Trophic relationships among cephalopod species along the water column inferred from stomach contents and stable isotope analyses

It is well known that cephalopods play a key role in the marine food webs, either as voracious predators or important prey of a large set of predators. In this study we investigated the trophic relationships among cephalopod species taken along the water column by means of stomach content and stable isotope analyses. With the main aim of determining if there are fluxes of matter between nectobenthic and pelagic domains mediated by cephalopods, we analysed different aspects such as diet composition, niche breadth, diet overlap and day-night feeding rhythms from samplings conducted in the western Mediterranean. Samples were collected on the shelf (200 m depth, bathymetric stratum 1) and slope (600-900 m, bathymetric stratum 2) during summer and autumn surveys. At the shelf bathymetric stratum, sampling was carried out at: 1) near surface (SUR1) from 0-60 m; 2) in the benthic boundary layer (BBL1), less than 50 m above the bottom; and 3) on the bottom (BOT1). At the slope bathymetric stratum, sampling was performed at: 1) near surface (SUR2) from 0-80 m; 2) in the 400-600 m deep scattering layers (DSL); and 3) on the bottom (BOT2). For comparative purposes, a few hauls were also performed near the bottom in this stratum (BBL2). In all cases, SUR, BBL and DSL samplings were performed using a mid-water trawl, while the BOT samplings were obtained using a bottom trawl. The stomachs of all cephalopod individuals caught in these samplings were analyzed, with the only exception of a few cases where random samples were taken owing to the large amount of available material. Whenever possible, a sample of three individuals per species was collected for stable isotope analyses. A total of 1286 stomachs from 26 cephalopod species belonging to 12 Families were analyzed. Although the percentage of empty stomachs was slightly higher in autumn (48%) than in summer (41%), this pattern was not general for all species. Significant diet overlap (Schoener index>0.6) was only found for a reduced number of species (Abralia veranyi vs Histioteuthis reversa vs Sepietta oweniana; and Heteroteuthis dispar vs Rondeletiola minor). Levins’ standardized niche breadth was lowest for Loligo forbesi (0.022) and highest for Pteroctopus tetracirrhus (0.720); for all other species this index ranged from 0.118 to 0.639. In most species diet composition changed with season, and, in general, prey diversity was higher in summer than in autum

Structure and dynamics of cephalopod assemblages in the water column on shelf-break and slope grounds of the western Mediterranean

The structure and dynamics of cephalopod assemblages in different bathymetric strata from the surface to bottom grounds, down to a depth of 900 m, in the western Mediterranean, were analysed. Data were collected both on the shelf-break and slope during the summer and early autumn surveys, using a midwater trawl and a bottom trawl gear, to catch pelagic and nektobenthic species, respectively. The pelagic tows were not random, but targeted at the strongest and widest acoustic sound layers. A total of 26 cephalopod species belonging to 12 families were collected. With regard to the abundance, biomass and frequency of occurrence, we did not find a common seasonal trend for all the species, suggesting that their population dynamics are not governed by major environmental drivers. Most assemblage metrics (e.g., diversity, species richness, abundance and biomass) showed similar, low values in the pelagic layers compared to the bottom grounds. In general, assemblage metrics were lower in summer than in autumn on the shelf-break, while showing an inverse seasonal trend on the slope. There was a clear general increase in all metrics during the night compared to the day. Cluster results revealed differences in diel migratory strategies by stratum, vertical movements being scarce in the shelf-break species, but intense in the slope species.En prensa2,65

Uncommon pelagic and deep-sea cephalopods in the Mediterranean: new data and literature review

Compared with their shelf-living relatives, the biology and ecology of most pelagic and deep-sea cephalopods are presently relatively little known because of the difficulty in catching them. To compensate for the lack of information regarding these cephalopods, scientists have had to make use of the limited and fragmentary data gathered from different sources, such as sporadic captures, strandings or stomach contents of their predators. In this study, we provide some biological and ecological information on eleven uncommon pelagic and deep-sea cephalopods collected over more than fifteen years of fishery surveys in the western Mediterranean Sea. The cephalopods investigated include two epipelagic octopuses (Ocythoe tuberculata and Tremoctopus violaceus), one deep-sea cirrate octopus (Opisthoteuthis calypso), the sepiolid Stoloteuthis leucoptera and seven teuthoid species inhabiting, preferentially, the mesopelagic and bathypelagic waters (Abraliopsis morisii, Ancistrocheirus lesueurii, Brachioteuthis riisei, Chiroteuthis veranyi, Chtenopteryx sicula, Onychoteuthis banksii and Taonius pavo). Although all of these species are either cosmopolitan or present a wide distribution in other oceans, they are nevertheless relatively rare in catches, and therefore, remain lesser known. The finding of T. pavo represents the first record of this cephalopod in the Mediterranean watersPublicado

Are pelagic cephalopods in the Mediterranean as abundant as suggests the stomach contents of their predators?

Final workshop IDEADOS: The wrapping up of the IDEADOS project, International Workshop on Environment, Ecosystems and Demersal Resources and fisheries, 14-16 November 2012, Palma de Mallorca, SpainPeer reviewe

Elasmobranch spatial segregation in the western Mediterranean

Basic information on the distribution and habitat preferences of ecologically important species is essential for their management and protection. This study focuses on the depth related trends and the geographic patterns that shape the community of the elasmobranch species in the Balearic Islands (Mediterranean Sea) using data collected from 2001 to 2009. Non-metric Multi-Dimensional Scaling (MDS) ordination was used to detect zonation patterns in the community. Generalized Additive Models (GAMs) were applied to analyse spatial and temporal variation in elasmobranch community descriptors (abundance, biomass, mean fish weight, number of species and diversity), as well as the abundance and mean length of the four individual species (S. canicula, G. melastomus, R. clavata, R. miraletus). Depth was the main factor determining the assemblage composition, and the MDS analysis identified four main groups with 60% of the similarity found to correspond to the continental shelf, shelf break, upper slope and middle slope of the surveyed area. GAM analysis identified spatial patterns that were independent of the bathymetric distribution preference. Although depth was a strong predictor for all the analyses performed, the geographic variation in the elasmobranch abundance was also important. The results also show a reduction in the mean length of the elasmobranch species in the areas with high fishing intensity. Our study evidences a clear spatial segregation of the main species throughout the ontogeny because the geographic and bathymetric effects were highly size dependent, with clear differences between the bathymetric distributions of juveniles and adults but no clear spatial overlapping. This study sheds new light on the spatial distribution of the elasmobranch species off the Balearic Islands, which is essential information for protecting marine organisms along with their habitats and promoting ecosystem based managementPublicado

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Life history of the deep-sea cephalopod family Histioteuthidae in the western Mediterranean

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