Stable Isotopes and Heavy Metals as Trophic Discriminators among Southeast Alaska Gray Wolves and Northern Sea Otters
Location
HCAS Guy Harvey Oceanographic Center, Nova Southeastern University
Start
2-13-2025 2:00 PM
End
2-13-2025 2:15 PM
Type of Presentation
Oral Presentation
Abstract
Gray wolves in coastal Southeast Alaska and British Columbia are a genetically distinct subspecies (Canis lupus ligoni) that have unique connections to the ocean, both in habitat and diet. In the past 10 years, evidence suggests this subspecies has incorporated more marine species into their diet, including northern sea otters (Enhydra lutris). In central Southeast Alaska three distinct populations of wolves exist: Juneau, Gustavus, and Pleasant Island. Wolves in Juneau subsidized most of their diet with terrestrial prey; Gustavus wolves feed predominantly on terrestrial prey and opportunistic marine organisms while Pleasant Island wolves, situated between Gustavus and Juneau, eat a large quantity of marine prey and only occasionally terrestrial prey. The mean wolf hair δ13C and δ15N in Juneau (-25.0‰, 4.70‰), Gustavus (-22.2‰, 7.88 ‰), and Pleasant Island (-17.5‰, 11.3‰), respectively, indicate trophic enrichment from a terrestrial-based to a marine-based diet. Sea otter hair from Gustavus and Pleasant Island had δ13C and δ15N values (-15.2‰, 11.2 ‰ and -15.1‰, 11.3 ‰, respectively) indicative of high sea otter contribution to Pleasant Island wolf diet and only limited contribution to Gustavus wolves. Heavy metal analysis indicates significant differences in cadmium (Cd), mercury (Hg), selenium (Se), and vanadium (V) among the 3 groups of wolves. Cadmium concentrations in Pleasant Island wolves were significantly different than all other wolves in the study and correlate with higher Cd concentrations in sea otter hair. The high concentrations of both V and Mn in the Pleasant Island wolves may be related to high concentrations and physiological utilization of both elements by marine invertebrates. The Se:Hg ratios in all wolves suggests potential mercury toxicity. The combined stable isotope and heavy metal analyses present the importance of the marine diet in select populations of coastal gray wolves in Southeast Alaska.
Stable Isotopes and Heavy Metals as Trophic Discriminators among Southeast Alaska Gray Wolves and Northern Sea Otters
HCAS Guy Harvey Oceanographic Center, Nova Southeastern University
Gray wolves in coastal Southeast Alaska and British Columbia are a genetically distinct subspecies (Canis lupus ligoni) that have unique connections to the ocean, both in habitat and diet. In the past 10 years, evidence suggests this subspecies has incorporated more marine species into their diet, including northern sea otters (Enhydra lutris). In central Southeast Alaska three distinct populations of wolves exist: Juneau, Gustavus, and Pleasant Island. Wolves in Juneau subsidized most of their diet with terrestrial prey; Gustavus wolves feed predominantly on terrestrial prey and opportunistic marine organisms while Pleasant Island wolves, situated between Gustavus and Juneau, eat a large quantity of marine prey and only occasionally terrestrial prey. The mean wolf hair δ13C and δ15N in Juneau (-25.0‰, 4.70‰), Gustavus (-22.2‰, 7.88 ‰), and Pleasant Island (-17.5‰, 11.3‰), respectively, indicate trophic enrichment from a terrestrial-based to a marine-based diet. Sea otter hair from Gustavus and Pleasant Island had δ13C and δ15N values (-15.2‰, 11.2 ‰ and -15.1‰, 11.3 ‰, respectively) indicative of high sea otter contribution to Pleasant Island wolf diet and only limited contribution to Gustavus wolves. Heavy metal analysis indicates significant differences in cadmium (Cd), mercury (Hg), selenium (Se), and vanadium (V) among the 3 groups of wolves. Cadmium concentrations in Pleasant Island wolves were significantly different than all other wolves in the study and correlate with higher Cd concentrations in sea otter hair. The high concentrations of both V and Mn in the Pleasant Island wolves may be related to high concentrations and physiological utilization of both elements by marine invertebrates. The Se:Hg ratios in all wolves suggests potential mercury toxicity. The combined stable isotope and heavy metal analyses present the importance of the marine diet in select populations of coastal gray wolves in Southeast Alaska.