Algunas observaciones sobre el ciclo biológico del anfípodo de agua dulce Echinogammarus longisetosus Pinkster, 1973 (Amphipoda: Gammaridae) en Cataluña(España, N de la península ibérica)

Aspects of the population structure and reproductive biology of the freshwater amphipod Echinogammarus longisetosus were studied in the northeastern Iberian Peninsula (Catalonia, Spain). Amphipods were sampled at approximately monthly intervals from September 1999 to October 2000. Pairs in precopula and ovigerous females were present all year round. The sex ratio was not significantly different from 1:1. Juveniles were abundant in all samples (> 40%). The number of eggs carried by females (N) was related to the size of the females (LP3) (range: 9–68, mean value: 28.2): N = 0.594 LP3 3.141 (n = 80, r 2 = 0.7136, LP3 were measured from the anterior part of the head to the posterior edge of the third pereional segment; total length was approximately 3.5 times greater than LP3 ). The mean embryo diameter was 0.45 mm (mean of measurements of the long and short axes of recently laid eggs). The egg volume increased during development (2 fold by eggs close to hatching).Se estudian varios aspectos relacionados con la estructura poblacional y la biología reproductiva del anfípodo Echinogammarus longisetosus, basándose en muestras obtenidas en el nordeste de la península ibérica (Cataluña, España). Los anfípodos se muestrearon a intervalos de aproximadamente un mes desde septiembre de 1999 hasta octubre de 2000. Se capturaron parejas en precópula y hembras ovígeras en todas las muestras obtenidas durante el período estudiado. La relación de sexos no fue significativamente diferente de 1:1. Los individuos jóvenes eran abundantes en todas las muestras (> 40%). El número de huevos transportados por las hembras ovígeras (N) estaba relacionado con el tamaño de éstas (LP3) (rango: 9–68, valor medio: 28,2): logN= 3,142LP3 – 0,226 (n = 80, r = 0,845; LP3 = longitud del céfalon más los tres primeros pereionitos; la longitud total era aproximadamente 3,5 veces LP3). El diámetro medio de los huevos era de 0,45 mm (media de la longitud del eje mayor y del eje menor de los huevos al principio del desarrollo embrionario). El volumen de los huevos se incrementaba durante el desarrollo embrionario (2 veces en los huevos a punto de eclosionar)

Desarrollo postlarvario y dimorfismo sexual de Maja brachydactyla (Brachyura: Majidae)

The post-larval development of the majid crab Maja brachydactyla Balss, 1922 was studied using laboratory-reared larvae obtained from adult individuals collected in the NE Atlantic. The morphology of the first juvenile stage is described in detail, while the most relevant morphological changes and sexual differentiation are highlighted for subsequent juvenile stages, until juvenile 8. The characteristic carapace spines of the adult phase are present in the first juvenile stage, though with great differences in the degree of development and relative size. The carapace shows a high length/weight ratio, which becomes similar to that of adults at stage 7-8. Males and females can be distinguished from juvenile stage 4, based on sexual dimorphism in the pleopods and the presence of gonopores. In addition, the allometric growth of the pleon is sex-dependent from juvenile stage 4, with females showing a positive allometry (b=1.23) and males an isometric allometry (b=1.02).El desarrollo postlarvario del májido Maja brachydactyla ha sido estudiado en el laboratorio después del cultivo larvario realizado a partir de individuos adultos capturados en el NE del Atlántico. La morfología del primer estadio juvenil se ha descrito en detalle y el desarrollo juvenil, hasta el estadio 8, ha sido estudiado en lo referente a los cambios morfológicos y la diferenciación sexual. En el primer juvenil, las espinas del cefalotórax características de los adultos están presentes, pero existen grandes diferencias en el grado de desarrollo y el tamaño relativo. El cociente longitud/anchura muestra valores elevados que tienden a parecerse a los de los adultos a partir del juvenil 7-8. Machos y hembras se pueden diferenciar a partir del cuarto estadio juvenil, según el dimorfismo sexual en los pleópodos y la presencia de gonoporos. Además, existen diferencias sexuales en el crecimiento alométrico del pleon a partir del cuarto estadio juvenil: las hembras muestran una alometría positiva (b= 1.23) y los machos muestran un crecimiento isométrico (b= 1.02)

First record and evidence of an established population of the North American mud crab Dyspanopeus sayi (Brachyura: Heterotremata: Panopeidae) in the western Mediterranean

The panopeid crab Dyspanopeus sayi (Smith, 1869) is reported here from the Ebro Delta (Mediterranean coast of the Iberian Peninsula). Originally endemic to the Atlantic coast of North America, D. sayi was involuntarily introduced into Britain, France and the Netherlands, and into the Adriatic and Black Sea within the last thirty years. Here we provide the first record of this species from the western Mediterranean Sea. Occurrences of ovigerous females at different localities of the delta and in different years provide evidence that the population is well established. Mitochondrial DNA confirms the identity of the species and indicates that the introduced population consists of at least three female lineages. The first zoeal stage of D. sayi was obtained in the laboratory from an ovigerous female captured in August 2010 with embryos in an advanced stage of development. The morphology of the zoea I is described here in detail and is similar to the one previously reported for native populations.Travel funds to CDS and students were made possible through an exchange program of the DAAD (D/03/40344) and the Spanish Ministerio de Ciencia y Tecnología – Acciones Integradas (HA2003-078), with José A. Cuesta as Spanish collaborator. Florian Gmeiner, Silke Reuschel and Lapo Ragionieri assisted during field collections in 2005 and 2006 respectively and students at the University of Regensburg helped with the molecular work. Financial support to GG (post-doctoral fellowship; INIA) was provided by the Ministry of Science and Research. The authors would like to thank Agustí Benito, fisherman of Sant Carles de la Ràpita for his collaboration in catching crabs. PA acknowledges research project CGL2009-12912-C03-03 from the Ministerio de Ciencia e Innovación (Spain). Paul Clark kindly made available important literature and shared his own unpublished description of the first zoeal stage of Dyspanopeus sayi.info:eu-repo/semantics/publishedVersio

Cambios bioquímicos relacionados con el ciclo de muda y desarrollo en las larvas del cangrejo, Maja brachydactyla (Brachyura: Majidae).

Ontogenetic changes in dry weight, elemental composition (CHN), and digestive enzyme activities (total protease, amylase) were studied during the moulting cycle of all larval instars (zoea I-II, megalopa; ZI, ZII, M) of the spider crab Maja brachydactyla Balss, 1922 reared in the laboratory. A gradual but significant increase in biomass was observed throughout the zoeal instars, followed by steeper growth in the megalopa. Maximum values were reached in moult stage D2. Digestive enzyme activities also increased significantly throughout larval development. The ZI showed a continuous increase in total protease activity during its moult cycle, suggesting that newly hatched larvae have a gradually increasing need to take up proteins to provide amino acids, which are prime materials for growth and development, and possibly to use them as a metabolic energy source. The largest variations in digestive enzyme activites in relation to the moult cycle were observed in the megalopa instar. After an initial increase in postmoult, enzyme activities decreased to low levels similar to those measured in the zoeal instars at intermoult, followed by another increase to a maximum level in premoult. Metamorphosis involves great physiological and behavioural changes, which could explain the large variations in the megalopa moult cycle. We therefore suggest that the moult cycle stages should be taken into account when nutritional condition indices are used to estimate the physiological performance of decapod crustacean larvae.Se han estudiado los cambios ontogénicos en peso seco, composición elemental (CHN), y actividad enzimática (proteasas totales, amilasas) durante el ciclo de muda en todos los estadios larvarios (zoea I-II, megalopa; ZI, ZII, M) del centollo Maja brachydactyla Balss, 1922 cultivados en el laboratorio. Se ha observado un incremento gradual y significativo en la biomasa durante los estadios de zoea, seguido de un crecimiento brusco en la megalopa alcanzando valores máximos en el estado de muda D2. La actividad enzimática también aumentó significativamente durante el desarrollo larvario. Las ZI presentaron un continuo incremento de la actividad de las proteasas totales durante el ciclo de muda, sugiriendo que las larvas recién eclosionadas tienen una necesidad inmediata y creciente de utilizar las proteínas como fuente de aminoácidos para el crecimiento y el desarrollo, y posiblemente, como fuente de energía. Las mayores variaciones durante el ciclo de muda en las actividades enzimáticas digestivas se observaron en el estado de megalopa. Después de un incremento inicial en postmuda, las actividades enzimáticas decrecieron a valores bajos comparados con aquellos medidos en los estados de zoea en intermuda y, a continuación, se alcanzaron los niveles máximos en premuda. La metamorfosis implica cambios fisiológicos, los cuales podrían explicar las fuertes variaciones observadas en el ciclo de muda de la megalopa. De ahí que sugiramos que los estadios del ciclo de muda deberían tenerse en cuenta en determinados estadios larvarios cuando se usen índices de condición nutricional para estimar el estado fisiológico de las larvas de crustáceos decápodos

Morfología de los estadios larvarios de una población Mediterránea del cangrejo alóctono, Dyspanopeus sayi (Decapoda: Brachyura: Panopeidae)

[EN] In this study the complete larval development (including four zoeal stages and a megalopa stage) of Dyspanopeus sayi is described and illustrated in detail based on larvae reared in the laboratory. Ovigerous females were collected in Alfacs Bay, Ebro Delta (NW Mediterranean) where the species was recently introduced. These larval stages were compared with others collected in the plankton from the same area, the larval stages described previously for this species and the larval stages of the two other Panopeidae that inhabit the Iberian Peninsula: Panopeus africanus and Rhithropanopeus harrisii. Differences were found in both zoeal and megalopal larval characters between D. sayi and the other two species, which could raise doubt about their placement in the same family.[ES] En este estudio se describe e ilustra en detalle el desarrollo larvario (4 estadios zoea y un estadio megalopa) de Dyspanopeus sayi , a partir de larvas cultivadas en el laboratorio. Las hembras ovígeras fueron capturadas en la Bahía de Alfacs (NO Mediterráneo), donde la especie ha sido recientemente introducida. Los estadios larvarios descritos han sido comparados con larvas del plancton capturadas en la misma zona, con descripciones previas de esta especie y con descripciones de los estadios larvarios de las otras dos especies de Panopeidae que habitan en la Península Ibérica: Panopeus africanus y Rhithropanopeus harrisii. Se han encontrado diferencias destacables en algunos caracteres de los estadios, zoea y megalopa, lo cual podría poner en duda la posición de estas especies dentro de la misma familia.This study was funded by the Spanish “Ministerio de Ciencia e Innovación, Plan Nacional I+D” and the European FEDER funds through project MEGALO - PADN (CGL2009-11225). The “Ministerio de Ciencia e Innovación” also supported a FPI PhD grant to EMH (BES-2010-033297); results here presented are part of her PhD thesis project. Financial support to GG (post-doctoral fellowship; INIA) was provided by the Ministry of Science and Research.Peer reviewe

Developmental and moult cycle related biochemical changes in larvae of the spider crab, Maja brachydactyla (Brachyura: Majidae)

Ontogenetic changes in dry weight, elemental composition (CHN), and digestive enzyme activities (total protease, amylase) were studied during the moulting cycle of all larval instars (zoea I-II, megalopa; ZI, ZII, M) of the spider crab Maja brachydactyla Balss, 1922 reared in the laboratory. A gradual but significant increase in biomass was observed throughout the zoeal instars, followed by steeper growth in the megalopa. Maximum values were reached in moult stage D2. Digestive enzyme activities also increased significantly throughout larval development. The ZI showed a continuous increase in total protease activity during its moult cycle, suggesting that newly hatched larvae have a gradually increasing need to take up proteins to provide amino acids, which are prime materials for growth and development, and possibly to use them as a metabolic energy source. The largest variations in digestive enzyme activites in relation to the moult cycle were observed in the megalopa instar. After an initial increase in postmoult, enzyme activities decreased to low levels similar to those measured in the zoeal instars at intermoult, followed by another increase to a maximum level in premoult. Metamorphosis involves great physiological and behavioural changes, which could explain the large variations in the megalopa moult cycle. We therefore suggest that the moult cycle stages should be taken into account when nutritional condition indices are used to estimate the physiological performance of decapod crustacean larvae.Bench fees were funded by INIA (RTA2008- 00003-00-00 project) to GR. Financial support was provided by the Ministry of Science and Research to GG (post-doctoral fellowship; INIA). The authors would like to thank Glòria Macià and Sandra Molas for their support as hatchery and laboratory technicians at IRTA, Sant Carles de la Ràpita, and Julia Haafke at AWI, Helgoland, for the CHN analysesinfo:eu-repo/semantics/publishedVersio