The Presence of Dirofilaria immitis in Domestic Dogs on San Cristobal Island, Galapagos

This study's concept was outlined around the principle of conservation medicine in a biodiversity hotspot from the Neotropical realm: the Galapagos Islands. The wildlife balance has been modified by multi-host parasites introduced with some domestic animals (dogs and cats). The endemic and endangered species, the Galapagos sea lion (GSL, Zalophus wollebaeki), has been exposed to pathogens of canine and feline origin that could become a significant conservation problem for this species. One of these potential cases is the filarial heartworm infection, Dirofilaria immitis, which has been reported on other pinnipeds, with fatalities and clinical symptoms. Therefore, this study evaluated the presence of the microfilaria of D. immitis in dogs from Puerto Baquerizo Moreno, San Cristobal Island, where the largest rookery of GSLs lives and where the proximity to domestic dogs is the most intimate compared to other rookeries of the archipelago. Between July and September 2021, 587 blood samples were collected from owned dogs of Puerto Baquerizo Moreno. Overall, 10 dogs (1.7%) were positive for the presence of the microfilaria of D. immitis with a confidence interval of 0.7%-2.8%. No other filarial species were identified. Significant differences in prevalence between different dog categories were observed only for the age (p = 0.001). This study represents the first report of D. immitis, the agent of canine heartworm disease, in dogs from San Cristobal Island. Hence, the presence of the microfilaria of D. immitis in the blood of dogs could increase the risk of infection to which the GSL is exposed in the region.

Population Genetics and Phylogeography of Galapagos Fur Seals

Pinnipeds found across islands provide an ideal opportunity to examine the evolutionary process of population subdivision affected by several mechanisms. Here, we report the genetic consequences of the geographic distribution of rookeries in Galapagos fur seals (GFS: Arctocephalus galapagoensis) in creating population structure. We show that rookeries across four islands (nine rookeries) are genetically structured into the following major groups: 1) a western cluster of individuals from Fernandina; 2) a central group from north and east Isabela, Santiago, and Pinta; and possibly, 3) a third cluster in the northeast from Pinta. Furthermore, asymmetric levels of gene flow obtained from eight microsatellites found migration from west Isabela to Fernandina islands (number of migrants Nm = 1), with imperceptible Nm in any other direction. Our findings suggest that the marked structuring of populations recovered in GFS is likely related to an interplay between long-term site fidelity and long-distance migration in both male and female individuals, probably influenced by varying degrees of marine productivity.

Influence of hunting strategy on foraging efficiency in Galapagos sea lions

The endangered Galapagos sea lion (GSL, Zalophus wollebaeki) exhibits a range of foraging strategies utilising various dive types including benthic, epipelagic and mesopelagic dives. In the present study, potential prey captures (PPC), prey energy consumption and energy expenditure in lactating adult female GSLs (n = 9) were examined to determine their foraging efficiency relative to the foraging strategy used. Individuals displayed four dive types: (a) epipelagic (<100 m; EP); or (b) mesopelagic (>100 m; MP) with a characteristic V-shape or U-shape diving profile; and (c) shallow benthic (<100 m; SB) or (d) deep benthic (>100 m; DB) with square or flat-bottom dive profiles. These dive types varied in the number of PPC, assumed prey types, and the energy expended. Prey items and their energetic value were assumed from previous GSL diet studies in combination with common habitat and depth ranges of the prey. In comparison to pelagic dives occurring at similar depths, when diving benthically, GSLs had both higher prey energy consumption and foraging energy expenditure whereas PPC rate was lower. Foraging efficiency varied across dive types, with benthic dives being more profitable than pelagic dives. Three foraging trip strategies were identified and varied relative to prey energy consumed, energy expended, and dive behaviour. Foraging efficiency did not significantly vary among the foraging trip strategies suggesting that, while individuals may diverge into different foraging habitats, they are optimal within them. These findings indicate that these three strategies will have different sensitivities to habitat-specific fluctuations due to environmental change.