Marine mammal occurrence and ocean climate off central California, 1986 to 1994 and 1997 to 1999

Keiper, Carol; Ainley, David G.; Allen, Sarah G.; Harvey, JT

doi:10.3354/meps289285

Cited by 50 publications

(50 citation statements)

References 45 publications

(40 reference statements)

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“…This natural perturbation to the global Hg cycle is expected to intensify with rising Hg concentrations in pelagic food webs (2) and to geographically shift as marine mammal distributions respond to changes in ocean climate and prey availability (42,43). Because marine mammals forage in biologically productive areas, their distribution is highly correlated with human fisheries that yield the highest catch (42).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, these regions are often developed and prone to persistent anthropogenic Hg inputs. For example, the Central Coast of California, where Año Nuevo is situated, drains rich agricultural regions, lies adjacent to a historic gold mining district where millions of kilograms of Hg were used (27), and also supports one-third of the world's cetacean species and six pinniped species (43). This juxtaposition of economic and biologic demands makes prioritizing conservation efforts a complex challenge.…”

Section: Discussionmentioning

confidence: 99%

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Mercury offloaded in Northern elephant seal hair affects coastal seawater surrounding rookery

Cossaboon

Ganguli

Flegal

2015

Proc. Natl. Acad. Sci. U.S.A.

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Methylmercury (MeHg) is a potent neurotoxin that is biomagnified approximately 1-10 million-fold in aquatic carnivores such as the Northern elephant seal (Mirounga angustirostris), whose excreta and molted pelage, in turn, constitute a source of environmental MeHg contamination at the base of marine food chains. The potential for this top-down contamination is greatest in coastal areas with productive marine ecosystems that provide ideal habitats for large marine mammal colonies that can number in the thousands. This recycling of MeHg was evidenced by comparing total mercury (HgT) and MeHg concentrations in seawater, and HgT in molted pelage of M. angustirostris, at the Año Nuevo State Reserve pinniped rookery with concentrations at neighboring coastal sites in Central California. Seawater MeHg concentrations around the rookery (average = 2.5 pM) were markedly higher than those at the comparison coastal sites (average = 0.30 pM), and were as high as 9.5 pM during the M. angustirostris molting season. As a consequence, excreta and molts from this marine mammal colony, and presumably other marine predator populations, constitute a major source of MeHg at the base of the local marine food chain. mercury | biogeochemistry | marine mammals | biomagnification | environmental toxicology

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Mercury offloaded in Northern elephant seal hair affects coastal seawater surrounding rookery

Cossaboon

Ganguli

Flegal

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…During that El Niño, sightings of Dall's porpoises were greatly reduced, whereas common and Risso's dolphin sightings increased. Furthermore, Pacifi c white-sided dolphin sightings decreased after this period, while sightings of common (particularly the long-beaked species) and bottlenose dolphins increased (Keiper et al, 2005).…”

Section: Implications In Regard To Climate Changementioning

confidence: 96%

“…For example, Dall's porpoises and Pacifi c white-sided dolphins dominated the odontocete species assemblage off central California in the decade before the strong El Niño of 1997-98 (Benson et al, 2002;Keiper et al, 2005). Keiper et al (2005) noted that during the strong El Niño of 1997-98 there was a deepened thermocline, a narrow, inshore distribution of Pacifi c Sardine eggs, and an overall decrease in abundance of macrozooplankton. During that El Niño, sightings of Dall's porpoises were greatly reduced, whereas common and Risso's dolphin sightings increased.…”

Section: Implications In Regard To Climate Changementioning

confidence: 99%

Effects of fluctuations in sea-surface temperature on the occurrence of small cetaceans off Southern California

Henderson¹,

Forney²,

Barlow³

et al. 2014

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Abstract-The link between ocean temperature and spatial and temporal distribution patterns of 8 species of small cetaceans off Southern California was examined during the period 1979-2009. Averages and anomalies of sea-surface temperatures (SSTs) were used as proxies for SST fluctuations on 3 temporal scales: seasonal, El Niño-Southern Oscillations (ENSO), and Pacific Decadal Oscillations (PDO). The hypothesis that cetacean species assemblages and habitat associations in southern California waters co-vary with these periodic changes in SST was tested by using generalized additive models. Seasonal SST averages were included as a predictor in the models for Dall's porpoise (Phocoenoides dalli), and common dolphins (Delphinus spp.), northern right whale dolphin (Lissodelphis borealis), and Risso's dolphin (Grampus griseus). The ENSO index was included as a predictor for northern right whale, long-beaked common (Delphinus capensis), and Risso's dolphins. The PDO index was selected as a predictor for Dall's porpoise and Pacific white-sided (Lagenorhynchus obliquidens), common, and bottlenose (Tursiops truncatus) dolphins. A metric of bathymetric depth was included in every model, and seafloor slope was included in 5 of the 9 models, an indication of a distinctive spatial distribution for each species that may represent niche or resource partitioning in a region where multiple species have overlapping ranges. Temporal changes in distribution are likely a response to changes in prey abundance or dispersion, and these patterns associated with SST variation may foreshadow future, more permanent shifts in distribution range that are due to global climate change.Cetaceans are higher-trophic-level marine predators whose movement patterns and habitat preferences are typically related to the distribution of their prey (Wishner et al., 1995;Gowans et al. 2007). Unlike baleen whales, small cetaceans (porpoises, dolphins, and small-toothed whales) generally do not undertake oceanscale annual migrations to track prey or to move between breeding and feeding grounds. Rather, small cetaceans may display a high degree of site fi delity, or they may move seasonally inshore and offshore or along regional-scale coastlines (Leatherwood et al., 1984;Dohl et al., 1986;Shane et al., 1986;Forney and Barlow, 1998).Although many small cetacean species may overlap in any one region of their total range, they often differ in their occurrence or habitatuse patterns, perhaps refl ecting competitive exclusion or niche partitioning. This separation of habitat and resources often occurs along depth, slope, and sea-surface temperature (SST) gradients (Reilly, 1990;Forney, 2000;Ballance et al., 2006;MacLeod et al., 2008). Habitat preferences likely refl ect differences in preferred prey. Dolphins may follow prey habitats as they shift not only seasonally but through large-scale climatedriven changes such as the El Niño-Southern Oscillation (ENSO) or the Pacific Decadal Oscillation (PDO) (Shane, 1995;Defran, 1999;Benson et al., 2002;Ballance et al., 200...

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“…Telemetry arrays sited on the continental shelf-slope are particularly well suited for the study of juvenile salmon, as this period of their life history is thought to be essentially shelf-limited (3,5,6,(13)(14)(15). Continental shelves are also of key ecological importance: although they cover less than 8% of the global ocean by area (16), they contribute 69% of the world fish catch [89% if upwelling zones are included (17)], and support high biodiversity and large populations of marine mammals (18) and seabirds (19).…”

mentioning

confidence: 99%

In situ measurement of coastal ocean movements and survival of juvenile Pacific salmon

Welch

Melnychuk

Payne

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

111

120

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Many salmon populations in both the Pacific and Atlantic Oceans have experienced sharply decreasing returns and high ocean mortality in the past two decades, with some populations facing extirpation if current marine survival trends continue. Our inability to monitor the movements of marine fish or to directly measure their survival precludes experimental tests of theories concerning the factors regulating fish populations, and thus limits scientific advance in many aspects of fisheries management and conservation. Here we report a large-scale synthesis of survival and movement rates of free-ranging juvenile salmon across four species, 13 river watersheds, and 44 release groups of salmon smolts (>3,500 fish tagged in total) in rivers and coastal ocean waters, including an assessment of where mortality predominantly occurs during the juvenile migration. Of particular importance, our data indicate that, over the size range of smolts tagged, (i) smolt survival was not strongly related to size at release, (ii) tag burden did not appear to strongly reduce the survival of smaller animals, and (iii) for at least some populations, substantial mortality occurred much later in the migration and more distant from the river of origin than generally expected. Our findings thus have implications for determining where effort should be invested to improve the accuracy of salmon forecasting, to understand the mechanisms driving salmon declines, and to predict the impact of climate change on salmon stocks.

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Marine mammal occurrence and ocean climate off central California, 1986 to 1994 and 1997 to 1999

Cited by 50 publications

References 45 publications

Mercury offloaded in Northern elephant seal hair affects coastal seawater surrounding rookery

Mercury offloaded in Northern elephant seal hair affects coastal seawater surrounding rookery

Effects of fluctuations in sea-surface temperature on the occurrence of small cetaceans off Southern California

In situ measurement of coastal ocean movements and survival of juvenile Pacific salmon

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