Weight-length relationships of six shrimp species caught off the Madeira Archipelago, Northeastern Atlantic / Relações peso-comprimento de seis espécies de camarão capturados ao largo do arquipélago da Madeira, Atlântico Nordeste

Abstract Length and weight relationships and descriptive statistics are reported for six shrimp species caught off the Madeira archipelago between 1983 and 2014 using bottom and floating traps from depths ranging from 50 to 1,300 m. The parameter b ranged between 2.36 for Plesionika ensis and 2.97 for Plesionika williamsi. All species showed a pattern of negative allometric growth. To the authors' knowledge all weight-length relationships presented herein are recorded for the first time from the Madeira area, and in the cases of Ligur ensiferus and Plesionika ensis are the first references worldwide.

Resumo As relações peso-comprimento e a estatística descritiva foram estimadas para seis espécies de camarões, capturados ao largo do arquipélago da Madeira, entre 1983 e 2014, usando armadilhas de fundo e alvoradas entre os 50 e 1.300 metros de profundidade. O parâmetro b variou entre 2,36 para Plesionika ensis e 2,97 para Plesionika williamsi. Todas as espécies evidenciaram um padrão de crescimento alométrico negativo. De acordo com o conhecimento dos autores, todas as relações peso-comprimento são aqui apresentadas pela primeira vez para a área da Madeira e no caso de Ligur ensiferus e Plesionika ensis são a primeira referência mundial.

Distribution and abundance of freshwater decapods in an Atlantic rainforest catchment with a dammed future / Distribuição e abundância de decápodes de água doce e sua associação com variáveis ambientais em uma bacia hidrográfica de Mata Atlântica que será represada

Abstract Variations in physical characteristics along the course of a river influence habitat availability which reflects in species distribution. Knowledge of ecology and diversity of lotic species is important for evaluating how river ecosystems will respond to environmental impacts. Freshwater decapods are a group of high ecological and economic importance, but the knowledge about factors influencing their distribution is scarce in Brazil. We performed a survey of decapods to describe their abundance and distribution as well as to study their relationships with stream physical variables and especially their association with different substrates types. We studied 23 sites located in 15 tributaries of Guapiaçú River, RJ, where we collected decapods in different substrates types and measured a set of physical variables. We found five decapods species, including amphidromous and non-amphidromous shrimps and crabs. Decapods were strongly associated with leaf-litter substrates and their abundance was related to a multivariate axis describing longitudinal changes in stream characteristics. We concluded that decapods occurring in the Guapiaçú catchment inhabit mainly small streams with preserved riparian forests where they find shelter and potential prey of invertebrates. The ongoing project to build a dam on the Guapiaçú River will have negative consequences to migrating shrimps and we strongly recommend that mitigating actions, such the construction of structures to allow the passage of migrating fauna, should be taken.

Resumo Variações nas características físicas de um rio ao longo do seu curso influenciam a disponibilidade de habitas e dessa forma a distribuição de espécies. O conhecimento sobre a ecologia e diversidade de espécies lóticas é importante para avaliar como esses ecossistemas responderão a impactos ambientais. Decápodes de água doce são um grupo de grande importância ecológica e econômica, contudo o conhecimento sobre fatores influenciando sua distribuição ainda é escasso no Brasil. Nós realizamos um levantamento de decápodes para descrever sua abundância e distribuição, bem como estudar sua relação com características físicas dos rios, especialmente sua associação com tipos diferentes de substrato. Nós estudamos 23 localidades distribuídas em 15 rios tributários do Rio Guapiaçú, RJ, onde coletamos decápodas em diferentes tipos de substratos e medimos um conjunto de variáveis físicas. Nós encontramos cinco espécies de decápodas incluindo camarões anfídromos e não anfídromos e caranguejos. Esses organismos foram fortemente associados a substratos de folhiço alóctone e sua abundância foi relacionada com um eixo PCA que descreve as mudanças nas características físicas longo do curso do rio. Nós concluímos que os decápodas que ocorrem na bacia do Rio Guapiaçú habitam principalmente pequenos córregos com mata ciliar preservada, onde podem encontrar abrigo e um potencial campo de caça onde predam invertebrados. O projeto atualmente em curso para a construção de uma represa no Rio Guapiaçú irá afetar negativamente a fauna de camarões anfídromos, assim nós recomendamos fortemente que ações mitigadoras, como a construção de estruturas para permitir a passagem da fauna migrante sejam tomadas.

New records of the striped cleaner shrimp Lysmata grabhami (Gordon, 1935) from Brazil, Southwestern Atlantic / Novos registros do camarão limpador Lysmata grabhami (Gordon, 1935) no Brasil, Atlântico Sul Ocidental

Abstract New records for Lysmata grabhami (Gordon, 1935) in Brazilian waters are presented. Four adult individuals from coastal waters off the city of Vitória, Espírito Santo coast and one adult from Trindade Island were collected during scuba diving in depths between 20-40 meters. These two records represent the southernmost published finding of this species in the Atlantic and the record for Vitória, Espirito Santo is the first from Brazilian coastal waters.

Resumo Novos registros de ocorrência de Lysmata grabhami (Gordon, 1935) em águas brasileiras são apresentados. Quatro indivíduos foram coletados próximo à costa da cidade de Vitória, Espírito Santo, e um na Ilha da Trindade, por mergulhadores autônomos em profundidades entre 20-40 metros. O presente registro é a ocorrência mais meridional conhecida para esta espécie no Atlântico e o registro em Vitória é o primeiro para águas costeiras brasileiras.

Do omnivorous shrimp influence mayfly nymph life history traits in a tropical island stream?

Interspecific interactions can play an important role in determining habitat selection and resource use between competing species. We examined interactions between an omnivorous shrimp and a grazing mayfly, two co-dominant taxa found in Puerto Rican headwater streams, to assess how predator presence may influence mayfly resource use and instantaneous growth in a tropical rainforest ecosystem. We conducted a series of behavioral and growth experiments to determine the effects of the freshwater shrimp, Xiphocaris elongata, on the growth rate and resource selection of mayfly nymphs in the family Leptophlebiidae. For resource choice assessments, we conducted a series of five day laboratory experiments where mayflies were given access to two resource substrate choices (cobble vs. leaves) in the presence or absence of shrimp. To assess for the effects of shrimp on mayfly fitness, we measured mayfly growth in laboratory aquaria after five days using four treatments (cobble, leaves, cobble + leaves, no resource) in the presence or absence of shrimp. In resource choice experiments, mayflies showed preference for cobble over leaf substrata (p<0.05) regardless of the presence of shrimps, however, the preference for cobble was significantly greater when shrimp were present in the leaf habitat. In growth experiments, there were no statistical differences in mayfly growth in the presence or absence of shrimp (p=0.07). However, we measured increased mayfly nymph growth in the absence of predators and when both cobble and leaves were available. Our results suggest that interspecific interactions between these taxa could potentially influence organic matter resource dynamics (e.g., leaf litter processing and export) in Puerto Rican streams. Rev. Biol. Trop. 62 (Suppl. 2): 41-51. Epub 2014 April 01.

Las relaciones interespecíficas pueden jugar un papel importante en la determinación del uso de recursos y selección de hábitat entre especies que compiten. Hemos examinado las interacciones entre un camarón omnívoro y un efemeróptero que se alimenta de vegetación , dos taxones codominantes en las partes altas de arroyos de Puerto Rico, para evaluar el efecto de los depredadores en el uso de recursos del efemeróptero y el crecimiento instantáneo en un ecosistema de selva tropical. Examinamos experimentalmente el efecto del camarón Xiphocaris elongata sobre la tasa de crecimiento y selección de recursos en ninfas efemerópteras (Leptophlebiidae). Hicimos experimentos de laboratorio de 5 días, dando a los efemerópteros acceso a dos opciones de sustrato (piedrecillas u hojas) en presencia o ausencia del camarón. Para evaluar los efectos sobre el crecimiento probamos cuatro tratamientos (piedrecillas, hojas , piedrecillas + hojas, sin ambas), en presencia o ausencia del camarón. Los efemerópteros prefirieron las piedrecillas a las hojas ( p < 0,05 ) independientemente de la presencia de los camarones. Esta preferencia fue mayor cuando junto a las hojas había camarones. Los camarones no afectaron el crecimiento de los efemerópteros (p = 0,07). Las ninfas efemerópteras crecieron mejor sin camarones y en acuarios con piedrecillas y hojas. Nuestros resultados sugieren que las interacciones interespecíficas entre estos animales podrían influir en la dinámica de la materia orgánica (por ejemplo, procesamiento de la hojarasca y su exportación) en los arroyos puertoriqueños.

Effects of insect and decapod exclusion and leaf litter species identity on breakdown rates in a tropical headwater stream

High species richness of tropical riparian trees influences the diversity of organic detritus entering streams, creating temporal variability in litter quantity and quality. We examined the influence of species of riparian plants and macroinvertebrate exclusion on leaf-litter breakdown in a headwater stream in the Luquillo Mountains of Puerto Rico. Leaf litter of Dacryodes excelsa (Burseraceae), Guarea guidonia (Meliaceae), Cecropia scheberiana (Moraceae), Manilkara bidentata (Sapotaceae), and Prestoea acuminata (Palmae) were incubated in litter bags in a pool of Quebrada Prieta. Fine mesh bags were used to exclude macroinvertebrates during leaf breakdown, and coarse mesh bags allowed access to decapod crustaceans (juvenile shrimps and crabs) and aquatic insects (mainly mayflies, chironomids, and caddisflies). D. excelsa and G. guidonia (in coarse- and fine-mesh bags) had significantly higher breakdown rates than C. scheberiana, M. bidentata, and P. acuminata. Breakdown rates were significantly faster in coarse-mesh bag treatments for all leaf types, thus indicating a positive contribution of macroinvertebrates in leaf litter breakdown in this headwater stream. After 42 days of incubation, densities of total invertebrates, mayflies and caddisflies, were higher in bags with D. excelsa and G. guidonia, and lower in P. acuminata, C. scheberiana y M. bidentata. Decay rates were positively correlated to insect densities. Our study highlights the importance of leaf identity and macroinvertebrate exclusion on the process of leaf litter breakdown in tropical headwater streams. Rev. Biol. Trop. 62 (Suppl. 2): 143-154. Epub 2014 April 01.

La gran variedad de especies vegetales junto a los ríos tropicales afecta la diversidad de detritos orgánicos que llegan a los arroyos, creando variaciones temporales en cantidad y calidad de hojarasca. Examinamos la influencia de las especies vegetales y de la exclusión de macroinvertebrados sobre la descomposición de hojarasca en la parte alta de un arroyo en las montañas Luquillo de Puerto Rico. Incubamos hojarasca de Dacryodes excelsa (Burseraceae), Guarea guidonia (Meliaceae), Cecropia scheberiana (Moraceae), Manilkara bidentata (Sapotaceae) y Prestoea acuminata (Palmae) en bolsas descomposición que colocamos en una poza de Quebrada Prieta. Usamos bolsas de malla fina para excluir los macroinvertebrados y de malla gruesa para permitir la entrada a crustáceos decápodos (camarones y cangrejos jóvenes) e insectos acuáticos (principalmente efemerópteros, quironómidos y tricópteros). D. excelsa y G. guidonia (en ambos tipos de malla) tuvieron tasas de descomposición más altas que C. scheberiana, M. bidentata y P. acuminata. La descomposición fue más rápida para todas las especies de hoja con la malla gruesa, resaltando el papel de los descomponedores en este hábitat. Tras 42 días de esta incubación, las densidades totales de invertebrados, efemerópteros y tricópteros fueron mayores en las bolsas con hojas de D. excelsa y G. guidonia, e inferiores en P. acuminata, C. scheberiana y M. bidentata. A mayor densidad de insectos hubo mayor tasa de descomposición. Nuestros resultados indican la importancia de la especie de las hojas y de la presencia de macroinvertebrados en el proceso de descomposición de hojarasca en partes altas de arroyos tropicales.

Suscetibilidade dos estágios ontogenéticos: padrão osmorregulatório em camarões peneídeos e palemonídeos / Susceptibility of ontogenetic stages: osmoregulatory standard in penaeid and palaemonid shrimps / Susceptibilidad de etapas ontogenéticas: estándar osmorregulatorio en camarones peneídeos y palemonídeos

A invasão da água doce por crustáceos ocorreu repetidamente ao longo dos anos, pressionando um ajuste em seus processos fisiológicos. A habilidade de sobreviver aos diferentes ambientes foi encontrada em traços osmorregulatórios, e estão relacionadas à capacidade de regular o fluido extracelular. Portanto, o objetivo deste manuscrito é explorar os processos osmorregulatórios de camarões palemonídeos e peneídeos, visualizando um padrão na capacidade osmorregulatória em ambas as famílias e, em particular, tratar de assuntos pertinentes aos efeito no ciclo ontogenético e o efeito ocasionado pelo nitrito na hemolinfa de crustáceos. Comparando palemonídeos e peneídeos, percebe-se que o sucesso da conquista do ambiente dulcícola, e a não necessidade de hiporregulação, levou à perda dessa capacidade na maioria dos palemonídeos. Dessa forma, se supõem um ancestral com capacidade hiporregulatória, uma vez que invertebrados marinhos são, parcimoniosamente, osmoconformadores. Compara-se também que o nitrito apresenta efeito nas proteínas presentes na hemolinfa dos crustáceos quando submetidos à exposição natural ou induzida deste composto, e que a capacidade osmorregulatória é, portanto, variada de acordo com seus estágios...

The invasion of freshwater by crustaceans has occurred repeatedly over the years, pressing for an adjustment in their physiological processes. The ability to survive in different environments was found in osmoregulatory traits and is related to the ability to regulate the extracellular fluid. Therefore, the purpose of this manuscript is to explore the osmoregulatory processes in palaemonid and penaeid shrimps, which display a pattern of osmoregulatory capacity in both families and, in particular, to deal with matters related to the effects on ontogenetic cycle and the effect raised by nitrite in crustacean hemolymph. By comparing palaemonid and peneid shrimps, it is possible to note the success of conquering freshwater environment, and not the need for hypo-regulation, has led to the loss of this capability in most palaemonids. Thus, it is assumed that they share an ancestor with hypo-regulatory capacity, since marine invertebrates are sparsely osmoconformers. The article also compares that nitrite has effect on proteins present in the hemolymph of crustaceans when subjected to natural or induced exposure to these compound, and osmoregulatory capacity is therefore varied according to their stages...

La invasión del agua dulce por crustáceos ocurre repetidamente a lo largo de los años, pulsando un ajuste en sus procesos fisiológicos. La capacidad de sobrevivir en diferentes ambientes se ha encontrado en rasgos osmorregulatorios y están relacionados a la capacidad de regular el fluido extracelular. Por lo tanto, el objetivo de este manuscrito es el de explotar los procesos osmorregulatorios de camarones palemonídeos y peneídeos, se muestra un estándar en la capacidad osmorregulatoria en ambas las familias y, en especial, trata de cuestiones relativas a los efectos sobre los ciclo ontogenético y el efecto causado por nitrito en la hemolinfa de crustáceos. Comparando palemonídeos y peneídeos, se da cuenta de que el éxito de la conquista del ambiente dulcícola, y sin necesidad de hipo regulación, condujo a la pérdida de esa capacidad en la mayoría de los palemonídeos. Así, se supone un ancestral con capacidad hipo regulatoria, una vez que los invertebrados marinos son, parsimoniosamente, osmoconformadores. Se compara también que el nitrito presenta efectos en las proteínas presentes en la hemolinfa de los crustáceos cuando sometidos a la exposición natural o inducida por estes compuesto, y que la capacidad osmorregulatoria es, por lo tanto, variada de acuerdo con sus etapas...

In vitro fertilization of the rock shrimp, Rhynchocinetes typus (Decapoda, Caridea): a review

This review compiles all the research done on gametes and fertilization in the rock shrimp, R. typus, and describes the sequence of events from the first gamete interaction to zygote formation and the first cleavage of the embryo, with light, fluorescence confocal and electron microscopes. Early studies showed that sperm from the vas deferens have a tack-shape with a "needle-like process" or rigid spike (RS) that extends from a semi-spherical body that contains the arms with chromatin and spines. Upon contact with seawater and by action of Na +, the arms and spines extend, producing an inverted umbrella form of the spermatozoa. The first sperm-oocyte interaction occurs between protein receptors type lectins of the sperm RS and oocyte chorion sperm ligands. These ligands contain residues of a-Glu, Man (a 1-3) Man, a and p-GlcNAc and a-GalNA terminal residues. It was found that a-Man and GlcNAc residues are the ligands that are directly related to the adhesion process and further penetration of sperm. After this first interaction, the RS enters the oocyte envelope by the action of a trypsin-like enzyme, rhynchocinecine, present in the acicular process. Later, arms and spines penetrate the oocyte cytoplasm, where the chromatin of the arms begin to migrate to the central area of the sperm, condensing in a cup-shaped structure near the connecting piece, which forms the male pronucleus.

Genetic population structure of an anchialine shrimp, Metabetaeus lohena (Crustacea: Alpheidae), in the Hawaiian Islands

Anchialine habitats in the Hawaiian Islands, characterized as coastal bodies of land-locked salt or brackish water that fluctuate with the tides due to subterranean connections, are the only ecosystems of this type found within the United States. These habitats are currently subject to anthropogenic impacts tha t threaten their future existence. Previous research has shown strong genetic population structure of an endemic atyid shrimp, Halocaridina rubra, in these habitats. The native alpheid shrimp, Metabetaeus lohena, whose known range entirely overlaps that of H. rubra, has feeding and reproductive behaviors that are biologically distinct from H. rubra. Its historic scarcity and status as a candidate for the US Fish and Wildlife Department’s Endangered Species List, make M. lohena an ideal species to compare against the known genetic structure of H. rubra. We investigated the population structure of this native anchialine shrimp to test the hypothesis that genetic population structure differs between the two shrimp species and that M. lohena is genetically unstructured across its range. A survey of 605 bp of the mitochondrial cytochrome c oxidase subunit I (COI) gene from 127 individuals collected at 7 sites spanning the islands of O’ahu, Maui and Hawaii revealed 43 haplotypes. The most common haplotype was represented in similar proportions from all sites sampled, accounting for 44% of the surveyed sequences. Analyses of molecular variation (AMOVA), pairwise ΦST values, Bayesian estimates of migration (M), Mantel tests and Nested Clade Analyses (NCAs) all failed to reveal evidence of major barriers to gene flow among most populations separated by inter-island channels. This lack of genetic structure in M. lohena is found to be in stark contrast with the highly structured population of H. rubra, and may be attributed to oceanic dispersal strategies and/or a recent introduction to the Hawaiian Islands. Rev. Biol. Trop. 58 (1): 159-170. Epub 2010 March 01.

Los hábitats de los alfeidos de las islas de Hawaii, se caracterizan por ser zonas cerradas de aguas saladas o salobres, que fluctúan con las mareas, debido a las conexiones subterráneas, son los únicos ecosistemas de este tipo que se encuentran en Estados Unidos. Estos hábitats actualmente están sujetos a impactos antropogénicos que amenazan su existencia futura. La investigación anterior ha demostrado una fuerte estructura genética de una población de camarones atíidos endémicos, Halocaridina rubra, en estos hábitats. El camarón alfeido nativo, Metabetaeus lohena, cuya área de distribución conocida se superpone totalmente con la de H. rubra, tiene comportamientos alimenticios y reproductivos que son biológicamente diferentes a los de H. rubra. Su escasez histórica y su condición de candidato para aparecer en la Lista de Especies en Peligro del Departamento de Pesca y Vida Silvestre de Estados Unidos, hace de M. lohena una especie ideal para comparar su estructura genética con la de H. rubra. Se investigó la estructura de la población de este camarón alfeido nativo para probar la hipótesis que la estructura genética de la población difiere entre las dos especies y que la de M. lohena está genéticamente no estructurada en todo su ámbito. El análisis de 605 pb de la oxidasa mitocondrial citocromo c subunidad I (COI) de genes de 127 individuos recolectados en 7 sitios que abarcan las islas de Oahu, Maui y Hawaii reveló 43 haplotipos. El haplotipo más común fue representado en proporciones similares en todos los sitios incluidos en la muestra, de acuerdo al 44% de las secuencias estudiadas. El análisis de variación molecular (AMOVA), los valores de ΦST pareados, la estimación bayesiana de la migración (M), las pruebas de Mantel y los Análisis Cladísticos no pudieron revelar la existencia de importantes barreras al flujo genético entre las poblaciones más separadas por los canales entre las islas. La falta de estructura genética en M. lohena contrasta con la muy estructurada población de H. rubra, y puede ser atribuida a las estrategias de dispersión oceánica y/o una introducción reciente en las islas hawaianas.

Daños por depredación y tamaño de concha del caracol diádromo Neritina virginea (Gastropoda: Neritidae) en el Río Mameyes, Puerto Rico

Predator damage and shell size on the diadromous snail Neritina virginea (Gastropoda: Neritidae) in the Mameyes River, Puerto Rico. We compared predators’ damage with shell size in live individuals and empty shells (n=5066) of the snail Neritina virginea in the Mameyes River (Puerto Rico, Greater Antilles). According to the literature and direct observations, damages on empty shells were attributed to predation by aquatic birds (e.g. Gallinula chloropus) and decapods (e.g. Macrobrachium spp.), while damages on live individuals were due to rasping by co-specifics and erosion. Predation by decapods and birds, as estimated by the proportion of empty shells, was low (2 and 0.36%, respectively). Shell size was significantly different between types of predators (range: decapods: 3.5-15.0mm, birds: 8.1-19.4mm). By comparing sizes of the empty shells and the live individuals, we concluded that decapods specialize on large groups of small migratory juveniles, while birds specialize on the largest resident individuals. Worn shells were highly frequent in both empty shells and live individuals, and sizes did not differ between samples. A comparison by slow-flow and fast-flow habitats showed that predators do not discriminate shell sizes between environments. However, the frequency of damage by birds and decapods was greater under slow-flow conditions. Despite of the little contribution of predation to the population dynamics in this species, predation might be an important driver of size-dependent behavioral responses such as upstream migration and microhabitat selection. Rev. Biol. Trop. 57 (4): 1069-1080. Epub 2009 December 01.

Se compararon las abundancias y tamaños de conchas del gasterópodo Neritina virginea de acuerdo a los daños presentados en especimenes vivos y muertos (n= 5066) recolectados en el río Mameyes, Puerto Rico (Antillas Mayores). Se observaron daños por depredación de aves y camarones, y signos de erosión por la acción del raspado de la rádula por parte de otros individuos de la misma especie. La depredación fue aparentemente baja (<2.5%), pero los tamaños de concha depredados por aves y camarones fueron significativamente diferentes. Las primeras se especializan en los individuos residentes más grandes, mientras que los segundos se especializan en individuos juveniles que presentan un comportamiento migratorio. Estos tamaños no fueron diferentes entre dos hábitats, aunque se observó más conchas depredadas por decápodos que por aves. El desgaste fue común en conchas de todos los tamaños. A pesar de su baja contribución a la dinámica poblacional de los gasterópodos, la depredación podría ser un control importante de respuestas de comportamiento dependientes del tamaño, tales como la migración río arriba y la selección de microhábitats.

Crecimiento y reproducción del camarón Atya margaritacea (Decapoda: Atyidae) en el Río Presidio, Sinaloa, México

Growth and reproduction of the shrimp Atya margaritacea (Decapoda: Atyidae) in Río Presidio, Sinaloa, Mexico. Some growth and reproduction parameters of the population of the shrimp Atya margaritacea in Presidio River (Sinaloa, NW Mexico) were studied using 542 organisms collected with a Surber net in five sampling locations distributed from mid- to low river. Total lengths and gross weights ranged from 15 to 96 mm and 0.1 to 25.2 g. The male:female ratio was 1.96:1 and males had larger sizes and weights. The relations of total length (Lt) to gross weight (Pt) were Pt = 1.02x10-5 (Lt)3.2089 for males and Pt = 2.29x10-5 (Lt)3.0159 for females. Growth in males was positively allometric whereas in females it was isometric. The regressions between total lengths and cephalothorax (Lc) were Log Lc = 1.1118 (Log Lt)- 0.6087 for males and Log Lc = 0.9945 (Log Lt)- 0.4321 for females. The relative growth between these body parts was allometrically positive in males and isometric in females; this result indicates a clear sexual dimorphism. Ovigerous females appeared in the rainy season (July to November). The absolute fecundity ranged from 1 860 to 22 400 eggs in females of 43 to 59 mm in length and 1.9 to 6.0 g in weight. The equations relating the number of eggs to length and weight were Fec = 8.3x10-7 (Lt)5.8053 and Fec = 732 (Pt)1.836 respectively. Rev. Biol. Trop. 56 (2): 513-522. Epub 2008 June 30.

Se estudiaron el crecimiento y reproducción de de Atya margaritacea, con base en 542 organismos capturados en cinco sitios distribuidos desde la parte media de la cuenca hasta la desembocadura del río Presidio (Sinaloa, NW de México). La recolecta se realizó mediante el empleo de una red Surber, recolectándose organismos cuya longitud total y peso total variaron de 15 a 96 mm y 0.1 a 25.2 g respectivamente. La proporción macho:hembra fue 1.96:1 y los machos alcanzaron las mayores tallas y pesos. La relación entre la longitud total (Lt) y el peso total (Pt) se estableció mediante el modelo Pt = 1.02x10-5 (Lt)3.2089 para los machos y por Pt = 2.29x10-5 (Lt)3.0159 para las hembras. El crecimiento en machos resultó alométricamente positivo mientras que en hembras fue isométrico. La regresión entre la longitud total y longitud cefalotórax (Lc) fue Log Lc = 1.1118 (Log Lt)- 0.6087 en machos y Log Lc = 0.9945 (Log Lt)- 0.4321 en hembras. El crecimiento relativo entre estas partes del cuerpo resultó alométrico positivo en machos e isométrico en hembras, indicando un claro dimorfismo sexual de estos organismos. Hembras ovígeras se presentaron en la época de lluvias (julio a noviembre). La fecundidad absoluta varió de 1 860 a 22 400 huevos en hembras de 43 y 59 mm de longitud y de 1.9 a 6.0 g de peso. La ecuación que relacionó el número de huevos con la longitud y peso, fue Fec = 8.3x10-7 (Lt)5.8053 y Fec = 732 (Pt)1.836 respectivamente.

Development and functional morphology of the foreguts of larvae and postlarvae of three crustacean decapods

The development of the foregut structure and the digestive function of the decapods Litopenaeus vannamei, Sesarma rectum and Callichirus major larvae and post larvae were examined. The protozoeal foregut of L. vannamei is simple, lacking a cardiopyloric valve and bearing a rudimentary filter press. In mysis, the filter press is more developed. In the juvenile stage, grooves and a small lateral tooth arise. In S. rectum, the foregut has a functional cardiopyloric valve and a filter press. The megalopal and juvenile stages of this species have a gastric mill similar to those in adult crabs. In C. major, the foregut of the zoeae is specialized, with the appearance of some rigid structures, but no gastric mill was found. Calcified structures are observed in the megalopae and they become more developed in the juvenile stage. The results support suppositions, previously reported in other studies, that feeding behavior of each larval and postlarval stage is directly related to the morphological characteristics of the foreguts.

O desenvolvimento da estrutura do estômago e da função digestiva foi examinada em larvas e pós-larvas de Litopenaeus vannamei, Sesarma rectum e Callichirus major. O estômago do protozoea de L. vannamei é muito simples, sem válvula cárdiopilórica e apresenta um filtro pilórico rudimentar. Em mysis, o filtro pilórico parece ser mais desenvolvido. No juvenil I surgem calhas e dentes laterais pouco desenvolvidos. Os estômagos dos zoeae de S. rectum possuem a válvula cárdiopilórica e o filtro pilórico funcionais. Nos estágios megalopa e juvenil I o moinho gástrico é complexo. Em C. major, os estômagos dos zoeae se mostram especializados exibindo algumas estruturas rígidas, mas não apresentam moinho gástrico. Esta estrutura surge no megalopa e juvenil I. Os resultados suportam suposições anteriores que o comportamento alimentar de larvas e pós-larvas está diretamente relacionado com as características morfológicas dos estômagos.

Diversidad y distribución de los crustáceos estomatópodos y decápodos en el estuario del río Gallegos (Santa Cruz, Argentina) / Diversity and distribution of stomatopod and decapod crustaceans in the estuary of Gallegos river (Santa Cruz-Argentina)

Estudiamos la diversidad y distribución de los crustáceos estomatópodos y decápodos en el estuario del río Gallegos, Argentina. En todas las estaciones se registró la presencia de decápodos, pero solo en la estación exterior se registraron estomatópodos y anomuros. La diversidad, fue marcadamente mayor en la estación exterior. Se registra un total de seis especies (cinco decápodos y un estomatópodo), indicando que la riqueza de crustáceos en el estuario es baja con relación a la señalada para el mar argentino. Su abundancia es variable en las estaciones, dependiendo del tipo de fondo.

We studied the diversity and distribution of stomatopod and decapod crustaceans from the estuary of Gallegos River, Argentina. Decapods were found at all stations, while stomatopods and anomurans were found only at the exterior station. There was a marked difference in diversity, the exterior station being more diverse. A total of six species were found (five decapods and one stomatopod), a low value when compared with the surrounding sea. Abundance was variable at stations, depending on the type of bottom.

Controla la biomasa de pastos marinos la densidad de los peracáridos (Crustacea: Peracarida) en lagunas tropicales? / Does sea-grass biomass control the density of peracarids (Crustacea: Peracarida) in tropical lagoons?

We analyzed the time-space variation of the peracarid crustaceans that inhabit seagrasses of the Alvarado Lagoon System, Veracruz, Gulf of Mexico. The organisms were collected from 108 samples in six sites with Ruppia maritima beds (December 1992 to November 1994). The assemblage was composed of 11 species. Eight species of Amphipoda (Hourstonius laguna, Cerapus benthophilus, Apocorophium louisianum, Grandidierella bonnieroides, Leptocheirus rhizophorae, Gammarus mucronatus, Melita longisetosa and Haustorius sp.), one of Isopoda (Cassidinidea ovalis) and two of Tanaidacea (Discapseudes holthuisi and Leptochelia savignyi) were identified. Taxocoenosis, density and biomass of peracarids showed seasonal pulses related to R. maritima biomass, salinity variation, epicontinental affluent and inlets. The species C. ovalis, G. mucronatus, A. louisianum and D. holthuisi were dominant.

Current progress in shrimp endocrinology-a review.

One problem in aquaculture is obtaining brood because many commercially important species are incapable of spontaneous maturation under artificial conditions. Commercial shrimp hatcheries commonly use eyestalk ablation to stimulate gonadal maturation in shrimps. Research has been conducted on the inhibition of reproductive maturation by hormones originating in the eyestalk glands and on other endocrine sources (e.g.,brain, thoracic ganglion, ovary, mandibular organ, androgenic gland and Y-organs) to determine their roles. Alternate techniques for acceleration of gonad maturation through the use of synthetic hormones or neurotransmitters may benefit aquaculture. Neurohormones and neuroregulators have been shown to accelerate gonadal maturation but an effective delivery technique must be developed for use in a large-scale aquaculture operation.

Hermafroditismo en camarones: el sistema sexual y su relación con atributos socioeconómicos / Hermaphroditism in shrimps: the sexual system and its relatioship with sociecological attributes

Una pregunta importante en la ecología de reproducción es ¿por que hay sexos separados en algunas especies pero hermafroditismo en otras? Este artículo está enfocado en un sistema sexual recientemente descrito, hermafroditismo simultáneo protándrico (HSP), en camarones "limpiadores" del genero Lysmata. En este sistema, los individuos maduran primero en una fase masculina (FM) pero más tarde cambian a una fase femenina (FF). Aunque los individuos FF producen embriones como si fueran hembras, también retienen los ductos masculinos y producen esperma. Los FF son hermafroditas simultáneos que pueden copular como machos y fertilizar otros FF pero no pueden autofertilizarse. Es posible que el tamaño (edad) de cambio de FM a FF-sea dependiente de la abundancia relativa de los FM y FF en la población (determinación ambiental de sexo). Dada la amplia variación de los atributos socieconómicos entre especies de Lysmata, es difícil proponer una sola fuerza selectiva que pueda explicar la evolución de HSP. Se propone una hipótesis basada en la historia evolutiva de Lysmata. Se sugiere que el HSP no ocurre en otros grupos de carideos porque evolucionó bajo circunstancias únicas a Lysmata ("contingencia histórica"). Para entender este raro sistema sexual, hay que estudiar en detalle la ecología, etología y filogenia de Lysmata

Nutrición en juveniles del langostino Macrobrachium carcinus (Crustacea: Decapoda) con dietas de residuos vegetales y marinos / Nutrition of juvenile prawn Macrobrachium carcinus (Crustacea: Decapoda) with diets of vegetable and marine residues

Juvenile prawn Macrobrachium carcinus were fed two different diets: restaurant by-products (diet I) and fish and vegetable market by-products (diet II). These diets were evaluated by proximal analysis, assimilation efficiency and the factor conversion rate (FCR). Diet I registered a higher efficiency, but there was no difference in the growth rate. The growth mean (G. L.) for three months was 0.254 +/- 0.13 cm (diet I) and 0.191 +/- 0.1 cm (diet II). The conversion rate was good for both, suggesting that 6 to 7 kg of food are needed to obtain 1 kg of prawn. Survival was 76 PER CENT and 100 per cent for diets I and II, respectively