Background: Despite their ecological, economic and medical relevance, very little information is available on the distribution of planktonic cnidarians, this being particularly true for some regions of the ocean such as the Gulf of Mexico. In fact, the effect of locally important oceanographic features such as the offshore autumnal transport on the distribution of planktonic cnidarians has long been overlooked in this region. Because of this, the present study aimed to analyse the spatial patterns of planktonic cnidarian assemblages in the southern Gulf of Mexico during the autumn of 1998, when particularly intense conditions of convergence, offshore water transportation and productivity were recorded. The assemblages were described in terms of their composition, abundance (volume), diversity, dominance and equitability. Cluster (Bray-Curtis index) and ordination (multidimensional scaling (MDS)) analysis were performed in order to link the observed distribution of species with the environmental parameters.

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La laguna de Tamiahua es la tercera laguna más grande de México. En la última década sus 2 bocas han sido dragadas y sus escolleras rehabilitadas para mantener la comunicación permanente con el mar, lo que permite el libre flujo de especies. Se realizaron muestreos de zooplancton en 22 estaciones durante los meses de febrero, mayo, agosto y noviembre de 2011, con una red estándar de 500 m; simultáneamente se midió la salinidad y la temperatura superficial del agua. Se determinaron 40 especies pertenecientes a 37 géneros y 19 familias de peces. Lutjanus campechanus, Chasmodes bosquianus, Ctenogobius shufeldti, Microgobius thalassinus y Citharichthys arctifrons son nuevos registros para la laguna. Las especies dominantes fueron Anchoa mitchilli, Lagodon rhomboides, Membras martinica, Lupinoblennius nicholsi, Ctenogobius boleosoma y Brevoortia gunteri. En febrero la riqueza específica fue mayor (26) por el ingreso de especies marinas, mientras que la diversidad fue mínima (2.13) por la gran abundancia de L. rhomboides, A. mitchilli y B. gunteri del grupo iv en el dendrograma de asociación de larvas. La composición larvaria de la laguna de Tamiahua presentó una similitud del 61% al compararla con años anteriores, antes del dragado de la boca de Tampachichi. Derechos Reservados © 2015 Universidad Nacional Autónoma de México, Instituto de Biología. Este es un artículo de acceso abierto distribuido bajo los términos de la Licencia Creative Commons CC BY-NC-ND 4.0.

Stomach contents analyses showed that Leiostomusxanthurus (8.50-12.90 mm SL) had a wide trophic spectrum (15 food categories) with copepods and eggs of invertebrates as main components. In contrast, Micropogonias undulutus (6.65-12.20 mm SL) ingested only six food categories (copepods, eggs of invertebrates, crustacean nauplii, bamacle nauplii, amphipods and other crustaceans). There is an overlap of 73.2 to 83.0% in the diet of these two species. Bairdiella chrysoura (1.17-1.92 mm SL) fed primarily on juvenile pelecypods, crustacean nauplii, eggs of invertebrates, including gasteropods and copepods. Cynoscion nebulosus (1.50-2.42 mm SL) ingested juvenile pelecypods, copepods, crustacean nauplii, eggs of invertebrates and tintinnids, variability in overlap (47.4 to 79.5%) between these species was affected by size of the larvae.

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