Se presenta el primer listado de grupos de invertebrados bentónicos del sistema lagunar de Mandinga (SLM). Se realizaron siete colectas en temporadas de secas de 2008 a 2015 y una en temporada lluviosa de 2015. Los organismos endobénticos se colectaron con una draga y los organismos epibénticos, con una red tipo Renfro y chinchorro. Todos los organismos se identificaron hasta el nivel permisible. El listado está conformado por un total de 43 grupos zoológicos, distribuidos en ocho filos, siete clases, nueve órdenes, 16 familias y tres tipos de larvas. Los grupos Decapoda (10), Gastropoda (8), Amphipoda (4), Bivalvia (3), Tanaidacea (3) e Isopoda (3), fueron los más diversos, seguidos en menor medida por los grupos que se determinaron a niveles superiores a Familia (12). La diversidad de grupos es similar a la de otros sistemas costeros veracruzanos, donde los órdenes Decapoda, Amphipoda y Tanaidacea fueron los más diversos, seguidos por Isopoda. Los resultados de la presente investigación, representan un aporte importante para el conocimiento de la diversidad del sistema estudiado y de la distribución de los grupos en Veracruz y golfo de México.

The objective was to analyse the relative growth and size structure of Achelous spinicarpus associated with trawling in Veracruz. The organisms came from shrimp trawls carried out in July 2013. There were 45 trawls organized in two depth intervals (B: 22 to 46 m and C: >46 m) and 14 fishing quadrants. Abundance, mean and standard deviation, by sex and depth interval, and sex ratio were determined. An ANOVA was applied to compare CW means, depth intervals and fishing quadrants. The CW-weight relationship was obtained, and growth type was also determined. Length-frequency analyses were carried out. A total of 2377 crabs were collected, 1164 males and 713 females. The overall average CW was 3.65 ± 0.7677 cm, the minimum value was 1.50 cm, and the maximum was 6.00 cm. For males, the average CW was 3.65 ± 0.8242 cm, with1.50 cm minimum value and 6.00 cm maximum value. The average CW of females was 3.64 ± 0.6164 cm, with 1.60 cm minimum value and 5.90 cm maximum value. There were no statistically significant differences in CW between males and females. However, there were significant differences between depth intervals (B and C) for the total and sex CW data. The sex ratio was 2.94:1 and 2.05:1 for depth intervals B and C, and 2.33:1 for the total data set. Growth type was allometric negative for both sexes and overall, with significant differences in slopes between sexes. There was a unimodal pattern for the two fishing depth intervals and for each sex; crabs were between 2.40 and 4.00 cm (77.64%) and between 2.56 and 5.12 (91.12%) for the B and C intervals, respectively. In males, 88.46% were between 2.40 and 4.80 cm, and 90.46% of females were between 2.72 and 4.64 cm. Achelous spinicarpus is an essential species in the structure of the brachyuran assemblage and in benthic communities, as well as a food resource for various species of demersal fish. Thus, the present study provides information on the population subjected to the impact of fishing activity in the area, allowing comparisons between different populations in the species’ area of distribution.

<!--Galleys --> <!--Full Text:--> PDF <!--END GALLEYS---> 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.

Se determinó la calidad del agua en la presa Xhimojay, Estado de México, México, empleando indicadores biológicos. Se realizaron muestreos mensuales de enero a diciembre de 2013. Los sitios de colecta fueron georeferenciados. En cada sitio se registraron los parámetros fisicoquímicos. Se realizó una recolecta de zoobentos empleando una red de fondo con malla de 500 μm. Todos los ejemplares se fijaron, posteriormente se identificaron, se contaron y pesaron. La abundancia se estandarizó en -2 -2 individuos m y en g m . Se emplearon los índices biológicos FBI (Family Biological Index), BMWP (Biological Monitoring Working Party) y ASPT (Average Score Per Taxon). Se colectaron 17191 individuos, distribuidos en 20 taxones, se determinaron 16 a nivel de familia, dos a nivel de orden y dos a nivel de clase. Corixidae fue la familia más representativa (32,6%), mientras que las familias que presentaron las menores abundancias fueron Lymnaeidae (0,05%), Belostomatidae (0,02%) y Dytiscidae (0,02%), considerándose como grupos raros. De acuerdo con los valores del índice FBI, la calidad del agua en la presa Xhimojay se clasifica regular en ambas épocas. Los valores de los índices BMWPy ASPT clasifican la calidad de la presa en un intervalo de ligeramente contaminada y probable contaminación severa. En los tres índices se observa un ligero decremento en la contaminación en la época de lluvias. Se concluyó que la presa Xhimojay, se caracterizó como poco profunda, transparente, tibia, hiperoxigenada, blanda y excesivamente alcalina, la riqueza, diversidad y equitatividad fueron consideradas intermedias. Con los parámetros fisicoquímicos registrados se pudo caracterizar la presa Xhimojay, pero no pudieron emplearse como indicadores de la calidad del agua.

ECOLOGÍA POBLACIONAL DE GIRARDINICHTHYS MULTIRADIATUS (MEEK, 1904) (PISCES: GOODEIDAE) PEZ ENDÉMICO DE MÉXICO