Ultraviolet light alters experimental aquarium water microbial communities.

The effect of ultraviolet (UV) light exposure, alone and in combination with CO2 exposure, on the water microbial community composition was tested in replicate experimental aquaria using source water from an established Amazon-themed exhibit housing mixed species of fishes. Total bacterial abundance, α-diversity metrics, and ß-diversity metrics were determined 3 weeks and 1 week before, and weekly during 8 weeks of continuous treatment. The UV treatment significantly lowered the overall bacterial abundance while CO2 treatment had no effect. However, the UV exposure effect was variable across phyla. Some phyla were decreased while others were increased, including some of potential clinical significance. At the genus level, there were no significant differences in the relative abundance of Mycobacteria between treatments and an increase in the relative abundance of Aeromonas spp. with UV light treatment. Further work is needed to determine if the observed effects are dose-dependent or if different exposure doses produce different results.

IMMUNOMEDIATOR GENE TRANSCRIPTION PROFILING IN BELUGA WHALE (DELPHINAPTERUS LEUCAS) CLINICAL CASES.

There is an unmet need for specific diagnostics of immune perturbations and inflammation in beluga whale (Delphinapterus leucas) clinical care. Quantitative real-time polymerase chain reaction (qPCR) has been used to measure immunomediator gene transcription in beluga whales. The study hypothesis was that a qPCR-based immunomediator assay would supplement routine clinical data with specific and sensitive information on immune status. Two beluga whale clinical cases provided an opportunity to test this hypothesis: a whale with a skin laceration and a whale with gastrointestinal inflammation. Mitogen-stimulated immunomediator gene transcription (MSIGT) was compared between the cases and healthy contact whales. In both case studies, mitogens increased transcription of IL1B, PTGS2 (Cox-2), TNF, HIF1A, and IL2 but decreased IL10 transcription in peripheral blood mononuclear cells (PBMC) from the abnormal whale over the control. Correlations were identified between most immunomediators tested and one or more standard blood clinical values. Considering all 15 immunomediators tested, the whale with gastrointestinal inflammation had a more unique MSIGT signature than the whale with a laceration. These results support further elucidation of beluga whale PBMC cytokine profiles for use as immune biomarkers.

EVALUATION OF HEALTH PARAMETERS IN COWNOSE RAYS ( RHINOPTERA BONASUS) HOUSED IN A SEASONAL TOUCH POOL HABITAT COMPARED WITH AN OFF-EXHIBIT HABITAT.

Cownose rays ( Rhinoptera bonasus) are commonly displayed in zoo and aquarium touch pool exhibits; however, there is a gap in our understanding of how these practices might impact the health of these animals. The aim of this study was to evaluate and compare selected health parameters in cownose rays housed in a seasonal outdoor exhibit touch pool system with abundant public contact and an indoor off-exhibit holding system with minimal human contact. All animals underwent physical examination, ultrasound, cloacal wash and cytology, and blood collection for complete blood counts, point-of-care blood analysis, plasma protein electrophoresis, and plasma cholesterol electrophoresis in May and October 2014. Physical examination, ultrasound, and cloacal wash cytology findings were all unremarkable for both groups of animals. Significant differences in health parameters among animals by location and time point were few and included decreased heart rate ( F = 12.158, P = 0.001), increased lactate ( F = 6.838, P = 0.012), and increased low-density lipoproteins ( F = 19.961, P = 0.000) in touch pool animals over time. Based on these results, cownose rays inhabiting a touch pool exhibit and an off-exhibit system remained in comparable planes of health based on routine diagnostic modalities with few differences in measured health parameters.

ASSOCIATION BETWEEN POSITIVE CANINE HEARTWORM (DIROFILARIA IMMITIS) ANTIGEN RESULTS AND PRESENCE OF ACANTHOCHEILONEMA ODENDHALI MICROFILARIA IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

This study establishes a relationship between positive canine heartworm (Dirofilaria immitis) test results frequently observed in California sea lions (Zalophus californianus) and infection with the filarid nematode Acanthocheilonema odendhali. Four commercially available canine heartworm antigen tests were evaluated for cross-reaction with A. odendhali in California sea lions. Sera were tested from fifteen California sea lions with A. odendhali-associated microfilaremia, confirmed by blood smear, and with no evidence of D. immitis infection at necropsy. Ninety-five percent of tests were falsely positive for D. immitis. This study also determined that the prevalence of A. odendhali infection in stranded California sea lions from central California is approximately 23% by comparing the number of findings of mircofilaremia to the total number of California sea lions sampled at The Marine Mammal Center between 2005 and 2011, inclusive. Acanthocheilonema odenhali microfilaremia in California sea lions is likely to cross-react with canine heartworm antigen tests, and clinicians should interpret results with caution.

INTRAPERITONEAL DEXTROSE ADMINISTRATION AS AN ALTERNATIVE EMERGENCY TREATMENT FOR HYPOGLYCEMIC YEARLING CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

The Marine Mammal Center (TMMC) cares for malnourished California sea lion (CSL) (Zalophus californianus) pups and yearlings every year. Hypoglycemia is a common consequence of malnutrition in young CSLs. Administering dextrose during a hypoglycemic crisis is vital to recovery. Traditional veterinary approaches to treat hypoglycemia pose therapeutic challenges in otariids, as vascular access and catheter maintenance can be difficult. The current approach to a hypoglycemic episode at TMMC is to administer dextrose intravenously (i.v.) by medically trained personnel. Intraperitoneal (i.p.) dextrose administration is an attractive alternative to i.v. administration because volunteer staff with basic training can administer treatment instead of waiting for trained staff to treat. This study compares the effects of i.v., i.p., and no dextrose administration on serum glucose and insulin in clinically healthy, euglycemic CSL yearlings. Three groups of animals, consisting of five sea lions each, were treated with 500 mg/kg dextrose using one of the following routes: i.v., i.p., or no dextrose (control). A jugular catheter was placed, and blood samples were collected at times 0, 5, 15, 30, 60, 120, 180, and 240 min after dextrose administration. I.v. dextrose administration resulted in an increase of serum glucose concentrations from a baseline level of approximately 150 mg/dl to a peak of approximately 350 mg/dl. The resulting hyperglycemia persisted for approximately 2 hr and was associated with an attenuated plasma insulin response compared with most terrestrial mammals. Intraperitoneal dextrose administration resulted in increases of serum glucose to approximately 200 mg/dl, which gradually declined to baseline by 2 hr after dextrose administration. These data suggest that the initial treatment of a hypoglycemic crisis in young malnourished CSLs can be accomplished with i.p. dextrose, thus enabling minimally trained volunteer staff to respond immediately to a crisis. Further studies are needed to determine the most appropriate long-term treatment.

CUTANEOUS SQUAMOUS CELL CARCINOMA IN A PANTHER CHAMELEON (FURCIFER PARDALIS) AND TREATMENT WITH CARBOPLATIN IMPLANTABLE BEADS.

A 3-yr-old male panther chameleon (Furcifer pardalis) presented with bilateral raised crusted skin lesions along the lateral body wall that were found to be carcinoma in situ and squamous cell carcinoma. Similar lesions later developed on the caudal body wall and tail. A subcutaneous implantable carboplatin bead was placed in the first squamous cell carcinoma lesion identified. Additional new lesions sampled were also found to be squamous cell carcinomas, and viral polymerase chain reaction was negative for papillomaviruses and herpesviruses. Significant skin loss would have resulted from excision of all the lesions, so treatment with only carboplatin beads was used. No adverse effects were observed. Lesions not excised that were treated with beads decreased in size. This is the first description of cutaneous squamous cell carcinoma and treatment with carboplatin implantable beads in a panther chameleon.

Aquarium microbiome response to ninety-percent system water change: Clues to microbiome management.

The bacterial community composition and structure of water from an established teleost fish system was examined before, during and after a major water change to explore the impact of such a water-change disturbance on the stability of the aquarium water microbiome. The diversity and evenness of the bacterial community significantly increased following the 90% water replacement. While the change in bacterial community structure was significant, it was slight, and was also weakly correlated with changes in physicochemical parameters. Interestingly there was a significant shift in the correlative network relationships between operational taxonomic units from before to after the water replacement. We suggest this shift in network structure is due to the turnover of many taxa during the course of water replacement. These observations will inform future studies into manipulation of the microbiome by changing system environmental parameter values to optimize resident animal health.

LAPAROSCOPIC GASTROPEXY FOR CORRECTION OF A HIATAL HERNIA IN A NORTHERN ELEPHANT SEAL (MIROUNGA ANGUSTIROSTRIS).

A female northern elephant seal (Mirounga angustirostris) weaned pup presented with malnutrition. During rehabilitation, the seal developed regurgitation and reduced lung sounds on auscultation. Radiographs and endoscopy performed under sedation suggested a diaphragmatic hernia. A Type I (or sliding) hiatal hernia was confirmed with a positive contrast upper gastrointestinal study, revealing varying degrees of herniation of the gastric fundus through the diaphragm into the caudal thorax as well as esophageal reflux. The animal was treated preoperatively with an H2 antagonist and antinausea medication. A laparoscopic gastropexy was performed under general anesthesia. The animal recovered well postoperatively and resolution of clinical signs was achieved. The animal was released back into the wild 21 kg above admit weight. To our knowledge, we report here the first surgical correction of a hiatal hernia in a marine mammal.

PHARMACOKINETICS OF TRAMADOL HYDROCHLORIDE AND ITS METABOLITE O-DESMETHYLTRAMADOL FOLLOWING A SINGLE, ORALLY ADMINISTERED DOSE IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

Tramadol is a synthetic, centrally acting, opiate-like analgesic that is structurally related to codeine and morphine. The objective of this study was to determine the pharmacokinetics of tramadol hydrochloride and its major active metabolite O-desmethyltramadol (M1) in the California sea lion (Zalophus californianus). A single dose of tramadol was administered orally in fish at 2 mg/kg to a total of 15 wild California sea lions admitted for rehabilitation. Twenty-four total blood samples were collected post drug administration at 10, 20, 30, and 45 min and at 1, 3, 5, 6, 8, 12, and 24 hr. Blood plasma was separated and stored at -80°C until analysis with high-performance liquid chromatography was performed to determine levels of tramadol and M1, the major active metabolite. The results indicate that the plasma levels of parent tramadol are low or negligible during the first 30-45 min and then reach the predicted mean maximum plasma concentration of 358 ng/ml at 1.52 hr. The M1 metabolite was not detectable in 21 of 24 plasma samples, below the level of quantification of 5 ng/ml in one sample, and detectable at 11 and 17 ng/ml in two of the samples. This study suggests that a 2 mg/kg dose would need to be administered every 6-8 hr to maintain concentrations of tramadol above the minimum human analgesic level for mild to moderate pain. Based on dosing simulations, a dose of 4 mg/kg q8 hr or q12 hr, on average, may represent an adequate compromise, but further studies are needed using a larger sample size. Pharmacodynamic studies are warranted to determine if tramadol provides analgesic effects in this species. The potential for tramadol toxicosis at any dose also has not been determined in this species.

Pharmacokinetics of ceftiofur crystalline-free acid (EXCEDE sterile suspension) administered via intramuscular injection in wild California sea lions (Zalophus californianus).

The pharmacokinetics of ceftiofur crystalline-free acid (EXCEDE Sterile Suspension, 200 mg ceftiofur equivalents/ml) were determined for the California sea lion (Zalophus californianus). A single dose of EXCEDE was administered intramuscularly at 6.6 mg/kg to 12 wild California sea lions during rehabilitation. The first 10 animals were each assigned to two blood collection time points, with a total of 10 time points at: 6, 12, 24, 48, 72, 96, 120, 144, 168, and 192 hr after administration of the drug. An additional two animals were sampled 1, 2, 3, 4, 5, and 6 hr postinjection. Plasma was separated within 10 min of blood collection and stored at -20 degrees C until analysis. Plasma concentrations of ceftiofur, desfuroylceftiofur, and related metabolites, were determined using liquid chromatography with tandem mass spectrometry (MS). Maximum plasma concentrations of ceftiofur and related metabolites were observed 24 hr postdosing with a mean concentration of 3.6 microg/ml. The half life (60 hr) and area under the curve (270 microg x hr/ml) were also determined. These data indicate that a single dose of EXCEDE at 6.6 mg/kg i.m. would likely maintain a mean plasma drug level >0.6 microg/ml for 5 days and >0.5 microg/ml for 8 days.

Serologic response in bottlenose dolphins Tursiops truncatus infected with Brucella sp. using a dolphin-specific indirect ELISA.

Marine-origin Brucella infections and serologic evidence of exposure have been documented in multiple cetacean species. A dolphin-specific indirect enzyme-linked immunosorbent assay (ELISA) was developed to screen bottlenose dolphin sera for anti-Brucella antibodies. A total of 131 serum samples collected over a 2 to 18 yr period from 6 bottlenose dolphins Tursiops truncatus with confirmed Brucella infections were analyzed for the presence and magnitude of antibody titers against marine-origin Brucella to compare individual antibody responses to various disease manifestations. Additionally, an epidemiologic serologic survey of a managed population of 64 bottlenose dolphins was performed to evaluate for the presence of antibodies and to determine whether there were any clinical pathology predictors for exposure or infection. The serologic results revealed that the dolphins with Brucella-associated abortions were seronegative for 7 to 18 yr until after the abortion and maintained positive titers for several years, with 2 of 3 animals returning to seronegative status. In contrast, the dolphins with Brucella-associated pulmonary or bone lesions maintained persistent positive titers for 2 to 18 yr. The population serosurvey revealed no significant differences in antibody levels among males and females, and dolphins between the ages of 17 and 25 yr were 6.8 times more likely to be Brucella antibody positive compared to those that were younger or older. Seropositive dolphins did not have significant inflammation compared to seronegative dolphins but were more likely to have higher levels of aspartate aminotransferase and gamma-glutamyl transpeptidase. Among 16 dolphins that tested seropositive, 13 (81.3%) had previously been seropositive for at least 3 to 5 yr.

Risk factors associated with perianesthetic mortality of stranded free-ranging California sea lions (Zalophus californianus) undergoing rehabilitation.

The objective of this study was to identify risk factors associated with perianesthetic mortality of stranded free-ranging California sea lions (Zalophus californianus) undergoing rehabilitation. Hospital records of California sea lions that underwent heavy sedation or general anesthesia from 2004 through 2008 were reviewed, including records from 419 anesthetic events. Procedures that resulted in death during or in the subsequent 72 hr of anesthesia were classified as cases (n = 15). Procedures in which the animal survived were classified as controls (n = 334). Procedures that resulted in euthanasia (n = 70) were removed from subsequent analysis. The following risk factors were reviewed: gender, age class, health status, duration of anesthetic period, atropine premedication, induction protocols, maintenance protocols, and history of prior anesthesia. The prevalence of fatalities during anesthesia was 3.4% (n = 12) over the 5-yr period. With the inclusion of animals that died within 72 hr after anesthesia, the total mortality prevalence rose to 4.3% (n = 15). The most common time of death was during anesthetic maintenance. Health status was the single best predictor of anesthetic outcome, and sea lions premedicated with atropine had increased odds of anesthetic-related death.

Towards understanding microbial degradation of chloroquine in large saltwater systems.

Circulating saltwater aquariums hosting marine animals contain a wide range of microorganisms, which have strong implications on promoting animal health. In this study, we investigated the degradation of chloroquine phosphate, an anti-parasitic bath pharmaceutical used in saltwater quarantine and exhibition systems, and attributed the reduction in drug concentration to microbial degradation of chloroquine associated with pipeline microbial communities. To advance our knowledge on chloroquine degradation in aquatic systems, we conducted microbial and chemical analyses on three tropical saltwater systems. Our findings show that aquarium microbiome composition is shaped by sampling location (i.e., tank water and pipeline; PERMANOVA R2 = 0.09992, p = 0.0134), chloroquine dosing (PERMANOVA R2 = 0.05700, p = 0.0030), and whether the aquarium is occupied by marine animals (PERMANOVA R2 = 0.07019, p = 0.0009). Several microbial taxa belonging to the phyla Actinobacteria, Bacteroidetes, Chloroflexi, and Proteobacteria, along with functional genes related to pathways such as phenylethylamine degradation and denitrification, appeared to have differential (relative) abundance between samples where chloroquine degradation was observed and those without degradation (Benjamini-Hochberg adjusted p-value <0.05). Together, these results provide practical mitigation options to prevent or delay the development of chloroquine-degrading microbial communities in saltwater aquariums. Our results further demonstrate the need to improve our understanding of the interactions between nitrogen availability and microbial activity in saltwater systems.

Antemortem diagnosis of a ventricular septal defect in a California sea lion Zalophus californianus.

A yearling California sea lion Zalophus californianus stranded in poor body condition, and on physical examination a heart murmur was audible bilaterally. The sea lion was diagnosed with a left-to-right shunting membranous ventricular septal defect (VSD) using B-mode, color-flow Doppler and continuous-wave Doppler echocardiography. A left-to-right intracardiac shunting lesion was confirmed during cardiac angiographic computed tomography. The VSD defect was verified during the necropsy examination. On histologic examination concurrent mild multifocal myocarditis with focal mild ventricular free-wall myocardial necrosis were identified. A specific cause for the myocarditis and myocardial necrosis was not found, and association with the VSD and resultant myocardial dysfunction was presumed. This is the first report of the antemortem diagnosis of a VSD in a marine mammal and the first report of a VSD in a California sea lion.

An integrative review of lateral line depigmentation in marine and freshwater fish.

OBJECTIVE: To qualitatively review reports on lateral line depigmentation (LLD) in marine and freshwater fish. SAMPLE: English-language publications concerning LLD published before March 1, 2020. PROCEDURES: Electronic searches of CAB abstracts, PubMed, and Web of Science databases and the proceedings of the International Association of Aquatic Animal Medicine were performed. Records were systematically screened and selected for inclusion in an integrative review. Bibliographies of records included in the review were examined to identify other records to be screened. Included records were qualitatively reviewed. Evidence level and quality were graded according to previously described criteria. Information pertinent to epidemiological factors, etiopathogenesis, clinical and histopathologic findings, treatment, and prevention of LLD was collected. RESULTS: 401 records were screened, and 24 unique publications (16 peer-reviewed articles, 1 textbook, and 7 abstracts) were included in the study; 12 (50%), 1 (4%), 6 (25%), and 5 (21%) were classified as evidence level I (experimental), II (quasi-experimental), III (nonexperimental), and V (clinical reports or clinician experience), respectively. Seventeen (71%) and 7 (29%) reports were classified as high quality and good quality, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: LLD should be considered a clinical observation indicative of a dermatologic response of fish to suboptimal conditions; LLD should continue to be adopted as the preferred term to describe the classic signs. Whereas gross findings are similar among species, histologic findings can vary. Evidence-based treatment of LLD for individual fish consists of source control (changing tanks or systems), topical treatment with 0.01% becaplermin gel, supportive care, and antimicrobial treatment when warranted. For schools of fish, treatment and prevention of LLD should be focused on improving suboptimal environmental and physiologic conditions.

Evaluation of a portable nanopore-based sequencer for detection of viruses in water.

The newly emerged nanopore sequencing technology such as MinION™ allows for real-time detection of long DNA/RNA fragments on a portable device, yet few have examined its performance for environmental viromes. Here we seeded one RNA virus bacteriophage MS2 and one DNA virus bacteriophage PhiX174 into 10 L well water at three levels ranging from 1 to 21,100 plaque-forming units (PFU)/mL. Two workflows were established to maximize the number of sequencing reads of RNA and DNA viruses using MinION™. With dead-end ultrafiltration, PEG precipitation, and random amplification, MinION™ was capable of detecting MS2 at 155 PFU/mL and PhiX174 at 1-2 PFU/mL. While the DNA workflow only detected PhiX174, the RNA workflow detected both MS2 and PhiX174. The virus concentration, or relative abundance of viral nucleic acids in total nucleic acids, is critical to the proportion of viral reads in sequencing results. Our findings also highlight the importance of including control samples in sequencing runs for environmental water samples with low virus abundance.

Intestinal polycyclic aromatic hydrocarbon-DNA adducts in a population of beluga whales with high levels of gastrointestinal cancers.

Carcinogenic polycyclic aromatic hydrocarbons (PAHs) were disposed directly into the Saguenay River of the St. Lawrence Estuary (SLE) by local aluminum smelters (Quebec, Canada) for 50 years (1926-1976). PAHs in the river sediments are likely etiologically related to gastrointestinal epithelial cancers observed in 7% of 156 mature (>19-year old) adult beluga found dead along the shorelines. Because DNA adduct formation provides a critical link between exposure and cancer induction, and because PAH-DNA adducts are chemically stable, we hypothesized that SLE beluga intestine would contain PAH-DNA adducts. Using an antiserum specific for DNA modified with several carcinogenic PAHs, we stained sections of paraffin-embedded intestine from 51 SLE beluga (0-63 years), 4 Cook Inlet (CI) Alaska beluga (0-26 years), and 20 beluga (0-46 years) living in Arctic areas (Eastern Beaufort Sea, Eastern Chukchi Sea, Point Lay Alaska) and aquaria, all with low PAH contamination. Stained sections showed nuclear light-to-dark pink color indicating the presence of PAH-DNA adducts concentrated in intestinal crypt epithelial lining cells. Scoring of whole tissue sections revealed higher values for the 51 SLE beluga, compared with the 20 Arctic and aquarium beluga (P = 0.003). The H-scoring system, applied to coded individual photomicrographs, confirmed that SLE beluga and CI beluga had levels of intestinal PAH-DNA adducts significantly higher than Arctic and aquarium beluga (P = 0.003 and 0.02, respectively). Furthermore, high levels of intestinal PAH-DNA adducts in four SLE beluga with gastrointestinal cancers, considered as a group, support a link of causality between PAH exposure and intestinal cancer in SLE beluga. Environ. Mol. Mutagen. 60:29-41, 2019. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Characterization of a parainfluenza virus isolated from a bottlenose dolphin (Tursiops truncatus).

A novel member of the parainfluenza virus family was identified in a bottlenose dolphin with respiratory disease. The case animal was a 19-year old male Atlantic bottlenose dolphin (Tursiops truncatus) that presented with signs of respiratory illness, including raspy, foul-odored breaths and cream-colored exudate from the blowhole. Focally extensive pyogranulomatous bronchointerstitial pneumonia with moderate numbers of intralesional yeast organisms was identified on histopathological examination. Other significant microscopic findings included multifocal erosive and ulcerative tracheitis and laryngitis consisting of active laryngeal lymphatic tissue and dilated glands with eosinophilic fluid. The cause of death was attributed to respiratory disease of unknown etiology. In addition to the postmortem isolation of Candida glabrata and mixed bacteria from lung tissue, a virus was isolated from two antemortem affected lung aspirates collected over a 2-month period and two postmortem samples (mediastinal lymph node and left lung tissue homogenate). The morphology of the virions on negative staining and transmission electron microscopy was consistent with that of paramyxoviruses. Two genomic fragments, comprising 532 and 419 nucleotides from the open reading frames that code for the viral polymerase and fusion protein, respectively, were amplified by polymerase chain reaction using degenerate primers. Phylogenetic analyses of the two viral RNA segments showed that the isolate comprised a novel virus strain, tentatively named T. truncatus parainfluenza virus type 1 (TtPIV-1). The virus is monophyletic with, but genetically distinct from, the various bovine parainfluenza virus type 3 strains.

West Nile virus seroconversion in penguins after vaccination with a killed virus vaccine or a DNA vaccine.

To investigate the serologic response of penguins to West Nile virus (WNV) vaccines, four species of exclusively indoor-housed penguins, negative for WNV by serology, were evaluated: Humboldt (Spheniscus humboldti), Magellanic (Spheniscus magellanicus), Gentoo (Pygoscelis papua), and Rockhopper (Eudyptes chrysoscome) penguins. Birds were inoculated with either a killed virus vaccine or a plasmid-mediated DNA WNV vaccine, and postinoculation serology was evaluated. Both vaccines induced seroconversion in all four species, and no adverse reactions were noted. Postvaccination serology results varied across species and vaccine types. However, in all four species, the killed virus vaccine resulted in a greater seroconversion rate than the DNA vaccine and in a significantly shorter time period. Additionally, the duration of the seropositive titer was significantly longer in those birds vaccinated with the killed virus vaccine compared with those vaccinated with the DNA vaccine. A subset of unvaccinated penguins serving as negative controls remained negative throughout the duration of the study despite the presence of WNV in the geographic locations of the study, suggesting that indoor housing may minimize exposure to the virus and may be an additional means of preventing WNV infection in penguins.

Ecotoxicoparasitology of the gastrointestinal tracts of pinnipeds: the effect of parasites on the potential bioavailability of total mercury (THg).

Acanthocephalans, cestodes, and some species of nematodes acquire nutrients from the lumen contents in the gastrointestinal (GI) tract of their definitive host. These parasites are exposed to toxicants, such as mercury (Hg), through passive or active feeding mechanisms; therefore, the focus of this study was to determine if there is an effect of parasites on the dietary availability of total mercury (THg) within piscivorous pinniped hosts. THg concentrations ([THg]) in selected host tissues, parasites, and GI lumen contents from 22 California sea lions (Zalophus californianus), 15 ringed seals (Phoca hispida), and 4 spotted seals (Phoca largha) were determined. Among all pinnipeds, [THg] in acanthocephalans of the large intestine were significantly higher than concentrations in other samples (host lumen contents, other parasites and host intestinal wall), irrespective of location within the host GI tract. δ15N values of parasites depended both on parasite group and location within the GI tract. δ15N values were consistently higher in parasites inhabiting the large intestine, compared to elsewhere in the GI tract, for both sea lions and seals. δ13C values in parasites did not differ significantly from host GI tissues. Based on both [THg] and stable isotope values, parasites are likely affecting the Hg bioavailability within the GI lumen contents and host tissues, and toxicant-parasite interactions appear to depend on both parasitic taxon as well as their location within the host intestine.