Advancing fishery-independent stock assessments for the Norway lobster (Nephrops norvegicus) with new monitoring technologies

The Norway lobster, Nephrops norvegicus, supports a key European fishery. Stock assessments for this species are mostly based on trawling and UnderWater TeleVision (UWTV) surveys. However, N. norvegicus are burrowing organisms and these survey methods are unable to sample or observe individuals in their burrows. To account for this, UWTV surveys generally assume that "1 burrow system = 1 animal", due to the territorial behavior of N. norvegicus. Nevertheless, this assumption still requires in-situ validation. Here, we outline how to improve the accuracy of current stock assessments for N. norvegicus with novel ecological monitoring technologies, including: robotic fixed and mobile camera-platforms, telemetry, environmental DNA (eDNA), and Artificial Intelligence (AI). First, we outline the present status and threat for overexploitation in N. norvegicus stocks. Then, we discuss how the burrowing behavior of N. norvegicus biases current stock assessment methods. We propose that state-of-the-art stationary and mobile robotic platforms endowed with innovative sensors and complemented with AI tools could be used to count both animals and burrows systems in-situ, as well as to provide key insights into burrowing behavior. Next, we illustrate how multiparametric monitoring can be incorporated into assessments of physiology and burrowing behavior. Finally, we develop a flowchart for the appropriate treatment of multiparametric biological and environmental data required to improve current stock assessment methods

New records of rare species in the Mediterranean Sea (October 2020)

This Collective Article presents information about 21 taxa belonging to seven Phyla (one Ochrophyta, one Porifera, three Cnidaria, two Arthropoda, three Mollusca, one Echinodermata, and ten Chordata) and extending from the western Mediterranean Sea to the Levantine Sea. The new records were reported from nine countries as follows: Spain: first records of three deep-sea species from the Blanes Canyon along the Catalan margin, namely the gorgonian Placogorgia coronata, the bivalve Acesta excavata, and the Azores rockling Gaidropsarus granti; Italy: first record of the mesopsammic nudibranch Embletonia pulchra from Ligurian shallow-waters; first record of the deep-sea carnivorous sponge Lycopodina hypogea from the north-central Tyrrhenian Sea, living in dense clusters over dead black corals; new records of the Portuguese man o’ war Physalia physalis from Sardinian and Sicilian waters; first Italian record of the large asteroid Coronaster briareus from the Ionian Sea; first record of the white grouper Epinephelus aeneus in the northernmost point of the Adriatic Sea; Croatia: first record of the gastropod Haliotis mykonosensis for the Adriatic Sea; Malta: new sightings of Physalia physalis from Maltese waters; Libya: first record of the sand crab Albunea carabus from two localities along the Libyan coast; Greece: first records of the deep-sea black coral Parantipathes larix from the eastern Mediterranean Sea; first verified record of the agujon needlefish Tylosurus imperialis in the Hellenic Ionian Sea; first confirmed record of the brown algae Treptacantha squarrosa in the eastern Mediterranean Sea; new records of three deep-sea fish species from the Aegean Sea, namely the bluntnose sixgill shark Hexanchus griseus, the Atlantic pomfret Brama brama, and the rudderfish Centrolophus niger; new record of the tripletail Lobotes surinamensis from Lesvos Island; new record of the shrimp Brachycarpus biunguiculatus from the gut content of the non-indigenous lionfish Pterois miles; Turkey: new record of the imperi- al blackfish Schedophilus ovalis from Turkish waters; Lebanon: first record of the slender sunfish Ranzania laevis, stranded along the Lebanese coast; Israel: new record, after about 60 years from the last catch, of the spotted dragonet Callionymus maculatus.peer-reviewe

Bathyal Megabenthic Diveristy on the Ajaccio and Valinco Submarine Canyons (West Corsican Margin)

Deep-sea environments in the Mediterranean Sea have been widely degraded over the past decades and thus there is an urgent need to implement protection measures. Within European Union’s Mediterranean waters vast extensions of the deep-sea ecologically relevant ecosystems have been protected by integrating them to the Natura 2000 network. Inside the French Exclusive Economic Zone, this network is currently expanding to offshore areas, beyond 12 nautical miles. This study is focused on the megabenthic biodiversity on a volcanic promontory on the south flank of the Ajaccio submarine canyon and a wall of the Valinco Canyon (SW Corsica), between 1690 and 2250 m depth. We addressed differences in organism abundance and megabenthic assemblage composition between substrates and characterized lebensspuren and benthic litter in these two sites. By means of a photogrammetric analysis, four megabenthic assemblages segregated by substrate were identified. Hard substrate assemblages were characterized by the presence of sponges, the squat lobster Munida tenuimana, polychaetes and gastropods while soft sediment assemblages were characterized by the elpidiid holothurian Penilpidia ludwigi and an unidentified sabellid Lebensspuren likely derived from the activity of epibenthic, infaunal and bathypelagic organisms. Litter was not abundant at these offshore sites. Litter at the Valinco site, had both a land-based and marine origin while the one at the Ajaccio site had a marine origin. This study provides new understanding on the ecology and diversity of Mediterranean deep-sea environments in the 2000 m bathymetric zone, stressing the persistent knowledge gap surrounding deep-sea escarpments in the basin

Rediscovery of Cereopsis studeri Koch, 1891, a forgotten Mediterranean soft coral species, and its inclusion in the genus Nidalia Gray, 1835 (Octocorallia, Alcyonacea, Nidaliidae)

Cereopsis studeri was described by G. von Koch in 1891 with material from Naples. However, it was subsequently synonymized, erroneously identified, and overlooked in subsequent soft coral literature of the twentieth century. After the original description, this species was not recorded or correctly described for 120 years. The study of newly collected material from the North Western Mediterranean permits the re-description of this forgotten species and its assignation to the genus Nidalia in the family Nidaliidae. The main features of Nidalia studeri com. nov. are: colony torch-like, a capitulum light orange in colour, not laterally flattened, dome-shaped and not distinctly projecting beyond the stalk, introvert with sclerites transversally placed in two longitudinal rows per interseptal space, anthocodial crown with 28–38 sclerite rows, points separated from polyps distally, formed by 6–9 pairs of sclerites, and the presence of intermediate points (secondary points) between principal (interseptal) ones. Nidalia studeri is here compared with its closest congeners, especially with the Indonesian species N. simpsoni, species from the West Indian Region N. dissidens, N.occidentalis, N. deichmannae, and the recently described Nidalia aurantia from the Mid-Atlantic Ocean. This is the first time that the genus Nidalia and the family Nidaliidae have been reported with certainty for the Mediterranean Sea

Morphological features of the gorgonian Paramuricea macrospina on the continental shelf and shelf edge (Menorca Channel, Western Mediterranean Sea)

Morphological variability in gorgonians is frequent and commonly associated with habitat variability, often resulting in segregated morphotypes. Paramuricea macrospina is an endemic Mediterranean gorgonian species found on rocky bottoms between 40 and 160 m depth and has recently been reported as one of the most abundant species in continental shelf and shelf edge environments. Three different chromatic forms of P. macrospina were observed in the Menorca Channel: a yellow form and a light purple form occurring on maërl beds of the continental shelf, and a dark purple form occurring on rocky substrates of the shelf edge. The objective of the present work is to verify if these P. macrospina forms may represent distinct taxonomic units by analysing differences in colony morphology and sclerite size and shape of the three chromatic forms. No significant differences were found in colony shape, suggesting that environmental variability between the continental shelf and the shelf edge is not influential enough to significantly alter colony morphology. Significant differences in sclerite size and shape were found amongst all forms, suggesting that sclerites may be influenced by environmental conditions. However, the co-occurrence of the yellow and light purple forms side by side on the continental shelf may indicate a certain degree of genetic differentiation

An Automated Pipeline for Image Processing and Data Treatment to Track Activity Rhythms of Paragorgia arborea in Relation to Hydrographic Conditions

Imaging technologies are being deployed on cabled observatory networks worldwide. They allow for the monitoring of the biological activity of deep-sea organisms on temporal scales that were never attained before. In this paper, we customized Convolutional Neural Network image processing to track behavioral activities in an iconic conservation deep-sea species—the bubblegum coral Paragorgia arborea—in response to ambient oceanographic conditions at the Lofoten-Vesterålen observatory. Images and concomitant oceanographic data were taken hourly from February to June 2018. We considered coral activity in terms of bloated, semi-bloated and non-bloated surfaces, as proxy for polyp filtering, retraction and transient activity, respectively. A test accuracy of 90.47% was obtained. Chronobiology-oriented statistics and advanced Artificial Neural Network (ANN) multivariate regression modeling proved that a daily coral filtering rhythm occurs within one major dusk phase, being independent from tides. Polyp activity, in particular extrusion, increased from March to June, and was able to cope with an increase in chlorophyll concentration, indicating the existence of seasonality. Our study shows that it is possible to establish a model for the development of automated pipelines that are able to extract biological information from times series of images. These are helpful to obtain multidisciplinary information from cabled observatory infrastructures

Effets néfastes de l'acidification des océans sur le corail rouge méditerranéen (Corallium rubrum), d'importance économique.

International audienceThe mean predicted decrease of 0.3–0.4 pH units in the global surface ocean by the end of the century has prompted urgent research to assess the potential effects of ocean acidification on the marine environment, with strong emphasis on calcifying organisms. Among them, the Mediterranean red coral (Corallium rubrum) is expected to be particularly susceptible to acidification effects, due to the elevated solubility of its Mg-calcite skeleton. This, together with the large overexploitation of this species, depicts a bleak future for this organism over the next decades. In this study, we evaluated the effects of low pH on the species from aquaria experiments. Several colonies of C. rubrum were long-term maintained for 314 days in aquaria at two different pH levels (8.10 and 7.81, pHT). Calcification rate, spicule morphology, major biochemical constituents (protein, carbohydrates and lipids) and fatty acids composition were measured periodically. Exposure to lower pH conditions caused a significant decrease in the skeletal growth rate in comparison with the control treatment. Similarly, the spicule morphology clearly differed between both treatments at the end of the experiment, with aberrant shapes being observed only under the acidified conditions. On the other hand, while total organic matter was significantly higher under low pH conditions, no significant differences were detected between treatments regarding total carbohydrate, lipid, protein and fatty acid composition. However, the lower variability found among samples maintained in acidified conditions relative to controls, suggests a possible effect of pH decrease on the metabolism of the colonies. Our results show, for the first time, evidence of detrimental ocean acidification effects on this valuable and endangered coral species.La diminution moyenne prédite de 0,3 à 0,4 unités de pH dans l'océan mondial en surface d'ici la fin du siècle a suscité des recherches urgentes pour évaluer les effets potentiels de l'acidification des océans sur l'environnement marin, mettant fortement l'accent sur les organismes calcifiants. Parmi eux, le corail rouge méditerranéen (Corallium rubrum) est susceptible d'être particulièrement affecté par les effets de l'acidification, en raison de la solubilité élevée de son squelette en Mg-calcite. Ceci, associé à la surpêche importante de cette espèce, dessine un avenir sombre pour cet organisme au cours des prochaines décennies. Dans cette étude, nous avons évalué les effets du faible pH sur l'espèce à partir d'expériences en aquarium. Plusieurs colonies de C. rubrum ont été maintenues à long terme pendant 314 jours dans des aquariums à deux niveaux de pH différents (8,10 et 7,81, pHT). Le taux de calcification, la morphologie des spicules, les principaux constituants biochimiques (protéines, glucides et lipides) et la composition en acides gras ont été mesurés périodiquement. L'exposition à des conditions de pH plus bas a entraîné une diminution significative du taux de croissance du squelette par rapport au traitement témoin. De même, la morphologie des spicules différait clairement entre les deux traitements à la fin de l'expérience, avec des formes aberrantes observées uniquement dans les conditions acidifiées. D'autre part, bien que la matière organique totale soit significativement plus élevée dans des conditions de faible pH, aucune différence significative n'a été détectée entre les traitements en ce qui concerne la composition totale en glucides, lipides, protéines et acides gras. Cependant, la variabilité plus faible trouvée parmi les échantillons maintenus dans des conditions acidifiées par rapport aux témoins suggère un possible effet de la diminution du pH sur le métabolisme des colonies. Nos résultats montrent, pour la première fois, des preuves d'effets néfastes de l'acidification des océans sur cette espèce de corail précieuse et menacée