Ontogenetic dietary and habitat shifts in goliath grouper Epinephelus itajara from French Guiana

Abstract

The ecology, particularly the trophic ecology, of the Critically Endangered goliath grouper Epinephelus itajara (Lichtenstein 1822) in French Guiana (France) is relatively unknown. Such information would provide a better understanding of the role that goliath groupers play in the marine ecosystem of French Guiana. This study focused on the feeding ecology of the goliath grouper through stomach-content and stable-isotope analyses of captured specimens. The dietary composition of goliath groupers in French Guiana was similar to that of goliath groupers from other areas of the species' range. However, in French Guiana, goliath groupers exhibited an ontogenetic shift in diet that has not been demonstrated elsewhere. Crustaceans, primarily crabs, were dominant in the diet of smaller individuals (<120 cm), whereas demersal fishes, particularly catfish (Siluriformes), dominated the diet of larger individuals. Analysis of δ 13 C and δ 15 N in muscle samples indicated that: (1) larger fish fed more on higher trophic levels; (2) low seasonal and spatial variation existed in the diet; and (3) an apparent migration of early juveniles occurred from mangrove areas to rocky reefs. In French Guiana, adult and juvenile goliath groupers share marine rocky habitat, and the data suggest they may avoid food competition by a shift in diet with size.

Causes and consequences of ontogenetic dietary shifts: a global synthesis using fish models

“…Profound multiple ODSs occurring over the life cycle are frequently seen in piscivorous fish species (e.g. Mittelbach & Persson, 1998;Hjelm, Persson & Christensen, 2000;Amundsen et al, 2003;Hanson, 2011;Artero et al, 2015). Typically, such dietary switches involve distinct shifts in prey sizes from millimetre to centimetre and finally to decimetre orders of magnitude.…”

“…freshwater versus marine), although a switch to piscivory, when fish become top predators, seems to be a common feature of many ecosystems (e.g. Winemiller, ; Jensen et al, ; Artero et al, ). Species with highly specialised diets in the adult period invariably also experience abrupt ODSs.…”

“…Importantly, the size‐related timing of the switch seems to be dependent upon the presence of small‐sized prey fish and competition with other species (Sánchez‐Hernández et al, ). Similarly, fish species typically become piscivorous above a threshold size in the marine environment (Hanson, ; Artero et al, ). For example, Hanson () observed that white hake [ Urophycis tenuis (Mitchill, 1814)] and Atlantic cod become piscivorous when they are greater than 350 and 450 mm in length, respectively.…”

Feeding habits of the leopard grouper, Mycteroperca rosacea (Actinopterygii: Perciformes: Epinephelidae), in the central Gulf of California, BCS, Mexico

“…Size-dependent feeding behaviour has been reported for other epinephelids (Mullaney 1994, Giménez et al 2001, Reñones et al 2002, Linde et al 2004, Condini et al 2011, Artero et al 2015. It should also be noted that the body shape of M. rosacea could play an important role in its feeding habits, because according to Gibran (2007) the genus Mycteroperca is characterized by a elongated and slim body that gives it high mobility within the water column and, therefore, greater preference for pelagic prey, such as clupeids (Hobson 1968, Parrish 1992, which was seen in this study with the great consumption of pilchard and euphausiids.…”

Dimorphism throughout the European eel's life cycle: are ontogenetic changes in head shape related to dietary differences?

“…The same change in diet is observed in goliath groupers (Artero et al. ). Although not switching from a crustacean to a teleost diet, European anchovies and pilchards (Costalago et al.…”