ABSTRACT The objective of this study was to analyze the brachyuran crab assemblages associated with shrimp fishing on the central-southern coast of Veracruz. Information was collected using 46 trawls organized within nine fishing quadrants. The total catch shrimp, bycatch, and discard were recorded and standardized (CPUE kg h−1). Value index by species, species richness, diversity using Shannon and Weaver index, and equitability were determined. A total of 3055 individuals were collected, which corresponded to nine families, 13 genera, and 14 species. Achelous spinicarpus species were identified at the greatest relative abundance (77.74%). Four new species records for the zone: Hepatus pudibundus, Iliacantha liodactylus, Leiolambrus punctatissimus, and Platylambrus granulatus. Species richness varied according to fishing quadrant and depth interval assessed. The highest value of species richness was eight, and observed Margalef species richness index values ranged from 0 to 2.23. The diversity values ranged from 0 to 2.41 bits ind−1; this may indicate that a few species share the greatest impact of trawling. The presence of lagoon systems was determined to define a portion of the composition of the assemblage. Understanding assemblage structure is important to improve knowledge on the impact of shrimp trawling activity on the ecosystem.

Abstract We evaluated the composition, distribution, and abundance of the decapod genera at different developmental stages of larvae and adult macro-crustaceans along the coastline of the Parque Nacional Sistema Arrecifal Veracruzano, SW Gulf of Mexico. Collections were made using light traps. Temperature, salinity, oxygen, and pH were measured in situ. The samples were fixed with 70 % alcohol, separated, and identified by developmental stage and genus level with specialized literature. The Olmstead-Tukey test, the Shannon-Wiener diversity index, and Pielou equitability test were applied. Canonical correlation and cluster analysis were performed. In total, 20,049 individuals of 56 stage-genera were collected, with Potimirim Holthuis, 1954 postlarvae being the most abundant ones. The most abundant taxa were Potimirim at Playa Martí, Macrobrachium Spence Bate, 1868 at Plaza de la Soberanía, and Pachygrapsus Randall, 1840 at Playa Villa del Mar and Playa Tortugas. At Playa Villa del Mar, the highest diversity was found (3.47 bits*individuals-1), and this is related to the complexity of the site. In May, the greatest diversity (3.64 bits*individuals-1) was found, related to the time of reproduction of most of the stage-genera. Most stage-genera were classified as rare. Cluster analysis resulted in two groups, one containing taxa found in cold and wet months and the other of taxa found in dry months. Thus, the dynamics of the taxocene structure is determined by the lifecycles of the species, responding to the migration, reproduction, and colonization of each stage-genera.

ABSTRACT Background: The Parque Nacional Sistema Arrecifal Veracruzano (PNSAV) is in the southern Gulf of Mexico and supports an important shrimp fishery based on three species of Dendrobranchiata: the brown shrimp, Penaeus aztecus, the white shrimp, P. setiferus and the pink shrimp, P. duorarum. Objective: Analyze the distribution and abundance of P. aztecus during the mysis stage and determine its relationship with environmental factors in the PNSAV. Methods: We measured temperature, salinity, and dissolved oxygen in situ. The planktonic samples from four transects were collected during cold fronts and rainy weather conditions from 2011 to 2013. Results: In rainy conditions the temperature varied from 27.49 ± 0.46 to 29.98 ± 0.02°C, salinity from 32.18 ± 0.06 to 35.40 ± 0.52, and dissolved oxygen from 3.64 ± 0.13 to 6.18 ± 0.64 mgL-1; during cold fronts the temperature varied from 23.21 ± 0.05 to 25.74 ± 0.37 °C, salinity from 34.59 ± 0.39 to 35.84 ± 0.17, and dissolved oxygen from 4.04 ± 0.06 to 6.02 ± mgL-1. The highest average density with 6,938 ± 326 mysis 100 m−3, was found during rainy season in 2011 in the southern transect nearshore, followed by 3,321 ± 339 mysis 100 m−3 in the offshoresouth-central transect during cold fronts weather conditions in 2013, and 3,056 ± 236 mysis 100 m−3 in the south-central foreshore transect during cold fronts weather condition in 2011. Conclusions: The highest density of P. aztecus during mysis stage was recorded in southward foreshore area from PNSAV, during rainy conditions and related to large values of dissolved oxygen concentrations.

RESUMEN Antecedentes: El Parque Nacional Sistema Arrecifal Veracruzano (PNSAV) está ubicado en el sur del Golfo de México y soporta una importante pesquería de camarones basada en tres especies de Dendrobranchiata: el camarón café, Penaeus aztecus, el camarón blanco, P. setiferus y el camarón rosado, P duorarum. Objetivo: Analizar la distribución y abundancia de P. aztecus en estadio de mysis y determinar su relación con los factores ambientales en el PNSAV. Métodos: Se midió la temperatura, la salinidad y el oxígeno disuelto in situ. Se recolectaron muestras planctónicas de cuatro transectos durante frentes fríos y condiciones climáticas lluviosas de 2011 a 2013. Resultados: La temperatura varió de 27.49 ± 0.46 a 29.98 ± 0.02 °C, la salinidad de 32.18 ± 0.06 a 35.40 ± 0.52 y el oxígeno disuelto de 3.64 ± 0.13 a 6.18 ± 0.64 mgL-1 en época de lluvias. Durante los frentes fríos, la temperatura varió de 23.21 ± 0.05 a 25.74 ± 0.37 °C, la salinidad de 34.59 ± 0.39 a 35.84 ± 0.17 y el oxígeno disuelto de 4.04 ± 0.06 a 6.02 ± mgL-1. La densidad media más alta fue de 6,938 ± 326 mysis 100 m−3, que se encontró durante las lluvias en 2011 en el transecto sur, cercano a la costa, seguido por 3,321 ± 339 mysis 100 m−3 en el transecto centro-sur, costa afuera durante los frentes fríos en 2,013 y 3,056 ± 236 mysis 100 m−3 en el transecto centro-sur durante los frentes fríos en 2011, en la zona de la costa. Conclusiones: La mayor densidad de mysis de P. aztecus se registró en la zona de playa al sur del PNSAV, durante las condiciones de lluvia y se relacionó con el aumento de las concentraciones del oxígeno disuelto.

RESUMEN En esta contribución se registra por primera vez a Poecilia mexicana en un estuario ciego bajo condiciones de hiperhalinidad en el golfo de México y se analizan diversas características ecológicas de la especie. Los especímenes, 170 en total (128 hembras y 42 machos), se recolectaron en mayo de 2013 en el estuario Laguna El Llano, Veracruz, México, el cual presentó aguas cálidas (31,4°C), bien oxigenadas (9,45 mg/L), transparentes, e hiperhalinas (promedio 73 UPS). Las hembras se recolectaron en un intervalo de tallas de 4,28-59,21 mm de longitud patrón y de 0,04-5,48 g en peso; los machos se colectaron en un intervalo de tallas de 15,7351,41 mm LP y de 0,091-2,97 g en peso. El intervalo de talla más numeroso fue de 10-29 mm de longitud patrón. Las hembras presentaron un crecimiento alométrico negativo; los machos presentaron un crecimiento isométrico. La hiperhalinidad del agua no pareció afectar el proceso de reproducción de P. mexicana, pues se encontraron hembras maduras con ovocitos, huevos y embriones, algunas de ellas con superfetación. La fecundidad se registró entre 12-179 ovocitos/hembra, 8-162 huevos/hembra y 29-72 embriones/hembra. El factor de condición se correlacionó positivamente con la longitud patrón y el peso. Esta especie se puede clasificar como un consumidor detritívoro que complementa su dieta con proporciones mínimas de diatomeas.

ABSTRACT In this contribution, Poecilia mexicana is recorded for the first time in a blind estuary study under hyperhalin conditions in the Gulf of Mexico and various ecological characteristics of the species are analyzed. 170 specimens in total (128 females and 42 males), were collected in May 2013 in the Laguna El Llano estuary, Veracruz, Mexico, which presented warm waters (31.4 °C), well-oxygenated (9.45 mg/L), transparent, and hyperhaline (average 73 UPS). Females were collected in a size range of 4.28-59.21 mm in standard length and 0.04-5.48 g by weight; males were collected in a size range of 15.73-51.41 mm LP and 0.091-2.97 g by weight. Largest size range was 10-29 mm standard length. The females presented a negative allometric growth; the males presented an isometric growth. Hyperhalinity of the water did not seem to affect the reproduction process of P. mexicana, since mature females were found with oocytes, eggs, and embryos, some of them presenting superfetation. Fertility was recorded between 12-179 oocytes/female, 8-162 eggs/female and 29-72 embryos/ female. Condition factor was positively correlated with the standard length and weight. This species can be classified as a detritivorous consumer that supplements its diet with minimal proportions of diatoms.

Abstract Estuaries are coastal ecosystems that contribute with different natural services to the organisms inhabiting them, but the ecological research on seasonally closed inlets by sand bars are scarce; in this contribution the fish assemblages from El Llano Lagoon estuary in May 2013 and May 2014 are described. We performed 9 monthly samplings, through which we recorded 37 species belonging to 22 families, most of them marine. The highest species richness with 21 and 20 species occurred in September 2013 and February 2014, respectively; the lowest one in May 2013 (4) when the inlet was closed and conditions of hypersalinity were present. Using NMDS indirect ordination analysis, 3 fish assemblages related to closed estuarine inlet and hypersalinity conditions were defined (> 70 PSU, May 2013), between dry-rainy seasons in euhaline and mesohaline salinity conditions (July-October 2013), and nortes-dry seasons in marine salinity condition (December 2013-May 2014), moreover Anosim test proved the differences among these fish assemblages and with Simper test was demonstrated that variations in abundance of dominant species and the occasional presence of marine and estuarine species produced the assemblage’s differences.

Resumen Los estuarios son ecosistemas costeros que aportan diferentes servicios naturales a los organismos que los habitan, pero son escasas las investigaciones que describen los procesos ecológicos en estuarios cuya boca se cierra temporalmente por una barra arenosa; por ésto se describen los ensamblajes de peces del estuario laguna El Llano entre mayo 2013 a mayo 2014. Se realizaron 9 recolectas, registrando 37 especies de 22 familias, la mayoría de origen marino. La mayor riqueza de especies ocurrió entre septiembre 2013 (21) y febrero 2014 (20), la menor (4) en mayo 2013 cuando el estuario estaba cerrado y en condiciones de hipersalinidad. Mediante un análisis de ordenación NMDS, se definieron 3 ensamblajes relacionados con la temporalidad hidrológica: boca estuarina cerrada e hipersalinidad (> 70 UPS, mayo 2013), entre las estaciones de secas-lluvias en condiciones de salinidad euhalina y mesohalina (julio-octubre 2013), y entre las estaciones de nortes-secas con boca semicerrada en condiciones de salinidad marina (diciembre 2013-mayo 2014). La prueba Anosim comprobó la diferencia entre los ensamblajes, el análisis Simper demostró que la variación de la abundancia de las especies dominantes y la aparición de especies marinas ocasionales y estuarinas, determinaron las diferencias entre los ensamblajes de peces.

The brown shrimp (Penaeus aztecus) fishery is the most important in the Gulf of Mexico. This fishery takes non-target species or by-catch fauna, mainly teleost fishes, which are incidentally captured. Some of the by-catch species has commercial use and the rest of them are discarded. Therefore, it is important to describe the composition of the discarded fauna, to determine the impacts under the ecosystem approach. Discarding catch of shrimp trawls carried out in 2013 on the continental shelf off the State of Veracruz in different depth intervals (22-46 and > 46 m) was analyzed. For each trawl, the shrimp catch, the commercial by-catch and the discarding were recorded and the catch ratios respect to shrimp, were obtained. A discard sample was taken and the species were identified, the total length was taken and the ecological parameters were calculated. The non-parametric multiple dimensional scaling test was performed. A total of 7,178 fishes were collected from 34 families, 46 genera and 51 species. The ratio of commercial species by-catch: shrimp and discard: shrimp was 15.41:1 and 40:1 kg, respectively. The species with high relative dominance were Citharichthys macrops, Synodus foetens, Diplectrum bivittatum, Rhomboplites aurorubens and Upeneus parvus. The species with greater importance index were C. macrops, S. foetens, and D. bivittatum. The 43.14% of the discarded species are used as food and 7.84% as bait. The maximum diversity (H´) was 3.76 bits ind-1 and the trophic level was 4.31. The study of discard composition is a basis to assess the impact generated by the shrimp trawlers and provides guidelines for identify changes in the community structure.

La pesquería del camarón café Penaeus aztecus es la más importante en el Golfo de México. En esta pesquería se capturan de manera incidental especies no objetivo compuestas mayormente por peces teleósteos. Es importante describir la composición del descarte, para determinar el impacto de los arrastres camaroneros bajo un enfoque ecosistémico. Se analizó la captura de descarte de arrastres camaroneros realizados en 2013 en la plataforma continental del Estado de Veracruz en 22-46 y >46 m de profundidad. Para cada arrastre se registró la captura de camarón, fauna de acompañamiento comercial, descarte y fauna de acompañamiento. Se tomó una muestra del descarte, se identificaron las especies y se calcularon los parámetros ecológicos de la muestra. Se realizó una prueba de escalamiento dimensional múltiple no paramétrica. De 87 lances de pesca, se analizaron 7.178 organismos correspondientes a 34 familias, 46 géneros y 51 especies. Las especies con mayor dominancia relativa y mayor valor del índice de importancia fueron: Citharichthys macrops, Synodus foetens, Diplectrum bivittatum, Rhomboplites aurorubens y Upeneus parvus. Un alto porcentaje de las especies de descarte (43,14%) presentan uso potencial de alimento y 7,84% carnada. En promedio, la relación Fauna de Acompañamiento Comercial:Camarón y Descarte:Camarón fue de 15,41:1 y 40:1 kg, respectivamente. El valor máximo de diversidad (H´) fue de 3,76 bits ind-1 y el Nivel Trófico de 4,31. El estudio de la composición de los descartes es base para evaluar el impacto generado por los arrastres de camarón en la costa veracruzana y proporciona pautas para identificar cambios en la estructura de la comunidad.

In this study, the structure of spatio-temporal variations of macrocrustacean assemblage were analyzed from the sandy beaches of Villa Rica, Veracruz. The nictemeral cycles related to lunar phases were taken into account; the non-metric multidimensional analysis showed an environmental stability trend. Within the macrocrustacean assemblages 9 species were recognized, of these, Emerita benedicti, Excirolana braziliensis, Excirolana sp. and Pseudohaustorius sp., were the dominant ones. The highest values of total density, species richness, and diversity were recorded during high tides. The cirolanid isopods and Emerita benedicti occurred in the lower unsaturated zone of the beach, and Pseudohaustorius sp. was found in the middle area. Macrocrustacean assemblage is simple, with low species richness (3-5) and low diversity values with significant differences throughout the study time; however, the assemblage structure complexity tended to be constant throughout time.

En este estudio se analizaron las variaciones espacio-temporales de la estructura del ensamblaje de macrocrustáceos de la playa arenosa de Villa Rica, Veracruz. Se tomaron en cuenta ciclos nictemerales relacionados con las fases lunares, el análisis multidimensional no-métrico mostró una tendencia a la estabilidad ambiental. En el ensamblaje de macrocrustáceos se reconocieron 9 especies, de estas, Emerita benedicti, Excirolana braziliensis, Excirolana sp. y Pseudohaustorius sp. resultaron dominantes. Los valores más altos de densidad total, riqueza de especies y diversidad se registraron durante las mareas altas, las especies de isópodos cirolánidos y Emerita benedicti se distribuyeron en la zona inferior no saturada de la playa, Pseudohaustorius sp. se encontró en la zona media. El ensamblaje de macrocrustáceos es simple, con riqueza específica baja (3-5) y valores de diversidad bajos, con diferencias significativas durante el tiempo de estudio; sin embargo, la complejidad de la estructura del ensamblaje tendió a mantenerse en el tiempo.

The present contribution integrates a species list of the aquatic isopods found in continental waters of Mexico with original taxonomic references, synonymies, type locality, and distributional data. The list comprises six families and 49 species, ten of which are epigean while the remaining 39 are hypogean, recorded from thermal springs and caves in the central and eastern portions of the country, and from cenotes in the states of Yucatan and Quintana Roo. The cirolanids and asellids are the most diversified groups in Mexico, in both surface and subterranean waters. While the most species rich area is the northeast, from Chihuahua to Tamaulipas, the entire Pacific slope along with some central and southern states lack records of aquatic isopods. Based on the existing records, the distribution pattern is discussed and the existence of four main areas of distribution is proposed. The conservation status of the aquatic isopods in Mexican continental waters is examined. A notable asymmetry is present between the rarity and vulnerability of most species and the level of protection was assigned for them by the Mexican government conservation agencies.

El presente trabajo integra una lista de especies de crustáceos isópodos acuáticos continentales de México con referencias taxonómicas originales, sinonimias, localidades tipo y distribución. El listado comprende un total 6 familias que agrupan 49 especies, de las cuales sólo 10 son epigeas, mientras que las 39 restantes son hipogeas registradas en manantiales termales y cuevas de los sectores oriental y centro del país, así como en cenotes de los estados de Yucatán y Quintana Roo. Los grupos más diversificados en México son cirolánidos y asélidos, que se encuentran tanto en aguas superficiales como en hábitats hipogeos. La región geográfica con mayor número de especies es el noreste, de Chihuahua a Tamaulipas, en tanto que carecen de registros toda la vertiente del Pacífico y algunos estados del centro y sur del país. Con base en los registros existentes se discute el patrón de distribución y se sugieren 4 áreas de concentración de especies en México. Se hace un análisis del estado de conservación de los isópodos acuáticos de México. Existe una notable asimetría entre la rareza y la vulnerabilidad de la mayoría de las especies y el grado de protección que se les asignó dentro de los instrumentos de conservación del gobierno mexicano.

Ejemplares del pez Dormitator maculatus (n=184) fueron recolectado en la laguna de Alvarado, México durante el período de un año (octubre 1993- 1994). El análisis helmintológico permitió registrar la presencia de Clinostomum complanatum (82.3%), Neoechinorhynchus golvani (76.1%), Spiroxys sp. (21.3 %), y Camallanus sp. (6.2%). La redución del hematocrito causada por la infección es estadísticamente significativa (t, = 0.05)

Dormitator maculatus (n=184) was collected in the Alvarado Lagoon, Mexico during a year period (Oct. 1993-1994). In the helminthologic review, the presence of Clinostomum complanatum (82.3%), Neoechinorhynchus golvani (76.1%), Spiroxys sp. (21.3 %), and Camallanus sp. (6.2%) was registered. Reduction of the hematocrit caused by such infection is significant (t, = 0.05)