Polar Biology最新文献

The diet of the Antarctic shags was investigated at Paradise Bay, Antarctic Peninsula, by the analysis of 20 pellets collected during the 2015/16 breeding season. Fish were the most frequent and important prey, accompanied by Polychaetes. Amongst fish, only benthic-demersal species were represented in the diet. Harpagifer antarcticus, followed by Notothenia coriiceps, was the most frequent prey and the most important by number and mass. The results are compared with the diet reported for this shag at other localities of the South Shetland Islands and of the Antarctic Peninsula and discussed in terms of geographical significance, breeding output, and population trend.

Female Weddell seals (Leptonychotes weddellii) display a mixed capital-income breeding strategy, losing up to 40% of their body mass between birthing and weaning their pups. How and when they regain energy stores, however, remains to be fully explored. To better understand the foraging by lactating Weddell seals, we fitted time-depth recorders and head-mounted cameras on 26 seals in Erebus Bay, Ross Sea, for ~ 5 days in November and December 2018 and 2019. We aimed to (1) identify prey species and foraging depth and (2) investigate relationships between seal physiology and demographics and probability of foraging. We recorded 2782 dives, 903 of which were > 50 m, maximum depth was 449.3 m and maximum duration was 31.1 min. Pup age likely contributes to the probability of a lactating Weddell seal foraging (Est. = 1.21 (SD = 0.61), z = 1.97, p = 0.0484). Among 846 prey encounters, the most frequent prey items were crustaceans (46.2%) and Antarctic silverfish (Pleuragramma antarcticum, 19.0%); two encounters were observed with juvenile Antarctic toothfish (Dissostichus mawsoni, 0.2%). We identified substantial variability in foraging behaviour, individually and between locations, and found that lactating seals target many species and some may specialise on certain prey groups.

Under the "One Health" concept, this paper aims to explore the occurrence of antimicrobial resistance in Enterobacterales (i.e., Escherichia coli and Salmonella enterica) among the South American Sea Lions on Argentina's northern Patagonian coast. From 177 fecal samples collected, conventional protocols were used to isolate E. coli and S. enterica. Antimicrobials classified as critically important by the WHO were evaluated by disk diffusion and agar spot (colistin) methods. Molecular tools were used to detect mcr genes as needed. A total of 176 antimicrobial-susceptible E. coli strains and 14 S. enterica strains were recovered. Twelve E. coli strains were colistin resistant (agar spot positive) but PCR negative for the mcr-1 to mcr-5 genes. Whole-genome sequencing revealed a chromosomal mutation, coding for Val161Gly change in PmrB protein, as the colistin resistance mechanism in one of these isolates. This study provides knowledge on AMR surveillance in wildlife associated with the marine environment in South America.

Gvozdarus svetovidovi (Nototheniidae) is the rarest notothenioid fish, represented by only two specimens collected in 1970 and 1988. As it is little known, we present aspects of the cranial osteology of this species and use this, and other features of its morphology, to infer fundamental aspects of its biology. As in other pelagic nototheniids, G. svetovidovi has an elongated neurocranium and jaws but it does not have a paedomorphic skeleton. Although not unique to G. svetovidovi, the bones of the skull have some well-developed ridges for support and possibly for containment of subcutaneous fat. The skeleton is most similar to that of Dissostichus. G. svetovidovi has a high fat content, primarily within the trunk musculature and in a layer over the skull. It is probably neutrally buoyant in mesopelagic waters, where it has been captured at 295–550 m depth north of the Antarctic Slope Front (approximately the shelf break) and south of the southern boundary of the Antarctic Circumpolar Current. It likely relies on vision and mechanosensation to detect its prey, including bioluminescent, energy-dense myctophids and krill in this resource-rich area of the Southern Ocean. Strays near shelf waters feed on Pleuragramma antarcticum. G. svetovidovi is unlike all other notothenioids in fundamental aspects of its biology including its habitat, diet and distribution. Although it may be on the path to extinction, if our postulated life history of G. svetovidovi is accurate, it expands the current perception of the bounds of the notothenioid radiation into a locality in the Southern Ocean not previously known to be occupied by this group.

Recent studies have documented poleward shifts in heavily targeted fish stocks on the Bering Sea Shelf. This study investigated whether commercial fishing vessels in the region have also shifted their distribution poleward in recent years. We used Vessel Management System data generated between January 1, 2013, and December 31, 2022, to identify regions over the shelf where vessel activity increased (emerging hot spots) and where it decreased (emerging cold spots) during this time period. We hypothesized that emerging hot spots would occur at the northern edge of the vessel operating range, while emerging cold spots would occur at the southern edge. Overall, northward shifts in vessel distribution were most evident during October–February and July–August, when the range of emerging hots spots was centered 204–515 km to the N, NE, or NW of the center of the range of emerging cold spots. The trend was strongest in August, when emerging hot spots were widespread in the Northern Bering Sea. We did not attempt to identify factors driving these distributional shifts, but the timing of shifts did coincide with the busiest fishing seasons over the Bering Sea Shelf and, in part, the open seasons for walleye pollock (Gadus chalcogrammus). If groundfish populations continue to move poleward with climate change, this study may serve as a window into the early stages of a long-term redistribution of commercial fishing effort in the Bering Sea, a region supporting one of the largest fishing industries in the world.

In the Southern Atlantic Ocean, asteroids are abundant among the benthic taxonomic groups. The development patterns include a pelagic larva (planktotrophic/lecithotrophic), or a retained larva (internal/oral retention). The main objective was to revise the Asteroidea species composition from the Southern Atlantic (including marine protected areas) and to study their development patterns in relation to environmental conditions. Information was compiled from oceanographic surveys, scuba diving, and the GBIF database. Four species have extended their distribution. The Isla de los Estados island (SIE) and Namuncurá/Burdwood Bank II Marine Protected Area (N MPA II) are separated as independent clusters. SIE would be functioning as a geographical barrier, and N MPA II presents deep sea species. Namuncurá/Burdwood Bank Marine Protected Area (N MPA) presented a majority of protected development species, while in the Beagle Channel, most registered species presented free-planktotrophic larvae. Species with free-planktotrophic larvae and oral brooding strategies are more likely in shallower waters, while internal brooding species occur in deeper waters. Species with free-lecithotrophic larvae are more probable in middle depths, below the euphotic layer. These results are expected to make a valuable contribution to better understanding the general distribution and development patterns of Asteroidea from subantarctic waters, a group of organisms that are top predators of benthic communities.

An invasive predator eradication campaign is planned for 2024 on Amsterdam Island, one of world’s top priority island for seabird conservation. In order to monitor the effects on seabird colonies post-eradication, a survey of burrow-nesting species and population monitoring of albatrosses, penguins, skuas and terns was organised pre-eradication. Several counting techniques and acoustic methods were used to infer presence/absence of burrow-nesting species and to estimate abundance of other species, as well as genetic methods for species identification. In total 14 breeding (or probably breeding) seabird species were detected on Amsterdam Island, among which eight burrowing petrels including two species never described on the island: the Juan Fernandez petrel Pterodroma externa and the sooty sherwater Ardenna grisea. Based on these new data, the introduced mammal eradication campaign on Amsterdam, if successful, will likely be extremely beneficial for seabird conservation, and may also favor the colonization of Amsterdam by new seabird species.

The Weddell seal (Leptonychotes weddellii) is a fast-ice obligate species that plays an important role as both predator and prey within the high-latitude, coastal Southern Ocean. Weddell seals are affected by pressures of marine resource extraction and variation in sea-ice extent and characteristics that are affected by climate. Thus, monitoring their population dynamics provides an indicator of the effectiveness of fisheries management, and impacts of changing climate in the high latitude Southern Ocean ecosystem. Satellite imagery is increasingly being used to monitor the populations of this species, but assessment techniques require a better understanding of the environmental factors influencing the likelihood that individuals will be on the sea-ice and therefore visible in a satellite image. Addressing that goal, we captured 5054 trail camera photos during spring 2017 in the 24-h light at Cape Royds, Antarctica, and then counted seals on the fast ice every 30 min over 59 days. Using a generalised additive model (63% deviance explained) we described the haulout behaviour of non-breeding Weddell seals according to time of day, date, air temperature, pressure, solar radiation, and wind speed. We found that the seals’ haulout cycle is driven to a significant degree by weather variables, primarily temperature and wind speed. Quantifying these haulout patterns can be used to determine the time of day, and under what conditions, that most seals are hauled out. Integrating environmental parameters to correct time-of-day patterns would allow better cross-site abundance comparisons, leading to better Weddell seal population estimates for the Ross Sea region and the wider coastal Antarctica.

The host/parasite relationship is a key tool for understanding the role of parasitism in the feeding ecology of Antarctic seabirds. Especially, birds with extensive migratory routes through isolated regions are particularly sensitive to new infections. Although research on parasitic diSseases in Antarctic birds is sparse and information is fragmentary, an increasing number of studies are currently underway in this area. The present study aims to provide new information on parasitic helminths in the Southern Giant Petrel Macronectes giganteus in some nesting areas from South Shetland Island and Antárctic Península, integrating different parasitological techniques. A total of 126 faecal samples, 16 regurgitates and six dead individuals (five adults and one chick) were analysed for helminth parasites. Members of four helminth groups (Cestoda, Digenea, Nematoda, Acanthocephala) represented the parasitic diversity of the Southern Giant Petrel in the studied localities. All dead birds analysed (P = 100%) harboured helminth parasites, additionally P = 49.2% of the faecal samples and P = 6.25% of the regurgitated individuals presented at least one of the different helminth groups found in the viscera. The combination of three diagnostic techniques allowed us to determine the presence of nine helminth species (Cosmocephalus obvelatus, Stegophorus macronectes, Stegophorus diomedeae, Contracaecum sp., Parorchites zederi, Tetrabothrius heteroclitus, Diphylobotrium sp., Corynosoma shackletoni, and Renicolidae). In addition, juvenile specimens of Tetrameres sp. and Anisakis sp. were found in the eviscerated host. We discuss the trophic relationships of the hosts and their influence in the helminth infestations. This study provides new knowledge about the parasitic diversity of the Southern Giant Petrel in its nestling areas with new records of helminth species in Antarctica.