Joan Enric Cartes

DEEP-WATER DECAPOD CRUSTACEAN COMMUNITIES IN THE NORTHWESTERN MEDITERRANEAN : INFLUENCE OF SUBMARINE CANYONS AND SEASON

The specific composition and abundance of bathyal decapods in the Catalan Sea were investigated. A total of 109 bottom trawls were effected at depths ranging from 141 to 730 m on the continental slope in the Catalan Sea (northwestern Mediterranean) during two sampling cruises in spring and autumn 1991. Multivariate analysis of the samples revealed four groups of the decapod crustacean communities: (1) A shelf-slope transition-zone group at depths between 146 and 296 m, primarily characterized by the presence of Plesionika heterocarpus; (2) an upper-slope community between 245 and 485 m, characterized by the presence of the mesopelagic species Pasiphaea sivado and Sergestes arcticus, with Processa nouveli, Solenocera membranacea and Nephrops norvegicus as secondary species; (3) a middle-slope community below 514 m, with Aristeus antennatus and Calocaris macandreae as the most abundant species; (4) a group at 430 to 515 m, comprising all samples collected exclusively within or in the vicinity of submarine canyons. Mesopelagic decapods were predominant on the slope, while benthopelagic fishes (Merluccius merluccius, Micromesistius poutassou, Gadiculus argenteus) replaced mesopelagic decapods on the shelf. There were seasonal variations, with higher densities of mesopelagic species in spring, which were probably related, among other factors, to variations in the photoperiod. Our surveys also revealed higher species richness in the canyons together with seasonal changes in the megafaunal biomass. Generally, the upper and middle-slope communities both displayed seasonal changes in the composition and abundance of megabenthos.

Dynamics of the bathyal Benthic Boundary Layer in the northwestern Mediterranean: depth and temporal variations in macrofaunal–megafaunal communities and their possible connections within deep-sea trophic webs

The distribution patterns of benthopelagic fauna and the macrofauna‐megafauna trophic relationships in the Benthic Boundary Layer (BBL) were studied. The study is based on data collected during 6 sampling cruises off the Catalan coast (western Mediterranean) during 1991‐1995 at depths ranging from 389‐1355 m. Crustaceans were the dominant benthopelagic macrofauna in the BBL level closest to the sea bed (~0‐1.5 m above bottom) on the Catalan Sea slope. Copepods and peracarid crustaceans (mysids, amphipods, isopods, and cumaceans) were dominant, whereas euphausiids and natantian decapods, some taxa of gelatinous plankton (siphonophores, medusae, and chaetognaths), and benthopelagic fishes were also well represented groups. Seasonal changes in megafaunal decapod crustaceans abundance seem to be linked to changes in the density and the biological cycle of BBL macrofauna, which constitute an important part of the available food exploited by megafauna. Both the advective and the vertical flow of organic matter in the north-western Mediterranean should simultaneously influence peaks of available food (BBL macrofauna) for bathyal‐megafaunal decapods. Recruitment of macrofaunal (suprabenthos and infauna) species at the level of canyons and neighbouring slope zones mainly occurred between late autumn‐late winter and would probably be mainly induced by an advective component. However, the macrofaunal sizes consumed by megafaunal decapods are found more abundantly represented in spring and summer populations. In parallel, the vertical fluxes seem to determine maxima in the abundance of planktonic organisms (especially copepods) which also occur in late spring‐summer. Size, natatory capability, and energetic value are important factors in the selection of food-resources by

Spatio-temporal variations in megabenthos abundance in three different habitats of the Catalan deep-sea (Western Mediterranean)

The spatio-temporal variations in the megafauna (fishes, crustaceans, and other invertebrates) in three different habitats on the slope in the Western Mediterranean (Catalan coast off Barcelona) have been investigated. Samples were collected at two fixed stations during 1991 and 1992, one inside and one outside a submarine canyon (at depths between 450 and 600 m) and additional samples were collected at another station on the lower slope (at a depth of 1200 m) in each season of the year. Three replicates of each sample were taken at each station. Differences observed between habitats, seasons, and zoological groupings were verified statistically by factorial ANOVA. The habitat appeared to be the main factor responsible for the differences observed in biomass and abundance values for the zoological groupings considered. Decapod crustacean biomass was higher in the submarine canyon than in neighbouring zones, and smaller species and juveniles were more abundant inside the canyon in the case of both fishes and crustaceans. Fish biomass was most abundant in the lower slope. Seasonality was also a factor, although to a lesser extent. Seasonal variations in biomass, especially fish biomass, were recorded in the deepest zone (1200 m). Crustaceans displayed lower sensitivity to seasonal factors, whereas other invertebrates did not, on the whole, exhibit seasonal variations.

Community structure of bathyal decapod crustaceans off south-west Balearic Islands (western Mediterranean): seasonality and regional patterns in zonation

The community structure of decapod crustacean assemblages was established and analysed from two experimental trawl samplings. The data were taken in the south-west Balearic Islands (Algerian Basin, western Mediterranean Sea) at depths ranging from ~200 to 1800 m. The results of multivariate analysis indicate that the community structure remained constant between samplings. The analysis also revealed that there exist differences between bathyal decapod communities at a regional level (< 1000 km) when compared with well-studied nearby areas. The differences relate mainly to the relative contribution of different species and feeding guilds, not to the taxonomic composition of the assemblages studied. It is proposed that these differences result from contrasting surface production regimes (coastal vs open sea) and food web organization (relative dependence on mesopelagic or infaunal prey).

Influence of depth and season on the diet of the deep-water aristeid Aristeus antennatus along the continental slope (400 to 2300 m) in the Catalan Sea (western Mediterranean)

The composition of the diet of the deep-sea aristeid shrimp Aristeus antennatus (Risso, 1816) was determined based on the analysis of 1578 stomach contents. Samples were collected using bottom trawls during 1984 to 1989 along the deep continental slope (380 to 2266 m) in the Catalan Sea (Western Mediterranea). A. antennatus displayed a high feeding activity on a large variety of endobenthic and epibenthic invertebrates, whereas benthopelagic prey were supplementary to its diet. The shrimps diet varied mainly as a function of depth. Various preferred prey items on the middle slope (Calocaris macandreae, Cirolana borealis, Abra longicallus) disappeared from its diet below 1300 m, coinciding with the transtion boundary between different taxocenoses in the Catalan Sea. Less mobile prey and inert remains (mainly pteropods) contributed a progressively larger share of the diet of Aristeus antennatus with increasing depth. The importance of seasonality in the changes in diet decreased with increasing depth, and was relatively high only in the upper middle slope (down to 1000 m depth), where two seasonal dietary groups were detected. The most distinct seasonal changes in diet were among benthopelagic prey. The diet of A. antennatus in the submarine canyons mainly consisted of endobenthic prey (large polychaetes, ophiuroids). The higher stomach-fullness values and less diversified diet in this area were probably related to high productivity in the submarine canyons.

Jelly-falls historic and recent observations: a review to drive future research directions

The biological pump describes the transport of particulate matter from the sea surface to the ocean’s interior including the seabed. The contribution by gelatinous zooplankton bodies as particulate organic matter (POM) vectors (“jelly-falls”) has been neglected owing to technical and spatiotemporal sampling limitations. Here, we assess the existing evidence on jelly-falls from early ocean observations to present times. The seasonality of jelly-falls indicates that they mostly occur after periods of strong upwelling and/or spring blooms in temperate/subpolar zones and during late spring/early summer. A conceptual model helps to define a jelly-fall based on empirical and field observations of biogeochemical and ecological processes. We then compile and discuss existing strategic and observational oceanographic techniques that could be implemented to further jelly-falls research. Seabed video- and photography-based studies deliver the best results, and the correct use of fishing techniques, such as trawling, could provide comprehensive regional datasets. We conclude by considering the possibility of increased gelatinous biomasses in the future ocean induced by upper ocean processes favouring their populations, thus increasing jelly-POM downward transport. We suggest that this could provide a “natural compensation” for predicted losses in pelagic POM with respect to fuelling benthic ecosystems.

Les Communautés Suprabenthiques Bathyales De La Mer Catalane (Méditerranée Occidentale): Données Préliminaires Sur La Répartition Bathymétrique Et L'Abondance Des Crustacés Péracarides

99 species of Peracarid Crustaceans (2 Mysidacea, 52 Amphipoda, 28 Cumacea, 15 Isopoda, and 2 Tanaidacea) were identified during a sampling performed on the muddy bottoms of the deep slope in front of Barcelona (western Mediterranean). Ten deep-water samples were performed between 552-1808 m using a small plankton net attached to a bottom trawl. Fifteen species should be considered as Mediterranean endemics: Ampelisca cf. anophthalma, Ampelisca dalmatina, Carangoliopsis spinulosa, Urothoe corsica, Lilljeborgia psaltrica, Idunella pirata, Bathymedon banyulsensis, Oediceropsis pilosa, Pardaliscoides stebbingi, Syrrhoe angulipes, Janirella bonnieri, Fageapseudes retusifrons, Diastyloides carpinei, Diastylis jonesi, and Makrokylindrus stebbingi, while 9 other species were recorded for the first time in the Mediterranean: Epimeria parasitica, Rhachotropis gracilis, Andaniexis abyssi, Chelator insignis, Desmosoma lineare, Belonectes parvus, Munnopsurus atlanticus, Ilyarachna longicornis, and Janirella nanseni. On the upper middle slope amphipods were the dominant taxa both in terms of species richness and abundance. Cumaceans were progressively more abundant when depth increased, being the dominant taxa on the lower slope. All these trends were discussed in the light of the sampling method used and in function of the ecological factors characterizing the deep bathyal environment in the Catalan Sea.

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.

Estimating secondary production in bathyal suprabenthic peracarid crustaceans from the Catalan Sea slope (western Mediterranean; 391–1255 m)

A first estimate of secondary production in populations of deep-water suprabenthic peracarids of the Catalan Sea slope (northwestern Mediterranean) was attempted. Estimates are based both on the size-frequency Hynes-Hamilton method and on two empiric models. Our data set was based on four oceanographic cruises carried out in 1991 and 1992 between 391 and 1255 m depth, covering the four annual seasons (April 1991, December 1991, March 1992, and July 1992). Production oscillated, depending of each species, between 0.129 mg DW/m2/year for the Cumacea Leucon longirostris and 9.002 mg DW/m2/year for the mysid Boreomysis arctica. P/B ratios ranged between 1.56 for L. longirostris and 12.64 for the Amphipoda Rhachotropis glabra. The extreme results cited were always obtained with the Hynes-Hamilton method. Comparing the two empiric models used, Brey’s (1990) equation values were always lower than the results obtained with the Morin and Bourassa (1992) model, both for production and P/B ratios. Our production values for deep-sea peracarids were always lower ( 4–5 orders of magnitude lower in the case of Amphipoda) than available data for marine littoral and shallow-water peracarids. However, P/B ratios obtained from our suprabenthic deep-water peracarids were within the same range as that cited for coastal and neritic species. Also, and summarising the available data, suprabenthos crustaceans showed higher P/B ratios than infauna, whereas P/B for our suprabenthic species were within the range cited for mesopelagic euphausiids.

Xenobiotic metabolism markers in marine fish with different trophic strategies and their relationship to ecological variables

Nine fish species of commercial interest from six teleost families and two species of elasmobranchs were selected for characterisation of hepatic biomarkers used in early-warning assessment of pollutant exposure. The sampling was carried out in front of the Barcelona coast (NW Mediterranean) during December 2006 at shelf (53 m) and slope (660 m) depths. The enzymes considered included the antioxidant defence catalase (CAT) and glutathione reductase (GR), phase I ethoxyresorufin O-deethylase (EROD) and phase II glutathione S-transferase (GST). Protein yield (PY) was used as a general marker of hepatic protein synthesis. Significant interspecies differences were evidenced, although each marker varied independently. Enzymatic activities in teleosts were higher than in elasmobranchs; they were very low in Scyliorhinus canicula (mainly a benthic feeder), but not so low in Galeus melastomus (pelagic feeder). In relation to depth, shallow water, shelf-living species had higher metabolic activities. Trophic variables were significantly related to PY and EROD activity, and were especially high in benthic/suprabenthic feeders. Trophic level (deduced from stable isotopy) and stomach fullness were associated with all hepatic markers, except GR. Swimming capacity was related to all hepatic enzymes. Our findings can be applied, not only from the perspective of conservation ecology regarding pollution, but also in fisheries, due to the economic interest of the species involved.