José G Rodriguez-Quintal’s research while affiliated with Central University of Venezuela and other places

RESUMEN Existe un grupo de pequeños peces bentónicos que por su tamaño y hábitos crípticos no son tan conspicuos en el arrecife, lo que aunado a una taxonomía compleja, ha generado su exclusión de la mayoría de los trabajos ecológicos relacionados con estos ambientes. Una de las familias más importantes del grupo es Chaenopsidae, donde el género Acanthemblemaria resulta entre los más representativos, siendo Acanthemblemaria rivasi la especie más común en los arrecifes costeros de Venezuela. El objetivo del presente trabajo fue realizar una contribución de los aspectos ecológicos de A. rivasi asociados al gradiente de profundidad del arrecife coralino de Isla Larga, Parque Nacional San Esteban, Venezuela. Para caracterizar las poblaciones de esta especie se realizaron censos visuales sobre banda transectas de 10x2 m, paralelas a la costa a lo largo del gradiente de profundidad, en 5 estratos diferentes. La mayor densidad de individuos se encontró en la zona somera, probablemente por la mayor disponibilidad de recursos (alimento y refugio), encontrándose agregaciones de hasta 7 individuos. A. rivasi se encontró estrechamente asociada a las especies de coral Montastraea annularis, Colpophyllia natans y Diploria strigosa, debido a la disponibilidad de oquedades que presentaban estos sustratos, refugio adecuado para estos peces. En cuanto al comportamiento resultó un organismo sedentario, fuertemente asociado al sustrato, mimetizándose con el entorno. Generalmente forma grupos sociales jerarquizados por tamaño, lo que disminuye la depredación, existiendo en algunos casos individuos que patrullan la colonia coralina. Y por último en cuanto a su dieta, la especie puede ser definida como un consumidor primario, que se alimenta de micro-crustáceos, principalmente de la columna de agua, presentando una alimentación continua a lo largo del día. Palabras clave: Peces criptobentónicos, Acanthemblemaria rivasi, comportamiento, estatus trófico y distribución. Abstract Coral reef ichthyofauna includes a group of small benthic fishes that due to their size and cryptic habits are not conspicuous in the reef, which added to a complex taxonomy has triggered its exclusion from most of the ecological researches related to these environments. One of the most important families from this group is Chaenopsidae, where the genus Acanthemblemaria is among the most representatives, being Acanthemblemaria rivasi the most common species in Venezuelan coastal coral reefs. The aim of this study was to make a contribution of A. rivasi ecological aspects associated to a depth gradient of a coral reef at Isla Larga, San Esteban National Park, Venezuela.

Seagrass beds are considered important feeding places for a variety of fish species characterized with complex trophic interactions. In this paper we described the trophic network of a fish community inhabiting a seagrass bed in the Venezuelan Caribbean. In addition, a consumption index (CI) for each prey ingested is proposed using two variables: abundance and consumption frequency. Eight samplings (at four time intervals: 6:00, 12:00, 18:00 and 24:00 hours) were done in August 2005 and January 2006. Fifty one fish species in 29 families were captured; Haemulidae was the most abundant. Crustacea was the most important food resource of the 28 food items identified. The relative importance of trophic guilds, considering abundance and taxonomic species richness, was: benthophagous>herbivorous>piscivorous. The features of the trophic network were: 1) high proportion of short chains (two links), 2) high number of intermediate species, 3) high consumption of benthos, 4) low CI values and 5) few species with a high number of linkages. Temporal (hourly and monthly) differences were obtained in fish species number (total, intermediate and top), total linkages, connectivity and maximal chain lengths. The connectance did not show significant temporal variation and it was similar to other environments with different species richness. In contrast, the connectivity was lower than the one reported for environments with low species richness. As in other reports, the temporal variation of the trophic parameters and the community structure was different. The values of CI for the different preys were low except for harpacticoid copepods and crustacean larvaes. The cluster value of CI was high for benthos (>80 %) and, in general, low for plankton and nekton preys. The seagrass bed studied was an important feeding place where the configuration of trophic network changed in different temporal scales and reflected the dynamic of the feeding relationships this fish community.