The benthic communities of the Cap de Creus canyon

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Ocean Circulation over North Atlantic underwater features in the path of the Mediterranean Outflow Water: Ormonde and Formigas seamounts, and the Gazul mud volcano

Seamounts constitute an obstacle to the ocean circulation, modifying it. As a result, a variety of hydrodynamical processes and phenomena may take place over seamounts, among others, flow intensification, current deflection, upwelling, Taylor caps, and internal waves. These oceanographic effects may turn seamounts into very productive ecosystems with high species diversity, and in some cases, are densely populated by benthic organisms, such corals, gorgonians, and sponges. In this study, we describe the oceanographic conditions over seamounts and other underwater features in the path of the Mediterranean Outflow Water (MOW), where populations of benthic suspensions feeders have been observed. Using CTD, LADPC and biochemical measurements carried out in the Ormonde and Formigas seamounts and the Gazul mud volcano (Northeast Atlantic), we show that Taylor caps were not observed in any of the sampled features. However, we point out that the relatively high values of the Brunt–Väisälä frequency in the MOW halocline, in conjunction with the slope of the seamount flanks, set up conditions for the breakout of internal waves and amplification of the currents. This may enhance the vertical mixing, resuspending the organic material deposited on the seafloor and, therefore, increasing the food availability for the communities dominated by benthic suspension feeders. Thus, we hypothesize that internal waves could be improving the conditions for benthic suspension feeders to grow on the slope of seamounts.En prens

Seafloor litter sorting in different domains of Cap de Creus continental shelf and submarine canyon (NW Mediterranean Sea). Marine Pollution Bulletin

We analyzed litter occurrence in 68 underwater video transects performed on the middle/outer continental shelf and submarine canyon off Cap de Creus (NW Mediterranean), an area recently declared Site of Community Importance (SCI). Low densities of urban litter were registered on the shelf (7.2 items ha−1), increasing in abundance towards the deepest part of the submarine canyon, with 188 items ha−1 below 1000 m depth. We hypothesize that the strong bottom currents that recurrently affect this area efficiently move litter objects from the shelf towards the deep. Of all litter items, approximately 50% had a fishing-related origin, mostly longlines entangled on rocks in the canyon head and discarded trawl nets in deeper areas. Over 10% of cold-water colonies observed had longlines entangled, indicating the harmful effects of such practices over benthic habitats. These results should be considered when designing mitigation measures to reduce litter pollution in Cap de Creus SC

Exploració amb submarí al cap de Creus: una activitat cabdal per a la recerca científica i l’educació marina. Annals de l’Institut d’Estudis Empordanesos (AIEE)

The year 2019 marks the 200th anniversary of the birth of Narcís Monturiol, an engineer andinventor behind the development of the first self-propelled manned submersible:Ictineu. Sincethen, submarines have played an important role in marine scientific research. In this work, wewant to give credit to this inventor by sharing the experience of the authors both in the field ofscientific research and education based on the studies performed by the submarineJAGOoverthe seabed of Cap de Creus.L’any 2019 es commemoraren els 200 anys del naixement de Narcís Monturiol, enginyer i inventor,en tant que creador, del primer submarí tripulat de propulsió autònoma: l’Ictineu. Des d’ençà, elssubmarins tingueren i estan tenint un rol cada vegada més rellevant en la recerca científicamarina. En aquest treball volem fer un reconeixement a l’inventor, tot explicant l’experiència delsautors en el camp de la recerca científica i de l’educació a partir dels estudisfets als fons marinsdel cap de Creus amb el submaríJAG

Differential response of two Mediterranean cold-water coral species to ocean acidification

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.Versión del editor

Seafloor litter sorting in different domains of Cap de Creus continental shelf and submarine canyon (NW Mediterranean Sea). Marine Pollution Bulletin

We analyzed litter occurrence in 68 underwater video transects performed on the middle/outer continental shelf and submarine canyon off Cap de Creus (NW Mediterranean), an area recently declared Site of Community Importance (SCI). Low densities of urban litter were registered on the shelf (7.2 items ha−1), increasing in abundance towards the deepest part of the submarine canyon, with 188 items ha−1 below 1000 m depth. We hypothesize that the strong bottom currents that recurrently affect this area efficiently move litter objects from the shelf towards the deep. Of all litter items, approximately 50% had a fishing-related origin, mostly longlines entangled on rocks in the canyon head and discarded trawl nets in deeper areas. Over 10% of cold-water colonies observed had longlines entangled, indicating the harmful effects of such practices over benthic habitats. These results should be considered when designing mitigation measures to reduce litter pollution in Cap de Creus SC

Community characterization of two Atlantic seamounts. First steps into addressing the influence of the Mediterranean Outflow Water (MOW)

An important goal of the ATLAS project is to improve our understanding of the ocean transport pathways and connectivity of water masses at basin and regional scales relevant for benthic marine ecosystems. The MEDWAVES cruise (21st September-26th October, 2016) aimed to better understand the characteristics of the Mediterranean Outflow Water (MOW) and its potential influence in the occurrence, composition and distribution of deep-sea benthic communities from the Mediterranean to the Azores. Among the geomorphological features targeted in MEDWAVES, two Atlantic seamounts were included: Ormonde (Portuguese continental shelf) and Formigas Bank (close to the Azores Archipelago). During MEDWAVES, the geomorphology and oceanography of the areas was characterised. Further submarine video transects were conducted by means of a Remotely Operated Vehicle (ROV). The transects were performed in the different flanks of the seamounts aiming to characterise the benthic communities considering different geographical orientations and the influence of water masses. The characteristics of the video transects allowed to perform a methodology for video analysis based on still images. The images were taken directly from the video recordings at regular length intervals based on the positioning of the ROV, generating a set of images that allowed for comparisons between different areas. To make such comparisons robust, a thorough filtering was carried out based on the position of the parallel laser beams on screen. Only images that had a similar area observed were selected, in which all megabenthic organisms are currently being identified to the lowest possible taxon. It is expected that this protocol can be used for the video processing in all benthic communities surveyed during MEDWAVES. Some examples of coral garden habitats and sponge grounds identified in these areas are presented. This proposed methodology and preliminary results represent the first steps in a larger study that aims to: (1) characterise the megabenthic communities, the species diversity and their distribution in Ormonde Seamount and Formigas Bank, (2) evaluate the influence of substrate type, flank orientation and the characteristics of the water masses in the patterns observed, and (3) do a comparison between both seamounts to determine differences in their biological composition