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Southern Hemisphere humpback whales breed in tropical waters and migrate to Antarctica to forage. While the breeding grounds are well defined, the population structure on Antarctic feeding grounds is poorly described. The Western Antarctic Peninsula (WAP) is of particular interest, where rapidly changing environmental conditions could alter prey distribution or migration pathways. To examine changes in the population of whales around the WAP, we used mitochondrial DNA (mtDNA) and 15 microsatellite loci. We compared our WAP dataset to a dataset collected 18 years earlier, and identified new haplotypes for the region, but found no significant difference between the datasets. We compared whales from the WAP to breeding populations in Oceania, Colombia, and Brazil. We used an Analysis of Molecular Variance to confirm significant genetic differentiation between the WAP and each breeding ground (overall FST = 0.035/0.007 mtDNA/microsatellite, p < 0.001) except Colombia. Bayesian mixed-stock analyses showed a large apportionment to Colombia (mtDNA 93.0%; CL 91–99%; microsatellites 86%; CL 72–93%) and a small apportionment to French Polynesia/Samoan Islands (mtDNA 2.9%; CL 0.0–11.5%; microsatellites 8.9%; CL 0–22%), supporting the strong connection between Colombia and the WAP. Assignment tests allocated 81 individuals to Colombia and two to French Polynesia/Samoan Islands. No other breeding grounds had significant apportionments. Direct connectivity of French Polynesia to the WAP was confirmed with the first genotype match of French Polynesia to a feeding area. Continued genetic monitoring will highlight the complex patterns of humpbacks in this rapidly changing climate. Our results serve as a baseline for humpback whale population structure, illustrate mixed-stock analysis as a useful tool for migrating wildlife, and aid in future management considerations for humpbacks. [ABSTRACT FROM AUTHOR]

The present study characterizes the spatial distribution of seaweed diversity on eight islands from the South Shetlands based on an updated taxonomic survey, discussing the higher number of species compared with previous studies and the possible relationships with environmental parameters. Seaweeds were sampled in Deception, Livingston, Halfmoon, Robert, Nelson, King George, Penguin, and Elephant Islands during the austral summer between 2010 and 2013 in intertidal and shallow subtidal zones. The taxonomic analyses evaluated morphological characteristics, reproductive structures, and molecular features. Physicochemical parameters of seawater were also monitored using standard analytical methods. A total of 104 species of benthic marine algae were identified (28 Phaeophyceae, 24 Chlorophyta, and 52 Rhodophyta), ~82% of all seaweeds taxa described to Antarctica, including six new records previously recorded only at lower latitudes, four confirmed taxa, and two putative new species. Spatial variation in species diversity was observed among the collecting sites, and Livingston and King George Islands showed the highest diversity among the islands. Deception, an area with geothermal activity and intense tourism, was dominated by opportunistic and broadly distributed filamentous green algae. Antarctic macroalgae diversity was higher than in previous studies, most likely due to more efficient techniques of sampling, and combined taxonomical methods. However, changes in the biogeographical distribution or introduction of some taxa, resulting from anthropogenic activities and/or climate changes, should be considered. Therefore, the higher number of taxa and the new records reported in this study suggest the need for long-term monitoring in the area for conservation purposes. [ABSTRACT FROM AUTHOR]

Sponge communities on the Antarctic continental shelf currently represent one of the most extensive sponge grounds in the world, and all sponge classes are known to occur in the Southern Ocean. Main objectives of this study conducted at the tip of the Antarctic Peninsula were (1) to identify all sampled sponges and (2) to investigate whether the species composition and species richness of Southern Ocean sponge communities in the area of the Antarctic Peninsula are significantly influenced by environmental variables. The studied material originated from 25 AGT catches and was sampled during the expedition ANT-XXIX/3 of RV Polarstern. Samples were collected in three large-scale areas in the vicinity of the Antarctic Peninsula: Bransfield Strait, Drake Passage and Weddell Sea. The following six environmental variables were measured from bottom water samples (except for sea-ice cover): depth (m), light transmission (%), oxygen (µmol/kg), salinity, sea-ice cover (%) and temperature (°C). Two hundred and sixty-three sponge samples were analyzed, and 81 species of 33 genera from all Porifera classes (Calcarea, Demospongiae, Hexactinellida and Homoscleromorpha) were identified. Total numbers of sponge species per sample station ranged from 1 to 29. A detrended correspondence analysis and a backward-stepwise model selection were performed to check whether species composition and richness were significantly influenced by environmental variables. The analyses revealed that none of the measured environmental variables significantly influenced species composition but that species richness was significantly influenced by (1) temperature and (2) the combination of temperature and depth. Results of this study are of crucial importance for development, performance and assessment of future protection strategies in case of ongoing climatic changes at the Antarctic Peninsula. [ABSTRACT FROM AUTHOR]

Benthic ecological surveys using standardized methods are crucial for assessing changes associated with several threats in the Southern Ocean. The acquisition of data on assemblage structure over a variety of spatial scales is important to understand the variation of biodiversity patterns. During the ANT XXIX/3 (PS81) expedition of RV Polarstern, three different regions at the tip of the Antarctic Peninsula were sampled: the northwestern Weddell Sea, the Bransfield Strait, and the northern boundary of the South Shetland Archipelago in the Drake Passage. The aim of this study was to characterize the distribution and biodiversity patterns of ophiuroid assemblages in these regions and depths. We quantified different community parameters in terms of the number of species, abundance, and biomass. Additionally, we calculated various components of species diversity (alpha, beta, and gamma diversity) over the three regions. Based on the benthic surveys, we collected 3331 individuals that were identified to species level (17 species). Overall, species diversity, as measured based on rarefaction, species richness and evenness estimators, was higher in the Bransfield Strait compared to the Weddell Sea and Drake Passage. Two deep stations in the Weddell Sea showed high dominance only of Ophionotus victoriae. Significant differences in the patterns of alpha diversity were found among the regions but not between depth zones, whereas beta diversity showed no differences. Regarding the resemblance among the ophiuroid assemblages of each region, there was a significant gradient from east to west with a maximum distance between the stations in the Drake Passage and the Weddell Sea. This study provides a baseline for detecting potential effects related to climate change, and it furnishes a basis for the implementation of monitoring schemes of Antarctic assemblages. [ABSTRACT FROM AUTHOR]

The Antarctic Peninsula is one of the areas where the climate is changing at the fastest pace, having several effects on the populations of pygoscelid penguins. Few studies have analysed the variation in immune parameters of antarctic birds in a geographical context; thus, analyses of geographical differences in the immune components of wild pygoscelid penguins are still scarce. Leukocyte counts in birds provide information on their immunity and physiological stress. The objective of this study was to analyse the leukocyte counts in penguins of the genus Pygoscelis (gentoo, Adélie and chinstrap penguins), covering sites along the South Shetland Islands and some islands on the west coast of the Antarctic Peninsula. Our results revealed differences in the number of heterophils and eosinophils and in the heterophil/lymphocyte ratio in the northeastern populations of gentoo and Adélie penguins as compared to the rest of the colonies studied. The results contribute to better understanding of the variations in physiological parameters of penguins related to a geographical context. [ABSTRACT FROM AUTHOR]

The aim of this study was to contribute to a general understanding of the response of the Antarctic macrobenthos to environmental variability and climate-induced changes. The change in population size of selected macrobenthic organisms was investigated in the Larsen A area east of the Antarctic Peninsula in 2007 and 2011 using ROV-based imaging methods. The results were complemented by data from the Larsen B collected in 2007 to allow a conceptual reconstruction of the environment-driven changes before the period of investigation. Both Larsen areas are characterised by ice-shelf disintegration in 1995 and 2002, respectively, as well as high inter-annual variability in sea-ice cover and oceanographic conditions. In 2007 one ascidian species, Molgula pedunculata, was abundant north and south of the stripe of remaining ice shelf between Larsen A and B. Population densities decreased drastically in the Larsen A between 2007 and 2011, coincident with the decrease in Corella eumyota, another ascidian. Among the ophiuroids, the population of deposit feeders increased, while suspension feeders halved their abundance. Current measurements indicated a northward flow between the Larsen B and Larsen A, suggesting that a major physical forcing on benthic population development comes from the South. The results demonstrate that Antarctic macrobenthic populations can exhibit dramatic population dynamics. Analyses of sea-ice dynamics, salinity, temperature and surprisingly ice-shelf disintegration history, however, did not provide any clear evidence for environmental drivers underlying the apparent changes. [ABSTRACT FROM AUTHOR]

We investigated one active and three abandoned Adélie penguin (Pygoscelis adeliae) colonies in northern Marguerite Bay, Antarctic Peninsula, during austral summer 2000. Extinct colonies were located by ground survey on small islands and recognized by concentrations of nest pebbles. The colonies were excavated to recover organic remains from ornithogenic soils. Radiocarbon dates on penguin bone and eggshell provided a 6,000-year occupation history after correction for the marine-carbon reservoir effect; this history was compared to the paleoclimate record (ice cores and marine sediments) to assess patterns in occupation by penguins with episodes of climate change. We quantified prey remains recovered from the sites to examine potential dietary shifts by penguins with climatic change. Two species, Antarctic silverfish (Pleuragramma antarcticum) and squid (Psychroteuthis glacialis), were most commonly represented in the sediments. The data indicate that silverfish may have been exploited more during cool, and squid in warm climatic intervals in the past. [ABSTRACT FROM AUTHOR]