[Show abstract][Hide abstract] ABSTRACT: Deep-sea communities associated to the so-called cold water corals (CWC), show unique complexity and species diversity, because corals act as potential areas of foraging, refuge and breeding for many deep-sea species, enhancing their ecological dimensions. In early '90, the coral Isidella elongata formed pristine forests on soft sediments in the north-western Mediterranean but from 1996 the habitat has been subjected to fishing activity. During the present study we found pour density colonies of the coral (decreased from 255 colonies/ha to 0.9 colonies/ha). We analysed infauna samples from two different habitats, mud and coral mud habitats, through multivariate analysis. We also investigated possible mesoscale gradients related to environmental variability. Despite the start of the fishing, we found that samples were segregated mainly according to the habitat, but also high variability within the same habitat has been observed. The coral mud habitat showed higher heterogeneity of species composition and biomasses and was dominated by detritivores (mainly crustaceans), while in mud habitat we found higher importance of carnivorous than in coral mud habitat. The higher quality of organic source in coral mud habitat and other favorable environmental variables with respect to the mud habitat permit to identify different infaunal assemblages.
WORKSHOP IN BIOSTATISTICS OF YOUNG RESEARCHERS, Santiago de Compostela; 06/2014
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: The Galicia Bank (NE Atlantic, 42°67′N–11°74′W) is an isolated seamount, near NW Spain, a complex geomorphological and sedimentary structure that receives influences from contrasting water masses of both northern and southern origins. Within the project INDEMARES, three cruises were performed on the bank in 2009 (Ecomarg0709), 2010 (BanGal0810) and 2011 (BanGal0811) all in July–August. Decapods and other macrobenthic crustaceans (eucarids and peracarids) were collected with different sampling systems, mainly beam trawls (BT, 10 mm of mesh size at codend) and a GOC73 otter trawl (20 mm mesh size). Sixty-seven species of decapod crustaceans, 6 euphausiids, 19 peracarids and 1 ostracod were collected at depths between 744 and 1808 m. We found two new species, one a member of the Chirostylidae, Uroptychus cartesi Baba & Macpherson, 2012, the other of the Petalophthalmidae (Mysida) Petalophthalmus sp. A, in addition to a number of new biogeographic species records for European or Iberian waters. An analysis of assemblages showed a generalized species renewal with depth, with different assemblages between 744 and ca. 1400 m (the seamount top assemblage, STA) and between ca. 1500 and 1800 m (the deep-slope assemblage over seamount flanks, DSA). These were respectively associated with Mediterranean outflow waters (MOW) and with Labrador Sea Water (LSW). Another significant factor separating different assemblages over the Galician Bank was the co-occurrence of corals (both colonies of hard corals such as Lophelia pertusa and Madrepora oculata and/or gorgonians) in hauls. Munidopsids (Munidopsis spp.), chirostylids (Uroptychus spp.), and the homolodromiid Dicranodromia mahieuxii formed a part of this coral-associated assemblage. Dominant species at the STA were the pandalid Plesionika martia (a shrimp of subtropical-southern distribution) and the crabs Bathynectes maravigna and Polybius henslowii, whereas dominant species in the DSA were of northern origin, the lithodid Neolithodes grimaldii and the crangonid Glyphocrangon longiristris, likely associated with LSW. The diversity (H and J) of small crustaceans (collected with BT) seemed to be controlled by the phytoplankton blooms (satellite Chl a data) over bank surface 3 months before the samplings, both at the top (Spearman r=0.57, p=0.03) and on the flanks (r=0.74, p=0.02) of Galicia Bank, while no significant relationships with Chl a were found for the larger decapods collected with GOC73, on average they feed at the higher trophic levels than those collected with BT.
Deep Sea Research Part II Topical Studies in Oceanography 01/2014; 106:165–178. · 2.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 m2 after trawling and integrating between 30,000 and 175,000 m2 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.
[Show abstract][Hide abstract] ABSTRACT: Bottom trawling is one of the main sources of anthropogenic disturbance in benthic habitats with important direct and indirect effects on the ecosystem functional diversity. In this study, the effect of this impact on a structure-building species, the sea urchin Gracilechinus acutus was studied in the Central Cantabrian Sea (southern Bay of Biscay) comparing its isotopic signature and additional population descriptors across different trawling pressures. Trawling disturbance had a significant effect on the studied descriptors. In trawling areas this urchin showed significantly lower values of biomass and mean size and significantly higher values of fullness index. Moreover, the trawling disturbance effect was also significant in the isotopic signature of G. acutus. Urchins inhabiting untrawled areas showed significant lower values of Delta15 N than urchins dwelling areas under trawling pressure. The urchins’ isotopic enrichment increased along the species ontogeny regardless of the trawling effort level. Stable isotopes analyses are a suitable tool to detect trawling disturbance on the trophic pathways but do not suffice to explain these changes, especially if there is a lack of baseline information.
Deep Sea Research Part II Topical Studies in Oceanography 10/2013; · 2.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The influence of mesoscale physical and trophic variables on deep-sea megafauna, a scale of variation often neglected in deep-sea studies, is crucial for understanding their role in the ecosystem. Drivers of megafaunal assemblage composition and biomass distribution have been investigated in two contrasting areas of the Balearic basin in the NW Mediterranean: on the mainland slope (Catalonian coasts) and on the insular slope (North of Mallorca, Balearic Islands). An experimental bottom trawl survey was carried out during summer 2010, at stations in both sub-areas located between 450 and 2200 m water depth. Environmental data were collected simultaneously: near-bottom physical parameters, and the elemental and isotopic composition of sediments. Initially, data were analysed along the whole depth gradient, and then assemblages from the two areas were compared. Analysis of the trawls showed the existence of one group associated with the upper slope (US=450–690 m), another with the middle slope (MS=1000–1300 m) and a third with the lower slope (LS=1400–2200 m). Also, significant differences in the assemblage composition were found between mainland and insular slopes at MS. Dominance by different species was evident when the two areas were compared by SIMPER analysis. The greatest fish biomass was recorded in both areas at 1000–1300 m, a zone linked to minimum temperature and maximum O2 concentration on the bottom. Near the mainland, fish assemblages were best explained (43% of total variance, DISTLM analysis) by prey availability (gelatinous zooplankton biomass). On the insular slope, trophic webs seemed less complex and were based on vertical input of surface primary production. Decapods, which reached their highest biomass values on the upper slope, were correlated with salinity and temperature in both the areas. However, while hydrographic conditions (temperature and salinity) seemed to be the most important variables over the insular slope, resource availability (gelatinous zooplankton and Calocaris macandreae) predominated and explained 59% of decapod assemblage variation over the mainland slope. Both fish and decapods were linked to net primary production recorded over the mainland 3 months before sampling, while the delay between the input of food from the surface and fish abundance was only 1 month on the insular slope. Our results suggest that trophic relationships over insular slopes probably involve a shorter food chain than over mainland slopes and one that is likely more efficient in terms of energy transfer.
Deep Sea Research Part I Oceanographic Research Papers 08/2013; · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We analyzed what are the best ecological conditions for megafauna associated with the bamboo coral Isidella elongata based on the geomorphological, physical and trophic information taken in 3 stations (St1, St2, St3) off the southern Catalonian coasts at 620 m depth in June 2011. Results were compared with assemblage compositions recorded in past cruises (May 1992, 1994) at the same 3 stations. St1 was in a fishing ground exploited since the 1940s over a relatively wide slope at ca. 22 km from the nearest canyon head; St2 and St3 were on a narrower slope closer to canyon heads and to the Ebro river mouth than St1. I. elongata had formed (to May 1994, at least) a dense coral forest at St2–St3 (to ca. 255 colonies/ha at St3), and some isolated colonies (to ca. 0.9 colonies/ha) were still collected in 2011. Fish and invertebrate communities significantly differed between St1 and St2/St3, with two macrourid fishes (Trachrhynchus trachyrhynchus and Nezumia aequalis) and two decapods (Plesionika martia and Plesionika acanthonotus) more abundant at St2/St3. The following ecological indicators imply better food conditions for megafauna at St2–St3 and for I. elongata itself: (i) greater density of zooplankton (copepods, euphausiids, and others) as potential prey for planktivores (including I. elongata); (ii) greater biomass and mean weight of epifaunal and infaunal deposit feeders; (iii) higher feeding intensity, F, at St3 for benthos feeders (Phycis blennoides, N. aequalis and Aristeus antennatus). Also, at St2–St3 we found higher near-bottom turbidity (indicating particle resuspension: food for suspension feeders) and finer and more reduced (Eh) sediments. The results let us suggest that corals and accompanying fauna preferently found optimal ecological conditions in the same habitat, while habitat-forming capacity by I. elongata seemed weak to generate these conditions. Coral forests may enhance detritus accumulations around them, improving habitat conditions for benthos feeders (e.g. macrourid fish). At St3 our side-scan sonar recorded three types of tracks produced by trawler doors, which match with three identified vessels occasionally operating in the area. After this low fishing activity off the Ebro Delta since the mid-1990s, almost all colonies of I. elongata has been removed. However, this impact has hardly altered fish and invertebrate composition without any significant loss of diversity, pointing also toward a rather low capacity of I. elongata facies in forming habitat for megafauna on muddy bottoms of the Mediterranean slope.
Deep Sea Research Part I Oceanographic Research Papers 06/2013; 76:52–65. · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Changes in the composition and biomass distribution of deep-living
zooplankton over wide gradients of depth (400-2300 m) and
longitude (~ 180 km) have been analyzed in the Balearic Basin (western
Mediterranean), seeking the environmental variables responsible for
these changes. Zooplankton tends to aggregate at different levels of the
water column (forming Deep Scattering Layers, DSL) and in the Benthic
Boundary Layer (BBL). Macrozooplankton biomass and composition were
analyzed along a transect performed in July 2010 in midwater (between ~
350 and 450 m) and near the bottom (at ~ 5-200 mab), over
soundings of 450-2263 m, including the top of Valencia Seamount
(at ~ 40° 25‧ N-02° 42‧ E, 1076 m).
Zooplankton changed significantly in composition at the mesoscale (~ 180
km) in both the DSL and the BBL. Siphonophores and calanoid copepods
were the most dominant deep zooplankton taxa, calanoids reaching higher
abundance in the BBL (1761-5177 individuals/1000 m3)
than in the DSL (1568-1743 individuals/1000 m3). There
was a significant increase in near-bottom zooplankton biomass over the
middle slope, at 1000-1300 m, linked to an increase in scyphozoans
and siphonophores (Lensia spp. and Abylopsis tetragona) with peaks of
1.5-2.0 gWW/1000 m3. The peak of near-bottom
zooplankton at 1000-1300 m coincided with the lowest temperatures
(13.08 °C) and maximum O2 concentration (4.40 ml/l) near
the bottom and below 1000 m with higher records in near-bottom
turbidity. Gelatinous zooplankton are the main prey in the diet of the
demersal fish Alepocephalus rostratus in the western Mediterranean, fish
responsible for the peak of megafauna biomass reported at around
1200-1400 m in the deep Mediterranean and at similar depths in
other oceanic areas (e.g. the NW Atlantic). We suggest that deep-sea
environmental conditions can govern peaks of near-bottom zooplankton, as
well as influence the structure of the demersal fish community.
Journal of Marine Systems 03/2013; · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We analyzed long-term changes in slope assemblages (ca. at between 300 and 600 m) of the Balearic Basin and neighbouring areas around Balearic Islands (western Mediterranean) after compiling ca. 60 hauls (from commercial trawls) since 1950s-1960s to 2007. A preliminar analysis showed as the most clear tendency the rarefaction of some bathyal sharks since 1950s-1970s, among which the most clear example was Etmopterus spinax, an ovoviviparous shark probably highly vulnerable to changes experimented by deep-sea ecosystems. Possible changes in ecosystems induced by human impacts will be more in-deep analyzed, including the influence of traditional aspects (fishing effort, pollutans in fish tissues), but also broad-scale changes occurring in the deep Mediterranean related with Nile damming and long-term oceanographic changes in the intermediate and deep waters. Some of these changes are found coupled with the decline of the deep–sea shrimp Aristaeomorpha foliacea in the last 60s in the north-western Mediterranean
Climate Research 01/2013; 55:239-251. · 2.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sinking of gelatinous zooplankton biomass is an important component of the biological pump removing carbon from the upper ocean. The export efficiency, e.g., how much biomass reaches the ocean interior sequestering carbon, is poorly known because of the absence of reliable sinking speed data. We measured sinking rates of gelatinous particulate organic matter (jelly-POM) from different species of scyphozoans, ctenophores, thaliaceans, and pteropods, both in the field and in the laboratory in vertical columns filled with seawater using high-quality video. Using these data, we determined taxon-specific jelly-POM export efficiencies using equations that integrate biomass decay rate, seawater temperature, and sinking speed. Two depth scenarios in several environments were considered, with jelly-POM sinking from 200 and 600 m in temperate, tropical, and polar regions. Jelly-POM sank on average between 850 and 1500 m d-1 (salps: 800–1200 m d-1; ctenophores: 1200– 1500 m d-1; scyphozoans: 1000–1100 m d-1; pyrosomes: 1300 m d-1). High latitudes represent a fast-sinking and low-remineralization corridor, regardless of species. In tropical and temperate regions, significant decomposition takes place above 1500 m unless jelly-POM sinks below the permanent thermocline. Sinking jelly-POM sequesters carbon to the deep ocean faster than anticipated, and should be incorporated into biogeochemical and modeling studies to provide more realistic quantification of export via the biological carbon pump worldwide.
Limnology and Oceanography 01/2013; 58(3):1113–1122. · 3.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Remotely operated vehicle (ROV) video observations were used to document benthic fauna at a hydrocarbon drilling location, at 2 720 m depth, in the poorly studied deep water off northern Egypt. The decapod Chaceon mediterraneus was the most common organism at the site and the only benthic megafaunal invertebrate observed. Three species of fish, Coryphaenoides mediterraneus, Cataetyx laticeps and Bathypterois mediterraneus, were also encountered. These findings confirmed these three species as the deepest-distributed benthic fish in the eastern Mediterranean, and confirmed that the deep Mediterranean, in particular the eastern basin, is one of the world's poorest deep-sea ecosystems in terms of diversity. The behaviour exhibited by the species observed was consistent with their natatory capacity, deduced from their feeding intensity (gut fullness) and diet (mainly suprabenthic prey were consumed), and conservative life strategies adapted to an extremely low energy environment.
[Show abstract][Hide abstract] ABSTRACT: During the summer of 2010 and 2011, 20 hauls were performed in the Galicia Bank. In addition the information from Demersal Survey in the Galicia shelf (Northwest of Spain Shelf) was taken into account to analyse the singularity of the Galicia Bank in comparison with the adjacent continental shelf, respect fish assemblages. In this case only was used the hauls (11) made in 2010 and 2011 deeper 500 m, from sectors Miño-Finisterre and Finisterre-Estaca de Bares (Serrano et al., 2010). The sampling unit consisted of 30-minute hauls at a speed of 3.0 knots, using a GOC73 otter trawl for Galicia Bank Survey and Baca 44/60 otter trawl gear for Cantabrian Sea Survey. To analysed fish assemblages, a hierarchical cluster analysis was applied to the species abundance matrix using the Euclidian Distance similarity index. The distance matrix was processed using the UPGMA algorithm Fish Assemblages Galicia Deep Shelf (560-760 m) Top of Bank (751-1025 m) Flank of Bank (>1410 m) Spatial distribution of hauls in Galicia Bank by cluster Results 94 fish species were identified in the Galicia Bank Surveys. Three assemblages were identified. The first dendrogram dichotomy separates the top of the Galicia Bank and the Galicia Deep Shelf from the deep zone of Galicia Bank (Bank flanks). For the first two clusters, one of the most important species (in biomass) is Hoplostethus mediterraneus, and both areas we could consider associated with the Mediterranean Outflow Waters (MOW) (van Aken, 2000). For the Galicia Deep Shelf the main species were Galeus melastomus, Hoplostethus mediterraneus, Chimaera monstrosa and Deania profundorum. The richness in these two years was 43. For the Galican Bank Summit, 40 species were identified, of which 32% were not found during the same period in the Galicia Shelf. The main species (in biomass) were Hoplostethus mediterraneus, Alepocephalus bairdii, Mora moro and Scymnodon ringens. It is important to note, that commercially important and abundant species in the Galican Deep Shelf as Galeus melastomus, Galeus atlanticus, and Merluccius merluccius , Helicolenus datylopterus have not been found in the Galicia Bank.
[Show abstract][Hide abstract] ABSTRACT: The spatio-temporal dynamics of benthic and bentho-pelagic assemblages of megafauna from the middle slope of the Catalan Sea (NW Mediterranean Sea) were studied. Nineteen bottom trawls were performed to collect megafauna on 5 cruises between February 2007 and February 2008. Samples were obtained from three depth strata, including as ubmarine canyon. Simultaneously, environmental variables were recorded and three levels of bottom-boundary layer macrofauna (infauna, suprabenthos and zooplankton), potential prey of megafauna, were sampled. Fish and decapod assemblages were explored individually. Depth was the main factor structuring megafaunal assemblages, with larger organisms usually observed at greater depths (based on mean individual weight). Nevertheless, in April, coinciding with the reproductive period of the dominant species, larger fish and decapods were observed inside the submarine canyon rather than at greater depths. Assemblages inside and outside the submarine canyons differed in species abundance and biomass, rather than in species composition; larger densities of endobenthic species were found inside the canyon. Also, higher abundance and biomass of megafauna were recorded inside the canyon on all cruises, generally linked to higher prey availability there. A seasonal trend related to size was also observed, associated with the stratification versus homogeneity of the water column. Larger amounts of smaller speciesf eeding atl ower trophic levels were found in periods of homogeneity, while assemblages during periods of stratification were characterised by larger species feeding at higher trophic levels. Environmental variables most strongly explaining changes in megafaunal assemblages from Spearman rank correlation and generalised linear models) were temperature (T) and salinity (S) close to the sea bottom, river discharges and turbidity above the sea bottom. Also, micronekton biomass explained changes in fish assemblages, while Polychaeta biomass and surface primary production were explanatory for decapods. All these variables directly or indirectly affect availability of trophic resources at bathyal depths. T and S are intrinsically related to depth, and are the variables to which organisms may be actually responding. Prey biomass plays an important role in the bathymetric and the topographic distribution of megafauna. T and S are also linked to the stratification or homogeneity of water masses. Peaks of surface primary production (SPP) in February and maximum river discharge in April corresponded to a maximum in megafaunal biomass in summer after ca. 3–5 months. High river discharges, channelled to bathyal depths through submarine canyons, were related to increases in water turbidity, associated with resuspension of organic matter (food for low trophic levels). On the other hand, low turbidity coincided with minimum river discharges, favouring deposition of organic matter in these diments. Peaks in abundance and biomass of megafauna were observed after peaks in key prey (zooplankton, micronekton and benthic infauna) with a lag of ca. 2 months. Diversity of megafaunal assemblages was coupled to food availability.
Deep Sea Research Part I Oceanographic Research Papers 03/2012; 61:84-99. · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The biological pump describes the trans-port 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 indi-cates that they mostly occur after periods of strong upwelling and/or spring blooms in temperate/subpolar zones and during late spring/early summer. A con-ceptual 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 oceano-graphic techniques that could be implemented to further jelly-falls research. Seabed video-and pho-tography-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 Guest editors: J. E. Purcell, H. Mianzan & J. R. Frost / Jellyfish Blooms: Interactions with Humans and Fisheries
[Show abstract][Hide abstract] ABSTRACT: Pandalidae is one of the most diverse families of marine shrimps. Most studies on pandalid shrimps focus on their vertical zonation, and there are few studies on their horizontal distribution and their relation to environmental factors. The aim of this paper was to study the small-scale spatial and temporal patterns of pandalid shrimps in two nearby areas off the Balearic Islands that have different environmental regimes, and determine the relationship between these patterns and the environmental conditions. Information was obtained from seasonal and annual experimental surveys. The abundance and biomass of all the pandalid shrimps caught as well as the length, weight, sex and maturity stage of the most abundant species were recorded. Environmental parameters were obtained from seasonal experimental surveys and included data on hydrography, trophic resources and sediment characteristics. Information about the trawl fleet was obtained through onboard sampling, and daily landings data were obtained from sales records. Eight pandalid species were found during the annual and seasonal experimental bottom trawl surveys carried out around the Balearic Islands. These species showed clear spatial differences in their population dynamics at the two study sites, the Algerian sub-basin (AsB) and the Balearic sub-basin (BsB), which could be related to the different environmental conditions of the two sub-basins. The relative importance of pandalid shrimps of the genus Plesionika in the slope crustacean communities was higher in the Algerian sub-basin. The abundances of Plesionika martia, Plesionika acanthonotus, Plesionika giglioli and Plesionika antigai were higher in the Algerian sub-basin, and only Plesionika heterocarpus, the most benthic species among those analysed, was more abundant in the Balearic sub-basin, where trophic webs are supported largely by suprabenthos rather than zooplankton biomass. The influence of water masses depends on the specific bathymetric distribution, and the shallowest species (P. antigai) was related to the Western Mediterranean Intermediate Waters, while the deepest species (P. martia and P. acanthonotus) were related to the warmer and more saline Levantine Intermediate Waters and Western Mediterranean Deep Waters. The two species found in intermediate waters (P. heterocarpus and P. giglioli) had a deeper distribution in the Algerian sub-basin, where the layer of Levantine Intermediate Waters is wider. The mean length of P. heterocarpus was higher in the Balearic sub-basin, and that of P. martia was higher in the Algerian sub-basin. The condition index was higher in the BsB than in the AsB for both P. heterocarpus and P. martia. This could be because the BsB is influenced to a greater extent by slope fronts that increase the primary production in the area, and thus enrich the trophic chain. The condition index also showed seasonal differences, which could be related to the reproductive cycle and to the availability of potential food resources. The strong relations found between the geographical distribution of the pandalid shrimps in the Balearic Islands and the environmental variables imply that there are important differences between populations of nearby areas when the environmental conditions in which they live differ.
Fisheries Research 01/2012; 119-120:33-47. · 1.70 Impact Factor