Institut de Ciències del Mar

The use of animal‐borne devices (= biologgers) has revolutionized the study of marine megafauna, yet there remains a paucity of data concerning the behavioral and physiological impacts of biologger attachment and retention. Here, we used animal‐borne cameras to characterize the behavior and dive duration of juvenile green turtles (Chelonia mydas) in The Bahamas for up to 210 min after biologger deployment (n = 58). For a “control,” we used unoccupied aerial vehicles (UAVs) to collect comparable data from nonhandled green turtles (n = 25) in the same habitats. Animal‐borne footage revealed that immediately after release turtles spent 70%–80% of their time swimming with a mean dive duration of 45.3 ± 34.3 s (SD). Over time, the percentage of time spent swimming decreased alongside an increase in dive duration until reaching a plateau around 90 min. However, the “control” UAV data for time spent swimming and dive durations were more comparable to the behaviors observed immediately after biologger deployment than during the plateau. We observed no significant differences in dive durations based on body size, and differences in behaviors based on body size were also minimal. We conclude that the effects of handling stress and biologger attachment on the behavior and dive duration of juvenile green turtles are evident up to 90 min postdeployment. After that, it is possible that either: (1) the effects of biologger deployment and retention are negligible, but UAVs may produce biased data that overestimates the proportion of time turtles typically spend swimming or (2) longer durations (> 210 min) are necessary for turtle behaviors to return to nonhandled levels and UAVs accurately represent the proportion of time turtles typically spend swimming. Answering this question, alongside further research into the physiological and behavioral implications of handling stress and biologger attachment, is essential to improve ethical biologging guidelines for sea turtles.

Heterotrophic prokaryotes play a vital role in organic matter cycling in the ocean and have been observed to undergo substrate‐controlled successions during phytoplankton blooms. However, there is limited understanding of the succession patterns during blooms triggered by upwelling events of different characteristics. Here we simulated eight upwelling scenarios of varying intensity and duration (single vs. recurring pulses) by adding nutrient‐rich mesopelagic waters into large‐scale mesocosms containing oligotrophic surface waters from the subtropical North Atlantic. Over a monitoring period of nearly 6 weeks, we observed that phytoplankton blooms displayed diverging outcomes depending on the upwelling mode: treatments with single upwelling pulses presented a unique, short‐lived bloom, whereas recurring upwelling resulted in blooms that were sustained over time. Prokaryotic abundances were positively related to upwelling intensity and presented three similar abundance cycles in all treatments, whereas heterotrophic activity differed between the two upwelling modes. The successional dynamics of free‐living and particle‐associated communities were consistent regardless of upwelling intensity and mode, with four or five prokaryotic assemblages sequentially proliferating during the experiment. Yet, some differences were observed in the taxa that formed the assemblages in both upwelling modes. Together, our results suggest that, despite differences in activity, prokaryotes seemed to be more influenced by processes taking place within the community than by phytoplankton bloom patterns, with similar succession dynamics even under widely distinct blooms. These findings can help advance our understanding on prokaryotic ecology and its relation to organic matter cycling across different upwelling scenarios.

Silicon is a major driver of global primary productivity and CO2 sequestration, and is a beneficial element for the growth and environmental stress mitigation of many terrestrial and aquatic plants. However, only a few studies have examined the occurrence of silicon in seagrasses, and its function within seagrass ecosystems and the role of seagrasses in silicon cycling remain largely unexplored. This study uses for the first time two methods, the wet-alkaline digestion and the hydrofluoric acid digestion, to quantify silicon content in seagrass leaves using the species Zostera marina and elaborates on the potential role of silicon in seagrass biogeochemistry and ecology, as well as the role of seagrass ecosystems as a silicon reservoir. The results revealed that seagrass leaves contained 0.26% silicon:dry-weight, which is accumulated in two forms of silica: a labile form digested with the alkaline method and a resistant form digested only with acid digestion. These findings support chemical digestions for silicon quantification in seagrass leaves and provide new insights into the impact of seagrasses on the marine silicon cycle. Labile silica will be recycled upon leaf degradation, benefiting siliceous organisms, while refractory silica will contribute to the ecosystem’s buried silica stock and coupled carbon sequestration. In the Bay of Brest (France), the seagrass silicon reservoir was estimated at 0.18 ± 0.07 g Si m⁻², similar to that of benthic diatoms, underscoring the potential role of seagrasses in silicon biogeochemistry in the land–ocean continuum, where they might act as a buffer for silicon transport to the ocean.

Methylmercury (MeHg) is a widespread contaminant that bioaccumulates in marine food webs, including those in the Mediterranean sea. It poses serious health risks, especially to developing infants and children, where exposure can cause neurological damage and developmental delays. In addition to health concerns, high MeHg Productivitylevels in seafood can lead to economic losses through cognitive impairments that reduce productivity. Despite seafood being a dietary staple in Mediterranean countries, the full extent of MeHg's health and economic impacts remains underexplored, especially with the rising international trade. This study aims to (a) estimate MeHg exposures in Mediterranean populations from consumption of Mediterranean seafood and (b) quantify the economic costs associated with MeHg intake. We assessed population exposures in Mediterranean countries by combining a highly granular seafood supply data on Aquatic Resource Trade in Species (ARTIS), alongside Global Dietary Database (GDD) and review of MeHg levels in Mediterranean seafood. The economic cost was then derived by linking MeHg intake to productivity losses associated with cognitive deficits. As a result, we estimate that Mediterranean countries experience over €10 billion in annual economic losses due to IQ-related productivity decline associated with MeHg exposure from consuming seafood sourced from various fishing areas of the Mediterranean Sea. The novelty of this research lies in its transdisciplinary approach to MeHg impact assessment that incorporates highly detailed seafood supply data with dietary surveys, and scientific literature to provide a more realistic and detailed view of MeHg exposures and the associated cost-of illness from local seafood consumption accross Mediterranean countries. These findings highlight a critical aspect of MeHg management: while international trade can mitigate local exposure by providing access to less-contaminated imports, it simultaneously exports the contamination burden to other regions. This duality emphasizes the importance of global cooperation in addressing seafood safety and managing transboundary MeHg risks.

Grazing can impart long‐lasting changes in vegetated ecosystems. How ecosystems respond to herbivory depends on the ecological and evolutionary histories of their foundational species. The overall ecosystem functioning and associated biodiversity depend on these responses but there is still little understanding on how the intensity and duration of herbivory interact and impact vegetated ecosystems. We experimentally tested in the field the responses of three seagrass species with distinct life history traits to increasing intensities of herbivory over time. Specifically, we assessed structural responses (i.e., canopy height and shoot density) to reflect the ecosystem state. Additionally, we used mechanistic models to assess induced and constitutive responses in the different seagrass species. Results show that seagrasses coped with herbivory differentially in relation to their life history traits. Posidonia oceanica (persistent species) was resistant and only registered declines in canopy height, whereas both canopy heigh and shoot density rapidly decreased for Cymodocea nodosa (intermediate‐colonizing species) and Zostera noltei (colonizing species). Seagrasses also differed in the type of structural response, with the colonizing species experiencing reductions in shoot density, and the persistent P. oceanica registering declines in canopy height. After months of exposure to cumulative herbivory, all three species showed signs of stability. Interestingly, none of the species disappeared completely even when exposed to extreme herbivory. Mechanistic models indicate that herbivory‐induced responses are a potential explanation for these patterns. This study suggests that given the long evolutionary history of herbivory, some seagrasses may be remarkably well adapted to both intense and cumulative herbivory.

Microplastics are ubiquitous in marine ecosystems and are suitable matrices for bacterial attachment and growth. Studies on the microbes growing on plastics are mainly done using flow cytometry and massive sequencing, which do not allow for the quantification of specific groups and their activity. Here we present the results from a mesocosm experiment, designed to compare the effects of biodegradable and conventional microplastics on planktonic communities of the Baltic Sea. Our specific aim was to study the effects on bacterial activity and abundance using epifluorescence microscopy techniques. Specifically, we applied BONCAT-FISH which simultaneously allows for phylogenetic identification and the detection of the activity of individual bacterial cells. In our experiment, mesocosms were filled with Baltic brackish seawater and amended with 20 microplastic beads·ml⁻¹ in triplicates for several treatments: (i) None (control), (ii) PS, (iii) PLGA and (iv) PS + PLGA. Our results show a low impact of the presence and quality of microplastics on marine bacterial communities during the first 11 days of exposure, with only weak differences in the activity of bacterial communities growing with biodegradable or conventional microplastics additions.

Numerous studies have explored whether and how the spread of the SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19), responds to environmental conditions without reaching consistent answers. Sociodemographic factors, such as variable population density and mobility, as well as the lack of effective epidemiological monitoring, make it difficult to establish robust correlations. Here we carry out a regional cross-correlation study between nine atmospheric variables and an infection index (Ic) estimated from standardized positive polymerase chain reaction (PCR) test cases. The correlations and associated time-lags are used to build a linear multiple-regression model between weather conditions and the Ic index. Our results show that surface pressure and relative humidity can largely predict COVID-19 outbreaks during periods of relatively minor mobility and meeting restrictions. The occurrence of low-pressure systems, associated with the autumn onset, leads to weather and behavioral changes that intensify the virus transmission. These findings suggest that surface pressure and relative humidity are key environmental factors that may be used to forecast the spread of SARS-CoV-2.

Coastal zones, particularly sandy beaches, are highly dynamic environments subject to a variety of natural and anthropogenic forcings. Instantaneous shoreline is a widely used indicator of beach changes in image-based applications, and it can display undulations at different spatial and temporal scales. Megacusps, periodic seaward and landward shoreline perturbations, are an example of such undulations that can significantly modify beach width and impact its usability. Traditionally, the study of these phenomena relied on video monitoring systems, which provide high-frequency imagery but limited spatial coverage. Instead, this study explored the potential of employing multispectral satellite-derived shorelines, specifically from Sentinel-2 (S2) and PlanetScope (PLN) platforms, for characterizing and monitoring megacusps’ formation and their dynamics over time. First, a tool was developed and validated to guarantee accurate shoreline detection, based on a combination of spectral indices, along with both thresholding and unsupervised clustering techniques. Validation of this shoreline detection phase was performed on three micro-tidal Mediterranean beaches, comparing with high-resolution orthomosaics and in-situ GNSS data, obtaining a good subpixel accuracy (with a mean absolute deviation of 1.5–5.5 m depending on the satellite type). Second, a tool for megacusp characterization was implemented and subsequent validation with reference data proved that satellite-derived shorelines could be used to robustly and accurately describe megacusps. The methodology could not only capture their amplitude and wavelength (of the order of 10 and 100 m, respectively) but also monitor their weekly–daily evolution using different potential metrics, thanks to combining S2 and PLN imagery. Our findings demonstrate that multispectral satellite imagery provides a viable and scalable solution for monitoring shoreline megacusp undulations, enhancing our understanding and offering an interesting option for coastal management.

Anthropogenic environments such as wastewater treatment plants (WWTPs) and landfills are sources of antimicrobial resistance (AMR). Black-headed gulls (Chroicocephalus ridibundus) frequently use WWTPs and may be vectors for AMR. We used GPS tracking data for 39 gulls for up to 8 months, combined with a shedding curve, to study sources and dispersal distances of AMR in Iberia. The gulls used 21 different WWTPs (684 visits) and three landfills (21 visits). Areas of high risk of AMR dissemination were an average of 25 km from the infection source, with a maximum of 500 km. Solar saltworks and natural waterbodies were particularly exposed to AMR dissemination, followed by agriculture, sports facilities, and tourist beaches. There was important variability between individual gulls in their habitat specialization, and which WWTPs they visited. Studying the spatial movements of gulls after visiting WWTPs and landfills helps pinpoint sensitive locations where pathogen transmission is most likely.

Macroplastic pollution is a pervasive global environmental challenge, adversely affecting marine ecosystems, wildlife and human health. Understanding temporal variations is crucial for identifying pollution sources and developing effective mitigation policies. However, in-situ data from beach surveys are often irregular, both spatially and temporally, and highly variable, complicating robust statistical conclusions. Here we employ a Bayesian machine learning framework to investigate seasonal variations, identify regional hotspots and elucidate their anthropogenic drivers. Using data from 3866 surveys across 168 western European beaches, we leverage a spatial log-Gaussian Cox Process to enhance statistical inference by integrating information from nearby beaches. Distinct seasonal patterns emerge, with winter and spring exhibiting the highest pollution levels, while pronounced regional differences highlight seasonal pollution hotspots in the western Iberian Peninsula, French coastline, Irish Sea and Skagerrak region. These peaks are attributed to riverine emissions and aquaculture activities, highlighting the potential impact of these sources on beach pollution. Our findings advocate for enhanced, time-specific monitoring to effectively manage litter hotspots, emphasizing the importance of aquaculture-related plastic emissions.

Background Association between global platelet function and the risk of venous thromboembolic disease (VTE) has been proposed, though the mechanisms do not involve increased platelet aggregation. However, platelet adhesiveness has not been systematically explored in VTE patients. Objectives To evaluate platelet adhesive functions in VTE patients. Methods Platelet adhesion was evaluated by using whole blood samples from VTE patients, selected based on short closure times on the PFA-100 ( n = 54), and matched healthy individuals ( n = 57) in: (i) the PFA-100, (ii) a cone plate analyzer (CPA), on a plastic surface, (iii) microfluidic devices, with two- and three-dimensional evaluation, and (iv) membrane glycoprotein analysis. Intraplatelet signaling was evaluated in isolated collagen type I (Col-I) activated platelets and platelets adhered on Col-I or von Willebrand factor (VWF) coated coverslips under flow. VWF antigen and ADAMTS-13 activity were measured in plasma samples. Results PFA-100 closure times remained significantly shorter in patients. The CPA test showed a significant increase in the platelet aggregates size when using blood from VTE patients. Platelet adhesion on Col-I revealed a higher area covered by platelets and increased aggregate volume when exposed to samples from VTE patients. Protein P-ZAP70/SYK72 showed a phosphorylation level significantly increased in patients' platelets. Plasma VWF was significantly elevated in VTE patients. Conclusions Platelets from VTE patients exhibit a proadhesive phenotype under flow conditions potentially related to the shortened occlusion times with the PFA-100. This enhanced adhesiveness may be explained by higher intraplatelet ZAP70/SYK72 phosphorylation and increased plasma VWF in patients. Therefore, primary hemostasis plays a significant role in the pathophysiology of VTE.

Ocean-emitted dimethyl sulfide (DMS) is a major source of climate-cooling aerosols. However, most of the marine biogenic sulfur cycling is not routed to DMS but to methanethiol (MeSH), another volatile whose reactivity has hitherto hampered measurements. Therefore, the global emissions and climate impact of MeSH remain unexplored. We compiled a database of seawater MeSH concentrations, identified their statistical predictors, and produced monthly fields of global marine MeSH emissions adding to DMS emissions. Implemented into a global chemistry-climate model, MeSH emissions increase the sulfate aerosol burden by 30 to 70% over the Southern Ocean and enhance the aerosol cooling effect while depleting atmospheric oxidants and increasing DMS lifetime and transport. Accounting for MeSH emissions reduces the radiative bias of current climate models in this climatically relevant region.

Extreme climatic events (ECEs), such as marine heatwaves (MHWs), are a major threat to biodiversity. Understanding the variability in ecological responses to recurrent ECEs within species and underlying drivers arise as a key issue owing to their implications for conservation and population recovery. Yet, our knowledge on such ecological responses is limited since it has been frequently gathered following “single-event approaches” focused on one particular event. These approaches provide snapshots of ecological responses but fall short of capturing heterogeneity patterns that may occur among recurrent ECEs, questioning current predictions regarding biodiversity trends. Here, we adopt a “multiple events” perspective to characterize the effects of recurrent ECEs on the ecological responses in Paramuricea clavata, a Mediterranean temperate coral threatened by MHWs. Through a common-garden experiment repeated three consecutive years with the same individuals from three populations, we assessed the respective roles of environmental (year effect), genetic (population effect), and phenotypic (population-by-environment interactions effect) components in the ecological response to recurrent heat stress. The environmental component (year) was the main driver underlying the responses of P. clavata colonies across experiments. To build on this result, we showed that: (i) the ecological responses were not related to population (genetic isolation) and individual (multilocus heterozygosity) genetic make-up, (ii) while all the individuals were characterized by a high environmental sensitivity (genotype-by-environment interactions) likely driven by in situ summer thermal regime. We confront our experimental results to in situ monitoring of the same individuals conducted in 2022 following two MHWs (2018, 2022). This confirms that the targeted populations harbor limited adaptive and plastic capacities to on-going recurrent ECEs and that P. clavata might face unavoidable population collapses in shallow Mediterranean waters. Overall, we underscore the need to consider the recurrence of ECEs to assess threats to biodiversity and to forecast its evolution.

Patchy global data on belowground litter decomposition dynamics limit our capacity to discern the drivers of carbon preservation and storage across inland and coastal wetlands. We performed a global, multiyear study in over 180 wetlands across 28 countries and 8 macroclimates using standardized litter as measures of “recalcitrant” (rooibos tea) and “labile” (green tea) organic matter (OM) decomposition. Freshwater wetlands and tidal marshes had the highest tea mass remaining, indicating a greater potential for carbon preservation in these ecosystems. Recalcitrant OM decomposition increased with elevated temperatures throughout the decay period, e.g., increase from 10 to 20 °C corresponded to a 1.46-fold increase in the recalcitrant OM decay rate constant. The effect of elevated temperature on labile OM breakdown was ecosystem-dependent, with tidally influenced wetlands showing limited effects of temperature compared with freshwater wetlands. Based on climatic projections, by 2050 wetland decay constants will increase by 1.8% for labile and 3.1% for recalcitrant OM. Our study highlights the potential for reduction in belowground OM in coastal and inland wetlands under increased warming, but the extent and direction of this effect at a large scale is dependent on ecosystem and OM characteristics. Understanding local versus global drivers is necessary to resolve ecosystem influences on carbon preservation in wetlands.

Aim Determining the species distribution and factors shaping it is a major challenge for conservation planning. Ecological niche models (ENMs) facilitate the comprehension of how environmental factors may influence species occurrence, providing spatially explicit information relevant to conservation. Therefore, our aim was to estimate the potential distribution of key habitat‐forming Mediterranean gorgonians, whose conservation would protect many co‐occurring species. Location Mediterranean Sea. Methods We modelled the potential distribution of the Mediterranean gorgonians Eunicella singularis , Eunicella cavolini , Paramuricea clavata and Corallium rubrum , using an ensemble ENM that combines nine algorithms. An extensive dataset of presence records (> 4378) collected through scientific surveys and citizen‐science was intersected with oceanographic and topographic information within the coralligenous habitat depth range (< 150 m). This approach was used to map the habitat suitability of the study area for each species, assess related uncertainty, identify the most important factors shaping their distribution, and evaluate the overlap with the current network of Marine Protected Areas. Results The model identified higher habitat suitability for the occurrence of each gorgonian species in the NW Mediterranean, with roughness and temperature as the main drivers of their distribution. Conversely, the poorly sampled SE Mediterranean showed low habitat suitability, although there is a greater uncertainty associated with this estimate. The combined potential distribution of the four species is estimated to cover a quarter of Mediterranean shallow and mesophotic waters, but only 19% was included within protected areas. Main Conclusions The habitat suitability and uncertainty maps provide a valuable tool for the conservation and management of Mediterranean gorgonian species by offering spatially explicit information critical for marine spatial planning. The model estimates of habitat suitability showed low uncertainty for most of the study area, with few exceptions in the SE Mediterranean. Further studies, particularly in the SE Mediterranean will contribute to validate these results and will provide new information to improve future modelling efforts.

Recent developments in microscopic and molecular tools have allowed the implementation of new approaches for assessing parasitic infections in wildlife populations. This is particularly important for the noninvasive detection and quantification of endoparasites in live animals. Here, we combined copromicroscopic (Mini‐FLOTAC) and molecular (qPCR) techniques to detect the infection of the macroparasite Ligula intestinalis (Cestoda, Pseudophyllidea) in fresh droppings of Gull‐billed Terns Gelochelidon nilotica (Charadriiformes, Laridae) breeding in southwestern Spain. Additionally, we sequenced the cytochrome b gene in parasite isolates from Gull‐billed Terns (definitive host) and Common Bleak Alburnus alburnus (second intermediate host) sampled around tern colonies to explore potential genetic differences between the isolates. The qPCR test showed a higher prevalence (18%; in 13/73 samples) than Mini‐FLOTAC (9%; in 8/88 samples), indicating that qPCR was more sensitive for diagnostic purposes than fecal flotation alone. Although the agreement between both techniques was substantial (84.2%) mainly due to the large number of uninfected samples, only Mini‐FLOTAC allowed us to quantify parasite shedding. When combining techniques, the prevalence of infection did not differ between adults and chicks, suggesting frequent trophic transmission from parents to their offspring via food provisioning. Phylogenetic analyses identified four haplotypes in the isolates from Gull‐billed Terns and Bleak, all of which were placed within a European clade composed of tapeworms recovered exclusively from phylogenetically derived cyprinid fish. This, combined with the short lifespan of mature tapeworms, suggests that Gull‐billed Terns became infected after consuming infected fish around their breeding colonies rather than on their West African wintering grounds. Altogether, our results represent the first record of L. intestinalis in Gull‐billed Terns and the first molecular characterization of the parasite in the Iberian Peninsula. This integrative coprodiagnostic protocol can be applied to other host–parasite systems, allowing researchers to study helminth infections in wild populations using a noninvasive approach.