic mortality, can have significant effects on their populations (Johnston et al. 2005). However, for many species such as hooded seals, narwhal and beluga whales, very little is known about their responses to current changes in climate at regional scales or greater (Moore & Huntington, 2008).

Objectives

1. Support Duke Principal Investigators to select colleagues from other institutions to establish a working group for the study and conservation of climate change/ variability and high latitude marine mammals. The focus will be on ice seals, beluga and gray whales but will be open to the study of any high latitude species of concern. The proposed working group will further enable our group to engage with scholars on main campus and at other institutions to become a world leader in integrative studies of marine mammals facing the effects of climate change.
2. Hold a 3 day meeting to bring the working group together to set priorities and direction for possible research and educational goals of the working group. This would include supporting the ongoing development of a proposal to the National Science Foundation's Partnership in Research and Education (PIRE) program. Duke currently has a PIRE pre-proposal under consideration by NSF focusing on the conservation of high latitude marine mammals and climate change, in conjunction with the Russian Academy of Sciences Shirshov Institute of Oceanology. This working group would act as an important guiding body for the further development of this proposal and subsequent program when funded. The meeting would establish priorities for future proposals and provide guidance for the development of a new graduate climate science course to be taught at the Duke Marine lab.
3. Develop a new graduate course to be taught at the Duke University Marine Laboratory. This course will focus on climate variability and global change and their effects on high latitude marine mammals and other marine megafauna, including management and policy actions to mitigate harmful effects. The proposed course will compile, integrate and teach new developments in our understanding of how climate variability and global change are affecting sea ice conditions, oceanographic regimes and the ecology of lower trophic level fauna at high latitudes, as well as all forms of marine megafauna. These study themes will be conveyed to students within the context of how marine mammals will deal with changes predicted for high latitudes and how human systems can adapt to and manage these changes.

Working group members

David Johnston, Nicholas School of the Environment
Ari Friedlaender, Nicholas School of the Environment
Douglas Nowacek, Nicholas School of the Environment
Andrew Read, Nicholas School of the Environment
Pat Halpin, Nicholas School of the Environment
Susan Lozier, Nicholas School of the Environment
Richard Barber, Nicholas School of the Environment
Alexander Vedenev, Shirshov Institute of Oceanology, Russian Academy of Sciences
Dmitry Glazov, Shirshov Institute of Oceanology, Russian Academy of Sciences
Sue Moore, University of Washington/NOAA