The symptomatology and diagnosis of domoic acid toxicosis in stranded California sea lions (Zalophus californianus): a review and evaluation of 20 years of cases to guide prognosis.

Introduction: Domoic acid (DA) is a glutaminergic excitatory neurotoxin that causes the morbidity and mortality of California sea lions (Zalophus californianus; CSL) and other marine mammals due to a suite of effects mostly on the nervous and cardiac systems. Between 1998 and 2019, 11,737 live-stranded CSL were admitted to The Marine Mammal Center (TMMC; Sausalito, CA, USA), over 2,000 of which were intoxicated by DA. A plethora of clinical research has been performed over the past 20 years to characterize the range of toxic effects of DA exposure on CSLs, generating the largest dataset on the effects of natural exposure to this toxin in wildlife. Materials and methods: In this study, we review published methods for diagnosing DA intoxication, clinical presentation, and treatment of DA-intoxicated CSL and present a practical, reproducible scoring system called the neuroscore (NS) to help assess whether a DA-affected CSL is fit for release to the wild following rehabilitation. Logistic regression models were used to assess the relationships between outcome (released vs. euthanized or died) and multiple variables to predict the outcome for a subset of 92 stranded CSLs. Results: The largest proportion of DA-intoxicated CSLs was adult females (58.6%). The proportions of acute and chronic cases were 63.5 and 36.5% respectively, with 44% of affected CSL released and 56% either dying naturally or euthanized. The average time in rehabilitation was 15.9 days (range 0-169) for all outcomes. The best-performing model (85% accuracy; area under the curve = 0.90) assessing the relationship between outcome and predictor variables consisted of four variables: final NS, change in NS over time, whether the animal began eating in rehabilitation, and the state of nutrition on admission. Discussion: Our results provide longitudinal information on the symptomatology of CSL intoxicated by domoic acid and suggest that a behavioral scoring system is a useful tool to assess the fitness for the release of DA-intoxicated CSL.

Nasopulmonary mites (Halarachnidae) of coastal Californian pinnipeds: Identity, prevalence, and molecular characterization.

Mites from the family Halarachnidae Oudemans 1906 are obligate endoparasites that colonize the respiratory tracts of free-living and captive marine mammals. Infestations can range from mild to severe and result in respiratory tract irritation or impairment. Nasopulmonary acariasis was determined to be a contributing cause of death among several southern sea otters Enhydra lutris nereis Merriam 1904 in a longitudinal study of otter mortality, and proximity to Pacific harbor seals Phoca vitulina richardii Gray 1864 was a significant risk factor for sea otter infestation. Beyond scattered opportunistic reports, each halarachnid mite species' affinity for particular hosts and the extent of mite transmission between host species is poorly understood. We investigated the identity and prevalence of nasopulmonary mites from Pacific harbor seals, California sea lions Zalophus californianus Lesson 1828, northern elephant seals Mirounga angustirostris Gill 1866, northern fur seals Callorhinus ursinus Linnaeus 1758, and Guadalupe fur seals Arctocephalus philippii townsendi Merriam 1897 to complement published nasopulmonary mite findings from sympatric southern sea otters during a comparable timeframe. Halarachnid mite infestation was common among California sea lions (74.1%), northern fur seals (73.3%), and northern elephant seals (46.6%), but was less common among harbor seals (18.7%) and Guadalupe fur seals (8.8%). Observed host-mite relationships suggest a distinct host specificity, with genus Orthohalarachne infesting otariids, and genus Halarachne infesting phocids and lutrinids along the California coast. Harbor seals and southern sea otters were the primary hosts of H. halichoeri, but one nothern elephant seal was infested with both H. miroungae and a single H. halichoeri. We also present the first high-resolution SEM images for H. miroungae and O. attenuata and possible evidence for a new host record for H. halichoeri.

Isotopic variation in blood components based on their biochemistry and physiology: A comparison between sharks and fur seals.

Research using stable isotopes analysis (SIA) of carbon (δ13 C) and nitrogen (δ15 N) in blood components is lacking, because of the challenge of sample collection, processing, and storage in remote areas. There also is a paucity of information regarding the effect of tissue biochemical composition on isotopic ratios with few comparisons among taxa. We collected blood samples from shortfin mako sharks (n = 70; 2016) and Guadalupe fur seals (n = 25; 2017). All samples were centrifuged to obtain plasma from sharks and serum from the Guadalupe fur seals, and all the samples were prepared for SIA and analyzed using a Costech 4010 elemental analyzer interfaced with a Delta V Plus isotope ratio mass spectrometer. We found significant differences between plasma δ13 C values of shortfin mako sharks (-17.6 ± 0.9‰) and serum of Guadalupe fur seals (-20.3 ± 1.2‰), but we did not find any differences for δ15 N values between the two species. The differences in δ13 C values between species are probably due to the specific blood composition and to the different biochemical characteristics and different adaptations within taxa. These findings highlight the importance of further research on the influence of biochemistry features on isotopic results, in this way a more accurate assessment will be possible for this factor, separating it from the dietary influences on stable isotopic values.

Polyphasic Rhabdomyositis in California Sea Lions (Zalophus Californianus): Pathology and Potential Causes.

A myositis syndrome has been recognized for more than a decade in California sea lions (CSLs; Zalophus californianus) but a detailed description of the lesions and potential causes of this condition is lacking. The tissues of 136 stranded CSLs with rhabdomyositis were examined. Rhabdomyositis was considered incidental in 67% (91/136) of the CSLs, and a factor contributing to the animal stranding (significant rhabdomyositis) in 33% (45/136). Of the 91 cases with incidental rhabdomyositis, lesions consisted of a few small foci of lymphohistiocytic inflammation. Of the 45 cases with significant rhabdomyositis, 28 (62%) also presented with major comorbidities such as leptospirosis (2 animals) and domoic acid toxicosis (6 animals), whereas 17 (38%) had severe polyphasic rhabdomyositis as the only major disease process associated with mortality. In these animals, most striated muscles had multiple white streaks and diffuse atrophy. Microscopically, there was myofiber necrosis surrounded by lymphocytes and histiocytes admixed with areas of myofiber regeneration, and/or moderate to severe rhabdomyocyte atrophy usually adjacent to intact Sarcocystis neurona cysts. At the interface of affected and normal muscle, occasional T lymphocytes infiltrated the sarcoplasm of intact myocytes, and occasional myofibers expressed MHCII proteins in the sarcoplasm. S. neurona antibody titers and cyst burden were higher in animals with significant polymyositis antibody titers of (26125 ± 2164, 4.5 ± 1.2 cysts per section) and active myonecrosis than animals with incidental rhabdomyositis antibody titers of (7612 ± 1042, 1.7 ± 0.82 cysts per section). The presented findings suggest that S. neurona infection and immune-mediated mechanisms could be associated with significant polyphasic rhabdomyositis in CSLs.

Initial skill assessment of the California Harmful Algae Risk Mapping (C-HARM) system.

Toxic algal events are an annual burden on aquaculture and coastal ecosystems of California. The threat of domoic acid (DA) toxicity to human and wildlife health is the dominant harmful algal bloom (HAB) concern for the region, leading to a strong focus on prediction and mitigation of these blooms and their toxic effects. This paper describes the initial development of the California Harmful Algae Risk Mapping (C-HARM) system that predicts the spatial likelihood of blooms and dangerous levels of DA using a unique blend of numerical models, ecological forecast models of the target group, Pseudo-nitzschia, and satellite ocean color imagery. Data interpolating empirical orthogonal functions (DINEOF) are applied to ocean color imagery to fill in missing data and then used in a multivariate mode with other modeled variables to forecast biogeochemical parameters. Daily predictions (nowcast and forecast maps) are run routinely at the Central and Northern California Ocean Observing System (CeNCOOS) and posted on its public website. Skill assessment of model output for the nowcast data is restricted to nearshore pixels that overlap with routine pier monitoring of HABs in California from 2014 to 2015. Model lead times are best correlated with DA measured with solid phase adsorption toxin tracking (SPATT) and marine mammal strandings from DA toxicosis, suggesting long-term benefits of the HAB predictions to decision-making. Over the next three years, the C-HARM application system will be incorporated into the NOAA operational HAB forecasting system and HAB Bulletin.

A Systematic Review of Changes in Marine Mammal Health in North America, 1972-2012: The Need for a Novel Integrated Approach.

Marine mammals are often cited as "sentinels of ocean health" yet accessible, synthesized data on their health changes that could effectively warn of ocean health changes are rare. The objectives of this study were to 1) perform a systematic review of published cases of marine mammal disease to determine spatial and temporal trends in disease from 1972-2012, including changes in regions and taxa affected and specific causes; and 2) compare numbers of published cases of neoplasia with known, hospital-based neoplasia records to explore the causes of discrepancy between numbers of published cases and true disease trends. Peer-reviewed literature was compiled, and data were collected from The Marine Mammal Center database in Sausalito, California for comparison of numbers of neoplasia cases. Toxicoses from harmful algal blooms appear to be increasing. Viral epidemics are most common along the Atlantic U.S. coastline, while bacterial epidemics, especially leptospirosis, are most common along the Pacific coast. Certain protozoal and fungal zoonoses appear to be emerging, such as Toxoplasma gondii in southern sea otters in California, and Cryptococcus gattii in cetaceans in the Pacific Northwest. Disease reports were most common from California where pinniped populations are large, but increased effort also occurs. Anthropogenic trauma remains a large threat to marine mammal health, through direct mortality and indirect chronic disease. Neoplasia cases were under-reported from 2003-2012 when compared to true number of cases, and over-reported in several years due to case duplication. Peer-reviewed literature greatly underestimates the true magnitude of disease in marine mammals as it focuses on novel findings, fails to reflect etiology of multifactorial diseases, rarely reports prevalence rather than simple numbers of cases, and is typically presented years after a disease first occurs. Thus literature cannot guide management actions adequately, nor inform indices of ocean health. A real-time, nationally centralized system for reporting marine mammal disease data is needed to be able to understand how marine mammal diseases are changing with ecosystem changes, and before these animals can truly be considered 'sentinels of ocean health'.

Novel hemotrophic mycoplasma identified in naturally infected California sea lions (Zalophus californianus).

The hemoplasmas are the trivial name for a group of erythrocyte-parasitizing, non-cultivable in vitro bacteria of the genus Mycoplasma that have been described in several mammalian hosts worldwide. This study is the first report of hemoplasmas in marine mammals. EDTA anticoagulated whole blood samples from 137 California sea lions (Zalophus californianus) and 20 northern elephant seals (Mirounga angustirostris) admitted to the Marine Mammal Center (Sausalito, CA; www.marinemammalcenter.org) or live captured in Oregon were collected during 2008. Hemoplasma-specific genomic DNA was detected in blood samples from 12.4% California sea lions tested using PCR. Hemoplasma PCR positive blood specimens also were tested in reverse transcription polymerase chain reaction (RT-PCR) using the hemoplasma-specific primers for the 16S and 23S rRNA genes. The RT-PCR showed the presence the hemoplasmal rRNA, strongly suggesting the presence of potentially viable hemoplasmas in the bloodstream of the animals. BLAST search and phylogenetic analysis of the 16S rRNA sequences of the hemoplasma from California sea lions revealed that the organism is a novel hemoplasma species with only 92.1% of its nucleotide similarity to the 16S rRNA gene of the previously described hemoplasma species of alpacas, Candidatus Mycoplasma haemolamae. Thus, due to low level of genetic similarity of the hemoplasma to other described hemoplasmas and the mammalian host in which the hemoplasma was detected we propose that this novel hemoplasma species has been given the provisional name Candidatus Mycoplasma haemozalophi sp. nov.

Re-alimentation in harbor seal pups: effects on the somatotropic axis and growth rate.

The metabolic hormones, growth hormone (GH) and insulin-like growth factor (IGF)-I, together with IGF binding proteins (IGFBP), have been well studied in domestic species and are the primary components of the somatotropic axis. This hormone axis is responsive to nutrient intake, associated with growth rate, and accretion of protein and adipose. However, this relationship has not been evaluated in species that rely heavily on adipose stores for survival, such as pinnipeds. The primary objectives of this research were to investigate the response of the somatotropic axis to reduced nutrient intake and re-alimentation in rehabilitated harbor seal pups, and to assess if these hormones are related to nutritional status and growth rate in harbor seals. Stranded harbor seal pups (n=24) arrived at the rehabilitation facility very thin after fasting for several days (nutritional nadir). Throughout rehabilitation nutrient intake increased and pups gained mass and body condition. Concentrations of GH and IGFBP-2 decreased with re-alimentation, while IGF-I and IGFBP-3 concentrations increased. Overall, GH and IGFBP-2 were negatively associated and IGF-I and IGFBP-3 were positively associated with growth rate and increased body condition of harbor sea pups. Further, the magnitude of the growth response was related to the magnitude in response of the somatotropic axis to varied levels of intake. These data suggest that multiple components of the somatotropic axis may be used to assess the energy status of individuals and may also provide information on the level of feed intake that is predictive of growth rate.