EVALUATION OF TRACE ELEMENT CONCENTRATIONS IN THE SERUM AND VIBRISSAE OF PERUVIAN PINNIPEDS (ARCTOCEPHALUS AUSTRALIS AND OTARIA BYRONIA)

Concentrations of 15 trace elements (aluminum, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, tin, vanadium, and zinc) were determined in vibrissae (whiskers) and serum of two sympatric pinniped species, the Peruvian fur seal population (PFS; Arctocephalus australis Peruvian subpopulation) and South American sea lion (SASL; Otaria byronia) at Punta San Juan, Peru during 2011–19 sampling events. Element concentrations were 2–20 times higher in vibrissae than in serum. Vibrissae and serum concentrations of several elements, including aluminum, arsenic, and lead, suggest that environmental contaminants may affect the health of pinnipeds at Punta San Juan. Although toxicity thresholds are unknown in pinnipeds, high concentrations of some elements (especially aluminum, arsenic, and lead) may have adverse impacts on their health such as immunosuppression and impaired reproduction. Arsenic was the only element that increased in mean vibrissae concentration throughout the study period. Female SASL vibrissae contained a mean arsenic concentration three times higher than the male SASL vibrissae mean arsenic concentration, and twice as high as the arsenic mean for all PFS vibrissae. The mean male SASL vibrissae cadmium concentration was five times higher than the vibrissae cadmium mean for both PFS males and females and nearly three times higher than the vibrissae cadmium mean for SASL females. Serum concentrations of aluminum, arsenic, copper, and manganese were significantly higher during moderate to extreme El Niño years compared to La Niña years. With stronger and more frequent El Niño-Southern Oscillation events predicted in the future, it is vital to understand how these trace elements may affect pinniped population health

Sympatric otariids increase trophic segregation in response to warming ocean conditions in Peruvian Humboldt Current System

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

Maternal offloading of arsenic and other trace elements in Peruvian fur seals

The maternal transfer of 15 elements was examined in Peruvian fur seal (Arctocephalus australis) dam and pup paired vibrissae (whiskers), serum, and milk samples collected from 2009 to 2019. Pup vibrissae, grown in utero, represented gestational transfer, while milk represented lactational transfer. Element concentrations, except arsenic, were highest in vibrissae compared to serum and milk for both dams and pups. Mean arsenic concentrations in pup vibrissae (0.44 μg/g) and milk (0.41 μg/g) were twice as high as dam vibrissae concentrations (0.19 μg/g) and nearly ten times higher than dam (0.06 μg/g) and pup serum (0.04 μg/g) concentrations. Mean arsenic concentrations from 2011 to 2019 increased in dam vibrissae (0.026 μg/g to 0.262 μg/g) and milk (0.361 μg/g to 0.484 μg/g). Pup vibrissae had significantly higher concentrations for 11 of the 15 elements analyzed compared to dam vibrissae, suggesting that element transfer is occurring through recent exposure and remobilization of elements from dam body stores. Potentially high concentrations of aluminum, arsenic, copper, and lead in pup tissues may impact their survival and population health. The impact of regional mining activities can contribute to elevated trace elements through runoff and pose a possible threat to local marine environments

Peruvian pinnipeds as archivist of ENSO effects off the coast of Peru

Environmental fluctuations in the eastern Pacific Ocean are reflected in the tissues of one of its most vulnerable apex predators, the Peruvian fur seal Arctocephalus australis. The coastal waters off Peru are a region of great environmental fluctuations due to periodic (every 2-7 years) El Niño-Southern Oscillation (ENSO) events, which result in ecosystem-wide food web changes. Pinniped body tissues reflect the incorporation of prey from the region, which can be evaluated using stable carbon and nitrogen isotope ratios (δ13C and δ15N). Continuously growing tissues, like vibrissae (whiskers), can potentially provide a large scale timeline of environmental data in an ecosystem where changes regularly occur and human instrumentation to measure such changes is sparse. Sea surface temperature (SST) anomalies along the Peruvian coastline are encompassed in the body of water known as Niño 1+2; a SST anomaly index used to categorize ENSO events. This region distinguishes itself from the more widely studied water bodies Niño 3, 3.4, and 4 by exhibiting more frequent and shorter-lived heating and cooling oscillations in SST. These oscillations appear to coincide with the δ13C and δ15N signatures recorded in the Peruvian fur seal vibrissae collected from 2010 (n=29), 2011 (n=12), 2012 (n=11) and 2015 (n=12). The δ13C and δ15N covary along the vibrissal length except for distinct points where their patterns are inversely related. These points are identified as transition periods between the region’s rapidly changing El Niño/La Niña phases. Adult female δ13C values throughout all sampled years (n=49), ranged from -18.13 to -13.19 ‰ ± 0.33 ‰. This reflects wide fluctuations in ocean production over time, which is our proxy to ENSO effects. Preliminary δ15N values range from 15.83 to 21.55 ‰ ± 0.85 ‰. These data suggest that these fur seals might be using alternative foraging survival strategies during these ENSO periods by foraging at two or more trophic levels. These may be the first biologic data of their kind to reveal how abiotic, ecosystem-wide changes influence the trophic dynamics and resultant survivability of the Peruvian fur seal