Anthropogenic pollutants in Nephrops norvegicus (Linnaeus, 1758) from the NW Mediterranean Sea: Uptake assessment and potential impact on health.

Anthropogenic pollution is considered one of the main threats to the marine environment, and there is an imperious need to assess its potential impact on ecologically and economically relevant species. This study characterises plastic ingestion and tissue levels of potentially toxic metallic elements in Nephrops norvegicus and their simultaneous levels in abiotic compartments from three locations of the Catalan coast (NW Mediterranean Sea). A multidisciplinary assessment of the health condition of N. norvegicus through condition indices, enzymatic biomarkers and histological techniques is provided, and its relationship with anthropogenic pollutant levels explored. Plastic fibres were commonly found in stomachs of N. norvegicus (85% of the individuals), with higher abundances (13 ± 21 fibres · ind-1) in specimens captured close to Barcelona. The presence of long synthetic fibres in near-bottom waters, as well as the mirroring trends in abundance among locations for water and ingested plastics, suggest that uptake from water may be occurring potentially through suspension feeding. The spatial variability in the levels of metallic elements in N. norvegicus was poorly correlated to the variability in sediments. In any case, present levels in abdominal muscle are considered safe for human consumption. Levels of ingested plastics only showed significant, yet weak, correlations with glutathione S-transferase and catalase activities. However, no other health parameter analysed showed any trend potentially associated to anthropogenic pollutant levels. Neither the condition indices nor the histopathological assessment evidenced any signs of pathologic conditions affecting N. norvegicus. Thus, it was concluded that presently there is no evidence of a negative impact of the studied pollutants on the health condition of N. norvegicus in the studied grounds.

An affordable method for monitoring plastic fibre ingestion in Nephrops norvegicus (Linnaeus, 1758) and implementation on wide temporal and geographical scale comparisons.

Although the ingestion of plastics has been reported in a wide variety of organisms, there remains a lack of knowledge regarding the extent of spatial and temporal gradients and no consensus concerning the definition of monitor species for benthic marine environments. The present study aims at demonstrating the correlation between the presence of tangled balls of fibres and high levels of total plastic fibre ingestion in Nephrops norvegicus to assess the potential use of the prevalence of tangled balls as indicators of fibre pollution. To do so, the presence of plastics in stomach contents from several European populations of N. norvegicus is characterized in detail, including size distribution and polymer composition, and then its correlation with the prevalence of balls tested. Our results demonstrate that the prevalence of balls (>20%) is significantly correlated to higher levels of plastic ingestion, regardless of polymer composition and size distribution of ingested fibres. Plastic fibre ingestion levels across wide temporal and geographical scales are assessed using only the prevalence of balls, highlighting areas of increased fibre ingestion (e.g., the Gulf of Cadiz, N Barcelona) and areas of potentially lower fibre pollution (e.g., the Ebro Delta, the NW Iberian margin). Moreover, the relationship between the prevalence of balls and diet composition is analysed to discard a potential relationship with geographical differences in diet habits. Finally, we discuss the benefits and drawbacks of the use of the prevalence of tangled balls of fibres as an affordable, cost-effective and easy to implement indicator of fibre pollution for monitoring purposes in this species.

A closer look at anthropogenic fiber ingestion in Aristeus antennatus in the NW Mediterranean Sea: Differences among years and locations and impact on health condition.

Marine litter is one of the most concerning threats for marine wildlife especially regarding plastics and their micro-sized forms, widely known as microplastics. The present study evaluates mesoscale spatial (230 km, Catalan coast) and temporal (2007 vs 2017-2018, Barcelona area) differences on the ingestion of anthropogenic fibers in the deep-sea shrimp Aristeus antennatus in the NW Mediterranean Sea and its relation with shrimp's health condition. Synthetic fibers with lengths ranging between 0.16 and 37.9 mm were found in both stomach (where sometimes they were tangled up in balls) and intestine contents. The percentage of fiber occurrence was >65% at each sampling point. Tangled balls of fibers observed in stomach contents exhibited a wide range of sizes (up to a diameter of 1 cm) and were usually composed of fibers of different polymers, sizes and colours. Differences between locations (2018) were found, with greater fiber loads towards the south during spring and a great variability in summer, as shrimps caught off Barcelona showed a nearly thirty-times higher fiber load compared to shrimps from other localities. Highest concentrations were more likely to be related to major sources of fibers and currents in the area. Fiber load in shrimps from 2007 was comparable to that of shrimps captured in 2017 and 2018 (spring) yet a shift in the proportion of acrylic and polyester polymers was detected. No consistent effect on shrimp's health condition was found, with only a significant negative correlation found between gonadosomatic index and fibers for those shrimps with the highest values of fiber load (caught off Barcelona, summer 2018). Our findings contribute to the knowledge on plastic pollution for the NW Mediterranean Sea and highlight the potential use of this species as a sentinel species for plastic fiber contamination.

Drivers of parasite community structure in fishes of the continental shelf of the Western Mediterranean: the importance of host phylogeny and autecological traits.

We explored the relationships between features of host species and their environment, and the diversity, composition and structure of parasite faunas and communities using a large taxonomically consistent dataset of host-parasite associations and host-prey associations, and original environmental and host trait data (diet, trophic level, population density and habitat depth vagility) for the most abundant demersal fish species off the Catalonian coast of the Western Mediterranean. Altogether 98 species/taxa belonging to seven major parasite groups were recovered in 683 fish belonging to 10 species from seven families and four orders. Our analyses revealed that (i) the parasite fauna of the region is rich and dominated by digeneans; (ii) the host parasite faunas and communities exhibited wide variations in richness, abundance and similarity due to a strong phylogenetic component; (iii) the levels of host sharing were low and involved host generalists and larval parasites; (iv) the multivariate similarity pattern of prey samples showed significant associations with hosts and host trophic guilds; (v) prey compositional similarity was not associated with the similarity of trophically transmitted parasite assemblages; and (vi) phylogeny and fish autecological traits were the best predictors of parasite community metrics in the host-parasite system studied.

Spatial occurrence and effects of microplastic ingestion on the deep-water shrimp Aristeus antennatus.

Microplastic (MP) ingestion has been reported in a wide variety of organisms, however, its spatial occurrence and effects on wild populations remain quite unknown. The present study targets an economically and ecologically key species in the Mediterranean Sea, the shrimp Aristeus antennatus. 39.2% of the individuals sampled had MP in their stomachs, albeit in areas close to Barcelona city the percentage reached values of 100%. Overall, MP ingestion was confirmed in a wide spatial and depth (630-1870 m) range, pointing out the great dispersion of this pollutant. The benthophagous diet and close relationship with the sea bottom of A. antennatus might enhance MP exposure and ultimately lead to accidental ingestion. Detailed analysis of shrimps' diet revealed that individuals with MP had a higher presence of endobenthic prey. Microplastic fibers are probably retained for long periods due to stomach's morphology, but no negative effects on shrimp's biological condition were observed.

Petalophthalmus papilloculatus sp. nov. (Crustacea: Mysida: Petalophthalmidae), a new bathyal suprabenthic mysid from the Galicia Bank (NE Atlantic Ocean).

A new species of the genus Petalophthalmus (Crustacea: Mysida: Petalophthalmidae) is described, based on specimens collected from the Galicia Bank (northeastern Atlantic Ocean). This species can be distinguished from the other species of the genus Petalophthalmus by the presence of an ocular papilla on its eyes. P. papilloculatus sp. nov. is morphologically close to the cosmopolitan species P. armiger Willemoes-Suhm, 1875, but can be easily distinguished by the presence of an ocular papilla, the longer antennal scales bearing an apical lobe, the unique chitinous ridge on the molar process, the outwards lengthening of the three cuspidate setae on the outer margin of the uropodal exopod and the armature of the telson. This new species lives on fine and very fine sandy bottoms at the bank flanks, between 1536 and 1809 m depths. Probably related to the special biogeographic characteristics of seamounts, the morphological affinity between the new species and P. armiger supports the hypothesis on a common ancestry and recent divergence between both deep sea mysids. An identification key to world species of Petalophthalmus is provided.

Sinking jelly-carbon unveils potential environmental variability along a continental margin.

Particulate matter export fuels benthic ecosystems in continental margins and the deep sea, removing carbon from the upper ocean. Gelatinous zooplankton biomass provides a fast carbon vector that has been poorly studied. Observational data of a large-scale benthic trawling survey from 1994 to 2005 provided a unique opportunity to quantify jelly-carbon along an entire continental margin in the Mediterranean Sea and to assess potential links with biological and physical variables. Biomass depositions were sampled in shelves, slopes and canyons with peaks above 1000 carcasses per trawl, translating to standing stock values between 0.3 and 1.4 mg C m(2) after trawling and integrating between 30,000 and 175,000 m(2) of seabed. The benthopelagic jelly-carbon spatial distribution from the shelf to the canyons may be explained by atmospheric forcing related with NAO events and dense shelf water cascading, which are both known from the open Mediterranean. Over the decadal scale, we show that the jelly-carbon depositions temporal variability paralleled hydroclimate modifications, and that the enhanced jelly-carbon deposits are connected to a temperature-driven system where chlorophyll plays a minor role. Our results highlight the importance of gelatinous groups as indicators of large-scale ecosystem change, where jelly-carbon depositions play an important role in carbon and energy transport to benthic systems.

Estimating trends of population decline in long-lived marine species in the Mediterranean Sea based on fishers' perceptions.

We conducted interviews of a representative sample of 106 retired fishers in Italy, Spain and Greece, asking specific questions about the trends they perceived in dolphin and shark abundances between 1940 and 1999 (in three 20 year periods) compared to the present abundance. The large marine fauna studied were not target species of the commercial fleet segment interviewed (trawl fishery). The fishers were asked to rank the perceived abundance in each period into qualitative ordinal classes based on two indicators: frequency of sightings and frequency of catches (incidental or intentional) of each taxonomic group. The statistical analysis of the survey results showed that both incidental catches and the sighting frequency of dolphins have decreased significantly over the 60+ years of the study period (except for in Greece due to the recent population increase). This shows that fishers' perceptions are in agreement with the declining population trends detected by scientists. Shark catches were also perceived to have diminished since the early 1940s for all species. Other long-lived Mediterranean marine fauna (monk seals, whales) were at very low levels in the second half of the 20(th) century and no quantitative data could be obtained. Our study supports the results obtained in the Mediterranean and other seas that show the rapid disappearance (over a few decades) of marine fauna. We show that appropriately designed questionnaires help provide a picture of animal abundance in the past through the valuable perceptions of fishers. This information can be used to complement scientific sources or in some cases be taken as the only information source for establishing population trends in the abundance of sensitive species.

Hepatic biomarkers of xenobiotic metabolism in eighteen marine fish from NW Mediterranean shelf and slope waters in relation to some of their biological and ecological variables.

A suite of hepatic biomarkers currently used in pollution monitoring were measured in eighteen common fish species, comprising five orders, eleven families of teleosts and two elasmobranchs. The sampling was carried out seasonally in front of the Barcelona coast (NW Mediterranean) during 2007. The hepatic enzymes considered were the activities of catalase, glutathione reductase, ethoxyresorufin O-deethylase, carboxylesterase and glutathione S-transferase. As markers at higher levels of biological organization, feeding preferences (on benthic, suprabenthic or zooplanktonic species), swimming capability, stomach fullness and trophic level were considered. Significant species differences were found among all the biochemical parameters analysed, although no relationships among the biomarkers themselves were evidenced. In general enzymatic activities were much higher in teleosts than in elasmobranchs, and in perciforms than in gadiforms. Seasonality was observed in some species with higher activities usually corresponding to the winter period. No site related differences were observed in the two selected sites, which differ over a small pollution gradient. A multivariate canonical Correspondence analysis (CCA) was performed on shelf and slope species separately to relate biochemical markers with ecological variables. CCA revealed that for shelf species, EROD was positively related to benthos feeding as well as trophic level, while on the slope the clearest association was between suprabenthos feeders and trophic level. Our present results, including seasonality, slightly differ from former observations (Solé et al., 2009a) and reveal a more significant role of the ecological variables in controlling biomarkers expression in fish from the shelf.

Muscular cholinesterase activities and lipid peroxidation levels as biomarkers in several Mediterranean marine fish species and their relationship with ecological variables.

Muscular cholinesterase activities, as potential markers of neurotoxic exposure, and lipid peroxidation levels, indicative of oxidative stress damage, both currently used in early-warning pollution monitoring, were characterised in eighteen fish species of ecologic and/or economic importance. These species comprise five orders and eleven families of teleosts and two species of elasmobranchs, feed using different strategies (benthic, epibenthic, endobenthic and pelagic), belong to different trophic levels and express different swimming behaviour. Their habitat ranges from 50 to 60 m (shallow or continental shelf) and 600 to 850 m (middle continental slope). Sampling took place in front of the Barcelona coast (NW Mediterranean) during four seasonal cruises in 2007. In the summer sampling, another site potentially exposed to a different pollution load (Vilanova) was included for comparison. Species, seasonal and site differences were tested and discussed in relation to chemical analysis of the local sediment, systematic position, habitat depth, feeding strategy, trophic level and swimming activity. Greater inter species differences rather than seasonal or site trends were seen in accordance to little pollution fluctuations. Higher cholinesterase activities were recorded in suprabenthos feeders, regardless of depth habitat, whereas LP levels were similar in all species except for the shark Scyliorhinus canicula in which they were consistently elevated. This study confirms and broadens former observations carried out with a more reduced number of fish species (Solé et al., 2008a).

Biliary fluorescent aromatic compounds (FACs) measured by fixed wavelength fluorescence (FF) in several marine fish species from the NW Mediterranean.

The fixed wavelength fluoresce (FF) method was used to estimate the levels of fluorescent aromatic compounds (FACs) in the bile of fourteen fish species of commercial and/or ecological interest. Sampling was carried out in the NW Mediterranean at depths ranging from 50 to 1000 m during four seasonal cruises. During the summer sampling period, some species were also collected from another site (Vilanova fishing grounds) for comparison. Baseline levels of the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene, pyrene and benzo[a]pyrene were measured. Some seasonality was observed, with reduced FF levels in summer and no differences among sites, consistent with sediment PAH levels. We discuss our results in relation to fish phylogeny, season, depth, diet, trophic level and swimming capacity. Overall FF levels indicated differences among species; the suprabenthic feeders from shallow and deep communities, and Mullus barbatus in particular, displayed elevated FF values and are potential candidates for additional monitoring studies.