Phylogenomics and Pervasive Genome-Wide Phylogenetic Discordance Among Fin Whales (Balaenoptera physalus).

Phylogenomics has the power to uncover complex phylogenetic scenarios across the genome. In most cases, no single topology is reflected across the entire genome as the phylogenetic signal differs among genomic regions due to processes, such as introgression and incomplete lineage sorting. Baleen whales are among the largest vertebrates on Earth with a high dispersal potential in a relatively unrestricted habitat, the oceans.

Climate change is associated with higher phytoplankton biomass and longer blooms in the West Antarctic Peninsula.

The Antarctic Peninsula (West Antarctica) marine ecosystem has undergone substantial changes due to climate-induced shifts in atmospheric and oceanic temperatures since the 1950s. Using 25 years of satellite data (1998-2022), this study presents evidence that phytoplankton biomass and bloom phenology in the West Antarctic Peninsula are significantly changing as a response to anthropogenic climate change. Enhanced phytoplankton biomass was observed along the West Antarctic Peninsula, particularly in the early austral autumn, resulting in longer blooms.

Mercury Concentrations in Two Populations of the most Endangered Dolphin (Pontoporia blainvillei) from the Southwestern Atlantic Ocean.

Mercury contamination has been aggravated by emerging environmental issues, such as climate change. Top predators present concerning Hg concentrations once this metal bioaccumulates and biomagnifies. This study evaluated total mercury (THg) concentrations in tissues of 43 franciscanas (Pontoporia blainvillei) from two populations: the Franciscana Management Area (FMA) IIb and FMA IIIa.

Anthropogenic debris in three sympatric seal species of the Western Antarctic Peninsula.

Litter pollution is a growing concern, including for Antarctica and the species that inhabit this ecosystem. In this study, we investigated the microplastic contamination in three seal species that inhabit the Western Antarctic Peninsula: crabeater (Lobodon carcinophaga), leopard (Hydrurga leptonyx) and Weddell (Leptonychotes weddellii) seals. Given the worldwide ubiquity of this type of contaminant, including the Southern Ocean, we hypothesized that the three seal species would present anthropogenic debris in their feces.

The deep dive of organohalogen compounds: Bioaccumulation in the top predators of mesopelagic trophic webs, pygmy and dwarf sperm whales, from the Southwestern Atlantic ocean.

Kogia sima and Kogia breviceps are apex predators of mesopelagic trophic webs being far from most anthropogenic threats. However, chemical pollutants and naturally synthesized compounds may travel long distances. This study aimed to use kogiid whales as sentinels of mesopelagic trophic webs in the Southwestern Atlantic Ocean.

Mobilization of persistent organic pollutants in humpback whales: Insights from feeding areas in the Antarctic peninsula and Strait of Magellan to migration, breeding, and calving grounds along the Brazilian coast.

Southern Hemisphere Megaptera novaeangliae undertake the longest migration, which reflect their exposure to lipophilic contaminants. To assess these changes, persistent organic pollutants were analyzed in blubber samples of humpback whales from three regions: the Antarctic Peninsula (n = 46), the Strait of Magellan, Chile (n = 22), and the Brazilian coast (n = 38). The similarity in PCB and HCB levels between individuals from feeding grounds and breeding grounds suggests contamination during feeding.

Physical-biological drivers modulating phytoplankton seasonal succession along the Northern Antarctic Peninsula.

The Northern Antarctic Peninsula (NAP) shows shifts in phytoplankton distribution and composition along its warming marine ecosystems. However, despite recent efforts to mechanistically understand these changes, little focus has been given to the phytoplankton seasonal succession, remaining uncertainties regarding to distribution patterns of emerging taxa along the NAP. To fill this gap, we collected phytoplankton (pigment and microscopy analysis) and physico-chemical datasets during spring and summer (November, February and March) of 2013/2014 and 2014/2015 off the NAP.

An additional threat to populations predicted to collapse: Organobromine compounds of natural and anthropogenic sources in rough-toothed dolphins from the Southwestern Atlantic Ocean.

Organic contaminants with toxic effects, like the conventional brominated flame retardants (BFRs) and BFRs of emergent concern, and their synergistic effects with other micropollutants, can be an additional threat to delphinids. Rough-toothed dolphins (Steno bredanensis) populations strongly associated with coastal environments already face a potential risk of decline due to high exposure to organochlorine pollutants. Moreover, natural organobromine compounds are important indicators of the environment's health.

Cryptophytes: An emerging algal group in the rapidly changing Antarctic Peninsula marine environments.

The western Antarctic Peninsula (WAP) is a climatically sensitive region where foundational changes at the basis of the food web have been recorded; cryptophytes are gradually outgrowing diatoms together with a decreased size spectrum of the phytoplankton community. Based on a 11-year (2008-2018) in-situ dataset, we demonstrate a strong coupling between biomass accumulation of cryptophytes, summer upper ocean stability, and the mixed layer depth. Our results shed light on the environmental conditions favoring the cryptophyte success in coastal regions of the WAP, especially during situations of shallower mixed layers associated with lower diatom biomass, which evidences a clear competition or niche segregation between diatoms and cryptophytes.

Potential biases in dietary interpretation derived from stable isotope analysis of small dolphin teeth.

We analyzed δC and δN values in different tooth portions (Growth Layer Groups, GLGs) of franciscanas, Pontoporia blainvillei, to investigate their effect on whole tooth (WT) isotopic values and the implications for dietary estimates. Tooth portions included the dentin deposited during the prenatal development (PND), the first year of life (GLG) deposited during the nursing period and the central part of the tooth with no distinction amongst subsequent GLGs (Center). Isotopic mixing models estimating the contribution of PND, GLG and Center to WT showed that GLG has a strong effect on WT isotope values in juveniles, while Center only starts to affect WT isotopic values from age four.

Chemotaxonomic characterization of the key genera of diatoms in the Northern Antarctic Peninsula.

Diatoms are successful in occupying a wide range of ecological niches and biomes along the global ocean. Although there is a recognized importance of diatoms for the Southern Ocean ecosystems and biogeochemical cycles, the current knowledge on their ecology and distribution along the impacted Antarctic coastal regions remains generalized at best. HPLC-CHEMTAX approaches have been extensively used to this purpose, providing valuable information about the whole phytoplankton community, even for those small-size species which are normally difficult to identify by light microscopy.

Strong and lasting impacts of past global warming on baleen whales and their prey.

Global warming is affecting the population dynamics and trophic interactions across a wide range of ecosystems and habitats. Translating these real-time effects into their long-term consequences remains a challenge. The rapid and extreme warming period that occurred after the Last Glacial Maximum (LGM) during the Pleistocene-Holocene transition (7-12 thousand years ago) provides an opportunity to gain insights into the long-term responses of natural populations to periods with global warming.

Floating plastics and their associated biota in the Western South Atlantic.

The lack of information about plastic pollution in many marine regions hinders firm actions to manage human activities and mitigate their impacts. This study conducted for the first time a quali-quantitative evaluation of floating plastics and their associated biota from coastal and oceanic waters in South Brazil. Plastics were collected using a manta net, and were categorized according to their shape, size, malleability and polymer composition.

Long-Term Consequences of High Polychlorinated Biphenyl Exposure: Projected Decline of Delphinid Populations in a Hotspot for Chemical Pollution.

Rough-toothed dolphins, , are closely associated with coastal waters in the Southwestern Atlantic Ocean, increasing the exposure to multiple stressors, such as chemical pollution. Persistent organic pollutants (POPs) are known to affect the health of cetacean species. To comprehend the potential impacts of POPs on populations' viability, it is necessary to distinguish populations and predict their risk of long-term exposure.

Combining isotopic analysis of bulk-skin and individual amino acids to investigate the trophic position and foraging areas of multiple cetacean species in the western South Atlantic.

We investigated the trophic structure and habitat use of ten cetacean species occurring in the oceanic waters of the western South Atlantic using naturally-occurring stable isotopes. We analysed δN in individual amino acids (AA) to estimate cetacean trophic position (TP) and to evaluate the spatial differences in baseline δN (source AAs). We adjusted cetacean bulk-skin δC and δN for the effect of trophic level using their estimated TPs, obtaining δC and δN, respectively.

Diverse groups of fungi are associated with plastics in the surface waters of the Western South Atlantic and the Antarctic Peninsula.

Marine plastic pollution has a range of negative impacts for biota and the colonization of plastics in the marine environment by microorganisms may have significant ecological impacts. However, data on epiplastic organisms, particularly fungi, is still lacking for many ocean regions. To evaluate plastic associated fungi and their geographic distribution, we characterised plastics sampled from surface waters of the western South Atlantic (WSA) and Antarctic Peninsula (AP), using DNA metabarcoding of three molecular markers (ITS2, 18S rRNA V4 and V9 regions).

Ecological divergence and speciation in common bottlenose dolphins in the western South Atlantic.

Coastal and offshore ecotypes of common bottlenose dolphins have been recognized in the western South Atlantic, and it is possible that trophic niche divergence associated with social interactions is leading them to genetic and phenotypic differentiation. The significant morphological differentiation observed between these ecotypes suggests they represent two different subspecies. However, there is still a need to investigate whether there is congruence between morphological and genetic data to rule out the possibility of ecophenotypic variation accompanied by gene flow.

Persistent organic pollutants in blubber of fin whales (Balaenoptera physalus) from the Southern Ocean.

Persistent organic pollutants (POPs) were analyzed in eighteen blubber samples biopsied from fin whales (Balaenoptera physalus) during the feeding season near the Antarctic Peninsula in the summer of 2013. POP content (in ng g lipid weight) ranged from 46.4 to 708 for polychlorinated biphenyls (∑PCBs), 6.

Plastics in sea surface waters around the Antarctic Peninsula.

Although marine plastic pollution has been the focus of several studies, there are still many gaps in our understanding of the concentrations, characteristics and impacts of plastics in the oceans. This study aimed to quantify and characterize plastic debris in oceanic surface waters of the Antarctic Peninsula. Sampling was done through surface trawls, and mean debris concentration was estimated at 1,794 items.

Spatiotemporal use predicts social partitioning of bottlenose dolphins with strong home range overlap.

Ranging behaviour and temporal patterns of individuals are known to be fundamental sources of variation in social networks. Spatiotemporal dynamics can both provide and inhibit opportunities for individuals to associate, and should therefore be considered in social analysis. This study investigated the social structure of a Lahille's bottlenose dolphin () population, which shows different spatiotemporal patterns of use and gregariousness between individuals.

Effects of acidification on the isotopic ratios of Neotropical otter tooth dentin.

Rationale: Stable carbon and nitrogen isotope ratios are widely used in ecological studies providing important information on the trophic ecology and habitat use of consumers. However, some factors may lead to isotopic variability, which makes difficult the interpretation of data, such as the presence of inorganic carbon in mineralized tissues. In order to remove the inorganic carbon, acidification is a commonly used treatment.