Limacina rangii (d’Orbigny, 1835) is pelagic pteropod playing a key ecological and biogeochemical role in polar ecosystems, being the prey of a variety of species of higher trophic levels. They are also sensitive indicators that allow gauging environmental change. Despite their recognized ecological relevance, the influence of environmental descriptors on their biometric traits remains largely unexplored. In this study, specimens of L. rangii, including adults and larvae, were collected from the Ross Sea and Terra Nova Bay (Southern Ocean) during the XXXII Italian Antarctic Expedition (late summer 2017). Each sampling event was accompanied by in situ environmental measurements, including temperature, salinity, Chl-a concentration, and conductivity. To identify the most influential environmental drivers of body length, we employed a Random Forest machine learning algorithm. The results revealed that longitude, temperature, and conductivity were among the strongest predictors of body size, underscoring the role of both thermal regimes and oceanographic characteristics in constraining the growth and development of these pelagic gastropods. This study demonstrates that environmental variability exerts a control over the biometric traits of L. rangii, with local thermal regimes and oceanographic features acting as critical constraints on individual growth and population development. These insights are essential for forecasting the responses of pelagic calcifiers to climate-driven changes in the Southern Ocean.
The circumpolar Antarctic rock cod (Trematomus bernacchii) is an important bioindicator species for marine Antarctic coastal waters. Histopathological alterations of key organs in this species provide an indicator of anthropogenic impacts and overall ecological condition. As a long-lived benthic species with a small home range, assessments of histopathology and health status of Trematomus bernacchii are ideal for identifying spatial and temporal changes and impacts resulting from exposure to contaminants in their environment. A collection of microscopic anatomy and histopathological observations of representative normal compared to abnormal histology of key organs including gill, liver, spleen, kidney and gonad was compiled from fish near Davis station, East Antarctica. Fish were collected within 300 m of the wastewater outfall, and at reference sites up to 9 km away from any obvious signs of anthropogenic input or impacts. Sub-lethal histological alterations identified across multiple organs indicates impaired health in fish near the outfall, providing strong evidence of response to contamination. Familiarity with ‘normal’ baseline and common pathologies improves ability to detect changes due to contamination, and reduces the chance of subjective observations and misidentification of alteration. Having a standard microscopic anatomy and histological observation for comparative assessment of tissue samples reduces error associated with subjectivity and differing levels of experience of examiners, and enables direct comparisons between populations in coastal areas around the whole of Antarctica, across temporal and spatial scales. The value of histopathology as a key component in multiple-lines-of-evidence ecological risk assessments, is further strengthened when combined with a numeric histological health index (HHI) which quantifies overall site-specific severity of impact in the environment.
Littoral bryozoan communities remain critically understudied in Arctic coastal ecosystems despite their ecological importance and sensitivity to environmental change. We investigated species composition, biomass distribution, and environmental drivers of bryozoans in the upper littoral zone of Kola Bay (southern Barents Sea), a subarctic fjord experiencing rapid industrial development. Sampling at eight stations during July and September 2024–2025 yielded 11 bryozoan species, dominated by Boreo-Arctic and boreal taxa (45.5
The Arctic region is currently experiencing a rapid global warming due to climate change, with its effects, such as ice melting, glacier retreat, and/or thickness reduction. From July 31 to August 13, 2024 water samples from 4 stations in the open waters eastern part of the Kara Sea (n = 20), at 3 stations in Vilkitsky Strait (n = 15) and at 4 stations in the western part of the Laptev Sea located near the Severnaya Zemlya archipelago (n = 17) were collected and analyzed for the abundance of virioplankton, morphological characteristics and capsid sizes of viral particles, lytic and lysogenic viral infection of bacteria. In the Vilkitsky Strait and in the western part of the Laptev Sea, the average values of chlorophyll a concentration (0.298–0.395 µg L−1), the abundance (2.07–2.08 ×105 cell mL−1) and production (50.3–60.3 ×103 cell mL−1 day−1) of bacterioplankton, abundance (4.35–5.08 ×106 viruses mL−1) and production (124.4–146.7 × 103 viruses mL−1 day−1) of virioplankton, viral-induced mortality of bacteria (22.4–24.9
Themisto gaudichaudii belongs to the pelagic amphipods which can be very abundant in the Antarctic waters and can be an important food source for many Antarctic predators. T. gaudichaudii is generally associated with relatively warmer, ice-free waters, although it may co-occur with Euphausia superba and can also occur at low densities in colder regions. Over the past few decades, Antarctic krill has been declining in some regions of the Southern Ocean, which may lead predators to seek alternative food sources. Due to the tendency of Themisto species to occur in aggregations and at high densities, these species may represent such an alternative. However, detailed studies on the ecology of this crustacean are still lacking. The present research was carried out during the expedition PS112 on R/V Polarstern in 2018 in the vicinity of Elephant Island, Weddell Sea, South Shetland Islands, and in the Bransfield Strait from March to May. The average recorded abundances of T. gaudichaudii were high in the areas under the direct influence of Antarctic Circumpolar Current, and the highest abundances were observed in the Elephant Island region, probably due to its location and unique hydrological conditions. The population was dominated by juveniles presumably because the samples were collected after the spawning period.
