Implicaciones de la composición bioquímica y la condición energética de la centolla, "Maja brachydactyla" (Balss, 1922), en su ciclo reproductivo

[Resumen] Esta tesis doctoral aborda el estudio de la biología reproductiva de Maja brachydactyla, centrándose en el ciclo reproductivo y el ciclo de cría a partir del análisis de las puestas y de las gónadas de las hembras, y su variabilidad en función de las condiciones ambientales. El análisis de la biología de M. brachydactyla, se realiza mediante una aproximación que integra aspectos morfológicos, biométricos, y bioquímicos, permitiendo obtener una imagen global sobre la inversión maternal y los requerimientos nutricionales necesarios para los procesos de maduración gonadal y de embriogénesis. Los resultados obtenidos demuestran la existencia de diferencias importantes en las características de las puestas que cada hembra puede realizar en un mismo ciclo reproductivo. Estas diferencias podrían ser la consecuencia de un acoplamiento entre la condición fisiológica de las hembras, determinada por las condiciones ambientales cambiantes a lo largo de cada ciclo reproductivo, y la inversión maternal en cada puesta que da lugar a diferencias globales en el peso de la puesta y la fecundidad, así como a diferencias de calidad en términos de las características biométricas y bioquímicas de los embriones.[Resumo] Esta tese doutoral aborda o estudio da bioloxía reprodutiva de Maja brachydactyla, centrándose no ciclo reprodutivo e o ciclo de cría a partir da análise das postas e das gónadas das femias, e a súa variabilidade en función das condicións ambientais. A análise da bioloxía de M. brachydactyla realízase mediante unha aproximación que integra aspectos morfolóxicos, biométricos e bioquímicos, permitindo obter unha imaxe global sobre a inversión maternal e os requirimentos nutricionais necesarios para os procesos de maduración gonadal e de embrioxenia. Os resultados obtidos demostran a existencia de diferenzas importantes nas características das postas que cada femia pode realizar nun mesmo ciclo reprodutivo. Estas diferenzas poderían ser a consecuencia dun axuste entre a condición fisiolóxica das femias, determinada polas condicións ambientais cambiantes ó longo de cada ciclo reprodutivo, e a inversión maternal en cada posta que da lugar a diferenzas globais no peso da posta e a fecundidade, así como a diferenzas de calidade en termos das características biométricas e bioquímicas dos embrións.[Abstract] This PhD Research Thesis addresses the study of reproductive biology of Maja brachydactyla, focussing on the reproductive cycle and the breeding cycle, based on the analysis of broods and female gonads, and their variability according to environmental conditions. Analysis of the biology of M. brachydactyla is carried out through an approach that integrates morphological, biometric and biochemical aspects, allowing to obtain a global view about the maternal investment and the nutritional requirements needed for the gonadal maturation processes and for the embryogenesis. The obtained results show the existence of important differences in the characteristics of the broods that each female can carry out in the same reproductive cycle. These differences could be the consequence of an adjustment between physiological condition of the females, determined by the changing environmental conditions over each reproductive cycle, and the maternal investment in each brood that leads to global differences in brood weight and fecundity, as well as qualitative differences in terms of biometric and biochemical characteristics of the embryos

Estacionalidad de la muda terminal y la migración reproductiva en la centolla, "Maja brachydactyla" : evidencias de estrategias de apareamiento alternativas

[Resumen] Se analiza la temporalidad y sincronización de los procesos de muda terminal, maduración gonadal, acumulación de reservas energéticas y migración en la centolla, Maja brachydactyla, tanto a nivel individual como poblacional, y su variabilidad intra- e intersexual. Para explicar esta variabilidad en la temporalidad se plantean dos hipótesis: 1) hipótesis fisiológica: machos y hembras inician la migración cuando alcanzan un estado fisiológico adecuado (un nivel de reservas energéticas óptimo), y 2) hipótesis de oportunidades de apareamiento: la temporalidad de la migración trataría de maximizar las oportunidades de apareamiento y la calidad de las parejas. Nuestros resultados muestran que los machos llevan a cabo la muda terminal (con un pico en Julio) antes que las hembras (Agosto). En las hembras, el inicio de la madurez gonadal se produce entre dos y tres meses después de alcanzar la madurez morfométrica (a partir de Octubre), coincidiendo con el período previo y durante la migración de apareamiento a aguas profundas. El análisis de las espermatecas de las hembras primíparas reveló que en la zona somera no se producen prácticamente apareamientos, en el corredor migratorio se producen las primeras cópulas, y es en los deep mating grounds donde se producen probablemente la mayor parte de los apareamientos. En los machos la madurez gonadal se produce antes de la madurez morfométrica. El día promedio de inicio de migración obtenido para los machos fue el 8 de Octubre, mientras que para las hembras fue el 16 de Octubre, lo que confirma evidencias previas de un adelanto de los machos en el inicio de la migración. No se observaron diferencias en la condición fisiológica (índices de condición de músculo, gónada y hepatopáncreas) entre migradores y no migradores, lo que indica claramente que la hipótesis fisiológica no se cumple en esta especie, dado que incluso se capturó un mayor porcentaje de ejemplares en postmuda en el corredor migratorio que en aguas someras. La condición fisiológica mejoró con el tiempo en ambos sexos tanto en los ejemplares capturados en el área somera como en el corredor migratorio, y por tanto los ejemplares que migran primero lo hacen en peor condición fisiológica. Además, los migradores tempranos presentaron una talla media significativamente menor que los migradores tardíos. Nuestros resultados sugieren que la variabilidad intrapoblacional e intersexual estaría relacionada con diferentes estrategias reproductivas, y no con una limitación fisiológica. Así, los machos de peor calidad (y menor capacidad competitiva) deberían migrar al inicio de la temporada (antes o coordinadamente con las primeras hembras), mientras que los machos de alta calidad podrían retrasar la migración al momento en que sus reservas fueran máximas dado que podrían desplazar a los machos de baja calidad en los hábitats de apareamientoMinisterio de Ciencia y Tecnología; REN2000-0446MARXunta de Galicia; XUGA10301B9

Population dynamics of "Maja squinado" in the Ría de A Coruña (Galicia, NW Spain), using mark-recapture experiments

8th Colloquium Crustacea Decapoda Mediterranea, 2-6 September 2002, Corfu, Greec

Complex Patterns of Habitat Use by Juvenile Spider Crabs Maja Brachydactila Revealed by Stable Isotope Analyses

[Abstract] Patterns of habitat use by spider crab juveniles, Maja brachydactila, from two geographic areas in the NW coast of the Iberian Peninsula, were analyzed through the analysis of Carbon and Nitrogen stable isotope relations in two tissues (muscle and hepatopancreas). The main organisms that constitute the diet of spider crab juveniles in rocky and sandy habitats and the different organic matter sources in coastal food webs were analysed too. The isotopic ratios of C and N did not show any difference between habitats. The use of carapace colour and epibiosis as an indicator of habitat use was not supported by our data. These results suggest much more frequent movements between both types of habitats than those suggested by former studies (carried out using behavioural observations and sampling distributions) that hypothesized seasonal and ontogenetic changes. In the coastal food web, two main trophic compartments were identified according to the organic matter source: one based in plankton and seaweeds, that corresponds, mainly, with rocky habitats, and another based in sedimentary particulated organic matter that correspond with sandy bottoms. The relationships observed between the C and N isotopic ratios and the proportions of lipids and proteins in muscle and hepatopancreas seem to indicate a clear relation between the trophic origin of the food consumed by the spider crab juveniles and its energetic condition, and the individuals that spent more time feeding in sandy areas would show a better energetic condition. Juveniles of Maja brachydactila, independently of the habitat of capture, would consume in average approximately two thirds of the preys in rocky habitats and a third in sedimentary habitats. The results obtained indicate that, in exposed environments, large juveniles spend most of the time in sedimentary bottoms, where they find more refuge, but they move frequently (probably at night) to the nearby rocky substrates to feed.Ministerio de Ciencia y Tecnología; REN2000-0446MARMinisterio de Ciencia y Tecnología; REN2003-0481

An assessment of sample processing methods for stable isotope analyses of coastal foodwebs

[Abstract] The relative abundance of the light and heavy forms of stable isotopes of Carbon and Nitrogen is commonly used in the research of marine food webs. Dehydration of samples is needed for C and N isotopic analysis, and in those organisms with inorganic carbonate structures acidification with hydrochloric acid is also needed for sample preparation. There is not a consensus about the methodology appropriate for sample processing. In the present study, the effects of different sample processing methods in the relative abundance of stable isotopes of C and N in the different trophic compartments of a coastal food web are evaluated. The final purpose is to define an adequate methodology to be used in the construction of whole food webs. The results obtained after acidification show a decrease in carbon values for sedimentary organic matter, suspended particulate organic matter, plankton and invertebrates with carbonated structures, and a variable response for nitrogen values. According to our results we recommend sampling acidification for carbon analysis in compartments in which variations of this element were observed. For nitrogen analysis acidification should not be done. Different treatments of dehydration studied provoked significant differences only in nitrogen values, thereby freeze-drying seems the most adequate method. Muscle tissue should be used in invertebrate with carbonated structures whenever body sizes make it possible

Complex Patterns of Habitat Use by Spider Crabs Maja Squinado Revealed by Stable Isotope Analyses

38th European Marine Biology Symposium, Aveiro (Portugal), 8-12 September 200

Differences in Prevalence of Multiple Paternity in the Spiny Spider Crab Maja Brachydactyla in Two Localities That Differ in Female Fecundity, Fishing Intensity, and Management Measures

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Many marine species are under high fishing pressure, which can cause alterations in their mating systems and the structure of their populations. The spiny spider crab Maja brachydactyla is a commercial decapod on the east Atlantic coast. In Galicia, the most exploited region in Spain, the landing of ovigerous females is prohibited, favouring exploitation focused on males. The removal of males, especially the largest ones, may lead to sperm limitation and a reduction in the average size over generations. In these cases, polyandry can work as a mechanism to protect females against sperm limitation and to increase genetic diversity and effective population size. This study analyses the multiple paternity in M. brachydactyla in two localities that differ in female fecundity, fishing intensity, and management measures. Our results showed multiple paternity in this species for the first time, with a moderate bias between sires. However, the frequency of multiple paternity was almost seven times higher in the intensely exploited Golfo Ártabro (NW Spain; 69%) than in Carna (W Ireland; 10%), where exploitation levels and female fecundity are lower.This work was funded by a CTM2014-53838-R grant from the Spanish Government (Ministerio de Economía y Competitividad), by a GRC2014/050 grant from Xunta de Galicia (Programa de Investigación Competitiva do Sistema Universitario Galego, Modalidade de grupos de referencia competitiva: Grupo de Investigación en Biología Evolutiva), and by a PID2019-109194RB-I00 grant from the Spanish Government (Ministerio de Ciencia e Innovación). The researcher Elba Rodríguez-Pena was supported by the Axudas de apoio á etapa predoutoral from the Xunta de Galicia (Spain), co-financed by the European Social FundXunta de Galicia; GRC2014/05

Role of Lipid, Protein, Carbohydrate and Nucleic Acid As Indicators of the Moulting Cycle of Norway Lobster (Nephrops norvegicus)

ASLO Summer Meeting 2005, Santiago de Compostela, Spain, 19-24 June 200

Timing and seasonality of the onset of maturity, gonad maturation and mating in the spider crab "Maja squinado" : relationships with habitat use and social structure

Fifth International Crustacean Congress, 9-13 July 2001, University of Melbourne, AustraliaXunta de Galicia; XUGA10301B97Ministerio 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