An updated checklist and characterisation of the ichthyofauna (Elasmobranchii and Actinopterygii) of the Laguna de Tamiahua, Veracruz, Mexico

Background. Laguna de Tamiahua is ecologically and economically important as a nursery area that favours the recruitment of species that sustain traditional fisheries. It has been studied previously, though not throughout its whole area, and considering the variety of habitats that sustain these fisheries, as well as an increase in population growth that impacts the system. The objectives of this study were to present an updated list of fish species, data on special status, new records, commercial importance, dominance, density, ecotic position, and the spatial and temporal distribution of species in the lagoon, together with a comparison of Tamiahua with 14 other Gulf of Mexico lagoons. Materials and methods. Fish were collected in August and December 1996 with a Renfro beam net and an otter trawl from different habitats throughout the lagoon. The species were identified, classified in relation to special status, new records, commercial importance, density, dominance, ecotic position, and spatial distribution patterns. Results. The 45 species collected by the authors plus an additional 125 species previously reported provided an updated list of 170 species. Families with the highest number of species were Sciaenidae (16 spp.) and Gobiidae (12 spp.). Poecilia latipunctata Meek, 1904 is endemic to Mexico and in danger of extinction and Hippocampus zosterae Jordan et Gilbert, 1882 is under special protection. New records are Ariopsis assimilis (Günther, 1864), Mugil liza Valenciennes, 1836, Symphurus civitatium Ginsburg, 1951, and Aluterus schoepfii (Walbaum, 1792). Commercially important species are Lutjanus griseus (Linnaeus, 1758), Lutjanus synagris (Linnaeus, 1758), Bairdiella chrysoura (Lacepède, 1802), Cynoscion arenarius Ginsburg, 1930, Cynoscion nebulosus (Cuvier, 1830), Cynoscion nothus (Holbrook, 1848), and Archosargus probatocephalus (Walbaum, 1792). The highest densities were recorded for Eucinostomus melanopterus (Bleeker, 1863), Eucinostomus gula (Quoy et Gaimard, 1824), Syngnathus scovelli (Evermann et Kendall, 1896), Achirus lineatus (Linnaeus, 1758), and Cathorops aguadulce (Meek, 1904). The dominant species were Cathorops melanopus (Günther, 1864), Citharichthys spilopterus Günther, 1862, and E. gula. Conclusion. The majority of the fishes collected in the Laguna de Tamiahua favoured seagrass beds along ‘costa mar’, the islands Juan A. Ramírez and del Idolo, and areas near the northern and southern inlets. Of the 170 fish species, 10 were present in the 15 compared lagoons, five were recorded only in Tamiahua, and the other species were present in 2 to 14 lagoons. The lagoons most similar to Tamiahua regarding the composition of ichthyofauna were Tampamachoco, Términos, Alvarado, and Madre. This study contributed to the knowledge on a lagoon that sustains local and regional fisheries on which local communities depend

δ 13C of zooplankton, decapod crustaceans and amphipods from Laguna de Terminos, Campeche (Mexico), with reference to food sources and trophic position

Zooplankton, Penaeus setiferus, P. duorarum, Xiphopenaeus kroyeti, Callinectes sapidus, Dyspanopeus texanus, Palaemonetes spp., Hippolyte spp. and amphipods were isotopically characterized to identify the food sources they use and their relative trophic position, as well as to establish a relationship between the isotopic data and the isotopic “memory”, the isotopic convergence and the complexity of trophic chains. The δ 13C values of the animals were compared to those of the submerged vegetation, detritus and sediment of each locality. The range of δ 13C values of –7.2 to –24‰ indicates that consumers take advantage of sources of organic carbon of a diverse isotopic nature. The isotopic difference between the lager consumers, P. setiferus, P. duorarum, X. kroyeri, C. sapidus and D. texanus, and the primary producers indicates that the first occupy a high trophic level within their communities. There is a relationship between the migration of P. setiferus juveniles from the northeast (CTL = 11.5 mm) to the southwest (CTL = 22.5 mm) of the lagoon, and the variation in isotopic composition from heavier (–8.9‰) to lighter (–24.2‰) δ 13C values. Three cases are presented to explain the variety of δ 13C values of P. setiferus. In general, the isotopic composition of the above-mentioned species characterized two isotopically different areas: one to the northeast of the system with heavier values of –6.4 to –17.2‰ and another to the west, southwest and South with lighter values of –15.3 to –24.2‰

Caracterización isotópica ( S13C) de la carcinofauna del sistema lagunar de Alvarado, Veracruz, México

Isotopic ( S13 C) analyses of estuanne fauna give an indication of!he diet of organisms and the flow of carbon throughout trophic chains, and allow the establishment of relationships between community components. Values of -17.4 to -26.2 0/00 were obtained for penaeid and caridean shrimps and for swimming crabs collected in the lagoon system of Alvarado, Mexico. These values establish an isotopic gradient from the soul heast of the system (-25.0 to -26.90/00) to Laguna Camaronera in the northwest (-18.3 to -19.4 0/00) which, in the case of Penaeus setiferus, P. aztecus and Callinectes sapidus, points to a migration of organisms within the system. These three species also represent the highest trophic level in the macrocrustacean communities throughout the system.Los análisis isotópicos (ó13C) de la fauna estuarina proporcionan una indicación de la dieta de los organismos y del flujo del carbono a través de las cadenas tróficas, y permiten determinar las relaciones existentes entre los componentes de una comunidad. Valores de -1 7. 4 a -2 6.2 0/00 se obtuvieron para los camarones peneidos y carideos y para las jaibas del sistema lagunar de Alvarado, México. Estos valores reflejan un gradiente isotópico del sureste del sistema (-25.0 a -2 6.90/0 0) a Laguna Camaronera al noroeste (-18.3 a - 19.4 0/00) Y. en el caso de Penaeus setiferus, P. aztecus y Callinectes sapidus indican una migración de los organismos dentro del sistema. Estas tres especies también representan el nivel trófico mas alto de las comunidades de macrocrustáceos a lo largo del sistema