Description: Shallow water subtidal marine communities along the western Antarctic Peninsula are characterized by dense beds of macroalgae and strikingly dense assemblages of associated amphipods. However, direct grazing by amphipods on the dominant macroalgae is unlikely as most of these algae elaborate secondary metabolites known to be herbivore feeding deterrents. What resources, then, support this vast macroalgal-associated amphipod assemblage? We addressed this question by analyzing the gut contents, fatty acids, and stable isotopic ratios of 15 different amphipod species associated with the macrophyte community. The δ 15 N and δ 13 C stable isotope values revealed that most of the abundant species of amphipods are primary consumers whose ultimate carbon source is derived from some combination of brown macroalgae, epiphytic diatoms, and endo/epiphytic filamentous algae. Gut contents revealed that a large percentage of the amphipod diets are comprised of diatoms and macroalgal tissues, both filamentous and multiseriate. Fatty acid analysis corroborated our conclusions based on stable isotope and gut content data, demonstrating the importance of diatoms to assimilated material, but also highlighting the rich diversity of diets within the macroalgal-associated amphipod assemblage. Our findings suggest that amphipods routinely clean their host macrophytes of potentially harmful epiphytes, including both diatoms and emergent filaments from brown algal endophytes. Some prominent species of amphipods may also derive a small percentage of their carbon from palatable and, in one case, unpalatable, chemically defended red algae. These results, combined with previous studies showing that the amphipods gain refuge from predators by associating with unpalatable macroalgae, support the hypothesis that amphipods along the western Antarctic Peninsula are living in mutualism with their macrophyte hosts rather than consuming the host directly.

Description: Colobanthus quitensis is the only native dicotyledoneae in the Antarctic; therefore, it is the object of ample research regarding tolerance mechanisms to its extreme habitat. This species also represents a wide geographical distribution, from 68°S to 17°N and from 0 m a.s.l. in the south to 4200 m a.s.l. in the north of its distribution area. As the described habitats for different populations coincide in their extreme abiotic characteristics, there has been increasing interest in studying different populations in recent years, as well as the existence of phenotypic or genetic variability among them. In contrast, very little is known about its genome; knowledge of genome size and ploidy levels allows the development of strategies to generate information in population studies related to structure, gene flow and genetic diversity in order to describe phenotypic characteristics. Several studies have related genome size to the ecological requirements of the species distributed through an ample environmental gradient. For several years now, flow cytometry has become a simple method to determine genome size in a wide variety of species. In this paper, we determine genome size for three C. quitensis populations. The populations of Arctowski and La Marisma (Punta Arenas) have 2 C  = 1.95 pg, while the Conguillio population reported 2 C  = 0.84 pg, approximately half as much. This may evidence different ploidy levels between the populations, creating new questions with regard to the number of chromosomes and the possible existence of endopoliploidy. This would be related to the distribution and the adaptive mechanisms of this species throughout its wide distribution.

Description: The marbled moray cod, Muraenolepis marmorata Gunther, 1880, is one of the most common benthic fish in the Antarctic, but our knowledge about its biology and participation in parasitic life cycles as a host is quite scarce. The boundaries of its geographical distribution are unclear, but it definitely inhabits the Ross Sea, the Amundsen Sea, the slopes of seamounts, underwater elevations, and islands in the Indian Ocean sector of the sub-Antarctica, and it is endemic in the Antarctic. This article presents data on helminth infections of marbled moray cod in the Ross Sea and its eating habits. Specimens were examined during commercial longline fishing in the Ross Sea in January 2015. Being a benthophage, M. marmorata feeds on a variety of benthic invertebrates, including gastropods, bivalves, monoplacophores, polyplacophores, ophiuroids, and sea urchins. Twenty species and unidentified forms were found using standard parasitological methods. Most of the recorded species (60%) are trematodes, and four are specific for muraenolepidids. Heterosentis heteracanthus and Gonocerca crassa are recorded for M. marmorata for the first time. Comparison with an earlier studied infection of M. marmorata in the sub-Antarctic revealed the richness of the Ross Sea parasite fauna.

Description: The Paris Agreement , being the main result of the COP21 UN climate conference in 2015, included the ever most clearly defined political statement on anthropogenic climate change and the need for it to be reduced. In an opinion survey, Antarctic ecosystem researchers expressed their views, in which direction science should develop, after their mission to provide evidence for the existence of anthropogenic climate change and its impacts is accomplished. Four options for answers were offered. The majority voted in support for research for a better ecosystem understanding under climate change, since overarching questions seem to not yet be sufficiently answered. Applied research for mitigation received an intermediate amount of support. Similar amount of support was received for no changes in research strategies. This might be a result of an already existing lively progression of new developments, but might also be due to some old and burning questions, which still remain unanswered, e.g. on the Southern Ocean acting as a biological CO 2 sink. Fewest experts thought that scientists should define totally new scientific themes. The results were also analysed separately for different groups of respondents in terms of stage of career, employing institutions (mission orientated or independent), and terrestrial or marine scientists. New student courses and university degrees are proposed, since new requirements by stakeholders demand new research strategies but traditional academic education and creativity is also still needed.

Description: In Greenland waters, Atlantic cod ( Gadus morhua ) is showing signs of recovery following a collapse in the early 1990s, and quantitative diet studies are needed to address predation on highly commercial species such as northern shrimp ( Pandalus borealis ). We analyzed 2483 Atlantic cod stomachs from Greenland offshore waters and the correlation between Atlantic cod and northern shrimp abundance. Fish and crustacean prey accounted for 96% of the prey by weight, with the relative importance shifting from crustaceans to fish with increasing cod size. Spatial differences were distinct and northern shrimp dominated the diet in Northwest Greenland (〉50% by weight), but declined in importance in Southwest Greenland and was absent from the diet in East Greenland. Instead, other crustacean preys such as krill were important in Southwest Greenland while fish prey was most important in East Greenland. Southwest Greenland was sampled in both summer and autumn, and there was a significant seasonal effect on most prey groups, but most pronounced for Atlantic cod and krill both of which increased in importance. Extensive cannibalism was limited to the largest cod (]70–100 cm]) and mainly in Southwest Greenland. In Southwest Greenland, Atlantic cod and northern shrimp biomass were significantly negatively correlated, while no significant trends were found in Northwest or East Greenland.

Description: Arctic and subarctic environments are among the most inaccessible regions in the world, making biological surveys difficult to conduct. Thus, the insect fauna of these regions has remained inadequately surveyed. The aquatic insect orders Ephemeroptera, Plecoptera, and Trichoptera (EPTs) are particularly abundant and diverse at high latitudes, playing key roles in trophic chains where nutrients are scarce. However, particular aspects of their life cycle make them difficult to study. Specifically, species-level identification requires last-instar larvae or adults which, because they are short lived, are typically not available for all taxa during a particular collecting event. With the initial goal of surveying the biodiversity of these insect groups, we sampled ca.10,000 EPT specimens from 12 locations across northern Canada over two years. Approximately 800 of these were subsequently selected for COI DNA barcoding. Overall, we identified 155 EPT species (58 Ephemeroptera, 41 Plecoptera, 56 Trichoptera) based on a 2% divergence criterion. Compared to other similar studies on EPTs we found higher (particularly among the Plecoptera and Ephemeroptera) and more even diversity, potentially reflecting environmental differences in sampling localities. We further assessed phylogeographic divergence patterns among seven species, finding that eastern and western populations diverged during the Pleistocene Epoch (〈2.5 Ma), with overlapping time frames. This finding highlights the role of potential glacial refugia and subsequent recolonization, as well as the dispersal potential of some EPT species. This study exemplifies how large-scale DNA-based surveys can be combined with phylogeographic inference to better understand the biodiversity and natural history of northern aquatic insect communities.

Description: Global warming has led to a strong deterioration of the Arctic sea ice cover. Ice thickness, age and coverage have been strongly declining in recent years. Brine channels that form in sea ice when seawater freezes represent a unique habitat for bacteria, algae, proto- and small metazoans. We hypothesized that the loss of multi-year ice and the more prevalent formation of first-year ice even in central regions of the Arctic will lead to changes in the Arctic sea ice meiofauna community composition. We therefore analysed the sea ice meiofauna community composition of three different ice types sampled in summer and autumn 2007. Young, thin ice of few cm thickness was typified by taxa of pelagic origin or with good swimming abilities (ciliates, pelagic foraminifera, rotifers and platyhelminthes). Harpacticoid copepods and nematodes with poor swimming abilities were prevalent in older, thicker (〉0.5 m) first- and multi-year ice. Brash ice—which was likely a mix of older broken ice, slush and pancake ice—was characterized by a high abundance of platyhelminthes and rotifers. An experimental analysis of colonization efficiencies of artificial thin ice also revealed that species with poor swimming ability are less successful to colonize newly forming thin ice. We conclude that observed and predicted changes in the ice formation regime will likely result in changes in the composition of Arctic sea ice communities. We predict negative effects particularly for species with low dispersal capacities like harpacticoid copepods and endemic nematodes, as these are less successful in colonizing newly forming thin ice.

Description: The Southern Ocean salp, Salpa thompsoni (Tunicata, Thaliacea), is a pivotal species in the pelagic ecosystem of the Western Antarctic Peninsula (WAP), one of the fastest warming regions of the world oceans. This study produced a complete reference transcriptome for S. thompsoni containing 216,931 sequences; 41,210 (18%) were associated with predicted, hypothetical, or known proteins; 13,058 (6%) were mapped and annotated. Whole-transcriptome (RNA-seq) analysis of 39 samples collected during austral spring and summer 2011 in the WAP and in summer 2009 in the Indian Sector revealed clustering of samples by regions, seasons, and areas (Bray–Curtis similarity). The highest numbers of differentially expressed genes at the 4×, 20×, and 100× fold-change levels were found between salps collected during spring versus summer 2011 in the WAP (analysis of variance, ANOVA). Spring versus summer samples showed significant differential expression of 77 genes associated with environmental stress response and 51 genes associated with sexual reproduction (paired t tests, p  〈 0.05), with significant association between expression of these genes and temperature at the collection site shown by multidimensional scaling analysis. Gene Ontology (GO) term enrichment analysis identified 41 GO terms responsible for spring versus summer differences, including 156 genes associated with translation (i.e., protein synthesis). The reference transcriptome and characterization of time/space patterns of whole-transcriptome and target gene differential expression provide a foundation for functional analysis and identification of molecular markers of physiological condition, life history events, and responses to climate change in this key species in Antarctic pelagic ecosystems.

Description: The reporting and graphing of ecological data and statistical results often leave a lot to be desired. One reason can be a misunderstanding or confusion of some basic concepts in statistics such as standard deviation, standard error, margin of error, confidence interval, skewness of distribution and correlation. The implications of having small sample sizes are also often glossed over. In several situations, statistics and associated graphical representations are made for comparing groups of samples, where the issues become even more complex. Here, I aim to clarify these basic concepts and ways of reporting and visualizing summaries of variables in ecological research, both for single variables and for pairs of variables. Specific recommendations about better practice are made, for example describing precision of the mean by the margin of error and bootstrapping to obtain confidence intervals. The role of the logarithmic transformation of positive data is described, as well as its implications in the reporting of results in multiplicative rather than additive form. Comments are also made about ordination plots derived from multivariate analyses, such as principal component analysis and canonical correspondence analysis, with suggested improvements. Some data sets from this Kongsfjord special issue are amongst those used as examples.