The table also shows the mean and standard deviation of each cell type for pups born in 2014 and 2015 at San Benito Archipelago. (PDF) Click here for additional data file.(90K, pdf) S1 FileData used for the analyses presented in this paper. during the study years. In that sense, while possible, it p54bSAPK is unlikely that the CSL pups were affected by DA intoxication. In addition to eosinophilia, the second exception to the largely normal leukogram was the number of basophils, which were virtually absent in pups born in 2015, compared to pups born in 2014 and 2012. While circulating basophil numbers are typically low compared to other WBC types, an absence of basophils can be indicative of adrenocortical hyperfunction due to stress [48]. It is possible that pups born in 2015 might have experienced high levels AMG319 of stress due to suboptimal nursing, or could have been affected by maternal levels of stress [49], partially explaining the unusually high AMG319 number of abortions recorded at SBA at the beginning of May 2015, prior to the breeding season (unpublished data). Furthermore, pups born at SBA in 2014 and 2015 had almost nine times more band neutrophils than pups born in 2012. The presence of these immature cells tends to indicate that the demand for neutrophils exceeds its supply. As we found no clinical evidence of malaise, and the other WBC populations in these pups were within the ranges, it is possible that their presence was an early indication of subclinical infection [50]. Alternatively, the high numbers of band neutrophils could be undernutrition, as has been reported for starving juvenile Northern elephant seals, [51]. The fact that half of the AMG319 pups born in 2015, during the most severe high SST event, had hypersegmented neutrophils which are common during nutrient-deficiency anaemia in human neonates [52], would appear to support this possibility. We hypothesized that if pups were experiencing suboptimal nutrition, immunoglobulin synthesis might be constrained. We found evidence to support this, as the concentration of IgG and IgA (but not IgM) was markedly lower in pups born during atypical years. Given that pup blood glucose levels were found to be altered by the high SST events, the observed pattern was exactly as would be expected because class-switching of IgG and IgA happens via T-cell dependent (glucose-dependent) and T-cell self-employed pathways [53], while IgM class switching is definitely T-cell self-employed [54]. If nutritional and enthusiastic impoverishment impairs pups body condition and limits glucose-dependent immunoglobulin class switching, additional T-cell dependent immune reactions could also be affected. Indeed, we found that reactions to a mitogenic challenge were seriously impaired in individuals created under atypical environmental conditions. The apparent failure of these pups to respond to PHA is most likely due to insufficient enthusiastic reserves, as was evidenced AMG319 from the direct association between the magnitude of the swelling response to PHA and blood glucose concentration. This means that not only were the pups that were created during the SST anomaly less able to synthesize protecting antibodies; they were also limited in their ability to respond rapidly to nonspecific immune difficulties. Taken collectively, these results constitute evidence that atypical climatic conditions can encumber the enthusiastic reserves and immune competence of neonates, thus decreasing their fitness. Conclusions The consequences of having suboptimal immune reactions could be devastating to the entire CSL 2014 and 2015 cohorts, particularly if a highly virulent pathogen were to enter the population. Actually in absence of such challenging, without proper nourishment, pups are likely to be unable to elicit reactions against opportunistic pathogens, and mortality would expectedly become high. We returned to SBA in February 2016 and found that the entire CSL colony was reduced by 77%, relative to the previous yr during the same times (total count: 584 in 2016 em vs /em . 2,555 in 2015). Extremely few live pups were found at the archipelago (343 in 2016 em vs /em . 1,567 in 2015) and most of AMG319 those that were present were seriously emaciated and fragile. An unusual high number of carcasses were also recorded. It is too early to understand the impacts the abnormal oceanographic conditions will have on CSL pups later on in their existence, but based on life-history theory, their fitness would expectedly become poor. Furthermore, as the high SST conditions encompassed the northeastern Pacific, the entire CSL population could be impacted, as has been reported for additional pinnipeds during past El Ni?o events.