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Ocean acidification (OA) could become a serious threat for theAntarctic marine ecosystem over coming years, as the solubility of atmosphericCO2 and CaCO3 minerals increases at lower temperatures.We evaluated the effect of OA on the stress response of the limpet Nacella concinna by measuring geneexpression levels. The experiment was performed with the two ecotypes (Littoraland Sublittoral) of the species during 54 days (IPCC 2019 scenario RCP8.5; control, ~375 ppm;low-pH treatment, ~923 ppm). Exposure to low-pH treatment during 15 days triggered thedown-regulation of two heat-shock protein genes (HSP70A, HSP70B) only in sublittoralindividuals. Little variation in the relative expression values of all genes in both ecotypes was observed probably,due to a historicalexposure to the substantial daily naturalpH fluctuations recorded in the study area during the experiment. This study provides relevant baseline data for future OAexperiments on coastal species in Antarctica.

Censos visuales con escafandra autónoma, en arrecifes artificiales y en roca natural, en los que se cuentan y miden los ejemplares de langosta asentados. Se han fondeado 36 colectores artificiales a 25 m de profundidad, en tres zonas: Favàritx, La Mola e Illa de l’Aire. Los colectores constan de una base de hormigón, de un peso de 50 kg, sobre la que se fijan 3 pisos de 4 ladrillos cada uno. Los censos en roca natural se llevan a cabo en dos zonas: Cap de Cavalleria e Illa de l’Aire.

The Mediterranean Sea is particularly sensitive to climate oscillations and represents a key location to study past climatic and oceanographic changes. One valuable source of paleoceanographic information is through molecular biomarkers in deep sea sediments. This approach has been applied in a number of studies in this basin, but only covering the most recent glacial/interglacial cycles. Here we present, for the first time in the Mediterranean Sea, a molecular biomarker record from the Strait of Sicily that covers the last million years until the present, almost continuously. We present data on alkenone derived urn:x-wiley:25724517:media:palo21102:palo21102-math-0001 index sea surface temperatures (SST) and provide insights on the evolution of the phytoplankton community composition and terrestrial inputs through the analysis of the concentrations of alkenones, brassicasterol and long-chain alcohols. The urn:x-wiley:25724517:media:palo21102:palo21102-math-0002-SST record followed a climatic evolution modulated by glacial/interglacial cycles with a marked increase in the 100 kyr-amplitude of the glacial cycles at ∼430 ka, coincident with the Mid-Brunhes transition. In addition, SSTs were consistently higher compared with other records in the western Mediterranean, indicative of the progressive warming that surface waters experience along their transit from the Strait of Gibraltar to the Central Mediterranean. Regarding the concentrations of alkenones and brassicasterol, they displayed distinct alternate peaks, some of them coeval with the deposition of sapropels. This suggests that different environmental and oceanographic conditions characterized each sapropel which, together with changes in terrestrial inputs and the degree of oligotrophy, induced the alternate proliferation of coccolithophores and diatoms.

• Cold-water corals (CWC) form complex 3-D structures that are biodiversity hotspots. However, the knowledge about their ecophysiological response to global change stressors (i.e. warming, acidification, decrease of dissolved oxygen concentration) is still very limited, as well as their possible interactions with local stressors such as the impacts from mining and fishing activities. • Three long-term, multi stressor experiments will explore the combined impact of several environmental and local stressors based on the IPCC projections on different CWC species across the North Atlantic. • Further experiments will include the addition of particles from mining or sediment from trawling activities to all treatments after long-term experiments finish to study the potential physical damage and ecotoxicological effects. • The results from these studies will increase our knowledge on the potential consequences of global change and local stressors and their possible interactions on CWC species and ecosystems that they form. • The results will contribute to support science-based marine spatial planning for the North Atlantic.

We report on the presence of the pearl oyster Pinctada imbricata radiata (Leach, 1814) in two sheltered areas of the island of Minorca, Maó Harbour and Fornells Bay. Shallow depths (0-1.5 m) have been surveyed by free diving. Living oysters have been found in only 4 of the 22 surveyed sites, with densities ranging between 2.12 oysters·100 m-2 and 0.12 oysters·100 m-2, which indicates that the species is currently non-invasive. Average shell length in the observed specimens was 60.2 ± 13.9 mm (mean ± SD). According to the size of the oldest specimen found and the reports of a shellfish farmer from the Maó Harbour, date of introduction should be around year 2016. Since the introduction is recent, attention must be paid to the future spread of this species, regarding its high invasive capacity in several Eastern Mediterranean localities.

The Mediterranean Sea has certain characteristics that make it especially sensitive and vulnerable to changes in atmospheric CO2 and its gradual acidification. Some of the organisms that may be the first to be threatened by this impact are the cold-water corals. The few studies carried out up to date with these organisms by simulating in aquarium the acidified conditions expected for the year 2100 revealed a high variability between and within species. This chapter shows this highly variable response in the calcification of four of the most abundant cold-water coral species in the Mediterranean to low-pH conditions and their potential ecological implications.

Sea-ice and coastal glacier loss in the Western Antarctic Peninsula open new ice-free areas. They allowing primary production and providing new seabed for colonisation, both acting as a negative feedback of climate change. However, the injection of sediment-laden runoff from the melting of land-terminating glaciers may reduce this feedback. Changes in particulate matter will affect nutrition and excretion (faeces stoichiometry and properties) of suspension feeders, reshaping coastal carbon dynamics and pelagic-benthic coupling. Absorption efficiency and biodeposition of Euphausia superba and Cnemidocarpa verrucosa were quantified for different food treatments and varying sediment concentrations. Both species showed high overall absorption efficiency for free-sediment diets, but were negatively affected by sediment addition. High sediment conditions increased krill biodeposition, while it decreased in ascidians. Energy balance estimation indicated high carbon sink potential in ascidians, but it is modulated by food characteristics and negatively affected by sediment inputs in the water column.

The external morphology of sponges is characterized by high plasticity, generally considered to be shaped by environmental factors, and modulated through complex morphogenetic pathways. This work shows for the first time that explants of the Atlanto-Mediterranean demosponge Aplysina aerophoba reared in aquaria under different pH and temperature conditions produce reproductive buds with a phenotype determined by the donor individual. These results suggest, therefore, that genotype may be an important factor controlling different phenotypes in this species.

Presentation given at the 3rd ATLAS General Assembly, April 2018. Vulnerable Marine Ecosystems and biological features of the northeastern sector of the Gulf of Cádiz in relation to geological structures, oceanographic processes and fishing activity: A further contribution towards a potential “Gulf of Cádiz” EBSA. The Gulf of Cádiz (GoC) represents an area of socioeconomic and scientific importance for oceanographic, geological and biological processes. An interesting feature of the GoC is the presence of a large amount of mud volcanoes (MVs) and diapirs that display different seepage, seabed types, oceanographic settings and biological communities. Detailed exploration of some MVs is still needed for detecting Vulnerable Marine ecosystems (VMEs) that seem to be rare in other areas of the GoC, improving the current knowledge on its biodiversity and ecological attributes. During different expeditions (MEDWAVES-ATLAS, INDEMARES-CHICA 0610 & 0412 and ISUNEPCA 0616) carried out in different years, biological samples and videos were obtained in Gazul MV (Spanish Margin of the GoC). The study of those samples and videos has revealed the presence of several ecologically important VMEs (e.g. 3 species of reef framework-forming corals, coral gardens including solitary scleractinians, gorgonians and antipatharians, as well as deep-sea sponge aggregations and chemosynthesis-related structures) and a large number of species occurring in this MV, including new records for the European margin, threatened species and non-previously described species. The combination of different environmental and anthropogenic factors allowed the present-day persistence of these VMEs in the GoC. Some of Gazul MV biological and ecological attributes fit several criteria of the Convention on Biological Diversity for EBSA description (e.g. 1,3,4,6) that, together with those of other areas of the GoC, may contribute to the future potential nomination

The ubiquitous, biogenic trace gas dimethylsulfide (DMS) represents the largest natural source of atmospheric sulfur. Given DMS involvement in cloud formation and climate, understanding and parameterizing the oceanic DMS source and cycling processes is a necessary challenge. We report DMS cycling rates from microzooplankton dilution grazing experiments conducted monthly during 1 year in coastal northwestern Mediterranean waters. Concentrations of DMS, its algal precursor dimethylsulfoniopropionate (DMSPt) and chlorophyll a (Chla) ranged 0.9–11 nmol L−1, 10–71 nmol L−1, and 0.2–1.5 µg L−1, respectively. By comparing the growth and stock production rates of the DMSP-producing algae to those of total phytoplankton, we estimated that 3 ± 4% (range 0.4–12%) of the carbon primary production was invested in DMSP biosynthesis. Microzooplankton grazing rates on DMSP-producing phytoplankton (0.46–1.45 day−1) were generally higher than those on the bulk assemblage (0.08–0.99 day−1), except in midsummer months. This could have been due to the smaller size of most DMSP producers. There was no indication of micrograzer selection against DMSP-containing phytoplankton, since they were not grazed at lower rates than the bulk phytoplankton assemblage. A proportion of 6–20% of the grazed DMSP was converted into DMS, and this grazing-derived production accounted for 32–96% of dark gross DMS production by the total community. Bacteria consumed daily ≤ 14–100% of the gross DMS production, which resulted in biological DMS turnover times of 1 to ≥ 10 days. Throughout the year, grazing-mediated DMS production explained 73% of the variance in the DMS concentration, implying that microzooplankton grazing plays a major role in controlling DMS concentration in surface waters across a broad range of environmental and productivity conditions in the Mediterranean Sea. These findings should help improve the representation of herbivore grazing in prognostic models to predict the distribution and dyn

In September-October 2016 the oceanographic cruise MEDWAVES was conducted (in the frame of the ATLAS project H2020), in order to follow the path of the Mediterranean Outflow Water (MOW) in the Atlantic from Cádiz to the Azores. MEDWAVES aimed to investigate the influence of the MOW in the community composition of benthic assemblages in several Atlantic geomorphological features. One of the targeted areas was the Ormonde seamount in the Atlantic Ocean, 160 nautical miles SW off Cape St. Vincent, Portugal. This seamount, together with the Gettysburg seamount, is part of a volcanic ridge named Gorringe that rises from 5,000 m to less than 80m depth, respectively representing the abyssal plain until the photic zone. Its panoply of marine life and environments increased the demand for conservation measures. Consequently, Gorringe bank is currently protected by the Habitats Directive and part of Natura 2000 network since 2015. Other protective measures include the intention to designate the Gorringe Bank,as part of the seamount complex Madeira-Tore, as new Portuguese MPA of large dimensions delimited in deep oceanic areas, under the Marine Strategy Framework Directive implementation. Given its ecological importance and location through the pass of the MOW, the Ormonde seamount was selected as one of the main target areas during the MEDWAVES cruise. Six ROV dives were conducted with the Remotely Operated Vehicle (ROV) “Liropus” (IEO), covering the Northeast and North flanks of the seamount between 1,950 and 600 meters depth. As expected, the depth gradient revealed different benthic communities in the distinct depth zones. Ormonde seems to be a flourishing area for deep-sea sponges (e.g. Asconema sp.), present in high densities along with high species diversity. Scleractinian corals (e.g. Solenosmillia variabilis) as well as gorgonians (e.g. Viminella sp., Corallium tricolor) and black corals (e.g. Stichopathes sp.) were also present in the area displaying varying density

The MEDWAVES (MEDiterranean out flow WAter and Vulnerable EcosystemS) cruise targeted areas under the potential influence of the MOW within the Mediterranean and Atlantic realms. These include seamounts where Cold-water corals (CWCs) have been reported but that are still poorly known, and which may act as essential “stepping stones” connecting fauna of seamounts in the Mediterranean with those of the continental shelf of Portugal, the Azores and the Mid-Atlantic Ridge. During MEDWAVES sampling has been conducted in two of the case studies of ATLAS: Case study 7 (Gulf of Cádiz-Strait of Gibraltar-Alboran Sea) and Case study 8 (Azores). The initially targeted areas in the Atlantic were: the Gazul Mud volcano, in the Gulf of Cádiz (GoC) area, included in the case study 7, and the Atlantic seamounts Ormonde (Portuguese shelf) and Formigas (by Azores), both part of the case study 8. In the Mediterranean the targeted areas were The Guadiaro submarine canyon and the Seco de los Olivos (also known as Chella Bank) seamount. Unfortunately it was not possible to sample in Guadiaro due to time constraints originated by adverse meteorological conditions which obligate us to reduce the time at sea focusing only in 4 of the 5 initially planned areas. MEDWAVES was structured in two legs; the first leg took place from the 21st September (departure from Cádiz harbour in Spain) to the 13th October 2016 (arrival in Ponta Delgada, São Miguel, Azores, Portugal took place the 8th of October due to the meteorological conditions that obligated to conclude the first leg earlier as planned). during the Leg 1 sampling was carried out in Gazul, Ormonde and Formigas. The second leg started the 14th October (departure from Ponta Delgada) and finished the 26th October (arrival in Málaga harbour, Spain). MEDWAVES had a total of 30 effective sampling days, being 6 days not operative due to the adverse meteorological conditions experienced during the first leg which forced us to stay in Ponta Delgada

Cold-water coral (CWC) reefs constitute one of the most complex deep-sea habitats harboring a vast diversity of associated species. Like other tropical or temperate framework builders, these systems are facing an uncertain future due to several threats, such as global warming and ocean acidification. In the case of Mediterranean CWC communities, the effect may be exacerbated due to the greater capacity of these waters to absorb atmospheric CO2 compared to the global ocean. Calcification in these organisms is an energy-demanding process, and it is expected that energy requirements will be greater as seawater pH and the availability of carbonate ions decrease. Therefore, studies assessing the effect of a pH decrease in skeletal growth, and metabolic balance are critical to fully understand the potential responses of these organisms under a changing scenario. In this context, the present work aims to investigate the medium- to long-term effect of a low pH scenario on calcification and the biochemical composition of two CWCs from the Mediterranean, Dendrophyllia cornigera and Desmophyllum dianthus. After 314 d of exposure to acidified conditions, a significant decrease of 70 % was observed in Desmophyllum dianthus skeletal growth rate, while Dendrophyllia cornigera showed no differences between treatments. Instead, only subtle differences between treatments were observed in the organic matter amount, lipid content, skeletal microdensity, or porosity in both species, although due to the high variability of the results, these differences were not statistically significant. Our results also confirmed a heterogeneous effect of low pH on the skeletal growth rate of the organisms depending on their initial weight, suggesting that those specimens with high calcification rates may be the most susceptible to the negative effects of acidification.

Deep-water ecosystems are characterized by relatively low carbonate concentration values and, due to ocean acidification (OA), these habitats might be among the first to be exposed to undersaturated conditions in the forthcoming years. However, until now, very few studies have been conducted to test how cold-water coral (CWC) species react to such changes in the seawater chemistry. The present work aims to investigate the mid-term effect of decreased pH on calcification of the two branching CWC species most widely distributed in the Mediterranean, Lophelia pertusa and Madrepora oculata. No significant effects were observed in the skeletal growth rate, microdensity and porosity of both species after 6 months of exposure. However, while the calcification rate of M. oculata was similar for all colony fragments, a heterogeneous skeletal growth pattern was observed in L. pertusa, the younger nubbins showing higher growth rates than the older ones. A higher energy demand is expected in these young, fast-growing fragments and, therefore, a reduction in calcification might be noticed earlier during long-term exposure to acidified conditions.