Diet Composition And Fate Of Contaminants In Subsistence Harvested Northern Sea Otters Enhydra Lutris Kenyoni From Icy Strait Alaska
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Diet Composition And Fate Of Contaminants In Subsistence Harvested Northern Sea Otters Enhydra Lutris Kenyoni From Icy Strait Alaska
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Author : Kristin Lynn Brown
language : en
Publisher:
Release Date : 2020
Diet Composition And Fate Of Contaminants In Subsistence Harvested Northern Sea Otters Enhydra Lutris Kenyoni From Icy Strait Alaska written by Kristin Lynn Brown and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Sea otter categories.
Northern sea otters (Enhydra lutris kenyoni) in Southeast Alaska have experienced a significant population increase since their successful reintroduction to the area after previous near extirpation owing to historic fur trading. The purpose of this study was to examine sea otter diet and metals contamination in an area of Southeast Alaska with the most robust increases in sea otter numbers, Glacier Bay/Icy Strait, with the intent of gathering baseline data for a healthy population of sea otters and as a reflection of the local coastal environmental health of the area. This research was a collaborative effort with Alaska Native subsistence hunters and the Alaska Department of Environmental Conservation. In Chapter 1, sea otter stomachs (n=25) were obtained in April 2015 and April 2016 from Alaska Native subsistence hunters in Icy Strait, Alaska. There were no differences in sea otter diet between years. Bivalves dominated the sea otter diet. Northern horsemussels (Modiolus modiolus) made up the greatest proportion of the diet (0.46 ± 0.48). Fat gaper clams (Tresus capax) and northern horsemussels were found in the highest proportion of stomachs (0.64 and 0.60, respectively). There was not an apparent trend between sea otter age and the minimum number of total prey items, stomach contents mass, or mean frequency of occurrence of the top four prey species. Sea otters from this study are likely to be dietary generalists throughout their lives. In Chapter 2, brain, gonad, kidney, and liver tissues, as well as stomach contents were analyzed for arsenic, cadmium, copper, lead, total mercury, and selenium for the 2015-harvested sea otters that were also referenced in Chapter 1 (n=14). In general, arsenic and lead had the highest concentrations in stomach contents, cadmium and selenium were highest in the kidneys, and copper and total mercury were highest in the livers. While brains and gonads had the lowest metals concentrations of any tissue, the metal with the greatest concentration within the brain was copper, and within the gonads was selenium. Concentrations of arsenic, cadmium, total mercury, and lead demonstrated a relationship with sea otter length. In general, all the mean metals concentrations for these sea otters were below published effects threshold values for marine mammals. Only total mercury demonstrated biomagnification from the stomach contents (i.e., the prey) to all higher-level tissues. Selenium health benefit values were positive in all sea otter tissue types analyzed in the present study, indicating that concentrations of selenium had an overall health benefit in protecting those tissues against mercury toxicity. Evaluating how contaminants concentrate and get distributed in tissues of top trophic levels provides an indication for potential exposure to humans and demonstrates how these keystone species act as indicators of local coastal ecosystem health. The results of studies on dietary exposure and metals contamination in top trophic level consumers such as sea otters can be used in monitoring the health of sea otter populations and the local environment that they inhabit.
Sea Otter Diet Composition With Respect To Recolonization Life History And Season In Southern Southeast Alaska
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Author : Nicole L. LaRoche
language : en
Publisher:
Release Date : 2020
Sea Otter Diet Composition With Respect To Recolonization Life History And Season In Southern Southeast Alaska written by Nicole L. LaRoche and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Sea otter categories.
Until translocation efforts in the 1960s, sea otters (Enhydra lutris) were absent from Southeast Alaska due to extirpation by the fur trade in the 18th and 19th centuries. About 400 sea otters were reintroduced to six Southeast Alaska locations, including two sites near Prince of Wales Island in southern Southeast Alaska. The most recent US Fish and Wildlife Service population count, completed in 2012, estimated that about 25,000 sea otters inhabited Southeast Alaska. Sea otters will reduce invertebrate prey biomass when recolonizing an area. By quantifying sea otter diets and caloric intake according to recolonization patterns, we can better understand the ecosystem impacts of sea otter population increase and range expansion. The goal of this study was to quantify changes in seasonal diet composition and assess the energetic quality of sea otter prey in southern Southeast Alaska. I made visual foraging observations of 3,385 sea otter dives around Prince of Wales Island (POW) to determine diet composition during the spring and summer months. I then collected vibrissae from 45 sea otters obtained from subsistence hunters to assess year-round sea otter diets using stable isotopes. I collected sea otter prey items throughout POW in three seasons (May 2018, August 2018, and February 2019) to measure energy, lipid and protein content, and delta13C (carbon) and delta15N (nitrogen) values. Sea otter diets mainly consisted of clams, as quantified both from visual observations and stable isotope analysis. However, there was more variation in the diet estimates from stable isotope analysis. Stable isotope analysis revealed variation among individual diets of sea otters and individuality in diet within the POW region of sea otters. Sea otters seasonally increased consumption of some prey when the prey was highest in lipid and overall caloric content. Sea otters switched prey types when the prey was more energetically valuable. The results of this study will aid in future management of shellfisheries, subsistence hunting, and implementing co-management of a protected species by providing quantitative diet composition data for stakeholders. This work is a part of a large-scale project examining how the recovery of sea otters structures nearshore marine ecosystems, provides ecosystem services, and affects community sustainability.
Foraging Ecology And Population Dynamics Of Northern Sea Otters Enhydra Lutris Kenyoni In Washington State
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Author : Jessica Rhian Hale
language : en
Publisher:
Release Date : 2022
Foraging Ecology And Population Dynamics Of Northern Sea Otters Enhydra Lutris Kenyoni In Washington State written by Jessica Rhian Hale and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
Many marine mammal populations are currently recovering from population depletion after overharvest. As marine mammals are often important predators in shaping marine ecosystems, there is a need to understand the impacts of recovering populations on other species and the marine ecosystem as a whole. The depletion and subsequent recovery of these species presents biologists with natural experiments to study their ecology, including drivers of their population dynamics and the function of the species in the ecosystem. This dissertation focuses on the recovery of a translocated population of sea otters (Enhydra lutris kenyoni) in Washington State. The presence or absence of sea otters, a keystone species, can dramatically influence marine community structure. The overall aim of this dissertation was to utilize the natural experiment of sea otter translocation to Washington State to understand drivers of sea otter population dynamics as well as the ecological role that sea otters play in Washington State. In Chapter 2, my coauthors and I found that the sea otter population in Washington has grown from an estimated 21 adult sea otters in 1977 to 2,336 adult sea otters in 2019, and the population is predicted to continue to grow and expand primarily to the south of the current range over the next 25 years. We also estimated that Washington State can support twice as many sea otters than previously estimated (equilibrium abundance of 6,080 vs. 2,734 sea otters), and that estimates of mean equilibrium density in currently occupied areas had the largest impact on predictions of population growth and range expansion. In Chapter 3, we quantified how sea otter population status (i.e., sea otter cumulative density) and habitat type (i.e., sea otter foraging in open water, kelp canopy, emergent rock, or intertidal) influence sea otter diet, and found that habitat was 1.77 times more important than sea otter population status in determining sea otter diet composition. We also found that sea otter long-term average rate of energy intake and diet diversity were negatively and positively correlated with sea otter cumulative density, respectively. In Chapter 4, we demonstrated the ecological role of sea otters in the nearshore marine ecosystem in Washington as a keystone species. We found that temporal transitions in the amount of kelp canopy were related to the duration of sea otter occupation, and that this relationship was more complex than a simple linear function. We also found that sea urchins were present at higher densities at sites more recently occupied by sea otters compared to long-occupied sites. In Chapter 5, we demonstrated the impact of sea otters as a recovering predator on the Pacific razor clam (Siliqua patula). We found that the magnitude of sea otter predation effects varied over time and space, with sea otter-caused razor clam mortality surpassing natural mortality in 2018 at Kalaloch Beach, occupied by sea otters since 2005. We also found that sea otters selectively consume the larger “recruit” size razor clams, the size that is also targeted in the recreational fishery, despite the smaller pre-recruit size clams being more abundant. Collectively, these results provide a deeper understanding of sea otter recolonization in Washington State as well as the ecological consequences of this recolonization.
Assessment Of The Reproductive Ecology Of Harbor Seals Phoca Vitulina And Northern Sea Otters Enhydra Lutris Kenyoni In Alaska Using Subsistence Biosampling Programs
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Author : Emily A. Hutchinson
language : en
Publisher:
Release Date : 2014
Assessment Of The Reproductive Ecology Of Harbor Seals Phoca Vitulina And Northern Sea Otters Enhydra Lutris Kenyoni In Alaska Using Subsistence Biosampling Programs written by Emily A. Hutchinson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Harbor seal categories.
Harbor seals (Phoca vitulina) and northern sea otters (Enhydra lutris kenyoni) in Alaska have experienced extreme fluctuations in abundance in recent decades. The purpose of this study was to examine growth and determine the age and size at sexual maturity in populations of these two species, as spatial and temporal variations in environmental conditions and changes in ecological constraints as a result of population fluctuations can influence growth and reproductive characteristics of individuals. All samples for this research were collected via biosampling, the collection of measurements and biological tissue samples, as a component of subsistence harvesting by Alaska Natives. In Chapter 1, morphometric measurements and reproductive tracts were collected by the Alaska Native Harbor Seal Commission's Biosampling Program from female harbor seals harvested throughout the Gulf of Alaska from 1998 through 2005. Seals attained an asymptotic standard length (SE) of 147.7 ± 2.6 cm and body mass of 82.2 ± 4.8 kg. Female harbor seals did not mature until a minimum age of 3 yr, a standard length of 122 cm, and a weight of 48 kg. The average age of sexual maturity was 4.2 ± 0.7 yr (95% CI). Fetal growth was measured by standard length, curvilinear length, axillary girth, the cube root of fetal mass, skull length, condylobasal length, zygomatic width, and skull width against the day of the year the mother was harvested. The x-intercept of the linear regression of each fetal growth measurement against the day of the year produced estimates of the implantation date that ranged from September 22nd to October 17th, with a mean date of September 30th ± 8 d (SD). Harbor seals from this study are smaller in length, have a later implantation date, and are larger at sexual maturity compared to harbor seals in the Gulf of Alaska from the 1960s. In Chapter 2, morphometric measurements and reproductive tracts were collected by a Native Alaskan subsistence hunter from 40 male sea otters near Gustavus, in Southeast Alaska. The maximum recorded standard length and axillary girth were 160 cm and 78.7 cm, respectively. Sexual maturity was assessed by the histological examination of the testes and epididymides and the subsequent measurement and characterization of the seminiferous tubules. Male sea otters in the region reached sexual maturity at 3 to 4 yr of age, after attaining a standard body length of 130 cm., a mean seminiferous tubule diameter of 140 μm, and a baculum length of 14 cm. Sea otters outside Gustavus, Alaska exhibit increased body size and lower ages of sexual maturity compared to sea otters in other regions of Alaska, suggesting that resources are abundant and are not limiting maturation rates of male sea otters near Glacier Bay. In the future, as anthropogenic influences continue to increase and environmental conditions fluctuate, biosampling programs will be an invaluable tool for continued monitoring of marine mammals in Alaska.
Resource Competition Space Use And Forage Ecology Of Sea Otters Enhydra Lutris In Southern Southeast Alaska
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Author : Zachary N. Hoyt
language : en
Publisher:
Release Date : 2015
Resource Competition Space Use And Forage Ecology Of Sea Otters Enhydra Lutris In Southern Southeast Alaska written by Zachary N. Hoyt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Sea otter categories.
The growing sea otter population in southern Southeast Alaska is impacting commercial shellfish, through foraging and expanding in range and abundance except where hunted for subsistence. Sea otters and their prey have coexisted in the North Pacific Ocean for approximately 750,000 years, but due to exploitation of sea otters from the 1770s until 1911, the species became extinct over much of its range, including southern Southeast Alaska. Subsequently, invertebrate species flourished and were commercially targeted in the late 1900s. Sea otters were relocated (n = 106) to southern Southeast Alaska in 1968. In this dissertation, I evaluated this marine mammal-fisheries conflict through multiple approaches. In Chapter 1, I analyzed geoduck clam and red sea urchin abundance surveys (1994-2012) and catch and effort data from commercial Dungeness crab fisheries (1969-2010) to identify interactions between sea otters and commercial shellfish. In Chapter 2, I collected geo-locations from 30 instrumented sea otters (2011-2014) to identify space use and range expansion. In Chapter 3, I collected sea otter abundance and distribution data from fixed wing aircraft (2010-2014) and observational forage data from sea otters (2010-2013) to determine contemporary population growth and consumption of commercially important shellfish by sea otters. The sea otter population in southern Southeast Alaska has grown from 106 to an estimated 13,139 individuals between 1968 and 2011 with an annual growth rate of 12% and expansion of its range by 117 km2 y-1. Results from a before-after, control-impact analysis indicate that sea otters are rapidly impacting red sea urchin and significantly reducing geoduck clam densities. Further, breakpoints predicted from regression models of Dungeness crab catch are correlated with known sea otter colonization timing. Forty-six percent of the population level diet of sea otters represented commercially important prey. Sea otters targeted commercially important species, specifically red sea urchins and Dungeness crab, when first colonizing an area, after which the diet of sea otters became more diverse as colonization durations increased. Using habitat models based on a bivariate normal probability distribution function, environmental covariates and subsistence hunting pressure on sea otters, I determined that sea otter range expansion was limited by subsistence hunting. Further, female and non-territorial males segregated based on habitat and likely prey preferences. I conclude that sea otter populations will likely continue to grow, and that current shellfisheries cannot coexist with sea otters under existing management. Further, conservation and management of sea otter populations, whether to increase the distribution through translocation efforts or reduce the distribution to avoid human conflicts, could benefit from insights gained from spatially explicit modeling at the landscape level.
Sea Otters In Southeast Alaska
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Author : Wendel W. Raymond
language : en
Publisher:
Release Date : 2020
Sea Otters In Southeast Alaska written by Wendel W. Raymond and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Food chains (Ecology) categories.
The recovery of sea otters (Enhydra lutris) to Southeast Alaska is a conservation success story, but their increasing population raises questions about sea otter population dynamics and the ecological role of this top-level predator. In Chapter 1, we addressed these questions by investigating patterns and population effects of subsistence sea otter harvest. Subsistence harvest reduced populations at a small scale, with potential to slow or stop population growth, but across Southeast Alaska the population continues to grow, even with an average 3% subsistence harvest rate. In Chapters 2 and 3 we investigated the ecological role of sea otters in seagrass (Zostera marina) communities. When we tested for generality in a sea otter - seagrass trophic cascade across a large spatial scale in Southeast Alaska, we found a positive relationship between sea otters and seagrass. However, we found no evidence of a relationship between crabs and epifauna, suggesting that the ecological mechanisms in Southeast Alaska may differ from other regions. Our comparison of carbon and nitrogen stable isotopes (SI) to assess the role of sea otters on trophic structure and energetic pathways of seagrass beds found little effect of sea otters in overall community trophic niche space, suggesting similar carbon sources and food chain length in seagrass meadows regardless of sea otters. Conversely, the FA profiles of diverse consumer suggest variation in dietary sources with and without sea otters. This result suggests that the trophic cascade may not be the only or primary energetic pathway in Southeast Alaska seagrass communities. In all, our studies have revealed that sea otters in Southeast Alaska are linked to both people and a common Southeast Alaska nearshore habitat, seagrass. These results describe the varied interactions of a recovering top predator and highlight a need to consider these diverse interactions in resource management, conservation, and ecological research.
Individual Variation In Diet In The Female California Sea Otter Enhydra Lutris
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Author : Kathy J. Lyons
language : en
Publisher:
Release Date : 1989
Individual Variation In Diet In The Female California Sea Otter Enhydra Lutris written by Kathy J. Lyons and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Sea otter categories.
Activity Budget Field Metabolic Rate And Foraging Ecology Of Female Sea Otters Enhydra Lutris Kenyoni With Dependent Pups In Alaska
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Author : Ryan Christopher Wolt
language : en
Publisher:
Release Date : 2015
Activity Budget Field Metabolic Rate And Foraging Ecology Of Female Sea Otters Enhydra Lutris Kenyoni With Dependent Pups In Alaska written by Ryan Christopher Wolt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Sea otter (Enhydra lutris kenyoni) foraging behavior and prey preference (2001-2004) and the behavior and activity budgets of females with dependent pups (2005-2010) were studied during the summer (June-August) in Simpson Bay, Prince William Sound, Alaska. Unlike most previous studies of sea otters which were conducted in coastal areas with a rocky benthos and kelp canopy, the benthic habitat in this study was primarily soft sediment (mud or mixed mud and gravel) with no canopy-forming kelps. Foraging behavior and prey preference. A total of 1,816 foraging dives from 211 bouts were recorded. 87% of foraging dives were successful, and 44% of the prey was identified: 75% clams, 9% Pacific blue mussels, 6% crabs, 2% scallops and a variety of other invertebrates. Significantly more prey items/area were brought up from mixed mud/gravel than mud (p-value
Hydrocarbons In Sea Otters Enhydra Lutris And Their Habitat In Coastal British Columbia Canada
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Author : Katherine Anne Harris
language : en
Publisher:
Release Date : 2010
Hydrocarbons In Sea Otters Enhydra Lutris And Their Habitat In Coastal British Columbia Canada written by Katherine Anne Harris and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
The purpose of this work was to examine the source and fate of hydrocarbons, the primary constituents of oil, in sea otter (Enhydra lutris) habitat on the west coast of British Columbia (BC), Canada and their fate in the sea otter food web. Oil pollution is the primary threat to this recovering population, reflecting their extreme vulnerability as a result of several unique life history characteristics, including the absence of a blubber layer, reliance on their fur for insulation, and the fact that their entire lives can be spent at sea. While the vulnerability of sea otters to acute oil exposure has been demonstrated, chronic hydrocarbon exposure through dietary processes is not well understood. We measured hydrocarbon (alkane, hopane and sterane biomarker, and polycyclic aromatic) concentrations in sediments, prey items, and live-captured sea otters using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Background signatures were characterized for remote sediment sites, with polycyclic aromatic hydrocarbon (PAH) patterns revealing the predominance of petrogenic sources. However, PAH concentrations were up to three orders of magnitude higher at two small harbour sites, with patterns reflecting weathered petroleum and the combustion of fossil fuels and biomass. Concentrations at these sites exceeded both national and provincial sediment quality guidelines for the protection of aquatic life. Despite differences in habitat and feeding ecology, all sea otter prey species sampled exhibited PAH patterns dominated by petrogenic low molecular weight (LMW) compounds, highlighting the likely importance of water as an exposure route. While biota-sediment accumulation factors (BSAFs) generally decreased with increasing octanol-water partitioning coefficients (log Kow) for parent PAHs, BSAFs for alkyl PAHs increased, indicative of bioaccumulation by invertebrates. Biomagnification factors (BMFs) indicated that while parent PAHs biodiluted in sea otters, consistent with metabolic elimination, some higher alkylated 3- and 4-ring PAHs biomagnified, challenging the commonly held view that PAHs dilute in food webs. This retention was reflected in estimated?PAH body burdens, in which alkyl PAHs comprised 89? 7% and 84? 10% of totals in male and female otters, respectively. While vertebrates are efficient metabolizers of parent PAHs, this apparent retention of some alkyl PAHs in sea otters raises concerns about the potential toxicological effects of these poorly understood compounds. This research suggests that sea otters may be vulnerable to PAH-related health risks as a consequence of their large dietary requirements (~25% of body weight per day), even when prey PAH concentrations are low.
The Northern Sea Otter Enhydra Lutris Kenyoni Along The Washington Coast
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Author : Kristen Amy Walker
language : en
Publisher:
Release Date : 2005
The Northern Sea Otter Enhydra Lutris Kenyoni Along The Washington Coast written by Kristen Amy Walker and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Endangered species categories.