Kit M. Kovacs

Impacts of changing sea-ice conditions on Arctic marine mammals

Arctic sea ice has changed dramatically, especially during the last decade and continued declines in extent and thickness are expected for the decades to come. Some ice-associated marine mammals are already showing distribution shifts, compromised body condition and declines in production/abundance in response to sea-ice declines. In contrast, temperate marine mammal species are showing northward expansions of their ranges, which are likely to cause competitive pressure on some endemic Arctic species, as well as putting them at greater risk of predation, disease and parasite infections. The negative impacts observed to date within Arctic marine mammal populations are expected to continue and perhaps escalate over the coming decade, with continued declines in seasonal coverage of sea ice. This situation presents a significant risk to marine biodiversity among endemic Arctic marine mammals.

FEEDING RATES OF SEALS AND WHALES

SUMMARY (1) The hypothesis that rates of food consumption by marine mammals are similar to those of terrestrial mammals was tested by comparing rates of food consumption of nongrowing and growing, juvenile and adult pinnipeds (Carnivora: Caniformia) and whales (Cetacea) to terrestrial Carnivora of known mass. (2) Daily maintenance rates of energy ingestion for adult pinnipeds were not significantly different from those of adult terrestrial carnivores but were about 28% lower than those of terrestrial carnivores with the mustelids excluded. Apparent differences in energy requirements of phocid and otariid seals appeared to result from differences in activity among the experimental animals available for comparison. Data on energy required by cetaceans for maintenance were not available. (3) Among pinnipeds, there was no significant difference in the rates of energy ingested by growing juvenile phocid seals and growing juvenile otariids. Growing juvenile phocids ingested about 1 38 times more energy than juvenile phocid seals at maintenance. The latter required about 1-40 times more energy for maintenance than adult phocids of similar size. (4) The rate of energy ingestion by growing juvenile pinnipeds was relatively higher than for the juvenile terrestrial carnivores sampled. This result appears to arise from differences in body masses and growth rates represented by the two samples rather than from any fundamental differences between juvenile pinnipeds and terrestrial carnivores. (5) Rate of biomass consumption, although frequently used as a measure of food consumption, is not particularly appropriate in comparative studies because it neglects differences in the energy content of food. Nonetheless, the 95% confidence region for rates of biomass ingestion in relation to body mass in marine mammals (seals and whales) included most of the estimates for biomass ingestion rates of terrestrial carnivores held in

Biomagnification of polybrominated diphenyl ether and hexabromocyclododecane flame retardants in the polar bear food chain in Svalbard, Norway.

Concentrations of brominated flame retardants (BFRs), including polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD), were investigated in an arctic marine food chain consisting of four invertebrate species: polar cod (Boreogadus saida), ringed seals (Pusa hispida), and polar bears (Ursus maritimus). The most abundant BFR, brominated diphenyl ether (BDE)-47, was found in detectable concentrations even in zooplankton, the lowest trophic level examined in this study. Most of the investigated BFRs biomagnified as function of tropic level in the food chain. A noticeable exception occurred at the highest trophic level, the polar bear, in which only BDE-153 was found to increase from its main prey, the ringed seal, indicating that polar bears appear to be able to metabolize and biodegrade most BFRs. In contrast, lower-brominated PBDEs, particularly BDE-47, showed clear signs of bioaccumulation in zooplankton, polar cod, and ringed seals. We suggest that this discrepancy in the fate of BFRs among the different species may be related to greater induction of oxidative detoxification activities in the polar bear. Absorption and debromination rates may be more important for bioaccumulation rates of BFRs in zooplankton, polar cod, and ringed seals. Lipid weight-based concentrations (LWCs) and whole body-based concentrations (WBCs) of BFRs were used to assess biomagnification factors (BMFs). Whole-body concentrations gave the most realistic BMFs, as BMFs derived from LWCs seem to be confounded by the large variability in lipid content of tissues from the investigated species. This study demonstrates that PBDEs and HBCD have reached measurable concentrations even in the lower trophic levels (invertebrates and fish) in the Arctic and biomagnifies in the polar bear food chain.

Maternal investment and neonatal growth in phocid seals

(1) This paper draws together information on neonatal size at birth, weaning mass, growth rates during the nursing period and duration of lactation of phocid seals in order to examine similarities and differences in these aspects of life-history patterns within the group. Broader interspecific comparisons are also made in order to evaluate the adaptive developmental responses of phocid seals during the period of maternal investment in contrast to terrestrial carnivores and to mammals generally. (2) Individual phocid offspring of most species are large and precocial, but female phocid seals as a group do not invest more energy per litter than many other carnivores and not substantially more than mammals generally at the time of parturition. (3) The relative mass of individual phocid seals at weaning is more uniform within the group than is mass at birth. This similarity is achieved by compensatory variation of growth rates and the duration of lactation. (4) Although data are limited, it appears that maternal investment differs between the sexes in all species which are sexually dimorphic with respect to body size.

Comparative diving patterns of pinnipeds and seabirds

General ecological information resulting from modern dive studies has been limited because analyses and conclusions are study- and species-specific. In this work, a series of unrelated divers was studied and compared using the same analytical procedures. More than 230 000 dives from 12 species were analyzed, and ∼140 000 of these dives were classified according to dive shape. The species included one cormorant, three penguins, two eared seals, five true seals, and a walrus. Dive profiles could generally be characterized as one of four shapes: square, V, skewed right, or skewed left. In light of this, a universal shape classification protocol was developed that also offers potential solutions for “on board” memory limitations and transmission constraints for archival time–depth recorders and satellite-linked time–depth recorders. Comparisons of dive data recorded with different sample intervals indicated the need for a standardization relative to mean dive duration (i.e., an equal number of data points per...

The broad footprint of climate change from genes to biomes to people

Accumulating impacts Anthropogenic climate change is now in full swing, our global average temperature already having increased by 1°C from preindustrial levels. Many studies have documented individual impacts of the changing climate that are particular to species or regions, but individual impacts are accumulating and being amplified more broadly. Scheffers et al. review the set of impacts that have been observed across genes, species, and ecosystems to reveal a world already undergoing substantial change. Understanding the causes, consequences, and potential mitigation of these changes will be essential as we move forward into a warming world. Science, this issue p. 10.1126/science.aaf7671 BACKGROUND Climate change impacts have now been documented across every ecosystem on Earth, despite an average warming of only ~1°C so far. Here, we describe the full range and scale of climate change effects on global biodiversity that have been observed in natural systems. To do this, we identify a set of core ecological processes (32 in terrestrial and 31 each in marine and freshwater ecosystems) that underpin ecosystem functioning and support services to people. Of the 94 processes considered, 82% show evidence of impact from climate change in the peer-reviewed literature. Examples of observed impacts from meta-analyses and case studies go beyond well-established shifts in species ranges and changes to phenology and population dynamics to include disruptions that scale from the gene to the ecosystem. ADVANCES Species are undergoing evolutionary adaptation to temperature extremes, and climate change has substantial impacts on species physiology that include changes in tolerances to high temperatures, shifts in sex ratios in species with temperature-dependent sex determination, and increased metabolic costs of living in a warmer world. These physiological adjustments have observable impacts on morphology, with many species in both aquatic and terrestrial systems shrinking in body size because large surface-to-volume ratios are generally favored under warmer conditions. Other morphological changes include reductions in melanism to improve thermoregulation, and altered wing and bill length in birds. Broader-scale responses to climate change include changes in the phenology, abundance, and distribution of species. Temperate plants are budding and flowering earlier in spring and later in autumn. Comparable adjustments have been observed in marine and freshwater fish spawning events and in the timing of seasonal migrations of animals worldwide. Changes in the abundance and age structure of populations have also been observed, with widespread evidence of range expansion in warm-adapted species and range contraction in cold-adapted species. As a by-product of species redistributions, novel community interactions have emerged. Tropical and boreal species are increasingly incorporated into temperate and polar communities, respectively, and when possible, lowland species are increasingly assimilating into mountain communities. Multiplicative impacts from gene to community levels scale up to produce ecological regime shifts, in which one ecosystem state shifts to an alternative state. OUTLOOK The many observed impacts of climate change at different levels of biological organization point toward an increasingly unpredictable future for humans. Reduced genetic diversity in crops, inconsistent crop yields, decreased productivity in fisheries from reduced body size, and decreased fruit yields from fewer winter chill events threaten food security. Changes in the distribution of disease vectors alongside the emergence of novel pathogens and pests are a direct threat to human health as well as to crops, timber, and livestock resources. Humanity depends on intact, functioning ecosystems for a range of goods and services. Enhanced understanding of the observed impacts of climate change on core ecological processes is an essential first step to adapting to them and mitigating their influence on biodiversity and ecosystem service provision. Climate change impacts on ecological processes in marine, freshwater, and terrestrial ecosystems. Impacts can be measured on multiple processes at different levels of biological organization within ecosystems. In total, 82% of 94 ecological processes show evidence of being affected by climate change. Within levels of organization, the percentage of processes impacted varies from 60% for genetics to 100% for species distribution. Most ecological processes now show responses to anthropogenic climate change. In terrestrial, freshwater, and marine ecosystems, species are changing genetically, physiologically, morphologically, and phenologically and are shifting their distributions, which affects food webs and results in new interactions. Disruptions scale from the gene to the ecosystem and have documented consequences for people, including unpredictable fisheries and crop yields, loss of genetic diversity in wild crop varieties, and increasing impacts of pests and diseases. In addition to the more easily observed changes, such as shifts in flowering phenology, we argue that many hidden dynamics, such as genetic changes, are also taking place. Understanding shifts in ecological processes can guide human adaptation strategies. In addition to reducing greenhouse gases, climate action and policy must therefore focus equally on strategies that safeguard biodiversity and ecosystems.

Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century

Abstract Arctic marine mammals (AMMs) are icons of climate change, largely because of their close association with sea ice. However, neither a circumpolar assessment of AMM status nor a standardized metric of sea ice habitat change is available. We summarized available data on abundance and trend for each AMM species and recognized subpopulation. We also examined species diversity, the extent of human use, and temporal trends in sea ice habitat for 12 regions of the Arctic by calculating the dates of spring sea ice retreat and fall sea ice advance from satellite data (1979–2013). Estimates of AMM abundance varied greatly in quality, and few studies were long enough for trend analysis. Of the AMM subpopulations, 78% (61 of 78) are legally harvested for subsistence purposes. Changes in sea ice phenology have been profound. In all regions except the Bering Sea, the duration of the summer (i.e., reduced ice) period increased by 5–10 weeks and by >20 weeks in the Barents Sea between 1979 and 2013. In light of generally poor data, the importance of human use, and forecasted environmental changes in the 21st century, we recommend the following for effective AMM conservation: maintain and improve comanagement by local, federal, and international partners; recognize spatial and temporal variability in AMM subpopulation response to climate change; implement monitoring programs with clear goals; mitigate cumulative impacts of increased human activity; and recognize the limits of current protected species legislation.

Climate change and the ecology and evolution of Arctic vertebrates

Climate change is taking place more rapidly and severely in the Arctic than anywhere on the globe, exposing Arctic vertebrates to a host of impacts. Changes in the cryosphere dominate the physical changes that already affect these animals, but increasing air temperatures, changes in precipitation, and ocean acidification will also affect Arctic ecosystems in the future. Adaptation via natural selection is problematic in such a rapidly changing environment. Adjustment via phenotypic plasticity is therefore likely to dominate Arctic vertebrate responses in the short term, and many such adjustments have already been documented. Changes in phenology and range will occur for most species but will only partly mitigate climate change impacts, which are particularly difficult to forecast due to the many interactions within and between trophic levels. Even though Arctic species richness is increasing via immigration from the South, many Arctic vertebrates are expected to become increasingly threatened during this century.

Fatty acid composition of the blubber in white whales (Delphinapterus leucas)

Abstract Fatty acid (FA) composition of the blubber in free-ranging white whales (Delphinapterus leucas) from Svalbards waters was determined and compared with the fatty acid composition of potential prey species in an attempt to assess diet. This methodology is based on the common assumption that unique arrays of FAs found within groups of organisms are transferred, largely unaltered, up marine food chains and thus may be useful for assessment of diet composition. Complete-column blubber biopsies were sampled from white whales (n=7) during the summers of 1996 and 1997. All captured animals were adult males. FAs were extracted from 2–4 replicates taken from an area about 10 cm in front of the mid-dorsal ridge. FA data from a total of 12 potential prey species from the Svalbard area were compared to the white-whale blubber samples. Twenty-two FAs were consistently found in relative amounts >0.5% of the total FA composition in white whales. These FAs accounted for 94–96% of the total FAs present. The blubber was composed almost entirely of triacylglycerols. The major saturated FAs were 14:0 and 16:0; 16:1(n-7), 18:1(n-9) and 20:1(n-9) were the major monounsaturated FAs and 20:5(n-3) and 22:6(n-3) were the major polyunsaturated FAs. Sixteen of the 22 FAs consistently found in the white-whale blubber were also found in considerable amounts (>0.5% of total FAs) in most of the potential species. Principal Component Analysis run on these 16 FAs suggests that polar cod (Boreogadus saida) had the most similar FA composition to the white-whale blubber, followed by capelin (Mallotus villosus), the copepod Calanus hyperboreus and the shrimp Pandalus borealis.

Salinity and temperature structure of a freezing Arctic fjord: monitored by white whales (Delphinapterus leucas)

Received 10 May 2002; accepted 29 August 2002; published 11 December 2002. [1] In this study we report results from satellite-linked conductivity-temperature-depth (CTD) loggers that were deployed on wild, free-ranging white whales to study the oceanographic structure of an Arctic fjord, Storfjorden, Svalbard. The whales dove to the bottom of the fjord routinely during the study and occupied areas with up to 90% ice-cover, where performance of conventional ship-based CTD-castswouldhavebeendifficult.Duringtheinitialperiod of freezing in the fjord, over a period of approximately 2 weeks, 540 CTD profiles were successfully transmitted. The dataindicatethatStorfjordenhasasubstantialinflowofwarm NorthAtlanticWater;thisiscontrarytoconventionalwisdom thathassuggestedthatitcontainsonlycoldArcticwater.This study confirms that marine-mammal-based CTDs have enormous potential for cost-effective, future oceanographic studies; many different marine mammal species target oceanographic discontinuities for foraging and thus may be good ‘adaptive samplers’ that naturally seek areas of high oceanographic interest. INDEX TERMS: 4294 Oceanography: General:Instrumentsandtechniques;4536Oceanography:Physical: Hydrography; 4219 Oceanography: General: Continental shelf processes; 1635 Global Change: Oceans (4203); KEYWORDS: CTD-measurements, Arctic oceanography, marine mammals, satellite telemetry. Citation: Lydersen, C., O. A. Nost, P. Lovell, B. J. McConnell, T. Gammelsrod, C. Hunter, M. A. Fedak, and K. M. Kovacs, Salinity and temperature structure of a freezing Arctic fjord—monitored by white whales (Delphinapterus leucas), Geophys. Res. Lett. , 29(23), 2119, doi:10.1029/2002GL015462, 2002.