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Global warming, through increasing temperatures, may facilitate the spread and proliferation of outbreak-forming species which may find favourable substrate conditions on artificial aquaculture structures. The presence of stinging organisms (cnidarian hydroids) in the facilities fouling community are a source of pollution that can cause critical problems when in-situ underwater cleaning processes are performed. Multiple stressor experiments were carried out to investigate the cumulative effect on farmed mussels' functional traits when exposed to realistic stressful conditions, including presence of harmful cnidarian cells and environmental conditions of increasing temperature and short-term hypoxia. Exposure to combined stressors significantly altered mussels' performance, causing metabolic depression and low filtering activity, potentially delaying, or inhibiting their recovery ability and ultimately jeopardizing organisms' fitness. Further research on the stressors properties and occurrence is needed to obtain more realistic responses from organisms to minimize climate change impacts and increase ecosystem and marine economic activities resilience to multiple stressors.

Single-species Gadget models were used to assess the effects of using a sorting grid mounted on the traditional trawl net used by Sicilian trawlers to exploit the deep-water rose shrimp in the Strait of Sicily. The main commercial by-catch species of this fleet is the European hake (Merluccius merluccius), often caught at sizes well below the minimum conservation reference size. Selectivity curves based on the results of an experimental survey carried out in the area using a commercial trawler equipped with an ad hoc-designed sorting grid were incorporated into single-species Gadget models to forecast the effects of changing fishery selectivity on the performance of the two stocks in terms of catch and biomass. The models included catch data from the Italian, Tunisian and Maltese fleets as well as MEDITS trawl survey data for the period 2002-2016. Several scenarios were defined to simulate the effect of the Italian trawlers’ adopting the sorting grid under different stock-recruitment assumptions. The results obtained, when compared with status quo simulations of fishing without a sorting grid mounted on the trawl net, indicated a beneficial effect for both stocks in terms of an increase in biomass and for the fleets in terms of the amount and size composition of annual landings., Se usaron modelos monoespecíficos Gadget para evaluar el efecto del uso de una rejilla separadora acoplada a la red de arrastre tradicional que usan los arrastreros sicilianos para explotar la gamba blanca en el estrecho de Sicilia (SoS). La principal especie en las capturas accesorias de esta flota es la merluza europea (Merluccius merluccius), que contiene a menudo tallas muy por debajo de la Talla de Referencia Mínima de Conservación (MCRS). Se incorporaron en Gadget las curvas de selectividad obtenidas en una campaña experimental en la misma área con un arrastrero comercial equipado con un modelo de rejillas separadora diseñado específicamente para el estudio, para pronosticar los efectos del cambio de la selectividad pesquera en la evolución de los dos stocks en términos de captura y biomasa. Los modelos incluyen datos de captura de las flotas italiana, tunecina y maltesa, así como datos de las campañas MEDITS para el periodo 2002-2016. Se definieron distintos escenarios para simular el efecto de la adopción de la rejilla separadora por parte de los arrastreros italianos bajo distintas asunciones del modelo stock-reclutamiento. La comparación de los resultados obtenidos con simulaciones de pesca sin montar la rejilla separadora en la red de arrastre (status quo) indican un efecto neto beneficioso para los dos stocks debido al incremento de biomasa y, en consecuencia, para las flotas en términos de cantidad y composición de las capturas anuales.

13 pages, 6 figures, 2 tables.-- This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License, The rapid, global spread of COVID-19, and the measures intended to limit or slow its propagation, are having major impacts on diverse sectors of society. Notably, these impacts are occurring in the context of other anthropogenic-driven threats including global climate change. Both anthropogenic stressors and the COVID-19 pandemic represent significant economic challenges to aquaculture systems across the globe, threatening the supply chain of one of the most important sources of animal protein, with potential disproportionate impacts on vulnerable communities. A web survey was conducted in 47 countries in the midst of the COVID-19 pandemic to assess how aquaculture activities have been affected by the pandemic, and to explore how these impacts compare to those from climate change. A positive correlation between the effects of the two categories of drivers was detected, but analysis suggests that the pandemic and the anthropogenic stressors affect different parts of the supply chain. The immediate measurable reported losses varied with aquaculture typology (land vs. marine, and intensive vs. extensive). A comparably lower impact on farmers reporting the use of integrated multitrophic aquaculture (IMTA) methods suggests that IMTA might enhance resilience to multiple stressors by providing different market options under the COVID-19 pandemic. Results emphasize the importance of assessing detrimental effects of COVID-19 under a multiple stressor lens, focusing on areas that have already locally experienced economic loss due to anthropogenic stressors in the last decade. Holistic policies that simultaneously address other ongoing anthropogenic stressors, rather than focusing solely on the acute impacts of COVID-19, are needed to maximize the long-term resilience of the aquaculture sector., The Open Access publication of the MS was funded by M. Cristina Mangano FOE N. 418 at Stazione Zoologica Anton Dohrn (personal OA publication fund). People at Laboratory of Ecology have been found by the PRIN-MAHRES project (Ministry of Italian Research; MUR) 2017MHHWBN_003 Linea C and by the HARMONY Project Italy-Malta 2016 (grant C1-3.1-31) funded by the Sicilian Region and Maltese Government. A. Nogueira thanks FCT/MCTES for the financial support to CESAM (UIDP/50017/2020+UIDB/50017/2020), through national funds. J.M.F. Babarro thanks project PID2019-106008RB-C21 for support through Spanish Government funds

The upside-down jellyfish Cassiopea is a benthic scyphozoan, considered a non-indigenous invasive species in the Mediterranean, forming large blooms in eutrophic areas. Taxonomy of the genus Cassiopea is extremely difficult because morphological/meristic characters used are variable within the same species, overlapping among different species, and cryptic species have been identified by molecular markers; nine Cassiopea species are recognized on the basis of molecular study. Mediterranean records of Cassiopea have been ascribed to andromeda species on the basis of a hypothesized invasion pathway from the Suez Canal. In the current study, an analysis of the main morphological characters of the sampled Cassiopea jellyfish from Palermo (Tyrrhenian Sea) was carried out and subsequently, molecular analyses were performed by using COI barcode in order to identify the species. Molecular data were compared with published information in GenBank. Morphological characters were highly variable, but molecular analyses confirmed that Mediterranean Cassiopea specimens belong to andromeda species. Moreover, high values of sequence divergence were found between Mediterranean Cassiopea and the other C. andromeda from the Red Sea, Hawaii and Florida. These results lead to a discussion of possible explanations linked to life history features of the species. Two different explanations are proposed; the first is that Mediterranean C. andromeda, finding a suitable ecological niche good for colonization and proliferation, could have been isolated in Palermo Harbour. The second considers the possibility of multiple introduction events by human transport as demonstrated for other non-indigenous jellyfish; in this case Cassiopea genetic differences increased in the invaded area.

Mediterranean trawl fisheries are characterized by a critical combination of high fishing effort and low size at first capture for most commercial species. In this study we tested the use of sorting grids installed on bottom trawl nets to minimize the catch of undersized deep-water rose shrimp (Parapenaeus longirostris, DPS) and European hake (Merluccius merluccius, HKE). The catch of a traditional trawl net was compared with that obtained with the same net equipped with ad hoc designed juveniles and trash excluder devices (JTEDs) during an experimental survey. Three different JTEDs were tested: the first (G1-SM40) was built with a net of 40-mm square mesh; the second (G2-ST20) and third (G3-ST25) with vertical steel bars spaced 20 and 25 mm, respectively. The probability of retaining DPS and HKE by length class in trawl nets with and without JTED was analysed using generalized additive mixed models. With G1-SM40, the reduction of undersized individuals in the cod-end was about 60% and 44% for DPS and HKE, respectively. With G2-ST20, a 34% catch decrease of HKE individuals smaller than 20 cm total length was observed. A loss of marketable fractions of DPS was recorded with G1-SM40 (–25%) and G2-ST20 (30%). Finally, JTD G3-ST25 was efficient at reducing the catch of undersized specimens of DPS and HKE, but showed a higher loss of marketable fractions than the other JTEDs. Although further fishing trials would be required to maximize the sorting efficiency of the grids, the results obtained clearly indicated that grids can substantially reduce unwanted catches of undersized DPS and HKE in Mediterranean bottom trawl fisheries., Las pesquerías de arrastre mediterráneas se caracterizan por una combinación crítica de un alto esfuerzo de pesca y un tamaño de captura por debajo de la talla legal para la mayoría de las especies comerciales. En este estudio, probamos el uso de rejillas separadoras instaladas en redes de arrastre de fondo para minimizar la captura de la gamba rosada (Parapenaeus longirostris; DPS) y la merluza (Merluccius merluccius; HKE). La captura obtenida con una red de arrastre tradicional se comparó con la obtenida con la misma red equipada con “Juveniles Trash Excluder Devices” (JTED) diseñados específicamente para cada caso durante un estudio experimental. Tres JTEDs diferentes se probaron: el primero (G1-SM40) se construyó con una res de 40 mm de malla cuadrada; el segundo (G2-ST20) y el tercero (G3-ST25) se fabricaron con barras verticales de acero separadas 20 y 25 mm, respectivamente. La probabilidad de retener DPS y HKE según clase de talla en redes de arrastre con y sin JTED se analizó utilizando Modelos Mixtos Aditivos Generalizados (GAMM). Usando G1-SM40, se consiguió una reducción de individuos de talla por debajo de la talla legal en el copo, de 60% y 40% para DPS y HKE respectivamente. Con respecto a HKE, utilizando G2-ST20 se observó una disminución en la captura del 34% de individuos de menos de 20 cm TL. Sin embargo, se registró una pérdida de fraccion comercializable de DPS usando G1-SM40 del –25% y usando G2-ST20 del 30%. Finalmente, el JTED G3-ST25 resultó eficaz para reducir la captura de especímenes de DPS y HKE de talla ilegal, pero se observó una mayor pérdida de fraccion comercializable que con los otros JTEDs. Aunque se necesitarían más ensayos de pesca para maximizar la eficiencia de las rejillas separadoras, los resultados obtenidos indicaron claramente que las rejillas pueden contribuir a reducir sustancialmente las capturas no deseadas de DPS y HKE de talla ilegal en las pesquerías de arrastre de fondo del Mediterráneo.

Biodiversity plays a key role for our planet by buffering ongoing and future changes in environmental conditions. We tested if canopy-forming algae enhancing biodiversity (CEB) in a Mediterranean intertidal reef ecological community could alleviate the effect of stressors (heat waves and pollution from sewage) on community metabolic rates (as expressed by oxygen consumption) used as a proxy of community functioning. CEB exerted a buffering effect related to the properties of stressor: physical-pulsing (heat wave) and chronic-trophic (sewage). After a simulated heat wave, CEB was effective in buffering the impacts of detrimental temperatures on the functioning of the community. In reefs exposed to chronic sewage effluents, benefits derived from CEB were less evident, which is likely due to the stressor's contextual action. The results support the hypothesis that ecological responses depend on stressor typology acting at local level and provide insights for improving management measures to mitigate anthropogenic disturbance.

17 pages, 7 figures, 2 tables, supplementary material https://doi.org/10.3389/fmars.2021.610241.-- Data Availability Statement: The datasets presented in this article are not readily available because some of the original raw data are protected by confidentiality. Requests to access the datasets should be directed to GM, giacomo.milisenda@szn, The recent establishment of the “landing obligation” under the reformed EU Common Fishery Policy has the twofold objective of reducing the excessive practice of discarding unwanted catch at sea and encouraging more selective and sustainable fisheries. Within this context, the awareness of the spatial distribution of potential unwanted catches is important for devising management measures aimed to decrease discards. This study analyzed the distribution of Hot Spot density areas of demersal fish and crustaceans below the Minimum Conservation Reference Size (MCRS) in four different southern European seas: continental Portuguese coast, Catalan Sea, South of Sicily, Liguria and northern Tyrrhenian Seas using both bottom trawl survey data and information on the spatial distribution of commercial fisheries. Critical areas for discarding were identified as zones where the highest densities of individuals below MCRS were consistently recorded throughout a series of years. Results clearly showed a patchy distribution of undersized individuals in each investigated area, highlighting the overlap between high density patches of both discards and fishing effort. The present findings provide a relevant knowledge for supporting the application of spatial-based management actions, such as the designation of Fisheries Restricted Areas (FRAs), in order to minimize the by-catch of undersized specimens and improve the sustainability of demersal fisheries, This work was funded by the European Commission’s Horizon 2020 Research and Innovation Program under Grant Agreement No. 634495 for the project Science, Technology, and Society Initiative to minimize Unwanted Catches in European Fisheries (MINOUW). This study received Portuguese national funds from FCT-Foundation for Science and Technology through project UIDB/04326/2020, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Independence of science and best available science are fundamental pillars of the UN-FAO code of conduct for responsible fisheries and are also applied to the European Union (EU) Common Fishery Policy (CFP), with the overarching objective being the sustainable exploitation of the fisheries resources. CFP is developed by DG MARE, the department of the European Commission responsible for EU policy on maritime affairs and fisheries, which has the Scientific, Technical and Economic Committee for Fisheries (STECF) as consultant body. In the Mediterranean and Black Sea, the General Fisheries Commission for the Mediterranean (FAO-GFCM), with its own Scientific Advisory Committee on Fisheries (GFCM-SAC), plays a critical role in fisheries governance, having the authority to adopt binding recommendations for fisheries conservation and management. During the last years, advice on the status of the main stocks in the Mediterranean and Black Sea has been provided both by GFCM-SAC and EU-STECF, often without a clear coordination and a lack of shared rules and practices. This has led in the past to: i) duplications of the advice on the status of the stocks thus adding confusion in the management process and, ii) a continuous managers’ interference in the scientific process by DG MARE officials hindering its transparency and independence. Thus, it is imperative that this stalemate is rapidly resolved and that the free role of science in Mediterranean fisheries assessment and management is urgently restored to assure the sustainable exploitation of Mediterranean marine resources in the future., SI

15 pages, 6 figures, 4 tables, supplementary data https://doi.org/10.1016/j.fishres.2020.105714, Discards is an important issue in fisheries around the world. The spatial management of discards has attracted interest as a potential tool for minimizing the unwanted catch. The aim of the present work was to identify areas with high quantities of bottom trawl discarded catch regarding species subjected to MCRS, in six areas of southern European waters (southern Portuguese waters, Catalan Sea, Ligurian and northern Tyrrhenian Seas, Strait of Sicily, eastern Ionian Sea, and Aegean Sea). Analyses were based on two types of data: (a) the undersized catch of species subjected to MCRS from bottom trawl surveys and (b) the actual discarded catch (including undersized and non-undersized individuals) of species subjected to MCRS from commercial bottom trawling. Geostatistical analysis techniques were applied to the first type of data and Generalized Additive Models using environmental variables were applied to the second one. Subsequently, areas that persistently presented high quantities of discarded catch (i.e., “iDC grounds”) or undersized catch (i.e., “iUC grounds”) were identified and mapped. The “iDC grounds”/“iUC grounds” were located either over the slope or within the continental shelf and over marine plateaus, largely depending on the main target species of each fishery. Next, the overlap of “iDC grounds”/“iUC grounds” with the existing Fisheries Restricted Areas (FRAs) and the proposed Marine Protected Areas (MPAs) was estimated aiming to explore how spatial closures could contribute to the reduction of bottom trawl discarded catch/undersized catch. Certain spatial closures were more effective in the Central Mediterranean and others to the Eastern Mediterranean. The overlapping of existing FRAs with “iDC grounds”/“iUC grounds” did not exceed 24 % in any study area, whereas proposed MPAs, like the CIESM Marine Peace Parks, reached up to 90 % for the same study area, This work was funded by the European Commission’s Horizon 2020 Research and Innovation Program under Grant Agreement No. 634495 for the project Science, Technology, and Society Initiative to minimize Unwanted Catches in European Fisheries (MINOUW). We thank people involved in the MEDISEH project (MAREA PROJECT MEDISEH: Mediterranean Sensitive Habitats, Specific Contract No 2, SI2.600741) for data provision regarding FRAs and MPAs, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

In this study we investigated the spatio-temporal distribution of gurnards (8 species of Triglidae and one species of Peristediidae) in the northern Mediterranean Sea using 22 years of MEDITS bottom trawl survey data (1994-2015). Gurnards showed significant differences in terms of abundance, dominance and composition among geographical sub-areas and ecoregions, with the highest relative biomass (BIy) being found in Malta, eastern Corsica, the Balearic Islands and the eastern Ionian Sea. The lowest gurnards BIy were observed in the highly exploited areas of the western Mediterranean and the Adriatic Sea, where the largest number of species with a negative linear trend in BIy was also found. The temporal trends in species abundances highlighted a general decrease for the coastal species (C. lucerna, C. lastoviza, C. obscurus) as compared with the species inhabiting the deep continental shelf and slope (T. lyra, P. cataphractum). The results provide for the first time an overview of the spatiotemporal trend in the abundance of gurnards over the wide spatial scale of the northern Mediterranean Sea, also suggesting the possible use of these species as indicators for monitoring the impact of fishing pressure on demersal fish assemblages., En este estudio hemos investigado la distribución espacio-temporal de los gurnardos (8 especies de Triglidae y 1 especie de Peristediidae) en el norte del Mediterráneo usando 22 años de datos de la campaña de pesca de arrastre MEDITS (1994-2015). Los gurnardos mostraron diferencias significativas en la abundancia, dominancia y composición entre las distintas sub-areas geográficas (GSAs) y las ecoregiones, encontrándose las mayores biomasas relativas (BIy) en Malta, el este de Córcega, las Islas Baleares y el oeste del mar Jónico. Por otro lado, los menores valores de BIy fueron observados en las áreas más explotadas del oeste del Mediterráneo y del Mar Adriático, donde también se observó el mayor número de especies con una tendencia lineal negativa en relación a BIy. La tendencia temporal en la abundancia de especies evidenció una disminución general en las especies costeras (C. lucerna, C. lastoviza, C. obscurus) respecto a las especies que habitan la profunda plataforma y pendiente continentales (T. lyra, P. cataphractum). Los resultados proporcionan por primera vez una visión general de las tendencias espacio-temporales en la abundancia de los gurnardos en la amplia escala espacial del norte del Mediterráneo, sugiriendo también la posibilidad de usar estas especies como indicadores para monitorear el impacto de la presión de pesca sobre los ensamblajes de peces demersales.

Over the last 50 years, there has been an increased frequency and severity of negative impacts affecting marine fishery and aquaculture sectors, which claimed significant economic losses due to the interference of stinging gelatinous organisms with daily operational activities. Nevertheless, original scientific information on jellyfish-related incidents, their consequences, and potential preventative and mitigation countermeasures is limited and scattered across gray literature, governmental technical reports, and communication media. A literature scan searching for records of any interactions between jellyfish and the marine fishery/aquaculture sectors were carried out. Out of 553 papers, 90 contained original information, referring to more than 130 cases worldwide of negative impacts of jellyfish on marine fishery/aquaculture over the last century. Calling attention on too often neglected socioeconomic and ecological impacts of jellyfish blooms, the purpose of this paper is to review and analyze the most up-to-date research on this subject and to provide a global perspective on the importance of jellyfish impacts and their cascading effects on marine fishery and aquaculture sectors.

The high variability of trammel fisheries, due to a marked seasonality in target species and fishing activities needs to be investigated with high spatial and temporal resolution. The present study focuses on trammel net fishery in southwestern Sicily (central Mediterranean Sea) identifying and characterizing the main metiers in relation to some key aspects of the fishery such as the target species, composition of landings, main fishing grounds and time of the year. For this purpose, a multivariate statistical approach based on landings and effort data of the Mazara del Vallo southwestern Sicily, Italy) trammel fleet in the period 2009–2013 was applied. A total of 153 different landed species and four different trammel net metiers were identified. These metiers showed differences in target species (i.e. Sepia officinalis, Palinurus elephas, Mullus surmuletus and a mix of species), fishing season, fishing grounds and dimension of fishing vessels. The metiers identified were significantly different in terms of total average landing per unit of effort (LPUE) with metier 1 targeting M. surmuletus, showing the highest average LPUE (2047 (192 s.e.) g*(h)−1*103 m net) and metier 2 targeting S. officinalis, exhibiting the lowest value (1175 (119 s.e.) g*(h)−1*103 m net). The study provides new knowledge on the dynamics of trammel fisheries in southwestern Sicily also showing that the complex nature of this peculiar fishery should be taken into account in any future sampling program aimed at the monitoring and management of artisanal fisheries in this area and more in general in the Mediterranean Sea.

In the Mediterranean Sea, dolphinfish fishery has employed a great number of anchored Fish Aggregating Devices (FADs) arranged in lines, that represents a threat to navigation and to the marine environment and is economically disadvantageous to fishers. In this research, echo-sounder buoys were tested for the first time in the Mediterranean, and it was evaluated if this technological method can be useful to studies aimed to reduce the impact of FADs from the perspective of sustainable fishery. The study was carried out in November and December 2015 in a Tyrrhenian area where echo-sounder buoys were tied to anchored and drifting FADs and aggregated biomass estimates were recorded daily. Comparisons were made to evaluate whether there are: a relation between the number of anchored FADs and associated biomass; and differences, in terms of aggregated biomass, between anchored and drifting FADs. No clear correlation was found between the number of anchored FADs and biomass, while the drifting FADs showed a greater power of attraction than the anchored FADs. Anyway, the echo-sounder buoys may be suitable for future studies. It was highlighted that their simple use in the Mediterranean FADs fishery could facilitate a reduction of the high number of anchored FADs.

Special issue Vectors of change in the marine environment.-- 11 pages, 7 figures, 1 table, supplementary data https://doi.org/10.1016/j.ecss.2016.01.002, Investigations on sexual reproduction of jellyfish are essential to understanding mechanisms and patterns of outbreaks formation. Pelagia noctiluca (Forskål, 1775) (Scyphozoa) is known as the predominant jellyfish species with direct development in Western and Central Mediterranean Sea. In this paper we used integrated morphometric, histological, and biochemical approaches to investigate the annual reproductive biology of P. noctiluca from the Strait of Messina (South Thyrrenian Sea), a key proliferation area for this species due to favourable temperatures and high productivity. From November 2011 to September 2012, P. noctiluca sexual reproduction occurred throughout the year, with two seasonal peaks (autumn, spring) of spawning and embryonic development. Gonads of female P. noctiluca were characterized by a large amount of mature eggs of small size (diameter < 200 μm) during high food availability, whereas fewer, larger eggs (diameter > 200 μm) were detected during low availability of prey. Two morphometric indexes were applied: the Gonad-Somatic Index (GSI, gonadal/somatic tissue dry weight ratio) and Fecundity Index (FI, n° eggs mm−2 * gonadal dry weight). The FI showed longer spawning periods than the GSI, providing a better causal-mechanistic explanation for the year-round occurrence of P. noctiluca in the Strait of Messina. Protein contents of the gonads changed seasonally, with the highest concentrations during the pre-spawning periods. We suggest that investigations on jellyfish sexual reproduction can provide biological information relevant for understanding mechanisms of jellyfish blooms as well as for the management of coastal zones affected by outbreaks of gelatinous species, The research leading to these results received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under Grant Agreement No. 266445 for the project Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors (VECTORS – http://www.marine-vectors.eu)

12 pages, 3 figures, Climate change is already transforming the seascapes of our oceans by changing the energy availability and the metabolic rates of the organisms. Among the ecosystem-engineering species that structure the seascape, marine animal forests (MAFs) are the most widespread. These habitats, mainly composed of suspension feeding organisms, provide structural complexity to the sea floor, analogous to terrestrial forests. Because primary and secondary productivity is responding to different impacts, in particular to the rapid ongoing environmental changes driven by climate change, this paper presents some directions about what could happen to different MAFs depending on these fast changes. Climate change could modify the resistance or resilience of MAFs, potentially making them more sensitive to impacts from anthropic activities (i.e. fisheries and coastal management), and vice versa, direct impacts may amplify climate change constraints in MAFs. Such changes will have knock-on effects on the energy budgets of active and passive suspension feeding organisms, as well as on their phenology, larval nutritional condition, and population viability. How the future seascape will be shaped by the new energy fluxes is a crucial question that has to be urgently addressed to mitigate and adapt to the diverse impacts on natural system, We also thank the Marie Curie International Outgoing Fellowship project ANIMAL FOREST HEALTH (Grant Agreement Number 327845). This work contributes to the ICTA “Unit of Excellence” (MinECo, MDM2015-0552). We are also grateful with the CALMED project (CTM2016-79547-R) and the AGAUR Generalitat de Catalunya (MERS, 2017 SGR 1588). SR and MS thanks the CAPES-Print Programme and CNPq Research Productivity Fellowship (Brazil)

The large-scale distribution pattern of megafauna communities along the Mediterranean middle slope was explored. The study was conducted between 500 and 800 m depth where deep-water fishery occurs. Although community studies carried out deeper than 500 m are partly available for some geographic areas, few large-scale comparative studies have been carried out. Within the framework of the MEDITS survey programme, we compared the megafauna community structure in ten geographical sub-areas (GSAs) along the Mediterranean coasts. Additionally, the spatial distribution of fishing was analysed using vessel monitoring by satellite information. Overall, the community showed a significant difference between sub-areas, with a decreasing eastward pattern in abundance and biomass. Longitude was the main factor explaining variation among sub-areas (by generalized additive models). However, we found a region which did not follow the general pattern. GSA 6 (northern Spain) showed significantly lower abundance and a different composition structure to the adjacent areas. The decrease in community descriptors (i.e. abundance and biomass) in this area is probably a symptom of population changes induced by intense fishery exploitation. Overall, a combination of environmental variables and human-induced impacts appears to influence the bentho-pelagic communities along the slope areas of the Mediterranean., En este estudio se describe la estructura y patrones de distribución de la comunidad de megafauna que habita en el margen continental medio a lo largo del Mediterráneo. El estudio se realizó entre los 500 y 800 m, coincidiendo espacialmente con las pesquerías de profundidad. A pesar de que se conoce parcialmente la estructura de las comunidades que habitan por debajo de 500 m, existe la necesidad de estudiar estas comunidades a una escala espacial más amplia. Dentro del marco del proyecto internacional MEDITS, se comparó la estructura de las comunidades en diez sub-áreas geográficas (GSAs) a lo largo de las costas mediterráneas. Además se analizó la distribución espacial del esfuerzo pesquero utilizando la información de los datos de seguimiento de buques. En general los resultados mostraron diferencias significativas entre subáreas mostrando un patrón decreciente en los valores de biomasa hacia el este, siendo la longitud el principal factor explicativo del modelo de distribución (GAMs). Sin embargo, encontramos una subárea que no seguía el patrón general, la GSA6 (norte de España). La GSA6 mostró una biomasa y estructura de la comunidad diferente a las áreas adyacentes. La disminución de la biomasa en esta área parece ser un síntoma de los cambios poblaciones causados por la elevada intensidad de pesca en la zona. Los resultados sugieren que la distribución y estructura de las comunidades bento-pelágicas parecen estar moduladas por la combinación de las variables ambientales y los impactos producidos por la actividad humana.

Changes in the composition and biomass distribution of deep-living zooplankton over wide gradients of depth (0–1300 m) have been analyzed in the Central Ligurian Basin (Northwestern Mediterranean Sea), seeking the environmental variables responsible for these changes. Spring vertical distribution (early May 2013) and diel vertical migration (DVM) of some key species of macroplankton and micronekton communities were studied every 6 h during a 24 h cycle. The hauls, performed with the multiple opening/closing 230 µm BIONESS net system, made possible a detailed description of the vertical distribution of twenty-three species: one siphonophore, one pyrosomid, one salp, three pteropods, four amphipods, one mysid, eight euphausiids, two decapods, two fishes. Cluster analysis performed on major species of macroplankton and micronekton community assemblage mainly highlighted the presence of four well defined assemblages, based on the depth range in the water column: 0–60 m, 60–100 m, 100–600 m and from 600 to 1300 m. During daytime, vertical distributions of biomass exhibited similar profiles, with maxima in the 0–60 m layer. Highest abundances were recorded between 20–40 and 40–60 m depth, at midnight and in the morning. The highest values of both biodiversity and number of species were found in a deeper layer comprised between 400 and 600 m. Most of the species showed similar distributions throughout the sampled area, either with typical non-diel-migrating characters such as the euphausiid Stylocheiron longicorne and the fishes Cyclothone braueri and C. pygmaea, or with clear diel-migrant behaviour (e.g. the siphonophore Chelophyes appendiculata and the euphausiid Euphausia krohni). Some species (e.g. Vibilia armata, Phronima sedentaria, Scina crassicornis, Salpa fusiformis, Cavolinia inflexa, Gennadas elegans) exhibited a bimodal vertical distribution that could be attributed to different causes able to influence and modify their vertical migration. The lower values of chlorophylla concentrations found in the present studyinthe month of May corresponds to the transition period from a mesotrophic system to a rather oligotrophic one. Temperature and chlorophyll were the variables that principally influenced the distinction between shallow (0–60 m) and deep communities. Below 60 m depth, the dissolved oxygen and salinity become the most important variables affecting the zooplankton community.

Fishes have evolved various reproductive strategies including mechanisms that involve parental care and demersal eggs laid into nests. Symphodus ocellatus has a seasonal reproduction period during which large, dominant males become territorial and build nests with fragments of algae, where they attract females to spawn and provide care to the developing eggs. Based on the hypothesis that the S. ocellatus males choose the reproductive habitat based on some characteristics of the substrate, here we assessed whether, on a coastal area scale, the distribution of this species changes during the reproductive period because of the selection of some suitable sites or substrates, and whether the nesting microhabitat used by this species responding to certain requirements in relation to different characteristics. From April to September 2010, at four locations and on three substrate types, the fish were counted in three periods related to different stages of reproduction. Furthermore, several physical and biological variables have been recorded around numerous nests to select those with more recurrence. We found that S. ocellatus prefers to live on rocky substrates populated by photophilic algae, regardless of the phases of the reproductive cycle. We identified depth (1.7–3.2 m), the presence of a hole, a 10–20 cm algal canopy, and high algal coverage of Dyctiotales as nest requirements. S. ocellatus is mostly distributed in coastal sites sheltered from the action of waves. This allows the construction and maintenance of nests and the possibility to remain in a water temperature range similar to the reproductive physiological constraints.

16 pages, 5 figures, 3 tables, correction https://www.int-res.com/abstracts/meps/v591/c_p101-116/, Jellyfish have the potential to dominate the pelagic biomass of marine ecosystems, thereby negatively affecting pelagic fish. We investigated the trophic interactions of Pelagia noctiluca (medusae and ephyrae), one of the most abundant and conspicuous jellyfish on the Catalan coast in the NW Mediterranean. A combination of stable isotope and fatty acid analyses was used to obtain a broad picture of the feeding habits of this jellyfish in order to understand its potential interactions with the most abundant fish species (larvae and adults) during the summer in the area. The results suggested that in addition to predation on fish larvae by P. noctiluca, this jellyfish had similar feeding requirements to those of most fish larvae, suggesting potential competition. The trophic niche of medusae and ephyrae overlapped highly with that of larval Engraulis encrasicolus, Trachurus mediterraneus and Sardinella aurita and to a lesser extent with that of Serranus hepatus, Sparus pagrus and Mullus barbatus. No overlap was observed with Arnoglossus sp. larvae and adult E. encrasicolus, Sardina pilchardus, T. mediterraneus and S. aurita. Our findings demonstrated that P. noctiluca could be an important predator and competitor for fish larvae, but not for adult fish. Moreover, salps were found to be a significant food source for P. noctiluca. This study provides information that should be considered in near-future ecosystem-based fishery management in regions where P. noctiluca thrives, This work was supported by the Spanish Ministry of Economy and Competitiveness (FISHJELLY project: CTM2010-18874), and U.T. was supported by a predoctoral fellowship of the FPI program (Spanish Ministry of Economy and Competitiveness)

The effective management and conservation of fishery resources requires knowledge of their spatial distribution and notably of their critical life history stages. Predictive modelling of the European hake (Merluccius merluccius L., 1758) distribution was developed in the south-central Mediterranean Sea by means of historical fisheries-independent databases available in the region. The study area included the international waters of the south-central Mediterranean Sea and the territorial waters of Italy, Malta, Tunisia and Libya. Distribution maps of predicted population abundance index, and probabilistic occurrence of recruits and large adults were obtained by means of generalized additive models using depth and seafloor characteristics as predictors. Presence/absence data of the two life stages was obtained using threshold values applied to the mean weight of the survey catches. Modelling results largely matched previously reported knowledge on habitat preference of the species and its critical life phases. Hake recruits showed an occurrence peak at 200 m depth with preference for soft bottoms. Large adults preferred deeper and harder bottom substrates. Prediction maps allowed to improve our knowledge on the distributional patterns of one of the most important shared stocks in the south-central Mediterranean. This knowledge is essential for an appropriate development of regional-spatial-based management plans.

Surface-dwelling colonies of Velella velella occur throughout tropical to cold-temperate oceans of the world and sometimes are stranded in masses along hundreds of kilometers of beaches. Large-scale blooms in the Western Mediterranean Sea in 2013 and 2014 allowed the study of diet, prey digestion times and predation rates. Gastrozooid content analyses showed that 59% of the 769 identified prey were euphausiid larvae (calytopsis and furcilia) captured at night. Copepods (41%), fish eggs (2.2%) and larvae (0.5%) were captured both at day and night. Digestion times at ambient temperature (similar to 17 degrees C) of calytopsis, furcilia and copepods were estimated to be >6.5, 4.4 and 3.9 h, respectively. Estimated prey consumption was substantially lower in 2014 than in 2013 (41 vs. 75 prey day(-1) colony(-1)). Velella velella and other gelatinous species bloomed in the Mediterranean Sea and the northeastern Atlantic and Pacific oceans in 2013 and 2014. Because of the wide distribution of V. velella colonies, their mass occurrences, potential importance as predators and competitors of fish, additional production from symbiotic zooxanthellae and stranding on beaches, they could be important in open-ocean carbon cycling and in transport of pelagic production to landmasses.

11 pages, 8 figures, 2 tables, supplementary material http://journal.frontiersin.org/article/10.3389/fmars.2017.00240/full#supplementary-material, In recent years, caged finfish mariculture across European seas suffered production losses by severe fish mortality, following episodic outbreaks of invertebrate cnidarian stingers. Due to their stinging cells and injectable venoms, medusozoan jellyfish, or drifting propagules of polyp colonies at high density may impair caged fish health through toxic effects on vulnerable tissues of gills and skin, and related secondary bacterial infections. Gill disorders in European sea bass (Dicentrarchus labrax) fish farms along the Spanish Mediterranean coast are commonly reported, but regular monitoring of the frequency of cnidarian outbreaks and their potential impacts on caged fish is still poorly enforced. In this study, two sea bass mariculture farms in Southern Spain (Málaga; Almería) were monitored biweekly for zooplankton, phytoplankton and fish gills condition, over 13 or 30 months for the Málaga and Almería facilities, respectively, within the period 2012–2014. Significant, direct correlations were found among low water temperature, recorded fish mortalities, and high abundances of planktonic cnidarians, particularly of the hydrozoan siphonophores Muggiaea atlantica and M. kochii, and the larval stage of Ectopleura larynx, a common member of cage biofouling communities. A significant relationship between cnidarian densities and the quantitative scoring of gill pathology was also observed. In addition, high densities of long-bristled planktonic diatoms (Chaetoceros spp.) coincided with a major fish mortality event (April 2012, Almería farm). Standardised monitoring of plankton dynamics and composition may help in promoting response capacities of Mediterranean mariculture managers to fish health challenges (such as stinging plankton blooms) by (a) improving diagnostic tools and preventative countermeasures and (b) supporting the development of science-based spatial planning and sustainable growth of coastal mariculture, This work has received funding from the European Union's projects MED-JELLYRISK (grant n. I-A/1.3/098 - ENPI CBCMED programme), VECTORS (Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors, grant n. 266445, FP7th programme) and CERES (Climate Change and European Aquatic Resources, grant n. 678193, Horizon 2020 programme)

7 pages, 5 figures, 3 tables, supplemental material https://doi.org/10.1016/j.marpol.2016.11.005, In recent years, negative impacts of jellyfish blooms (JB) on marine human activities have been increasingly reported. Aquaculture has been affected by jellyfish outbreaks, mostly documented through repeated episodes of farmed salmon mortalities in Northern Europe; however, the valuation of JB consequences on the aquaculture sector still remains poorly quantified. This study aims to provide the first quantitative evaluation effects of JB on finfish aquaculture in the Mediterranean Sea and to investigate the general awareness of JB impacts among Mediterranean aquaculture professional workers. The aquaculture workers' perception about JB was assessed through a structured interview-based survey administered across 21 aquaculture facilities in central and western Mediterranean. The workers' awareness about JB impacts on aquaculture differed among countries. Italian and Spanish fish farmers were better informed about jellyfish proliferations and, together with Tunisian farmers, they all recognized the wide potential consequences of JB on sea bream and sea bass aquaculture. On the contrary, the majority of Maltese respondents considered JB as a non-significant threat to their activity, mostly based on off-shore tuna farming. This study for the first time shows that JB may negatively affect different Mediterranean aquaculture facilities from Tunisia (Sicily Channel) and Spain (Alboran Sea), by increasing farmed fish gill disorders and mortality, clogging net cages, or inflicting painful stings to field operators, with severe economic consequences. Available knowledge calls for the development of coordinated preventive plans, adaptation policies, and mitigation countermeasures across European countries in order to address the JB phenomenon and its impacts on coastal water activities, This work has received funding from the European Union's projects MED-JELLYRISK (grant n. I-A/1.3/098 - ENPI CBCMED programme), VECTORS (Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors, grant n. 266445, FP7th programme), and CERES (Climate Change and European Aquatic Resources, grant n. 678193, Horizon 2020 programme)

Submarine caves are environments of great ecological interest because of the occurrence of peculiar conditions, such as the attenuation of light and reduced water turnover, which can determine oligotrophic conditions from the entrance to the interior part of the cave. These environmental gradients may influence the distribution of the communities inhabiting submarine caves. In this study we investigated the meiofaunal community and nematode assemblages from the sediments inside and outside two submarine caves in Ustica Island Marine Protected Area (southwest Italy): Grotta Falconiera and Grotta dei Gamberi. Consistently with a general pattern of distribution reported by several studies on benthic organisms, our results showed a decrease in the abundance and changes in the taxa composition of the meiofaunal community along the exterior-interior axis of the caves, also highlighting the dissimilarity between the dark and semi-dark communities. We found a significant influence of the availability of organic matter (i.e. phytopigment concentrations) on the distribution and composition of both the meiofauna and the nematode community inside the caves. Different nematode assemblages characterized the inside and the outside of the two caves, with species occurring exclusively in the sediment of both caves, particularly in the dark portions, and completely absent in the external sediments. Environmental features of submarine caves may affect food resources inside the caves and consequently trophic nematode assemblages. Our results showed a difference in feeding strategies between nematodes inhabiting the caves and those living outside, suggesting that in the two caves investigated, bacteria might represent the most important food source for nematodes.

13 pages, 4 figures, 6 tables, Predation is the principal direct cause of mortality of fish eggs and larvae (ichthyoplankton). Pelagic cnidarians and ctenophores are consumers of ichthyoplankton and zooplankton foods of fish, yet few estimates exist of predation effects in situ. Microscopic analyses of the gastric 'gut' contents of gelatinous predators reveal the types and amounts of prey eaten and can be used with digestion time (DT) to estimate feeding rates (prey consumed predator?1 time?1). We measured the DT and recognition time (RT) of prey for Pelagia noctiluca, an abundant jellyfish with increasing blooms in the Mediterranean Sea. DT of fish larvae averaged 2.5 to 3.0 h for P. noctiluca (4?110 mm diameter) and was significantly related to jellyfish and larval sizes. In contrast, DT of fish eggs ranged from 1.2 to 44.8 h for jellyfish ?22 mm diameter ('ephyrae'), but DT was not significantly related to ephyra or egg diameter. Approximately half of the eggs ingested were not digested. DT of copepods averaged 4 h. We also measured DT and RT of salps, euphausiids, and miscellaneous zooplankton. Temperature (20?25C) generally did not significantly affect DT of any prey. Estimated potential predation effects of ephyrae on fish larvae in the Catalan Sea in 1995 showed great variability among 9 stations (0?3.7% consumed h?1). We discuss how sampling methods contributed to variation in predation estimates and offer recommendations to improve accuracy. Our results enable estimation of predation on ichthyoplankton and competition for zooplankton prey, which can have extremely important effects on fish populations globally. © Inter-Research 2014, This study was supported by the project MAR-CTM2010-18874. V.L.F. was funded by a JAE-DOC contract of CSIC co-financed by the FSE (European Social Fund)

In the Mediterranean, sea breams are the most effective Paracentrotus lividus and Arbacia lixula predators. Generally, seabreams dislodge adult urchins from the rocky substrate, turn them upside down and crush their tests. Sea urchins may respond to fish attacks clinging tenaciously to the substratum. This study is the first attempt to investigate sea urchin adhesion strength in two alternative algal assemblages of the rocky infralittoral and valuated its possible implication for fish predation. We hypothesized that (1) sea urchin adhesion strength is higher in rocky shores dominated by encrusting macro-algae (ECA) than in erected macro algae (EMA); (2) predation rates upon sea urchins are lower in ECA than in EMA; and (3) predation rate on A. lixula is lower than that on P. lividus. We observed that attachment tenacity of both sea urchins was higher in ECA than EMA and that A. lixula exhibited a stronger attachment tenacity than P. lividus in ECA. Results supported the importance of adhesion strength, as efficient defence against sea bream attacks, only for, P. lividus. A. lixula adhesion strength does not seem to be an important factor in avoiding fish predation, possibly because of the low palatability of the species.These patterns may deserve particular interest in understanding the processes responsible for the maintenance of sea urchin barrens that are dominated by ECA assemblage.