Ontogenetic changes in the diet of the coral reef grouper Plectropomus leopardus (Serranidae):patterns in taxa, size and habitat of prey

Abstract

Stomach contents and diet of a wide range of sizes (4.7 to 57.3 cm standard length [SL]) of the predatory coral trout Plectropomusleopardus (Fam Serranidae) collected mostly from the northern Great Barner Reef dunng the summers of 1991 and 1992 were examined. Overall, 422 prey In 28 families of fishes were Identified of which 3 families, Clupeidae, Pomacentridae and Labridae, represented more than 60% of the diet. Average daily consumption of prey in P leopardus was 2.8% of relative body weight and flsh of 20 to 49.9 mm SL were eaten by all slze classes. Juvenile (up to 20 cm SL) and adult P. leopardus have distinct diets. The major dietary shift in the type, species composition, length and shape of prey occurs at approximately 20 cm SL, just prior to the onset of maturity Juveniles consumed a high proportion of benthic dwelling crustaceans, mostly penaeid shrimps, whereas adults were almost entirely piscivorous. The number of families of fishes in the diet did not increase with the size of predator as some families were eaten exclusively by juveniles or adults. Abundances of fish families in the diet varied ontogenetically and among size classes in small adults. Predation was related to size of prey in juvenile and small adults. Up to 35 cm SL, the range of prey sizes widened with increases in predator length, as larger fish ate larger prey, concomitantly feeding on small fishes, especially schooling species. However, the composition of the diet and length of fish prey did not change in P. leopardus after 35 cm SL and prey did not deepen after 45 cm SL. Body depth of prey was more important than length in s~ze-related feeding on 2 common fam~lies of fishes with different shapes. In general, larger P leopardus appeared to feed optlmally on deep-bodied fikh, whereas juveniles avoided gape limitation by consuming more slender fish. All size-related predation in P. leopardus, however, was eas~ly decoupled by the presence of highly abundant small fishes in large visible schools.

Ontogenetic diet shifts in the reef fish Pseudanthias rubrizonatus from isolated populations on the North-West Shelf of Australia

“…Similar ontogenetic shifts in prey size have been observed in Plectropomus leopardus (Kingsford 1992, St John 1999 and Serranus atricauda (Morato et al 2000). A shift towards eating larger prey may occur simply because larger fishes may be physically able to eat larger prey (Scharf et al 2000), but such ontogenetic diet shifts may also indicate a change in nutritional requirements with development.…”

“…Olson 1996, Schleuter & Eckmann 2008, estuarine (e.g. Eggold & Motta 1992, St John 1999, Jackson & Rundle 2008 and reef (e.g. Avise & Shapiro 1986, Wells et al 2008) species.…”

Bathymetric trends of northeastern Brazilian snappers (Pisces, Lutjanidae): implications for the reef fishery dynamic

“…Indeed, when small individuals were exclusive to shallow waters and only large ones were caught in deep waters, mixed catch of medium and large fishes was reported at intermediate depths. This movement could be related to feeding, and reproductive habits (Uiblein, 1991;MacPherson, 1998;St-John, 1999;Grutter, 2000;Carrasson and Matallanas, 2001). …”

Disruptive colouration in reef fish: does matching the background reduce predation risk?

“…Predators were caught from the waters surrounding Lizard Island, Great Barrier Reef, Australia (14°41′06″ S, 145°26′32″ E) using barrier and hand nets (slingjaw wrasse, N=6) or hook and line (coral trout, N=9). These two species are also relatively easy to house and train in aquaria (Cortesi et al, 2015a;Vail et al, 2013Vail et al, , 2014, and have been shown to feed on humbugs in the wild (John et al, 2001;St John, 1999).…”

“…1B). The spatial frequency of backgrounds varied slightly for each of the two predator species, as slingjaw wrasse are likely to target juveniles and sub-adults whereas coral trout tend to predate on larger adult humbug damselfish (St John, 1999). The laminated photograph of a humbug used in slingjaw wrasse experiments was 30 mm (total length).…”