scholarly journals Species recovery and recolonization of past habitats: lessons for science and conservation from sea otters in estuaries

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8100 ◽  
Author(s):  
Brent B. Hughes ◽  
Kerstin Wasson ◽  
M. Tim Tinker ◽  
Susan L. Williams ◽  
Lilian P. Carswell ◽  
...  
Keyword(s):  
San Francisco ◽  
San Francisco Bay ◽  
Limited Range ◽  
Ecosystem Functions ◽  
Sea Otter ◽  
Historical Evidence ◽  
Sea Otters ◽  
Elkhorn Slough ◽  
Enhydra Lutris Nereis ◽  
High Production

Recovering species are often limited to much smaller areas than they historically occupied. Conservation planning for the recovering species is often based on this limited range, which may simply be an artifact of where the surviving population persisted. Southern sea otters (Enhydra lutris nereis) were hunted nearly to extinction but recovered from a small remnant population on a remote stretch of the California outer coast, where most of their recovery has occurred. However, studies of recently-recolonized estuaries have revealed that estuaries can provide southern sea otters with high quality habitats featuring shallow waters, high production and ample food, limited predators, and protected haul-out opportunities. Moreover, sea otters can have strong effects on estuarine ecosystems, fostering seagrass resilience through their consumption of invertebrate prey. Using a combination of literature reviews, population modeling, and prey surveys we explored the former estuarine habitats outside the current southern sea otter range to determine if these estuarine habitats can support healthy sea otter populations. We found the majority of studies and conservation efforts have focused on populations in exposed, rocky coastal habitats. Yet historical evidence indicates that sea otters were also formerly ubiquitous in estuaries. Our habitat-specific population growth model for California’s largest estuary—San Francisco Bay—determined that it alone can support about 6,600 sea otters, more than double the 2018 California population. Prey surveys in estuaries currently with (Elkhorn Slough and Morro Bay) and without (San Francisco Bay and Drakes Estero) sea otters indicated that the availability of prey, especially crabs, is sufficient to support healthy sea otter populations. Combining historical evidence with our results, we show that conservation practitioners could consider former estuarine habitats as targets for sea otter and ecosystem restoration. This study reveals the importance of understanding how recovering species interact with all the ecosystems they historically occupied, both for improved conservation of the recovering species and for successful restoration of ecosystem functions and processes.

Characterizing the impact of recovering sea otters on commercially important crabs in California estuaries

2020 ◽  
Vol 655 ◽  
pp. 123-137
Author(s):  
TM Grimes ◽  
MT Tinker ◽  
BB Hughes ◽  
KE Boyer ◽  
L Needles ◽  
...  
Keyword(s):  
Abiotic Factors ◽  
Sea Otter ◽  
Dungeness Crab ◽  
Sea Otters ◽  
Elkhorn Slough ◽  
Enhydra Lutris Nereis ◽  
Crab Abundance ◽  
Population Sizes ◽  
Commercially Important ◽  
The Impact

Protective legislation and management have led to an increase in California’s sea otter Enhydra lutris nereis population. While sea otter recovery has been linked to ecosystem benefits, sea otter predation may negatively affect commercially valuable species. Understanding the potential influence of sea otters is of particular importance as their range expands into estuaries that function as nurseries for commercially valuable species like Dungeness crab Metacarcinus magister. We consider how sea otter predation has affected the abundance and size of juvenile Dungeness crab in Elkhorn Slough, California, USA, and analyzed cancrid crab abundance and size across 4 California estuaries with and without sea otters to understand how biotic and abiotic factors contribute to observed variation in crab size and abundance. We compared trends in southern sea otters relative to Dungeness crab landings in California to assess whether increasing sea otter abundance have negatively impacted landings. In Elkhorn Slough, juvenile Dungeness crab abundance and size have declined since 2012, coinciding with sea otter population growth. However, the impact of sea otters on juvenile Dungeness crab size was habitat-specific and only significant in unvegetated habitat. Across estuaries, we found that cancrid crab abundance and size were negatively associated with sea otter presence. While abiotic factors varied among estuaries, these factors explained little of the observed variation in crab abundance or size. Although we found evidence that sea otters can have localized effects on cancrid crab populations within estuaries, we found no evidence that southern sea otters, at recent population sizes, have negatively impacted Dungeness crab landings in California from 2000-2014.

scholarly journals Assessing anthropogenic risk to sea otters (Enhydra lutris nereis) for reintroduction into San Francisco Bay

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10241
Author(s):  
Jane Rudebusch ◽  
Brent B. Hughes ◽  
Katharyn E. Boyer ◽  
Ellen Hines
Keyword(s):  
Risk Assessment ◽  
Population Growth ◽  
San Francisco ◽  
San Francisco Bay ◽  
Environmental Contaminants ◽  
Spatial And Temporal Variation ◽  
Spatially Explicit ◽  
Sea Otter ◽  
Sea Otters ◽  
Wide Range

Southern sea otters have been actively managed for their conservation and recovery since listing on the federal Endangered Species Act in 1977. Still, they remain constrained to a geographically small area on the central coast of California relative to their former coast-wide range, with population numbers far below those of the estimated optimal sustainable population size. Species managers have discussed reintroducing southern sea otters into parts of their historic range to facilitate sustained population growth and geographic range expansion. San Francisco Bay (SFB), historically home to several thousand sea otters, is one location identified as a candidate release site for these reintroductions. The return of sea otters to SFB could bring benefits to local ecosystem restoration and tourism, in addition to spurring sea otter population growth to meet recovery goals. However, this is a highly urbanized estuary, so sea otters could also be exposed to serious anthropogenic threats that would challenge a successful reintroduction. In light of these potential detriments we performed a spatially-explicit risk assessment to analyze the suitability of SFB for southern sea otter reintroduction. We looked at threats to sea otters specific to SFB, including: the impacts of vessel traffic from commercial shipping, high-speed ferries, and recreational vessels; environmental contaminants of methylmercury and polychlorinated biphenyls; major oil spills; and commercial fishing. Factors that influenced the relative threat imposed by each stressor included the spatio-temporal extent and intensity of the stressor and its mitigation potential. Our analysis revealed the complex spatial and temporal variation in risk distribution across the SFB. The type and magnitude of anthropogenic risk was not uniformly distributed across the study area. For example, the central SFB housed the greatest cumulative risk, where a high degree of vessel traffic and other stressors occurred in conjunction. The individual stressors that contributed to this risk score varied across different parts of the study area as well. Whereas vessel traffic, particularly of fast ferries, was a high scoring risk factor in in the north and central bay, in the south bay it was environmental contaminants that caused greater risk potential. To help identify areas within the study area that managers might want to target for release efforts, the spatially-explicit risk map revealed pockets of SFB that could provide both suitable habitat and relatively low overall risk. However in some cases these were adjacent or in close proximity to identified high-risk portions of habitat in SFB. This predictive suitability and risk assessment can be used by managers to consider the spatial distribution of potential threats, and risk abatement that may be necessary for sea otters to re-occupy their historic home range in SFB.

scholarly journals Predators, Disease, and Environmental Change in the Nearshore Ecosystem: Mortality in Southern Sea Otters (Enhydra lutris nereis) From 1998–2012

2020 ◽  
Vol 7 ◽  
Author(s):  
Melissa A. Miller ◽  
Megan E. Moriarty ◽  
Laird Henkel ◽  
Martin Tim Tinker ◽  
Tristan L. Burgess ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Population Level ◽  
Large Sample Size ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Sarcocystis Neurona ◽  
Enhydra Lutris Nereis ◽  
Protozoal Infection ◽  
Demographic Attributes

We compiled findings from 15 years (1998–2012) of southern sea otter (Enhydra lutris nereis) necropsies, incorporating data from 560 animals. Sensitive diagnostic tests were used to detect biotoxins, bacteria, parasites and fungi. Methods to classify primary and contributing causes of death (COD) and sequelae utilized an updated understanding of health risks affecting this population. Several interesting patterns emerged, including identification of coastal regions of high mortality risk for sea otter mortality due to shark bite, cardiomyopathy, toxoplasmosis, sarcocystosis, acanthocephalan peritonitis and coccidioidomycosis. We identified demographic attributes that enhanced the risk of disease in relation to age, sex, and reproductive stage. Death due to white shark (Carcharodon carcharias) bite increased dramatically during the study period and was the most common primary COD. However, when primary and contributing COD were combined, the most prevalent COD was infectious disease (affecting 63% of otters), especially fatal infections by acanthocephalans (Profilicollis spp.) and protozoa (e.g., Sarcocystis neurona and Toxoplasma gondii). Fatal bacterial infections were also extremely common as a primary process or a sequela, affecting 68% of examined otters. Substantial advances were made in identifying sea otters that died following exposure to the pervasive marine neurotoxin domoic acid (DA), and DA intoxication was conservatively estimated as a primary or contributing COD for 20% of otters. Cardiomyopathy was also highly prevalent as a primary or contributing COD (41%) and exhibited significant associations with DA intoxication and protozoal infection. For adult and aged adult females in late pup care through post-weaning at the time of death, 83% had end lactation syndrome (ELS) as a primary or contributing COD. This comprehensive longitudinal dataset is unique in its depth and scope. The large sample size and extensive time period provided an opportunity to investigate mortality patterns in a changing environment and identify spatial and temporal disease “hot spots” and emerging threats. Our findings will help improve estimates of population-level impacts of specific threats and optimize conservation and environmental mitigation efforts for this threatened species.

Primary intracranial fibrosarcoma in a southern sea otter Enhydra lutris nereis

2020 ◽  
Vol 138 ◽  
pp. 207-213
Author(s):  
AR Armwood ◽  
CE Anderson ◽  
T Clauss ◽  
AC Camus
Keyword(s):  
Smooth Muscle Actin ◽  
Brain Lesion ◽  
Acute Onset ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Mammal Species ◽  
Sea Otters ◽  
Enhydra Lutris Nereis ◽  
High Mitotic Count ◽  
Southern Sea Otter

Southern sea otters Enhydra lutris nereis, a threatened marine mammal species, face numerous environmental and infectious disease challenges in their native habitat of coastal California, USA. However, there are few published cases describing neoplasia in sea otters despite their relatively long life span when cared for in aquarium settings. An 18 yr old neutered male southern sea otter, born and raised in human care, presented with an acute onset of seizures and dull mentation. Magnetic resonance imaging of the head revealed a large, central brain lesion. After no improvement with treatment, euthanasia was elected due to a poor prognosis. Grossly, a poorly demarcated, granular, tan mass expanded the cranial meninges in the longitudinal fissure at the level of the cruciate sulcus and extended into the underlying gray matter and superficial white matter. Histologically, the mass was composed of spindle cells, forming haphazardly arranged interlacing bundles and herringbone patterns, with a high mitotic count, moderate cellular pleomorphism, and prominent vascularization. Neoplastic cells demonstrated positive immunoreactivity for vimentin and negative immunoreactivity for smooth muscle actin, factor VIII-related antigen, S100, melan-A, E-cadherin, desmin, glial fibrillary acidic protein, and cytokeratin AE1/AE3. Based on gross, histologic, and immunohistochemical findings, the mass was most consistent with a primary intracranial fibrosarcoma (PIF). PIFs are a rare neoplasm in both humans and other animals with few reports in the veterinary literature. This is the first recorded case of a PIF in a sea otter.

scholarly journals Type X strains of Toxoplasma gondii are virulent for southern sea otters ( Enhydra lutris nereis) and present in felids from nearby watersheds

2019 ◽  
Vol 286 (1909) ◽  
pp. 20191334 ◽  
Author(s):  
Karen Shapiro ◽  
Elizabeth VanWormer ◽  
Andrea Packham ◽  
Erin Dodd ◽  
Patricia A. Conrad ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Coastal Waters ◽  
Sea Otter ◽  
Type Ii ◽  
Enhydra Lutris ◽  
Chronic Infections ◽  
Sea Otters ◽  
Central California ◽  
Enhydra Lutris Nereis ◽  
Marine Wildlife

Why some Toxoplasma gondii -infected southern sea otters ( Enhydra lutris nereis ) develop fatal toxoplasmosis while others have incidental or mild chronic infections has long puzzled the scientific community. We assessed robust datasets on T. gondii molecular characterization in relation to detailed necropsy and histopathology results to evaluate whether parasite genotype influences pathological outcomes in sea otters that stranded along the central California coast. Genotypes isolated from sea otters were also compared with T. gondii strains circulating in felids from nearby coastal regions to assess land-to-sea parasite transmission. The predominant T. gondii genotypes isolated from 135 necropsied sea otters were atypical Type X and Type X variants (79%), with the remainder (21%) belonging to Type II or Type II/X recombinants. All sea otters that died due to T. gondii as a primary cause of death were infected with Type X or X-variant T. gondii strains. The same atypical T. gondii strains were detected in sea otters with fatal toxoplasmosis and terrestrial felids from watersheds bordering the sea otter range. Our results confirm a land–sea connection for virulent T. gondii genotypes and highlight how faecal contamination can deliver lethal pathogens to coastal waters, leading to detrimental impacts on marine wildlife.

A Qualitative Study of Ecstasy Sellers in the San Francisco Bay Area

2004 ◽  
Author(s):  
Sheigla Murphy ◽  
Paloma Sales ◽  
Micheline Duterte ◽  
Camille Jacinto
Keyword(s):  
Qualitative Study ◽  
San Francisco ◽  
San Francisco Bay ◽  
San Francisco Bay Area ◽  
Bay Area

Cyborg Jotería Pedagogies: Latinx Drag Queens Leveraging Communication Ecologies in the Age of the Digital and Social Displacement

2020 ◽  
Vol 14 (2) ◽  
pp. 44-66
Author(s):  
José Ramón Lizárraga ◽  
Arturo Cortez
Keyword(s):  
San Francisco ◽  
San Francisco Bay ◽  
San Francisco Bay Area ◽  
Digital Technologies ◽  
Physical World ◽  
Political Issues ◽  
Drag Queen ◽  
Bay Area ◽  
Online Presence ◽  
Drag Queens

Researchers and practitioners have much to learn from drag queens, specifically Latinx queens, as they leverage everyday queerness and brownness in ways that contribute to pedagogy locally and globally, individually and collectively. Drawing on previous work examining the digital queer gestures of drag queen educators (Lizárraga & Cortez, 2019), this essay explores how non-dominant people that exist and fluctuate in the in-between of boundaries of gender, race, sexuality, the physical, and the virtual provide pedagogical overtures for imagining and organizing for new possible futures that are equitable and just. Further animated by Donna Haraway’s (2006) influential feminist post-humanist work, we interrogate how Latinx drag queens as cyborgs use digital technologies to enhance their craft and engage in powerful pedagogical moves. This essay draws from robust analyses of the digital presence of and interviews with two Latinx drag queens in the San Francisco Bay Area, as well as the online presence of a Xicanx doggie drag queen named RuPawl. Our participants actively drew on their liminality to provoke and mobilize communities around socio-political issues. In this regard, we see them engaging in transformative public cyborg jotería pedagogies that are made visible and historicized in the digital and physical world.

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