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.