Aquatic primary productivity, mangrove ecology, and fish community dynamics were investigated in the Teacapán-Agua Brava lagoon-estuarine system, the most extensive mangrove ecosystem on the Pacific coast of Mexico with three species of mangroves distributed heterogeneously (Laguncularia racemosa, Rhizophora mangle, andAvicennia germinans). Tree density was 3,203 trees ha⁻¹ and basal area was 14.0 m² ha⁻¹. Litterfall was 1,417 g m⁻² yr⁻¹, characteristic of a productive riverine forest. The degradation constant forLaguncularia racemosa leaves varied from 1.71 to 4.7 yr⁻¹ and mean annual net aquatic productivity was 0.41 g C m⁻³ d⁻¹. There were high concentrations of humic substances (up to 150 mg l⁻¹) early in the wet season. Seasonal variations of the above parameters seemed closely related to the ecology of fish populations. There were 75 fish species distributed in two principal assemblages associated with wet and dry seasons. Diversity and biomass analysis indicated 18 dominant species. Total biomass of the community in this coastal system was estimated at 10 g wet wt m⁻². The highest biomass occurred in the wet season. The most common fish species wereMugil curema, Achirus mazatlanus, Galeichthys caerulescens, Arius liropus, Diapterus peruvianus, Lile stolifera, Centropomus robalito, andEucinostomus sp., all of which have fishery importance. Primary productivity and fish community ecology are controlled by habitat characteristics, river discharge, and climatic seasonality.

The trophic ecology of wetlands with mangrove forests remains poorly understood. Through the use of stomach contents analysis, stable isotope signatures, and Bayesian mixing models, the food web of a tropical wetland in the gulf of California was investigated. Consumers had heterogeneous diets, omnivores were the most abundant species (47%), followed by planktivorous (21%), minor piscivores (10%), major piscivores (10%), macrobenthivores (9%), and herbivores (3%). The values of δ¹³C (from −12 to −29‰) and δ¹⁵N (from 4 to 24‰) showed a wide range of isotopic values of the consumers. Most of the species had a broad isotopic niche and there was a large diet overlap of species due to the exploitation of a common set of food resources. Five trophic levels were identified, with the weakfish (Cynoscion xanthulus) as the top predator of this system with detritus coming from the mangrove as the main source that supports the food chain. This highlights the importance of the mangrove forests to such ecosystems, because not only they are the most important primary food source, but also, they offer habitat to a large suite of fauna, which are important components of the trophic chain.

The diets of scaldfish Arnoglossus laterna, dab Limanda limanda, lemon sole Microstomus kitt, long rough dab Hippoglossoides platessoides, solenette Buglossidium luteum, thickback sole Microchirus variegatus, plaice Pleuronectes platessa, witch Glyptocephalus cynoglossus and Dover sole Solea solea in the Irish Sea were determined for March and October 1997 and 1998 and compared. Similarities in diets were examined using multivariate analyses. In general, there were differences in diet between species and generally the diets were similar within a species. Smaller individuals tended to have a similar diet. There were seasonal changes in the diets of individual species. Likewise, the overlap in diets between species changed between seasons and to a certain extent between sediment types.