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Otariid gammaherpesvirus 1 (OtGHV1) is associated with high rates of urogenital carcinoma in free-ranging California sea lions (Zalophus californianus; CSL), and until recently was reported only in the Northern Hemisphere. The objective of this study was to survey free-ranging South American sea lions (Otaria byronia; SASL) and South American fur seals (Arctocephalus australis: SAFS) in Punta San Juan, Peru for OtGHV1 and to determine prevalence characteristics. Twenty-one percent (14/67) of urogenital swabs collected over three years (2011, 2014, 2015) from live pinnipeds of both species tested positive with a pan-herpesvirus conventional PCR. Sequencing of SAFS amplicons revealed 100% homology to OtGHV1 at the DNA polymerase, glycoprotein B, and viral bcl2-like genes. Sequencing of SASL amplicons revealed a novel related virus, herein called Otariid gammaherpesvirus 8 (OtGHV8). For comparison of sample sites, urogenital, conjunctival, and oropharyngeal swabs collected from 136 live pinnipeds of both species at Punta San Juan between 2011-2018 were then assayed using quantitative PCR for a segment of the OtGHV1/8 DNA polymerase gene using a qPCR assay now determined to cross-react between the two viruses. In total, across both species, 38.6% (51/132) of urogenital swabs, 5.6% (4/71) of conjunctival swabs, and 1.1% (1/90) of oropharyngeal swabs were positive for OtGHV1/8, with SASL only positive on urogenital swabs. Results from SASL were complicated by the finding of OtGHV8, necessitating further study to determine prevalence of OtGHV1 versus OtGHV8 using an alternate assay. Results from SAFS suggest a potential relationship between OtGHV1 in SAFS and CSL. Though necropsy surveillance in SAFS is very limited, geographic patterns of OtGHV1-associated urogenital carcinoma in CSL and the tendency of herpesviruses to cause more detrimental disease in aberrant hosts suggests that it is possible that SAFS may be the definitive host of OtGHV1, which gives further insight into the diversity and phyogeography of this clade of related gammaherpesviruses., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Tang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

South American sea lions (Otaria byronia) and Peruvian fur seals (Arctocephalus australis) are sympatric species inhabiting the coastal Peruvian marine ecosystem. Declining abundance has prompted population health monitoring programs, including temporal monitoring of blood parameters. Several methods exist to determine total leukocyte count, yet no studies have evaluated agreement between methods in pinnipeds. We assessed agreement between total leukocyte counts determined by blood film estimate, Leuko-TIC, HemoCue, and UNOPETTE methods by using archival results from pinnipeds at Punta San Juan, Peru. Blood film estimates were prospectively performed, and resulting data were compared with retrospective leukocyte counts obtained from both species between 2009 and 2019 by using the other methodologies. Agreement in hematologic counts between methods was evaluated using Passing-Bablok regression and Bland-Altman plots (α=0.05). In total, 295 individuals (201 A. australis and 94 O. byronia) were included in the analysis. The blood film estimate method resulted in the highest leukocyte values (P<0.0001). Leuko-TIC counts were significantly higher than HemoCue counts (P<0.0001). Constant and proportional error was present in the agreement between the blood film estimate method and the other methods. Given the variation demonstrated between the different methodologies, additional research is needed to further evaluate agreement between these methodologies. The results underscore the importance of maintaining consistency in leukocyte count methodology for monitoring trends in population health over time. Method consistency may be the more important clinical consideration for assessing changes in leucocyte count over time and avoiding apparent changes depending on the methodology used., (© Wildlife Disease Association 2023.)

Determining trophic habits of predator communities is essential to measure interspecific interactions and response to environmental fluctuations. South American fur seals, Arctocephalus australis (SAFS) and sea lions Otaria byronia (SASL), coexist along the coasts of Peru. Recently, ocean warming events (2014-2017) that can decrease and impoverish prey biomass have occurred in the Peruvian Humboldt Current System. In this context, our aim was to assess the effect of warming events on long-term inter- and intra-specific niche segregation. We collected whisker from SAFS (55 females and 21 males) and SASL (14 females and 22 males) in Punta San Juan, Peru. We used δ13C and δ15N values serially archived in otariid whiskers to construct a monthly time series for 2005-2019. From the same period we used sea level anomaly records to determine shifts in the predominant oceanographic conditions using a change point analysis. Ellipse areas (SIBER) estimated niche width of species-sex groups and their overlap. We detected a shift in the environmental conditions marking two distinct periods (P1: January 2005-October 2013; P2: November 2013-December 2019). Reduction in δ15N in all groups during P2 suggests impoverished baseline values with bottom-up effects, a shift towards consuming lower trophic level prey, or both. Reduced overlap between all groups in P2 lends support of a more redundant assemblage during the colder P1 to a more trophically segregated assemblage during warmer P2. SASL females show the largest variation in response to the warming scenario (P2), reducing both ellipse area and δ15N mean values. Plasticity to adapt to changing environments and feeding on a more available food source without fishing pressure can be more advantageous for female SASL, albeit temporary trophic bottom-up effects. This helps explain larger population size of SASL in Peru, in contrast to the smaller and declining SAFS population., Competing Interests: The authors have declared that no competing interests exist.

Sympatric species evolve mechanisms to avoid competition and coexist. In the Humboldt Current System (HCS), populations of South American sea lions (SASL, Otaria byronia) and South American fur seals (SAFS, Arctocephalus australis) fluctuate mostly due to ENSO events and prey availability. We evaluate population trajectories of Peruvian sympatric otariids and discuss mechanisms for competition and/or resource limitation. For this purpose, we analyzed population trajectories of SASL and SAFS in a sympatric breeding site in Punta San Juan, Peru between 2001 and 2019. Wavelet analysis was used to extract trends and derivatives to estimate rates and turning points. Age-class proportions and biomass times series were constructed from weekly counts and evaluated. Both populations show a growth phase and subsequent decline. SAFS started to decline ~2.25 years before and at a rate 1.5 times faster than SASL. Decrease in juvenile age-class suggests that resource limitation is the main contributing factor for current population decline., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The phylogeny and systematics of fur seals and sea lions (Otariidae) have long been studied with diverse data types, including an increasing amount of molecular data. However, only a few phylogenetic relationships have reached acceptance because of strong gene-tree species tree discordance. Divergence times estimates in the group also vary largely between studies. These uncertainties impeded the understanding of the biogeographical history of the group, such as when and how trans-equatorial dispersal and subsequent speciation events occurred. Here, we used high-coverage genome-wide sequencing for 14 of the 15 species of Otariidae to elucidate the phylogeny of the family and its bearing on the taxonomy and biogeographical history. Despite extreme topological discordance among gene trees, we found a fully supported species tree that agrees with the few well-accepted relationships and establishes monophyly of the genus Arctocephalus. Our data support a relatively recent trans-hemispheric dispersal at the base of a southern clade, which rapidly diversified into six major lineages between 3 and 2.5 Ma. Otaria diverged first, followed by Phocarctos and then four major lineages within Arctocephalus. However, we found Zalophus to be nonmonophyletic, with California (Zalophus californianus) and Steller sea lions (Eumetopias jubatus) grouping closer than the Galapagos sea lion (Zalophus wollebaeki) with evidence for introgression between the two genera. Overall, the high degree of genealogical discordance was best explained by incomplete lineage sorting resulting from quasi-simultaneous speciation within the southern clade with introgresssion playing a subordinate role in explaining the incongruence among and within prior phylogenetic studies of the family. [Hybridization; ILS; phylogenomics; Pleistocene; Pliocene; monophyly.]., (© The Author(s) 2020. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Intraocular pressures (IOPs) were measured using a rebound tonometer in 56 free-ranging adult South American sea lions ( Otaria byronia ) from Punta San Juan, Peru. All animals were anesthetized using medetomidine, midazolam, and butorphanol and determined to be in good health. No ocular abnormalities were observed affecting the cornea or ocular adnexa. Field conditions precluded evaluation of the lens and posterior segment of the eye. Mean (SD) IOP values for males ( n =37) were 31±11 mmHg (right eye) and 31±9 mmHg (left eye). The same values for females ( n =19) were 24±9 mmHg in the left eye and 27±10 mmHg in the right eye. These values are similar to those previously reported for pinnipeds under professional care and higher than those generally reported for terrestrial mammals.

The tissues and parasites collected from Peruvian fur seals (Arctocephalus australis) and South American sea lions (Otaria byronia) found dead at Punta San Juan, Peru were examined. The respiratory mite, Orthohalarachne attenuata infected 3 out of 32 examined fur seals and 3 out of 8 examined sea lions, however caused moderate to severe lymphohistiocytic pharyngitis only in fur seals. Hookworms, Uncinaria sp, infected 6 of the 32 examined fur seals causing variable degrees of hemorrhagic and eosinophilic enteritis. This parasite caused the death of 2 of these pups. In fur seals and sea lions, Corynosoma australe and Contracaecum osculatum were not associated with significant tissue alterations in the intestine and stomach respectively. Respiratory mites and hookworms have the potential to cause disease and mortality among fur seals, while parasitic infections do not impact significatively the health of sea lions at Punta San Juan, Peru.

The South American sea lion (Otaria flavescens) is widely distributed along the southern Atlantic and Pacific coasts of South America with a history of significant commercial exploitation. We aimed to evaluate the population genetic structure and the evolutionary history of South American sea lion along its distribution by analyses of mitochondrial DNA (mtDNA) and 10 nuclear microsatellites loci. We analyzed 147 sequences of mtDNA control region and genotyped 111 individuals of South American sea lion for 10 microsatellite loci, representing six populations (Peru, Northern Chile, Southern Chile, Uruguay (Brazil), Argentina and Falkland (Malvinas) Islands) and covering the entire distribution of the species. The mtDNA phylogeny shows that haplotypes from the two oceans comprise two very divergent clades as observed in previous studies, suggesting a long period (>1 million years) of low inter-oceanic female gene flow. Bayesian analysis of bi-parental genetic diversity supports significant (but less pronounced than mitochondrial) genetic structure between Pacific and Atlantic populations, although also suggested some inter-oceanic gene flow mediated by males. Higher male migration rates were found in the intra-oceanic population comparisons, supporting very high female philopatry in the species. Demographic analyses showed that populations from both oceans went through a large population expansion ~10,000 years ago, suggesting a very similar influence of historical environmental factors, such as the last glacial cycle, on both regions. Our results support the proposition that the Pacific and Atlantic populations of the South American sea lion should be considered distinct evolutionarily significant units, with at least two managements units in each ocean.

Arias-Schreiber (2003) found that 20% of SAFS and 32% of SASL samples contained cephalopod beaks, whereas in our study cephalopod consumption was significantly different between otariids, with 32% in SAFS in comparison with 1.6% in SASL. Trophic overlap was detected in the austral summer and fall of 2015 during an extraordinary El Niño event, in which both otariids consumed similar proportions of Peruvian anchovy (55% SAFS, 48.6% SASL), cephalopods (21.7% SAFS, 13.6% SASL) and red squat lobsters (9% SAFS, 2% SASL). Keywords: diet; foraging ecology; fur seal; Peru; sea lion EN diet foraging ecology fur seal Peru sea lion 775 790 16 05/13/22 20220601 NES 220601 Abstract Resource partitioning can contribute to species coexistence by reducing interspecific competition. In regard to crustaceans, Arias-Schreiber (2003) found 8% of SAFS and 60% of SASL samples contained red squat lobster, similar to the 5% and 70% for SAFS and SASL, respectively, found in our study. [Extracted from the article]

The article presents the study on the impacts of harmful algal toxins like domoic acid and okadaic acid on Peruvian fur seals such as Arctocephalus australis ssp. and South American sea lions such as Otaria byronia in Peru. Topics discussed include dietary exposure to natural toxins produced by phytoplankton blooms; reproductive failure and chronic neurological disease due to algal toxins; and impacts of El Niño Southern Oscillation on Peruvian fur seals populations.