New approaches to the behavioural ecology of decapod crustaceans using telemetry and electronic tags

The original publication is avaliable at www.springerlink.comDecapod crustaceans have complex life histories and behaviour in aspects such as foraging, mating and reproduction, moulting and growth, habitat selection and migration. New technologies have enabled us to use an individual, field-based approach to analyze these problems, although they have been less developed in decapods than in marine vertebrates. These new possibilities are discussed here mainly from a biological point of view. There is a brief review of previous applications of telemetry to analyze habitat selection, foraging behaviour, energetics, moulting site selection and migrations in decapods, and two case studies are discussed in more detail. The first one refers to the study of differences in habitat use and movement patterns in juveniles and adults of coastal species that show ontogenetic habitat shifts, related to differences in selective pressures affecting both life history stages (predation risk, and growth and reproduction optimization). The second case study is dedicated to the migratory patterns in spider crabs combining telemetry and electronic tags. Operational limitations in tracking make it impossible to get detailed information on movement patterns during migration, which in turn involve an important bathymetric gradient and a change in the oceanographic environment (mainly temperature).Monitoring depth and temperature in the immediate habitat of the animals, using electronic data storage tags recovered by the fishery, allow for movement patterns to be modeled using supplementary information on the topography and hydrography of the study area. This approach is being tested using both telemetry and electronic tags simultaneousl

Interactions of the fishery of the spider crab Maja squinado with mating, reproductive biology and migrations

[Abstract] In this paper different aspects of the fishery and life history of the spider crab Maja squinado in southern Galicia (NW Spain) are analyzed to evaluate the potential effects of the fishery on the sperm limitation of the reproductive effort (egg production) of the population. Juveniles of the spider crab inhabit shallow waters, where they carry out a terminal moult in August-September, attaining sexual maturity when they are 2+ years old. A short time after the terminal moult (October-November), adults migrate to deeper waters (up to 100 m), where mating occurs (January-February). Field and laboratory data show that multiple matings and sperm storage in female seminal receptacles occur, indicating that females are able to fertilize multiple broods during the annual breeding cycle using stored sperm. The spider crab is the target of a tangle-net fishery, characterized by a very high fishing effort similar for both sexes. The fishing season is from November-December until May-June and is mostly dependent on migrating animals. Data from catch composition (percentage of recent recruits at the beginning of the season), recaptures from the fishery of females tagged with ultrasonic transmitters and electronic archival tags, and CPUE trends over the course of the fishing season (Leslie analyses of stock depletion) indicate that more than 90% of postpubertal (primiparous) adults are caught during the fishing season. The fishery is almost exclusively dependent on the autumn recruitment of the annual cohort of primiparous adults. Most of the catches are made in autumn and early winter, before or during the mating season (for 4 fishing seasons an average of 45 and 66% of the catches are made before January and February respectively). The volume of sperm stored in the seminal receptacles and the percentage of females with sperm is lower for females caught in the field during or immediately after the mating season than for females kept in laboratory with a high density of males, and decreases throughout the annual breeding cycle. These two facts may be brought about the low density of both sexes in the mating grounds due to fishery exploitation. We hypothesized that, although sperm limitation probably does occur, the main factor in the severe fishery induced limitation of the reproductive effort of the Galician spider crab populations, as opposed to other crab fisheries targeting only males, is the mortality imposed on females before or during breeding. More information about mating habitat, seasonality and behaviour would be needed for an accurate evaluation of the potential effects of the fishery (and of different management strategies) on sperm limitation.Ministerio de Cultura y Educación; PB94-050

Epibiosis and masking material in the spider crab Maja squinado (Decapoda: Majidae) in the Ría de Arousa (Galicia, NW Spain)

[Abstract] Majid crabs present a marked masking behaviour, which, in addition to the phenomenon of epibiosis on their exoskeleton, constitutes a complex camouflage system to ward off predators. This paper presents a study on the floral and faunal composition of the epibiont and masking material of the decapod Maja squinado in the Ría de Arousa (Galicia, NW Spain). A total of 309 taxa were identified. Seaweeds (87 species), cnidarians (48), polychaetes (46), crustaceans (36) and molluscs (30) were the groups with a higher number of species. The frequency of occurrence of these groups was about 70%. Ascidians, poriferans, bryozoans and echinoderms were less important in number of species and frequency of occurrence. The quantitative impact of each of these groups and their species composition varies considerably, and depends on the area of the ría where M. squinado was found and the time that had elapsed since the terminal moult. The pre-pubertal spider crabs found in shallow water areas showed strong masking behaviour, while epibiosis was very scarce. Once individuals have undergone the pubertal moult, epibiosis begins, while the masking behaviour decreases and finally disappears.[Résumé] Les crabes majidés ont un comportement de camouflage bien marqué, auquel s'ajoute l'installation d'épibioses sur leur exosquelette, l'ensemble les protégeant des prédateurs. Cette étude porte sur la composition Holistique et faunistique des épibiontes et du matériel prélevé dans le milieu par le décapode Maja squinado de la Ría de Arousa (Galice, NW de l'Espagne). En tout, 309 taxons ont été identifiés. Les algues (87 espèces), cnidaires (48), crustacés (36) et mollusques (30) sont les groupes qui présentent le plus grand nombre d'espèces. La fréquence d'apparition de tous ces groupes se situe autour de 70 %. Ascidies, éponges, bryozoaires et échinodermes sont aussi présents, mais en moins grand nombre en ce qui concerne aussi bien le nombre d'espèces que leur fréquence d'apparition. L'importance quantitative et le nombre d'espèces de chacun de ces groupes faunistiques montrent une grande variabilité selon la zone où les spécimens de M. squinado sont récoltés et selon le temps écoulé après la mue terminale. Les araignées de mer trouvées dans les zones de faible profondeur montrent un comportement de camouflage remarquable, alors que l'épibiose est très rare. Lorsque les individus ont atteint la mue de puberté, le phénomène d'épibiose commence à se développer tandis que le comportement de camouflage diminue progressivement et finit par disparaître

Megabenthic decapod crustacean assemblages on the Galician continental shelf and upper slope (north-west Spain)

The original publication is avaliable at www.springerlink.comThe structure of megabenthic decapod crustacean assemblages on the Galician (north-west Spain) continental shelf (100 to 200 depth) and upper slope (200 to 500 m) was analyzed based on surveys carried out in autumn and spring, from 1980 to 1987. Forty species belonging to 19 families were caught. The portunid crab "Polybius henslowii", a species with pelagic phases, was the most abundant species, but displayed strong spatial and temporal fluctuations. Other dominant species were the Norway lobster "Nephrops norvegicus", the portunid "Liocarcinus depurator", the galatheids "Munida intermedia" and "M. sarsi", and the shrimps "Solenocera membranacea", "Plesionika heterocarpus", "Pasiphaea sivado" and "Dichelopandalus bonnieri". Total abundance and biomass (average values excluding Polybius henslowii = 255 individuals and 2.06 kg/30 min tow) and species richness and diversity, Ht (6.85 species and Ht = 1.45 per tow) displayed a significant positive correlation with depth, and strong interannual fluctuations. The factors determining community organization were depth and, to a lesser extent, spatial structure. There was clear evidence of bathymetric zonation, differentiating between species characteristic of the slope ("D. bonnieri" and "Pasiphaea sivado"), shelf-slope edge ("Macropipus tuberculatus", "Pontophilus spinosus", "Munida sarsi", "S. membranacea", "Processa spp.") and shelf ("L. depurator", "Macropodia tenuirostris", "Paguridae" and "Chlorotocus crassicornis"). The spatial zonation was related to changes in oceanography and sediment along the continental margin. "Goneplax rhomboides", "N. norvegicus", "C. crassicornis" and "Alpheus glaber" are benthic species which generally exhibit burrowing behaviour, and they were found mainly in the southern area where there are fine sediments due to the outwelling from the Rías Baixas. Different benthopelagic shrimps ("Pontophilus spinosus", "Plesionika heterocarpus", "Processa spp." and "Pasiphaea sivado") were typical of the zone just north of Fisterra, characterized by a convergence of water masses bringing about an increase in productivity due to upwelling. The benthic anomuran and brachyuran crabs "Munida intermedia", "M. sarsi", "L. depurator" and "Macropipus tuberculatus" were characteristic of the northwestern zone between Fisterra and Estaca, where the infauna reaches high biomass despite coarser sediments with a lower concentration of organic material than in the southern area. Lastly, both the "Paguridae" and "Macropodia tenuirostris" were species typically found in the waters in the northern shelf. Based on interannual changes in assemblage structure, two periods could be distinguished: between 1980 and 1984, when "Polybius henslowii", "D. bonnieri" and "Pasiphaea sivado" had abundance peaks; and another period from 1985 to 1987 when "L. depurator", "Munida intermedia", "M. sarsi" and "Macropipus tuberculatus" increased in abundanc

Growth at moulth, intermoult period and moulting seasonality of the spider crab "Maja brachydactyla" : combining information from mark-recapture and experimental studies

[Abstract] An analysis of growth at moult (for both the prepubertal and terminal moults), moulting seasonality and the intermoult period in the spider crab Maja squinado in the Ría de A Coruña (NW Spain) was carried out based on a mark-recapture experiment. Crabs between 70 and 130 mm carapace length (CL) undergo a mean increase at moult of 32.4% from their pre-moult size. Generalised Linear Models (GLMs) were used to construct growth models, employing a combination of information from the mark-recapture study and other previous studies performed in both laboratory and extensive culture, to estimate the effects of the biological variables and the study method. No differences were found in the growth rate between males and females. However, the effects of the study method, the premoult CL and the interaction between them were significant. The smallest-sized crabs undergo a greater increase in size in the laboratory and culture studies, while the largest individuals undergo greater growth in the field. The mean intermoult period estimated for prepubertal moults in the field ranged from 50 to 86 days, which Corgos et al., GROWTH AT MOULT OF MAJA BRACHYDACTYLA is similar to the 84.7 days observed in the laboratory study. The prepubertal moults occurred primarily in spring and autumn in the field, while under culture conditions, the crabs moulted mainly in the spring. The intermoult period for terminal moults was estimated to be around 90 days, slightly lower than the value of 104 days obtained in the laboratory. The terminal moult took place generally in summer (June-September) both at sea as well as in culture experiments. The intermoult period of juveniles at sea was highly variable, and some of the specimens did not moult for more than 5 months.Ministerio de Ciencia y Tecnología; REN2000-0446MARXunta de Galicia; XUGA10301B9

Movements of juvenile and adult spider crab ("Maja squinado") in the Ría da Coruña (NW Spain)

Presentado no Fifth Conference on Fish Telemetry held in Europe, 9-13 June 2003, Ustica, Palermo, Italy[Abstract] In August 2002, 12 juvenile and 12 adult (recently terminal moulted) spider crabs were tagged using ultrasonic pingers (Sonotronics, USA) in the Ría da Coruña (NW Spain). Both adults and juveniles were released in the same sandy shallow bottoms (5-10 m) in which they were caught. This area, as known from previous studies, is a typical juvenile area where juvenile spider crabs carry out their terminal moult before the autumn migration to deep bottoms. The tracking was carried out daily for a period of two weeks, although not all the crabs were located every day. Juvenile crabs were found to move small distances, performing non-directional movements near the coast, in protected areas up to 10 m deep. Two of the adult crabs performed small scale movements in the outer (more exposed) part of the estuary, at depths of up to 20 m. The rest of the adult crabs remained in the juvenile area, performing the same non-directional movements as the juveniles. Four male adult crabs were recaptured by commercial fisheries in the following months, three of them at more than 40 m deep, in the central channel of the estuary, probably while performing their seasonal descent migration. A female carrying eggs was recaptured in December near the coast, probably after carrying out both a descent and ascent migration.Ministerio de Ciencia y Tecnología; REN2000-0446/MA

Management strategies for sustainable invertebrate fisheries in coastal ecosystems of Galicia (NW Spain)

The original publication in avaliable at www. springerlink.comArtisanal coastal invertebrate fisheries in Galicia are socio-economically important and ecologically relevant. Their management, however, has been based on models of fish population dynamics appropriate for highly mobile demersal or pelagic resources and for industrial fisheries. These management systems focus on regulating fishing effort, but in coastal ecosystems activities that change or destruct key habitats may have a greater effect on population abundance than does fishing mortality. The Golfo Artabro was analysed as a representative example of a coastal ecosystem in Galicia, and the spider crab "Maja squinado" used as a model of an exploited coastal invertebrate, for which shallow coastal areas are key habitats for juvenile stages. The commercial legal gillnet fishery for the spider crab harvests adults during their reproductive migrations to deep waters and in their wintering habitats. Illegal fisheries operate in shallow waters. The annual rate of exploitation is higher to 90%, and lower to 10% of the primiparous females reproduce effectively at least once. A simple spatially-explicit cohort model was constructed to simulate the population dynamics of spider crab females. Yield- and egg-per-recruit analyses corresponding to different exploitation regimes were performed to compare management policies directed to control the fishing effort or to protect key habitats. It was found that the protection of juvenile habitats could allow increases in yield and reproductive effort higher than in the present system, with such protection based in the control of the fishing effort of the legal fishery. Additionally, there is an urgent need for alternative research and management strategies in artisanal coastal fisheries based on the implementation of a system of territorial use rights for fishers, the integration of the fishers into assessment and management processes, and the protection of key habitats (marine reserves) as a basic tool for the regulation of the fisheries.Xunta de Galicia; XUGA10301B9

Polygenic contribution to the relationship of loneliness and social isolation with schizophrenia

Previous research suggests an association of loneliness and social isolation (LNL-ISO) with schizophrenia. Here, we demonstrate a LNL-ISO polygenic score contribution to schizophrenia risk in an independent case-control sample (N = 3,488). We then subset schizophrenia predisposing variation based on its effect on LNL-ISO. We find that genetic variation with concordant effects in both phenotypes shows significant SNP-based heritability enrichment, higher polygenic contribution in females, and positive covariance with mental disorders such as depression, anxiety, attention-deficit hyperactivity disorder, alcohol dependence, and autism. Conversely, genetic variation with discordant effects only contributes to schizophrenia risk in males and is negatively correlated with those disorders. Mendelian randomization analyses demonstrate a plausible bi-directional causal relationship between LNL-ISO and schizophrenia, with a greater effect of LNL-ISO liability on schizophrenia than vice versa. These results illustrate the genetic footprint of LNL-ISO on schizophrenia

The action of obestatin in skeletal muscle repair: stem cell expansion, muscle growth, and microenvironment remodeling

The development of therapeutic strategies for skeletal muscle diseases, such as physical injuries and myopathies, depends on the knowledge of regulatory signals that control the myogenic process. The obestatin/GPR39 system operates as an autocrine signal in the regulation of skeletal myogenesis. Using a mouse model of skeletal muscle regeneration after injury and several cellular strategies, we explored the potential use of obestatin as a therapeutic agent for the treatment of trauma-induced muscle injuries. Our results evidenced that the overexpression of the preproghrelin, and thus obestatin, and GPR39 in skeletal muscle increased regeneration after muscle injury. More importantly, the intramuscular injection of obestatin significantly enhanced muscle regeneration by simulating satellite stem cell expansion as well as myofiber hypertrophy through a kinase hierarchy. Added to the myogenic action, the obestatin administration resulted in an increased expression of VEGF/VEGFR2 and the consequent microvascularization, with no effect on collagen deposition in skeletal muscle. Furthermore, the potential inhibition of myostatin during obestatin treatment might contribute to its myogenic action improving muscle growth and regeneration. Taken together, our data demonstrate successful improvement of muscle regeneration, indicating obestatin is a potential therapeutic agent for skeletal muscle injury and would benefit other myopathies related to muscle regeneration

Pasiphaeid shrimps in the western Mediterranean:geographical variability in distribution and population pattern

Summary: This work aimed to analyse the main characteristics of the bathymetric and geographic distribution, population size structure and size at maturity of the continental slope caridean shrimps Pasiphaea sivado and Pasiphaea multidentata in the western Mediterranean, as well as to try to relate the patterns obtained with geomorphologic and hydrographic characteristics. The study area encompassed the Mediterranean coast of the Iberian Peninsula. In both species, marked differences in depth distribution, density, and population size structure were found between Algerian basin populations, particularly in the Alboran Sea, and those in the Catalano-Balearic basin. Both shrimps showed a shallower bathymetric range in the westernmost region of the Algerian basin than in the rest of geographic sectors, linked to the occurrence of upwelling areas on the northwestern edges of the Alboran Sea. Populations of P. sivado reached larger densities, sizes and maturity size in the Algerian basin. No recruitment of P. multidentata was detected in the Algerian basin, whereas it was present in the Catalano-Balearic basin. In both species, the window range of bottom temperature and salinity was larger in juveniles than in adults. These different distribution and population dynamics imply that ecological functioning of these species differs between the two eomorphological basins of the western Mediterranean Sea.Versión del edito