Ecology of three sea catfishes (Ariidae) in a tropical coastal ecosystem - Southern Gulf of Mexico

Abstract

Catfishes of the Family Ariidae are characterized as eurythermal and euryhallne inhabitants of estuarine waters.In the Southern Gulf of Mexico (Terminos Lagoon) there are 3 species: Arius felis, A. melanopus, and Bagre rnarinus.Juveniles of A. melanopus occur in the fluvial-lagoon system (FLS) in areas with oysters Crassostrea virginica, while adults occur throughout the lagoon.A.melanopusreaches sexual maturity at 160 mm total length (TL) and reproduces in FLS in salinities < 12 ppt, temperatures 2 35 "C and high turbidity waters.Males of 160 to 222 mm TL with eggs and/or embryos in their mouths are abundant in August and September, after which they migrate towards areas of greater salinity, lower temperature and less turbidity Juveniles recruit towards the western inlet (estuarine) and central basin of the lagoon.The reproduclve pattern of A. felis is the inverse of A. melanopus.Juveniles are found in areas of hgher salinity in the lagoon, and adults occur throughout the lagoon.The species matures sexually after reaching 200 mm TL and reproduces in salinities > 12 ppt, temperatures 2 30 "C, and in less turbid areas dominated by Thalassia testudi~~um meadows.Males with eggs and/or embryos in their mouths are found In September.After the incubation period adults migrate toward the eastern inlet (marine) and luveniles toward the western inlet (estuarine).B. marjnus is found only in the western inlet (estuarine), central basin, and FLS of Terminos Lagoon.This specles reproduces along the coastline and enters the lagoon at the end of the rainy and winter storm or nortes season.Juveniles use the lagoon as nursery area.The Terminos Lagoon has a high diversity of habitats due to ecological interchange with rivers, swamps and the inner shelf.Three main strategies in the use of the system by catfishes in relation to reproduction and feeding may be characterized as: (1) spawning in the rivers and swamps followed by a migration of juveniles toward the central part of the estuarine system; (2) spawning in the estuarine system; and (3) s p a w ~n g in the sea followed by migration of juveniles to the FLS for feeding.Estuarine fish that have separate reproduction, growth, and feeding areas generally occur in great abundance and have adapted by reducing interspecific competition and temporal and spatial niche partition.In tropical high diversity ecosystems, biological cycles are closely related to high productivity of coastal waters, large supply of organic matter, increased food availability, and protection from predators.The estuary-inner shelf or swamp-estuary migrations can be interpreted as small-scale anadromous adaptations.