Chemical elements in mussels: Insights into changes in coastal environments due to the COVID-19 pandemic.

The concentrations of macro elements (Ca, K, Mg, and Na), essential trace elements (Cr, Cu, Fe, Li, Mn, Ni, and Zn), and nonessential trace elements (Al, As, Cd, Pb, and Ti) in the shell and soft tissues of Perna perna (L. 1758) mussels from Southeast Brazil are presented as a baseline reference for understanding the effects of the COVID-19 pandemic on the quality of coastal environments. For shells, the macro elements load was greater during the pandemic period at all sampling sites; however, for soft tissues, the opposite trend was recorded. On the contrary, the concentrations of trace elements in the shell were below the limit of quantification in most samples, and they tended to decrease in the soft tissues during the pandemic. Thus, the COVID-19 was a short-term conservation event that positively impacted the mussels. The results are relevant for monitoring the coastal environment in a post-COVID-19 scenario.

Ocean weather, biological rates, and unexplained global ecological patterns.

As on land, oceans exhibit high temporal and spatial temperature variation. This "ocean weather" contributes to the physiological and ecological processes that ultimately determine the patterns of species distribution and abundance, yet is often unrecognized, especially in tropical oceans. Here, we tested the paradigm of temperature stability in shallow waters (<12.5 m) across different zones of latitude. We collated hundreds of in situ, high temporal-frequency ocean temperature time series globally to produce an intuitive measure of temperature variability, ranging in scale from quarter-diurnal to annual time spans. To estimate organismal sensitivity of ectotherms (i.e. microbes, algae, and animals whose body temperatures depend upon ocean temperature), we computed the corresponding range of biological rates (such as metabolic rate or photosynthesis) for each time span, assuming an exponential relationship. We found that subtropical regions had the broadest temperature ranges at time spans equal to or shorter than a month, while temperate and tropical systems both exhibited narrow (i.e. stable) short-term temperature range estimates. However, temperature-dependent biological rates in tropical regions displayed greater ranges than in temperate systems. Hence, our results suggest that tropical ectotherms may be relatively more sensitive to short-term thermal variability. We also highlight previously unexplained macroecological patterns that may be underpinned by short-term temperature variability.

Deep-sea mining rock-fragment dispersal scenarios associated with submesoscale forcings: A case study in the Atlantic.

In the last few years, the exploitation of deep-sea regions for minerals extraction raised international attention as an economically viable source for the mining industry. However, most of these minerals are found close to sensitive ecosystems that can be harmed by mining activities. Given the potential impact, there is a need for the establishment of best practices towards the adoption of preventive strategies for the sustainable management and exploitation of deep-sea environments. To accomplish this objective, numerical models have proven to be reliable tools to support decision-making. In the present study, a high-resolution eddy-resolving ocean numerical model was configured and integrated with a semi-Lagrangian model aiming to map the transport of rock-fragments associated with mining activities. The model was applied to an area rich in polymetallic sulphides at the Northern Mid-Atlantic Ridge (NMAR). Model results showed that local topography and circulation dynamics played an important role for the dispersion and settling of the rock-fragments. In the presence of local submesoscale processes, the residence time do not follow the neutral relation H/vs. It was demonstrated that, depending on the local hydrodynamics, rock-fragments released at sub-surface depth can impact wider areas, with a predicted impact on pelagic and benthic organisms.

Differential association of key bacterial groups with diatoms and Phaeocystis spp. during spring blooms in the Southern Ocean.

Interactions between phytoplankton and heterotrophic bacteria significantly influence the cycling of organic carbon in the ocean, with many of these interactions occurring at the micrometer scale. We explored potential associations between specific phytoplankton and bacteria in two size fractions, 0.8-3 µm and larger than 3 µm, at three naturally iron-fertilized stations and one high nutrient low chlorophyll station in the Southern Ocean. The composition of phytoplankton and bacterial communities was determined by sequencing the rbcL gene and 16S rRNA gene from DNA and RNA extracts, which represent presence and potential activity, respectively. Diatoms, particularly Thalassiosira, contributed significantly to the DNA sequences in the larger size fractions, while haptophytes were dominant in the smaller size fraction. Correlation analysis between the most abundant phytoplankton and bacterial operational taxonomic units revealed strong correlations between Phaeocystis and picoeukaryotes with SAR11, SAR116, Magnetospira, and Planktomarina. In contrast, most Thalassiosira operational taxonomic units showed the highest correlations with Polaribacter, Sulfitobacteria, Erythrobacter, and Sphingobium, while Fragilariopsis, Haslea, and Thalassionema were correlated with OM60, Fluviicola, and Ulvibacter. Our in-situ observations suggest distinct associations between phytoplankton and bacterial taxa, which could play crucial roles in nutrient cycling in the Southern Ocean.

Ocean-colour anomalies quantified by the human eye.

Phytoplankton turn seawater green when their concentration increases. This allows us to monitor them using ocean colour. However, as the spectral properties of phytoplankton and their relationship with other coloured substances in seawater vary, subtle differences (anomalies) in ocean colour occur that can cause large errors in estimates of phytoplankton abundance. Identifying and understanding these anomalies is required to interpret ocean-colour data properly, but not all scientists have access to, or can afford, the in-situ instrumentation needed to do this. We show that practical, low-cost tools developed in the 19th century (a Secchi disk and Forel-Ule colour scale) can be used to quantify a colour anomaly in the Weddell Sea. Our findings imply that ocean-colour anomalies can be identified using affordable methods. Furthermore, records collected over the last century may contain clues on how ocean ecosystems have changed with climate.

Checklist of marine macroalgae in two contiguous Marine Protected Areas in the south-western Atlantic.

Background: The Costa das Algas Environmental Protection Area (EPA) and the Santa Cruz Wildlife Refuge (WR), located in the Espírito Santo Continental Shelf, Brazil, are outstanding marine protected areas due to their high biodiversity, particularly of macroalgae. Together, these two relatively small protected areas (1,150 and 177 km2, respectively) harbour about a quarter of all macroalgal species recorded in Brazil.The checklist presented herein updates the algal flora of these two protected areas with data obtained until 2019. Two hundred and sixty-five macroalgal taxa were recorded, most of which with vouchers. Checklists based on the collections of each protected area were published on: "Catálogo de Plantas das Unidades de Conservação do Brasil" (https://catalogo-ucs-brasil.jbrj.gov.br/). New information: Besides specimens collected between 2018 and 2019, the algal flora presented herein includes previous records from different Brazilian herbaria (e.g., SP, SPF, ALCB). Herbaria records may include species that do not occur in intertidal reefs (e.g., Laminaria). Overall, 249 macroalgal taxa and one marine angiosperm were recorded in the Costa das Algas EPA (87 new records) and 136 macroalgal taxa and one marine angiosperm in the Santa Cruz WR (46 new records). All taxa are native to Brazil and nine are endemic to Brazil. Our results provide a taxonomic foundation to support management, long-term monitoring and conservation in these protected areas.

Design and management considerations for the Kenya-Tanzania marine transboundary conservation area.

Although transboundary conservation areas (TCAs) are critical tools for protecting ecosystems and ecological processes that transcend national jurisdictions, they are challenging to create due to the differences in governance contexts and capacity and power dynamics among countries. Marine TCAs are also more difficult to enforce relative to terrestrial TCAs because most nations still treat oceans as open access. Current guidelines for TCA development and implementation also focus mostly on terrestrial TCAs, which are not practical for marine TCAs. Hence, we reviewed the challenges associated with the design and management of marine TCAs and devised analytical and practical approaches to support the application of spatial planning frameworks and adaptive governance mechanisms. We used the lessons from the review to examine the decisions made for the proposed marine TCA in the Kenya-Tanzania border region and created options and considerations to promote effective design and management processes. We found the obstacles to marine TCAs in general are related to issues of fit, particularly differences in environmental research capacity, socioeconomic contexts, and internal institutional arrangements. These included differences in knowledge and capacity for marine ecological research and conservation; ability to adjust and update data; differences in values, interests, and resource uses; conservation costs; jurisdictional differences; engagement of multiple levels of organization; and differences in legal bases and policy development processes. Understanding and reconciling these challenges during the TCA development process can help enhance meaningful discussions in the design of the TCA and cultivate the enabling conditions for collaborative governance across countries and within different levels of organization from national to local actors.

Consideraciones en el diseño y gestión del área marina de conservación transfronteriza en Kenia y Tanzania Resumen Aunque las áreas de conservación transfronterizas (ACT) son herramientas importantes para proteger los ecosistemas y los procesos ecológicos que trascienden la jurisdicción nacional, crearlas es un reto debido a la diferencia en los contextos de gobierno y la capacidad y las dinámicas de poder entre los países. Las ACT marinas también son más difíciles de ejecutar en relación a las terrestres porque la mayoría de los países todavía tratan al océano como de libre acceso. Los lineamientos actuales para el desarrollo e implementación de las ACT también se enfocan principalmente en las ACT terrestres, lo cual no es práctico para las ACT marinas. Por lo tanto, revisamos los retos asociados con el diseño y gestión de las ACT marinas y concebimos estrategias analíticas y prácticas para apoyar con la aplicación de los marcos de planeación espacial y los mecanismos de gobierno adaptativo. Usamos lo aprendido con la revisión para analizar las decisiones tomadas para la ACT marina propuesta en la región fronteriza de Kenia y Tanzania y creamos opciones y consideraciones para promover el diseño y procesos de manejo efectivos. Encontramos que los obstáculos para las ACT marinas en general se relacionan con temas de ajuste, en particular las diferencias en la capacidad de investigación ambiental, los contextos socioeconómicos y los acuerdos institucionales internos. Estos obstáculos incluyeron diferencias en el conocimiento y capacidad para la investigación ecológica marina; la habilidad para ajustar y actualizar datos; las diferencias en los valores, intereses y usos de los recursos; los costos de conservación; las diferencias jurídicas; la participación de varios niveles de organización; y las diferencias en las bases legales y los procesos de desarrollo de políticas. El entendimiento y reconciliación de estos retos durante el proceso de desarrollo de una ACT puede ayudar a mejorar las discusiones significativas en el diseño de la ACT y a cultivar las condiciones que permitan la gestión colaborativa entre los países y entre los diferentes niveles de organización, desde el nacional hasta los actores locales.

Novel high-throughput oxygen saturation measurements for quantifying the physiological performance of macroalgal early life stages.

Understanding how macroalgal forests will respond to environmental change is critical for predicting future impacts on coastal ecosystems. Although measures of adult macroalgae physiological responses to environmental stress are advancing, measures of early life-stage physiology are rare, in part due to the methodological difficulties associated with their small size. Here we tested a novel, high-throughput method (rate of oxygen consumption and production; V ̇ O 2 $$ \dot{V}{\mathrm{O}}_2 $$ ) via a sensor dish reader microplate system to rapidly measure physiological rates of the early life stages of three habitat-forming macroalgae, the kelp Ecklonia radiata and the fucoids Hormosira banksii and Phyllospora comosa. We measured the rate of O2 consumption (respiration) and O2 production (net primary production) to then calculate gross primary production (GPP) under temperatures representing their natural thermal range. The V ̇ O 2 $$ \dot{V}{\mathrm{O}}_2 $$ microplate system was suitable for rapidly measuring physiological rates over a temperature gradient to establish thermal performance curves for all species. The V ̇ O 2 $$ \dot{V}{\mathrm{O}}_2 $$ microplate system proved efficient for measures of early life stages of macroalgae ranging in size from approximately 50 µm up to 150 mm. This method has the potential for measuring responses of early life stages across a range of environmental factors, species, populations, and developmental stages, vastly increasing the speed, precision, and efficacy of macroalgal physiological measures under future ocean change scenarios.

Airborne organic pollutants impact phytoplankton in temperate and Antarctic seawaters.

Airborne Organic Pollutants (AOPs) reach remote oceanic regions after long range atmospheric transport and deposition, incorporating into natural microbial communities. This study investigated the effects of AOPs on natural microbial communities of the Mediterranean Sea, the Atlantic Ocean and the Bellingshausen Sea, by assessing the impact of both non-polar and polar AOPs on cell abundances, chlorophyll a concentrations and cell viabilities of different microbial groups. Our results indicate that almost all groups, except flagellates in the Bellingshausen Sea, were significantly affected by AOPs. While no significant differences in chlorophyll a concentrations were observed between non-polar and polar AOPs, significant variations in cell abundances were noted. Cell death occurred at AOP concentrations as low as five times the oceanic field levels, likely due to their high chemical activity. Cyanobacteria in temperate waters exhibited the highest sensitivity to AOPs, whereas medium and larger diatoms in the Bellingshausen Sea were more affected than smaller diatoms or flagellates, contrary to the expected size-related sensitivity trend. Additionally, microorganisms in temperate waters were more sensitive to the polar fraction of AOPs compared to the non-polar fraction, which showed an inverse sensitivity pattern. This differential sensitivity is attributed to variations in the ratio of polar to non-polar AOPs in the respective environments. Our findings underscore the varying impacts of AOPs on marine microbial communities across different oceanic regions.

Biogeographic patterns and community assembly mechanisms of bacterial community in the upper seawater of seamounts and non-seamounts in the Eastern Indian Ocean.

Seamounts are widespread underwater topographic features in the ocean that exert an influential role in shaping the microbial biogeographic distribution. Nevertheless, research on the differences in microbial biogeographic distribution between seamount and non-seamount upper water column is still lacking, particularly in the Indian Ocean where studies are limited. In the present study, a total of 45 seawater samples were collected from the water column (5-200 m) of seamounts (HS) and non-seamounts (E87 transect) regions in the Eastern Indian Ocean (EIO) for the analysis of microbial biogeographic patterns and community assembly processes. The results indicated that bacterial community diversity did not differ significantly between the HS and E87 transect regions; however, the community composition was significantly different. Additionally, bacterial community diversity, composition, as well as structure were more affected by depth than by region. Community diversity tended to increase with depth in E87 transect region, while it tended to decrease in HS region. A distance decay analysis also demonstrated that bacterial communities were more influenced by environmental and depth distances than geographic distances. In the assembly of bacterial communities on HS and E87 transect regions, as well as at different depths, stochastic processes, particularly dispersal limitation, were found to be predominant. These findings enhance our comprehension of bacterial community characteristics in the upper seawater of seamounts and non-seamounts regions in the EIO and offer insights into the assembly processes shaping microbial communities at varying depths. IMPORTANCE: By comparing the bacterial diversity, composition, and structure in the upper seawater of seamount and non-seamount areas, we provide valuable insights into the influential role of seamounts in shaping microbial biogeography. The finding that the depth had a more significant impact on bacterial community characteristics than region underscores the importance of considering vertical stratification when examining microbial distributions. Moreover, the dominance of stochastic processes, particularly dispersal limitation, in governing community assembly across both seamount and non-seamount areas offers critical implications for the mechanisms underlying microbial biogeographic patterns in these dynamic ocean environments. This study expands the current knowledge and lays the groundwork for further investigations into the complex interactions between oceanographic features, environmental gradients, and microbial community dynamics in the Indian Ocean.

Reduction scenarios of plastic waste emission guided by the probability distribution model to avoid additional ocean plastic pollution by 2050s.

Marine plastic pollution is progressing worldwide and will become increasingly serious if plastic waste emissions continue at the current rate or increase with economic growth. Here, we report a particle tracking-based probability distribution model for predicting the abundances of marine macroplastics and microplastics, which undergo generation, transport, and removal processes in the world's upper ocean, under various scenarios of future land-to-sea plastic waste emissions. To achieve the Osaka Blue Ocean Vision, which aims to reduce additional pollution by marine plastic litter to zero by 2050, plastic waste emission in ∼2035 should be reduced by at least 32 % relative to 2019. It is necessary to take stringent measures such as 'system change scenario' or 'improve waste management scenario' proposed in previous studies to reduce the marine plastic pollution by 2050.

Can niche plasticity mediate species persistence under ocean acidification?

Global change stressors can modify ecological niches of species, thereby altering ecological interactions within communities and food webs. Yet, some species might take advantage of a fast-changing environment, allowing species with high niche plasticity to thrive under climate change. We used natural CO2 vents to test the effects of ocean acidification on niche modifications of a temperate rocky reef fish assemblage. We quantified three ecological niche traits (overlap, shift and breadth) across three key niche dimensions (trophic, habitat and behavioural). Only one species increased its niche width along multiple niche dimensions (trophic and behavioural), shifted its niche in the remaining (habitat) was the only species to experience a highly increased density (i.e. doubling) at vents. The other three species that showed slightly increased or declining densities at vents only displayed a niche width increase in one (habitat niche) out of seven niche metrics considered. This niche modification was likely in response to habitat simplification (transition to a system dominated by turf algae) under ocean acidification. We further showed that, at the vents, the less abundant fishes had a negligible competitive impact on the most abundant and common species. This species appeared to expand its niche space, overlapping with other species, which likely led to lower abundances of the latter under elevated CO2. We conclude that niche plasticity across multiple dimensions could be a potential adaptation in fishes to benefit from a changing environment in a high-CO2 world.

Relationship between skin and body condition in three species of baleen whales.

The assessment of free-ranging cetacean health through the study of skin conditions using photographs has gained prominence in recent years. However, little attention has been given to the relationships between cetacean skin conditions, species, and body condition. To explore this relationship among baleen whale species along the northwestern coast of Spain, we employed a non-invasive method involving photograph analysis. In this study, we examined skin conditions (including injuries, epizoites and ectoparasites, pigmentation disorders, skin lesions, and anatomical malformations) and body condition (overall physical contours and form, as an indicator of nutritional status and health) in 3 species of whales (blue, fin, and minke whales). This methodology facilitated the identification of 29 subcategories of distinct skin conditions and an assessment of body condition over a 5 yr period (2017 to 2021). In our study, we present evidence linking hypopigmentation, protruding pieces of tissue, and tattoo-like lesions to 'Poor' body condition in the 3 baleen whale species. Fin whales exhibited a higher susceptibility to mottling (prevalence = 17.7%), while blue whales were more prone to starbursts (prevalence = 90.5%). Additionally, we found a significant relationship between skin condition diversity and individual body condition. Our findings contribute valuable information to the broader understanding of the health status of baleen whales. Further investigations are necessary to delve into the etiology of the documented skin conditions and their potential implications for individual survival. This study serves as a foundation for ongoing research aimed at advancing our comprehension of these findings.

Scaling up ocean conservation through recognition of key biodiversity areas in the Southern Ocean from multispecies tracking data.

Biodiversity is critical for maintaining ecosystem function but is threatened by increasing anthropogenic pressures. In the Southern Ocean, a highly biologically productive region containing many endemic species, proactive management is urgently needed to mitigate increasing pressures from fishing, climate change, and tourism. Site-based conservation is one important tool for managing the negative impacts of human activities on ecosystems. The Key Biodiversity Area (KBA) Standard is a standardized framework used to define sites vital for the persistence of global biodiversity based on criteria and quantitative thresholds. We used tracking data from 14 species of Antarctic and subantarctic seabirds and pinnipeds from the publicly available Retrospective Analysis of Antarctic Tracking Data (RAATD) data set to define KBAs for a diverse suite of marine predators. We used track2kba, an R package that supports identification of KBAs from telemetry data through identification of highly used habitat areas and estimates of local abundance within sites. We compared abundance estimates at each site with thresholds for KBA criteria A1, B1, and D1 (related to globally threatened species, individual geographically restricted species, and demographic aggregations, respectively). We identified 30 potential KBAs for 13 species distributed throughout the Southern Ocean that were vital for each individual species, population, and life-history stage for which they were determined. These areas were identified as highly used by these populations based on observational data and complement the ongoing habitat modeling and bioregionalization work that has been used to prioritize conservation areas in this region. Although further work is needed to identify potential KBAs based on additional current and future data sets, we highlight the benefits of utilizing KBAs as part of a holistic approach to marine conservation, given their significant value as a global conservation tool.

Ampliación de la conservación oceánica por medio del reconocimiento de áreas importantes de biodiversidad en el Océano Antártico a partir de datos de rastreo de varias especies Resumen La biodiversidad es fundamental para mantener la función de los ecosistemas, pero está amenazada por las crecientes presiones antropogénicas. En el Océano Antártico, una región con mucha producción biológica que contiene numerosas especies endémicas, se necesita urgentemente una gestión proactiva para mitigar las crecientes presiones de la pesca, el cambio climático y el turismo. La conservación basada en el sitio es una herramienta importante para gestionar los efectos negativos de las actividades humanas en los ecosistemas. El Estándar de Áreas Clave para la Biodiversidad (ACB) es un marco estandarizado que se utiliza para definir lugares vitales para la persistencia de la biodiversidad mundial con base en criterios y umbrales cuantitativos. Usamos datos del seguimiento de 14 especies de aves marinas y pinnípedos antárticos y sub­antárticos del conjunto de datos públicos Retrospective Analysis of Antarctic Tracking Data (RAATD) para definir las ACB de un conjunto diverso de depredadores marinos. Utilizamos track2kba, un paquete de R que permite la identificación de ACB a partir de datos telemétricos mediante la identificación de áreas de hábitat altamente utilizadas y estimaciones de abundancia local dentro de los sitios. Comparamos las estimaciones de abundancia en cada lugar con los umbrales de los criterios A1, B1 y D1 de las ACB (relacionados con especies amenazadas a nivel mundial, especies individuales restringidas geográficamente y agregaciones demográficas, respectivamente). Identificamos 30 ACB potenciales para 13 especies distribuidas por todo el Océano Antártico que eran vitales para cada especie individual, población y etapa del ciclo biológico para las que se determinaron. Estas áreas fueron identificadas como muy utilizadas por estas poblaciones con base a datos observacionales y complementan el trabajo en curso de modelos del hábitat y biorregionalización que se ha utilizado para priorizar las áreas de conservación en esta región. Aunque es necesario seguir trabajando para identificar posibles ACB basadas en conjuntos de datos adicionales actuales y futuros, destacamos los beneficios de utilizar las ACB como parte de un enfoque holístico de la conservación marina, dado su importante valor como herramienta de conservación global.

Remote sensing estimates of global sea surface nitrate: Methodology and validation.

Information about sea surface nitrate (SSN) concentrations is crucial for estimating oceanic new productivity and for carbon cycle studies. Due to the absence of optical properties in SSN and the intricate relationships with environmental factors affecting spatiotemporal dynamics, developing a more representative and widely applicable remote sensing inversion algorithm for SSN is challenging. Most methods for the remote estimation of SSN are based on data-driven neural networks or deep learning and lack mechanistic descriptions. Since fitting functions between the SSN and sea surface temperature (SST), mixed layer depth (MLD), and chlorophyll (Chl) content have been established for the open ocean, it is important to include the remote sensing indicator photosynthetically active radiation (PAR), which is critical in nitrate biogeochemical processes. In this study, we employed an algorithm for estimating the monthly average SSN on a global 1° by 1° resolution grid; this algorithm relies on the empirical relationship between the World Ocean Atlas 2018 (WOA18) monthly interpolated climatology of nitrate in each 1° × 1° grid and the estimated monthly SST and PAR datasets from Moderate Resolution Imaging Spectroradiometer (MODIS) and MLD from the Hybrid Coordinate Ocean Model (HYCOM). These results indicated that PAR potentially affects SSN. Furthermore, validation of the SSN model with measured nitrate data from different months and locations for the years 2018-2023 yielded a high prediction accuracy (N = 12,846, R2 = 0.93, root mean square difference (RMSE) = 3.12 µmol/L, and mean absolute error (MAE) = 2.22 µmol/L). Further independent validation and sensitivity tests demonstrated the validity of the algorithm for retrieving SSN.

Phthalates and fatty acid markers in free-ranging cetaceans from an insular oceanic region: Ecological niches as drivers of contamination.

Plastic additives, such as phthalates, are ubiquitous contaminants that can have detrimental impacts on marine organisms and overall ecosystems' health. Valuable information about the status and resilience of marine ecosystems can be obtained through the monitoring of key indicator species, such as cetaceans. In this study, fatty acid profiles and phthalates were examined in blubber biopsies of free-ranging individuals from two delphinid species (short-finned pilot whale - Globicephala macrorhynchus, n = 45; common bottlenose dolphin - Tursiops truncatus, n = 39) off Madeira Island (NE Atlantic). This investigation aimed to explore the relations between trophic niches (epipelagic vs. mesopelagic), contamination levels, and the health status of individuals within different ecological and biological groups (defined by species, residency patterns and sex). Multivariate analysis of selected dietary fatty acids revealed a clear niche segregation between the two species. Di-n-butylphthalate (DBP), diethyl phthalate (DEP), and bis(2-ethylhexyl) phthalate (DEHP) were the most prevalent among the seven studied phthalates, with the highest concentration reached by DEHP in a bottlenose dolphin (4697.34 ± 113.45 ng/g). Phthalates esters (PAEs) concentration were higher in bottlenose dolphins (Mean ∑ PAEs: 947.56 ± 1558.34 ng/g) compared to pilot whales (Mean ∑ PAEs: 229.98 ± 158.86 ng/g). In bottlenose dolphins, DEHP was the predominant phthalate, whereas in pilot whales, DEP and DBP were more prevalent. Health markers suggested pilot whales might suffer from poorer physiological conditions than bottlenose dolphins, although high metabolic differences were seen between the two species. Phthalate levels showed no differences by ecological or biological groups, seasons, or years. This study is the first to assess the extent of plastic additive contamination in free-ranging cetaceans from a remote oceanic island system, underscoring the intricate relationship between ecological niches and contaminant exposure. Monitoring these chemicals and their potential impacts is vital to assess wild population health, inform conservation strategies, and protect critical species and habitats.

The Commerson's dolphin as Subantarctic sentinel of POPs: insights into the pollutant status in one of the southernmost coastal areas of the globe.

Persistent organic pollutants (POPs) are halogenated contaminants found globally. Cetaceans are impacted by these pollutants, and nowadays, it is essential to understand their presence to mitigate their impacts. This study aimed to establish baseline levels of POPs in the blubber of Commerson's dolphins (Cephalorhynchus commersonii) within the Subantarctic ecosystem. A wide range of POPs concentrations were measured among individuals: ΣPCBs from 289.5 to 15264 ng. g-1 lw and ΣDDTs from 540.4 to 17657 ng. g-1 lw. Levels of HCB and mirex ranged from 48 to 1703.7 ng. g-1 lw and 5.1 to 1917.4 ng. g-1 lw, respectively. The predominant POPs were mid- to high molecular weight PCBs (hexa-PCBs), consistent with other findings in cetaceans of the southern hemisphere. The mean ratio of ΣDDT/ΣPCB was 0.44, with p,p'-DDE/ΣDDT at 0.56, indicating p,p'-DDE as the dominant DDT isomer. Furthermore, differences in POP concentrations were observed based on sexual maturity, with mature males exhibiting higher levels of Æ©PCBs, HCB, Æ©DDT, and mirex. Age and total body length of animals were strongly correlated with POP concentrations. Our study provides valuable insights into the pollutant status of POPs in the Subantarctic population of Commerson's dolphins inhabiting the southernmost coastal regions of South America.