Search

The Bay of Biscay is a structurally complex region, exhibiting high biodiversity and productivity and hosting a wide variety of benthic habitats. Unfortunately, current scientific knowledge of deep-sea ecosystems is limited. Our investigation provides an updated vision of the existing knowledge on key aspects of the deep-sea ecosystem and identifies research priorities for the definition of a research roadmap in support of sustainable management, including the protection and conservation of deep-sea ecosystem of the Bay of Biscay. To achieve this, firstly a revision of projects, surveys and studies conducted in the region, was carried out resulting in the identification of 62 publicly available scientific documents. Secondly, an online survey was carried out, receiving 51 responses from 24 research institutions in 9 countries. Finally, a workshop was attended by 39 scientists to identify and discuss ways forward on deep-sea research in the Bay of Biscay. Results indicate that knowledge of benthic habitats, and vulnerable and sensitive habitats/species is good or very good for 45% of the respondents, while limited knowledge was reported for deep pelagic habitats. Almost 75% of the scientists agreed that deep-sea processes affect shallower areas. Funding (71%) and research vessel availability (57%) were considered the most constraining aspects limiting deep-sea research. More than 50% of the scientists perceived a short- or medium-term threat from human activities and pressures, while over than 40% of the respondents considered that there are no, or limited, data available to assess the environmental status. Regarding climate change, 55% of scientists partially or fully agreed with the existence of evidence of climate change effects, but 47% of them totally or partially considered that climate change monitoring is insufficient to assess eventual changes and effects. Most respondents (63%) considered that deep-sea ecosystems are not properly represented in the current Marine Protected Areas network. In terms of future needs, the development of monitoring strategies to reduce costs and guarantee an optimal design, data sharing and an increase in transnational collaboration are most cited. Finally, a proposal for a roadmap to fill in knowledge gaps for a better understating of the ecosystem processes of the deep sea of the Bay of Biscay is delivered. • Scientific knowledge of the deep-sea ecosystem in the Bay of Biscay is limited. • An updated vision of current knowledge on key aspects of the deep-sea ecosystem is provided. • Research priorities for the definition of a research roadmap are identified. • Intended to support sustainable management, protection and conservation. [ABSTRACT FROM AUTHOR]

We studied the structure of digestive system of deep-sea torquaratorid Quatuoralisia malakhovi including the food-obtaining apparatus, microanatomy of all regions of digestive tract, and fine structure of various regions of the gut. The mouth of Q. malakhovi is surrounded by two symmetrical triangular lateral collar lips and one midventral collar lip, which may retract into the mouth. The ventral ciliary grooves run along the anterior-ventral edges of lateral lips and lead into the internal canals of the lips. The pharyngeal cavity is divided by left and right parabranchial ridges into the median pharyngeal zone with gill bars and two symmetrical peripheral canals, which fuse behind the site of genesis of new gill bars. The gill pharynx is followed by the hepatic region with metameric hepatic sacculations comprising cells with numerous large phagosomes indicating active intracellular digestion. The intestine is filled with undigested food residues including detritus flakes and remnants of various organisms. The intestine content was examined using SEM and histological studies. We analyzed the ratio of organic and mineral components of the bottom sediment from the habitat of Q. malakhovi , and the stable isotope composition of carbon and nitrogen in the intestine content, in the tissues, and in the sediment from the habitat of the studied acorn worm. Using the obtained data and the photographs and videotapes in situ , we have proposed a hypothesis explaining the feeding mechanism of Q. malakhovi. The width of the ventral ciliary groove of the lateral collar lips (100–200 μm) regulates the maximum size of particles that enter the pharynx of the animal. The minimum size of the sediment particles selected by Q. malakhovi is determined by the width of the gill pores and is 1–3 μm. The selected sediment particles move through the peripheral pharyngeal canals to the hepatic region, where the digestion of the food is carried out. In the posthepatic intestine, weight of the gut contents might serve as an anchor that holds the heavily watered jelly-like torquaratorid body at the bottom during the feeding. • Food-obtaining apparatus and digestive system of deep-sea acorn worm Quatuoralisia malakhovi from the Bering Sea. • Stable isotope composition of carbon and nitrogen in gut content, tissues, and sediment from habitat of studied acorn worm. • Hypothesis explaining the feeding mechanism of Quatuoralisia malakhovi. [ABSTRACT FROM AUTHOR]

Although cold-water coral (CWC) biology, physiology, and connectivity, have been extensively studied, few studies have so far focused on their reproductive biology. The reproductive biology of colonies of the reef-building Lophelia pertusa (Linnaeus 1758), now synonymised as Desmophyllum pertusum , and Madrepora oculata (Linnaeus 1758) from the Mediterranean Sea, an area particularly exposed to the effects of anthropogenic pressures, was investigated for the first time using histological techniques. Samples were collected from the Lacaze-Duthiers canyon in the Gulf of Lion, northwestern Mediterranean Sea, where the corals are living at 13 °C, close to their upper limit of thermal tolerance. The gametogenic cycle suggests a seasonal spawning of D. pertusum in autumn to early winter, similarly to population from the Gulf of Mexico. This period corresponds to the formation of storm-induced deep-sea water plumes, likely acting as a time giver for coral spawning and facilitates larval dispersal. Madrepora oculata shows continuous reproduction as already identified in eastern and western North Atlantic, with reproductive features of a species less opportunistic than D. pertusum , consistent with its other biological characteristics. This difference between the two species is of paramount importance to define strategies of conservation. • First data on the reproduction of two cold-water corals in the Mediterranean Sea. • Potential spawning date in autumn and/or early winter for Desmophyllum pertusum. • Role of deep-sea currents in timing of spawning for this species. • Madrepora oculata harbor different strategy, with a continuous reproduction. [ABSTRACT FROM AUTHOR]

Reproduction of the brooding feather star Phrixometra nutrix was studied from the deep southwestern Atlantic Ocean. Samples were collected using dredge trawlers and fishing nets on board the B/O Puerto Deseado, between 91 and 512 m depth. Reproductive biology was studied using modern optical techniques including histology and scanning electron microscopy. Here we present the first record of genital papillae for class Crinoidea. Genital papillae have been reported in all extant echinoderm classes except for Crinoidea. In addition, a high proportion (16%) of hermaphroditic specimens was found in the analyzed samples. Finally, cystidean and pentacrinoid stages were found inside the marsupium of Phrixometra nutrix. It is expected that this work will enable further discoveries of crinoid reproductive biology considering the ecological and phylogenetic importance of brooding crinoids. [ABSTRACT FROM AUTHOR]

Deep-sea habitats are home for a variety of yet poorly known fish species, some of which display specialized life strategies, as is the case of Bythitidae and Zoarcidae. With the purpose of elucidating biological and ecological aspects of representatives of these families in NW Mediterranean waters, a large dataset based on 599 specimens of Cataetyx alleni , 30 C. laticeps and 284 Melanostigma atlanticum captured during the last 30 years within the framework of different research projects was used to address their geographical and bathymetric distribution, population structure, reproduction, trophic ecology, parasitism and enzymatic markers in the Balearic basin. Present outcomes revealed a patchy distribution mostly for M. atlanticum , possibly related to aggregation during reproduction and to the association with specific sediments. For the three species, higher densities occurred in the mainland vs. the insular margin, and a diminishing trend in estimated densities over the last decades was observed for C. alleni and M. atlanticum likely linked to climatic oscillations. Trophic data indicated that the two Cataetyx species inhabit the water-sediment interface and mainly feed on suprabenthic prey, while M. atlanticum inhabits the water column near the bottom preying on pelagic organisms and moving towards the seabed during reproduction. These results were supported by the parasitological assessment, which revealed that parasite communities were moderately diverse and abundant for Cataetyx spp. while being highly depauperate for M. atlanticum. Present outcomes from the Mediterranean Sea confirmed reproduction of C. alleni during autumn-winter and of M. atlanticum during autumn. Spawning of the former species may occur in winter-spring, as suggested by the finding, by the first time, of two females captured in March with fully-developed embryos inside. Levels of enzymatic markers quantified in muscle were provided for C. alleni and M. atlanticum for the first time. The special interactions found between the distribution and biology of Bythitidae and Zoarcidae and the sedimentary bottoms that they inhabit indicates that such conventional habitats are more heterogeneous than it is generally assumed and deserve higher attention for future protection. • Specialized deep-sea Zoarcidae and Bythitidae show particular life histories. • Geographical heterogeneity occurred at various scales for Zoarcidae and Bythitidae. • Deep sedimentary grounds may not be as homogeneous as previously thought. • Diet, parasites and enzymatic activities proved useful indicators of habitat use. [ABSTRACT FROM AUTHOR]