ROV-based monitoring of passive ecological recovery in a deep-sea no-take fishery reserve.

Simple Summary The Norway lobster is a key species for European Atlantic and Mediterranean fisheries. We performed a global bibliographic survey using the VOSviewer software to investigate the status of research on Norway lobsters by extracting data from all relevant scientific literature published in SCOPUS since 1965. The analysis revealed three clusters: (1) fishery performance, stock assessment, and management; (2) biological cycles in growth, reproduction, and behavior; and (3) physiology and ecotoxicology (including food products). Intense research has emerged on ecotoxicology and fishery management (which also includes other commercially targeted and co-existing species). Finally, earlier studies generally focused on the morphological and physiological aspects of this species while more recent studies have focused on fisheries and on Norway lobster as a food resource. In summary, the results indicate that knowledge is scarce on how the burrowing behavior of N. norvegicus is influenced by environmental conditions and how this affects stock assessments. We attribute this to limited use of current and advanced monitoring technologies. Abstract The burrowing crustacean decapod Nephrops norvegicus is a significant species in European Atlantic and Mediterranean fisheries. Research over the decades has mainly focused on behavioral and physiological aspects related to the burrowing lifestyle, since animals can only be captured by trawls when engaged in emergence on the seabed. Here, we performed a global bibliographic survey of all the scientific literature retrieved in SCOPUS since 1965, and terminology maps were produced with the VOSviewer software to reveal established and emerging research areas. We produced three term-map plots: term clustering, term citation, and term year. The term clustering network showed three clusters: fishery performance, assessment, and management; biological cycles in growth, reproduction, and behavior; and finally, physiology and ecotoxicology, including food products. The term citation map showed that intense research is developed on ecotoxicology and fishery management. Finally, the term year map showed that the species was first studied in its morphological and physiological aspects and more recently in relation to fishery and as a food resource. Taken together, the results indicate scarce knowledge on how burrowing behavior and its environmental control can alter stock assessment, because of the poor use of current and advanced monitoring technologies.

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Established and Emerging Research Trends in Norway Lobster, Nephrops norvegicus

Nowadays, there is a growing awareness on the social and economic importance of the ocean. In this context, being able to carry out a diverse range of operations underwater is of paramount importance for many industrial sectors as well as for marine science and to enforce restoration and mitigation actions. Underwater robots allowed us to venture deeper and for longer time into the remote and hostile marine environment. However, traditional design concepts such as propeller driven remotely operated vehicles, autonomous underwater vehicles, or tracked benthic crawlers, present intrinsic limitations, especially when a close interaction with the environment is required. An increasing number of researchers are proposing legged robots as a bioinspired alternative to traditional designs, capable of yielding versatile multi-terrain locomotion, high stability, and low environmental disturbance. In this work, we aim at presenting the new field of underwater legged robotics in an organic way, discussing the prototypes in the state-of-the-art and highlighting technological and scientific challenges for the future. First, we will briefly recap the latest developments in traditional underwater robotics from which several technological solutions can be adapted, and on which the benchmarking of this new field should be set. Second, we will the retrace the evolution of terrestrial legged robotics, pinpointing the main achievements of the field. Third, we will report a complete state of the art on underwater legged robots focusing on the innovations with respect to the interaction with the environment, sensing and actuation, modelling and control, and autonomy and navigation. Finally, we will thoroughly discuss the reviewed literature by comparing traditional and legged underwater robots, highlighting interesting research opportunities, and presenting use case scenarios derived from marine science applications.

Underwater legged robotics: review and perspectives

Marine resources exploitation through bottom trawling affects marine ecosystems; thus, management should consider the presence of sensitive species as ecosystem health indicators. Epibenthic organisms such as sea pens are widely used to assess benthic conditions, as their populations are declining where trawling is intense. The Pomo/Jabuka Pits fishing ground in the Adriatic Sea, subject to various management measures over the years, is a nursery for European hake and hosts a small, but dense, population of Norway lobster and a remarkable abundance of pink shrimp. The sea pen Funiculina quadrangularis shares its habitat (sandy-muddy bottoms) with these crustaceans. Through UnderWater TeleVision surveys conducted from 2012 to 2019, F. quadrangularis abundance and distribution were quantified in relation to changes in the spatiotemporal distribution of fishing efforts. The average density (n/m2) of colonies was calculated for three periods: BEFORE implementation of measures (before 1 July 2015), during an INTERMEDIATE period in which limitations changed (2 July 2015 to 31 August 2017), and AFTER the implementation of a Fishery Restricted Area (from 1 September 2017). F. quadrangularis revealed an increase in density where fisheries were closed, even after a short period. This showed how management measures can positively influence epibenthic communities and that sea pens can be indicators of impact and/or recovery of habitats.

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Changes in Abundance and Distribution of the Sea Pen, Funiculina quadrangularis, in the Central Adriatic Sea (Mediterranean Basin) in Response to Variations in Trawling Intensity

From emblematic to problematic: The case of Astrospartus mediterraneus (Risso, 1826) (Echinodermata: Ophiuroidea) in the artisanal fishing grounds of the Cap de Creus area (NW Mediterranean Sea)

Deep-sea ecosystems of the Iberian margin have been widely impacted over the past decades, but the limited knowledge on their biodiversity and functioning limits our ability to contribute to their conservation. So far, in the Gulf of Cadiz, research has mostly been focused on megabenthic assemblages associated to mud volcanoes. However, several other geomorphological structures have remained widely unexplored. Here, by means of a quantitative analysis of 17 video transects conducted between 220 and 980 m depth, we investigated megabenthic assemblages associated to canyons, contouritic channels, contouritic furrows and open slopes. We report the presence of 8 different assemblages, segregated as a result of the different substrates and geomorphologic features. Megabenthic assemblages on hard substrates were characterized by mono or multispecific sponge assemblages. Soft bottoms hosted crinoid beds, pennatulacean meadows and fields of the gorgonian Radicipes gracilis. These results highlight the high diversity of megabenthic assemblages in deep-sea ecosystems of the Gulf of Cadiz and suggest that most of the geomorphological features that remained so far unexplored represent vulnerable marine ecosystems deserving protection and inclusion in future management plans. 

Megafaunal assemblages in deep-sea ecosystems of the Gulf of Cadiz, northeast Atlantic ocean

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.

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J. B. Company

Papers

Megafaunal assemblages in deep-sea ecosystems of the Gulf of Cadiz, northeast Atlantic ocean

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

ROV-based monitoring of passive ecological recovery in a deep-sea no-take fishery reserve.

Established and Emerging Research Trends in Norway Lobster, Nephrops norvegicus