Tidal-diel patterns in feeding and abundance of armed snook Centropomus armatus from macrotidal mangrove creeks of the tropical eastern Pacific Ocean.

We investigated the influence of temporal and spatial factors on the feeding habits of the armed snook Centropomus armatus (Centropomidae), the most abundant snook species in eastern Pacific mangrove ecosystems. The influence of the combination of semi-diurnal tides and diel cycles and salinity on the intertidal abundance, stomach fullness, diet composition and daily consumption of this species was investigated over 1 year in the macrotidal Colombian Pacific coast (Bahía Málaga). The abundance of juvenile C. armatus (5.6-23.6 cm total length) in the intertidal creeks was highest during neap tide-night conditions and lowest during spring-tide day conditions. Centropomus armatus fed predominantly on crustaceans (Alpheidae and Palaemonidae) and fishes. Stomach fullness index (ISF ), a proxy of feeding activity, was not influenced by salinity, but by tidal-diel conditions. Stomach fullness index was highest during neap tide nocturnal inundations, but lowest during diurnal neap tides. Nevertheless, the total daily consumption was higher at spring tide than at neap tides. Higher water temperatures in creeks during neap tides at night could explain not only high C. armatus abundance, but also greater accessibility to active prey. Comparison with the feeding patterns of fishes from other macrotidal mangrove ecosystems suggest that the habitat use and feeding patterns of intertidal fishes in mangroves are strongly influenced by the combination of spring-neap tide and diel cycles. However, the interaction between mangrove geomorphology and flooding regime of the specific mangrove forest might also play a role and deserves further investigation.

Tidepool fish assemblages of Gorgona Island, Colombian Pacific coast: a local and regional comparison / Ensambles de peces de poza de isla Gorgona, costa pacífica colombiana: una comparación local y regional

The ecology of tidepool fishes has been extensively investigated worldwide over the past 40 years. As in many other ecological fields, studies in temperate zones outnumber studies carried out in tropical areas. Here, we document the short-term spatio-temporal variation of a tidepool fish assemblage from the Tropical Eastern Pacific (Gorgona Island, Colombia), compare our data with previous surveys made in 1993 and provide the first latitudinal comparison of tidepool fish assemblages in the Eastern Pacific coast (43°N to 36°S). During April-July 2006, monthly samplings were carried in 18 tidepools located at three sites this Island. A relatively species-rich tidepool fish assemblage (53 species) was found at Gorgona Island. Labrisomidae, Gobiidae and Gobiesocidae were the dominant resident components of this assemblage, whereas Pomacentridae, Muraenidae and Labridae constituted the transient component. Although the same dominant species were observed in surveys from 1993 and 2006, suggesting a high persistence of this assemblage over time, clear differences in the relative abundance of some species were also detected. These differences were partly the result of using different sampling methodologies (rotenone vs clove oil). Comparisons with other studies performed in tropical and temperate areas of the Eastern Pacific coast indicate a clear latitudinal pattern in the composition of these assemblages that correspond to well-documented biogeographic subdivisions of the marine fauna in this region. Further investigation of the ecological role that tidepool fishes play in rocky intertidal and subtidal areas of Gorgona Island and the whole Tropical Eastern Pacific region will benefit our understanding of the functioning of these important coastal ecosystems. Rev. Biol. Trop. 62 (Suppl. 1): 373-390. Epub 2014 February 01.

A nivel mundial, la ecología de peces de charcos intermareales ha sido ampliamente investigada durante los últimos 40 años, especialmente en zonas templadas. En este trabajo, se documenta la variación espacio-temporal en corta escala de un ensamblaje de peces de charcos intermareales en el Pacífico Oriental Tropical (Isla Gorgona, Colombia), y se comparan nuestros resultados, con los resultados obtenidos durante muestreos realizados en la misma localidad en 1993. Además se realiza la primera comparación latitudinal de estos ensamblajes para la costa oriental del Océano Pacífico (43°N a 36°S). Durante abril a junio de 2006, se realizaron muestreos mensuales en 18 charcos intermareales distribuidos en tres localidades de Isla Gorgona, estableciendo un ensamblaje de peces de charcos intermareales con una alta riqueza de especies (53 especies). Labrisomidae, Gobiidae and Gobiesocidae fueron los componentes residentes dominantes en el ensamblaje, mientras que Pomacentridae, Muraenidae and Labridae fueron los componentes transitorios. Aunque el registro de las mismas especies dominantes en 1993 y 2006 sustenta la idea de una alta persistencia temporal de este ensamblaje, se detectaron diferencias significativas en la abundancia relativa de las especies. Estas diferencias podrían ser el resultado de las diferentes técnicas de captura utilizadas durante 1993 y 2006 (rotenona vs aceite de clavo). Al comparar los estudios sobre peces intermareales realizados en la zona tropical y zona templada de la costa oriental del Océano Pacífico, se identificó un claro patrón latitudinal en la composición de los ensamblajes, que es consecuente con la ampliamente documentada subdivisión biogeográfica de la fauna marina de esta región. Para comprender el funcionamiento de los ecosistemas costeros del Pacífico Oriental tropical, es necesario que futuros esfuerzos de investigación se encaminen a conocer el papel ecológico de los peces intermareales en esta región.