Breeding season of the South American fur seal (Arctocephalus australis, Otariidae: Carnivora): New data for establishing independent evolutionary histories?

The life history strategy of a fur seal hookworm in relation to pathogenicity and host health status

“…The lactogenic transmission during first days of pup life means that eggs released by these pups, once they become larvae in the rookery soil, could have higher chances to find a new host (females), in order to continue the parasite life cycle. This could occur because as shown in this study, the population density of fur seal rookeries decreases as the reproductive season advances, in part due to pup mortality, departure of adult males, juveniles, and some females without pups ( Paves and Schlatter, 2008 ; Paves et al, 2016 ). Many of these animals will only return to the rookery the next reproductive season ( Paves and Schlatter, 2008 ; Paves et al, 2016 ), and, given the fact that hookworm larvae do not survive in Guafo Island soil from one season to the next, the only chances for these animals to come in contact with hookworm larvae in the soil is during the first weeks of the pupping season (Late December early January at Guafo Island) before they leave the rookery.…”

“…Our epidemiological data and evidence from similar studies in other pinniped species suggest that transmission of hookworm infective larvae to pups occurs only through fur seal's milk ( Castinel et al, 2007 ; Lyons et al, 2011 ; Marcus et al, 2014 ). Since many pinniped species have highly synchronized birth periods ( Paves et al, 2016 ), transmission of hookworms occurs with initiation of lactation in a short period of time for most of the pup population. This fact plus the early clearance of adult hookworms from the pups' intestine gives pinniped hookworms little time for growth, reproduction, eggs shedding, and development of larvae in the soil.…”

“…In the fur seal hookworm life history, there is remarkable timing in egg shedding, which is probably associated with the synchronization of reproductive cycles of SAFS at Guafo Island, where up to 90% of births occur in a two-week span ( Paves and Schlatter, 2008 ; Paves et al, 2016 ). Therefore, most pups in the rookery are born and infected through their mother's colostrum during a short period of time, which translates in hookworm egg shedding starting in about 80% of the pups the first week of January, which is approximately 2 weeks (the prepatent period) after the peak births at Guafo Island (December 15, Paves and Schlatter, 2008 ).…”

“…The universal and early clearance of hookworms by fur seals significantly reduces the parasite time to release eggs. However, it is possible that extending the infectious period does not payoff as much in terms of fitness for the parasite as producing more eggs over a short period of time, due to the marked seasonal density changes in pinniped populations ( Paves and Schlatter, 2008 ; Paves et al, 2016 ). Additionally, avoidance of clearance usually involves host immunomodulation, which is energetically costly for parasites ( Loukas et al, 2005 ; Mulvenna et al, 2009 ), therefore a significant advantage for the parasite is probably necessary to favor this trade-off.…”

Sighting patterns and habitat use of marine mammals at Guafo Island, Northern Chilean Patagonia during eleven austral summers

“…South American fur seals have a discontinuous distribution in the south Atlantic and south Pacific Oceans, and are included in the least concern conservation category of the IUCN (Cárdenas-Alayza et al 2016a, Pavés et al 2016. However, South American fur seal populations in the eastern South Pacific Ocean experienced a decline close to 60% in the last decade of the 20 th century, being the cause of this decline unknown as well as the current population trends (Venegas et al 2002, Pavés 2008, Cárdenas-Alayza et al 2016a.…”