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Abstract Seagrasses are important primary producers in oceans worldwide. They live in shallow coastal waters that are experiencing carbon dioxide enrichment and ocean acidification. Posidonia oceanica, an endemic seagrass species that dominates the Mediterranean Sea, achieves high abundances in seawater with relatively low concentrations of dissolved inorganic nitrogen. Here we tested whether microbial metabolisms associated with P. oceanica and surrounding seawater enhance seagrass access to nitrogen. Using stable isotope enrichments of intact seagrass with amino acids, we showed that ammonification by free-living and seagrass-associated microbes produce ammonium that is likely used by seagrass and surrounding particulate organic matter. Metagenomic analysis of the epiphytic biofilm on the blades and rhizomes support the ubiquity of microbial ammonification genes in this system. Further, we leveraged the presence of natural carbon dioxide vents and show that the presence of P. oceanica enhanced the uptake of nitrogen by water column particulate organic matter, increasing carbon fixation by a factor of 8.6–17.4 with the greatest effect at CO2 vent sites. However, microbial ammonification was reduced at lower pH, suggesting that future ocean climate change will compromise this microbial process. Thus, the seagrass holobiont enhances water column productivity, even in the context of ocean acidification.

The Mediterranean Sea is a hotspot of global change, particularly exposed to ocean warming and the increasing occurrence of marine heatwaves (MHWs). However, experiments based on long-term temperature data from the field are scarce. Here, we investigate the response of the zooxanthellate coral Cladocora caespitosa and the azooxanthellate coral Astroides calycularis to future warming and MHWs based on 8 years of in situ data. Corals were maintained in the laboratory for five months under four temperature conditions: Warming (3.2°C above the in situ mean from 2012 to 2020), Heatwave (temperatures of 2018 with two heatwaves), Ambient (in situ mean) and Cool (deeper water temperatures). Under the Warming treatment, some C. caespitosa colonies severely bleached and A. calycularis colonies presented necrosis. Cladocora caespitosa symbiosis was impaired by temperature with a decrease in the density of endosymbiotic algae and an increase in per cent whiteness in all the treatments except for the coolest. Recovery for both species was observed through different mechanisms such as regrowth of polyps of A. calycularis and recovery of pigmentation for C. caespitosa. These results suggest that A. calycularis and C. caespitosa may be resilient to heat stress and can recover from physiological stresses caused by heatwaves in the laboratory.

The global increase in anthropogenic CO2 is leading to ocean warming and acidification, which is threatening corals. In Ischia, Italy, two species of Mediterranean scleractinian corals-the symbiotic Cladocora caespitosa and the asymbiotic Astroides calycularis-were collected from ambient pH sites (average pHT = 8.05) and adjacent CO2 vent sites (average pHT = 7.8) to evaluate their response to ocean acidification. Coral colonies from both sites were reared in a laboratory setting for six months at present day pH (pHT ~ 8.08) or low pH (pHT ~7.72). Previous work showed that these corals were tolerant of low pH and maintained positive calcification rates throughout the experiment. We hypothesized that these corals cope with low pH by increasing their heterotrophic capacity (i.e., feeding and/or proportion of heterotrophically derived compounds incorporated in their tissues), irrespective of site of origin, which was quantified indirectly by measuring δ13C, δ15N, and sterols. To further characterize coral health, we quantified energy reserves by measuring biomass, total lipids, and lipid classes. Additional analysis for C. caespitosa included carbohydrates (an energy reserve) and chlorophyll a (an indicator of photosynthetic capacity). Isotopic evidence shows that ambient-sourced Mediterranean corals, of both species, decreased heterotrophy in response to six months of low pH. Despite maintaining energy reserves, lower net photosynthesis (C. caespitosa) and a trend of declining calcification (A. calycularis) suggest a long-term cost to low heterotrophy under ocean acidification conditions. Conversely, vent-sourced corals maintained moderate (C. caespitosa) or high (A. calycularis) heterotrophic capacity and increased photosynthesis rates (C. caespitosa) in response to six months at low pH, allowing them to sustain themselves physiologically. Provided there is sufficient zooplankton and/or organic matter to meet their heterotrophic needs, vent-sourced corals are more likely to persist this century and potentially be a source for new corals in the Mediterranean.

Locations in the ocean where CO2 naturally seeps from the seafloor can be used to infer potential responses to ocean acidification. Here the authors explore the functional composition of benthic communities along a natural CO2 gradient, showing a loss of functional diversity at high-CO2 sites.

Proportions and concentrations of seston fatty acids, n-alkanes and glycerol dialkyl glycerol tetraethers (GDGTs) were used to assess potential differences in the phytoplankton composition and food quality in the Humboldt Current System (winter 2006, summer 2007 and winter 2007) in surface, oxycline, intermediate and bottom water layers. The zone below the intermediate depth was poorer in fatty acids (minimum 15 – maximum 117mg fatty acids L

Fundamentos: La drogadicción no es una contraindicación para indicar tratamiento de la hepatitis C crónica (HCC), pero se ha observado que los consumidores de drogas abandonan más el tratamiento. El objetivo del trabajo es estudiar los factores predictivos de discontinuación del tratamiento en internos drogodependientes tratados de la HCC con interferon pegilado más ribavirina. Métodos: Estudio multicéntrico con presos drogodependientes tratados de HCC entre 01/01/2003-31/12/2007 y que permanecían encarcelados en 2008 (n=162). Se comprueba mediante la historia clínica informatizada cuántos finalizaron el tratamiento. Se emplea un cuestionario diseñado "ad hoc" para conocer posibles variables asociadas a la no finalización y se realiza un análisis multivariado mediante regresión logística para identificar factores predictivos. Resultados: El 82,7% era usuario de drogas intravenosas, el 21,7% estaba coinfectado por el VIH y el 20,5% realizaba tratamiento con metadona. El 91,4% completó el tratamiento, aunque el 33,1% consumió heroína y/o cocaína en alguna ocasión y el 7,9% reconoció haber compartido jeringas. El único factor predictivo de discontinuación fue la recaída en el consumo endovenoso, dentro o fuera de prisión (OR: 10,39. IC: 1,93-55,88. p= 0,006). Conclusión: Sólo el 9,6% de los casos discontinuó el tratamiento. La recaída en el consumo de drogas fue la única variable predictiva de discontinuación. Se recomienda, valorar y tratar la drogadicción con el fin de detectar y evitar interrupciones de tratamiento.

Ecological work carried out on the Antarctic and Magellan shelves since the first IBMANT conference held at the UMAG, Punta Arenas in 1997 is summarized to identify areas where progress has been made and others, where important gaps have remained in understanding past and present interaction between the Antarctic and the southern tip of South America. This information is complementary to a review on shallow-water work along the Scotia Arc (Barnes, 2005) and recent work done in the deep sea (Brandt and Hilbig, 2004). While principally referring to shipboard work in deeper water, above all during the recent international EASIZ and LAMPOS campaigns, relevant work from shore stations is also included. Six years after the first IBMANT symposium, significant progress has been made along the latitudinal gradient from the Magellan region to the high Antarctic in the fields of biodiversity, biogeography and community structure, life strategies and adaptations, the role of disturbance and its significance for biodiversity, and trophic coupling of the benthic realm with the water column and sea ice. A better understanding has developed of the role of evolutionary and ecological factors in shaping past and present-day environmental conditions, species composition and distribution, and ecosystem functioning. Furthermore, the science community engaged in unravelling Antarctic-Magellan interactions has advanced in methodological aspects such as new analytical approaches for comparing biodiversity derived from visual methods, growth and age determination, trophic modelling using stable isotope ratios, and molecular approaches for taxonomic and phylogenetic purposes. At the same time, much effort has been invested to complement the species inventory of the two adjacent regions. However, much work remains to be done to fill the numerous gaps. Some perspectives are outlined in this review, and suggestions are made where particular emphasis should be placed in future work, much of which will be developed in the frame of SCAR’s EBA (Evolution and Biodiversity in the Antarctic) programme.

Extreme events are rare, stochastic perturbations that can cause abrupt and dramatic ecological change within a short period of time relative to the lifespan of organisms. Studies over time provide exceptional opportunities to detect the effects of extreme climatic events and to measure their impacts by quantifying rates of change at population and community levels. In this study, we show how an extreme storm event affected the dynamics of benthic coralligenous outcrops in the NW Mediterranean Sea using data acquired before (2006-2008) and after the impact (2009-2010) at four different sites. Storms of comparable severity have been documented to occur occasionally within periods of 50 years in the Mediterranean Sea. We assessed the effects derived from the storm comparing changes in benthic community composition at sites exposed to and sheltered from this extreme event. The sites analyzed showed different damage from severe to negligible. The most exposed and impacted site experienced a major shift immediately after the storm, represented by changes in the species richness and beta diversity of benthic species. This site also showed higher compositional variability immediately after the storm and over the following year. The loss of cover of benthic species resulted between 22% and 58%. The damage across these species (e.g. calcareous algae, sponges, anthozoans, bryozoans, tunicates) was uneven, and those with fragile forms were the most impacted, showing cover losses up to 50 to 100%. Interestingly, small patches survived after the storm and began to grow slightly during the following year. In contrast, sheltered sites showed no significant changes in all the studied parameters, indicating no variations due to the storm. This study provides new insights into the responses to large and rare extreme events of Mediterranean communities with low dynamics and long-lived species, which are among the most threatened by the effects of global change.

There is still limited understanding of the processes underlying benthic species dynamics in marine coastal habitats, which are of disproportionate importance in terms of productivity and biodiversity. The life-history traits of long-lived benthic species in these habitats are particularly poorly documented. In this study, we assessed decadal patterns of population dynamics for ten sponge and anthozoan species that play key structural roles in coralligenous outcrops (∼25 m depth) in two areas of the NW Mediterranean Sea. This study was based on examination of a unique long-term photographic series, which allowed analysis of population dynamics over extensive spatial and time spans for the very first time. Specifically, 671 individuals were censused annually over periods of 25-, 15-, and 5-years. This long-term study quantitatively revealed a common life-history pattern among the ten studied species, despite the fact they present different growth forms. Low mortality rates (3.4% yr(-1) for all species combined) and infrequent recruitment events (mean value of 3.1±0.5 SE recruits yr(-1)) provided only a very small fraction of the new colonies required to maintain population sizes. Overall, annual mortality and recruitment rates did not differ significantly among years; however, some species displayed important mortality events and recruitment pulses, indicating variability among species. Based on the growth rates of these 10 species, we projected their longevity and, obtained a mean estimated age of 25-200 years. Finally, the low to moderate turnover rates (mean value 0.80% yr(-1)) observed among the coralligenous species were in agreement with their low dynamics and persistence. These results offer solid baseline data and reveal that these habitats are among the most vulnerable to the current increases of anthropogenic disturbances.

Increasing anthropogenic pressures urge enhanced knowledge and understanding of the current state of marine biodiversity. This baseline information is pivotal to explore present trends, detect future modifications and propose adequate management actions for marine ecosystems. Coralligenous outcrops are a highly diverse and structurally complex deep-water habitat faced with major threats in the Mediterranean Sea. Despite its ecological, aesthetic and economic value, coralligenous biodiversity patterns are still poorly understood. There is currently no single sampling method that has been demonstrated to be sufficiently representative to ensure adequate community assessment and monitoring in this habitat. Therefore, we propose a rapid non-destructive protocol for biodiversity assessment and monitoring of coralligenous outcrops providing good estimates of its structure and species composition, based on photographic sampling and the determination of presence/absence of macrobenthic species. We used an extensive photographic survey, covering several spatial scales (100s of m to 100s of km) within the NW Mediterranean and including 2 different coralligenous assemblages: Paramuricea clavata (PCA) and Corallium rubrum assemblage (CRA). This approach allowed us to determine the minimal sampling area for each assemblage (5000 cm(2) for PCA and 2500 cm(2) for CRA). In addition, we conclude that 3 replicates provide an optimal sampling effort in order to maximize the species number and to assess the main biodiversity patterns of studied assemblages in variability studies requiring replicates. We contend that the proposed sampling approach provides a valuable tool for management and conservation planning, monitoring and research programs focused on coralligenous outcrops, potentially also applicable in other benthic ecosystems.