An Insight into the Feeding Ecology of Serranus scriba, a Shallow Water Mesopredator in the Northern Adriatic Sea, with a Non-Destructive Method

Abstract

Serranus scriba is a common member of the coastal fish community in the Adriatic Sea, but knowledge about its feeding ecology is scarce. The aim of this paper is to present new evidence about its food preferences and feeding habits. An innovative non-destructive method of fecal pellet analysis was used for this study. This method does not require sacrificing specimens and the fish can be released back into the sea alive after the laboratory work. The results demonstrated that S. scriba mainly preys on decapods, followed by polychaetes, isopods, fish, mollusks and swarming shrimps. The calculated index of trophic diversity (ITD) value of 0.89 indicates that it is an opportunistic feeder that feeds on a wide range of different prey. According to the calculated trophic level of 3.43, which is higher than that of other members of the community, S. scriba is also an important piscivorous predator. With age, S. scriba undergoes an ontogenetic shift. The proportion of crustaceans, gastropods and polychaetes decreases with age and body size, while the proportion of fish increases.

Tool use by the orange wrasse Pseudolabrus luculentus and doubleheader Coris bulbifrons

“…Why P. luculentus and C. bulbifrons used anvils to handle crabs that were similar in size to their gapes (Figures 1a and 2a) is a question that remains to be answered. Their goals may have been to (a) break the exoskeleton to more easily access the flesh and/or make crabs more compressible prior to ingestion (Mihalitsis & Bellwood, 2017), (b) break off the legs and chelipeds to remove less profitable parts (parts providing less energy per unit handling time) and indigestible parts (Lokovšek et al, 2022) and/or reduce the circumference of crabs that extend their legs and chelipeds when bitten (Field, 1990), (c) reduce the size of crabs that are too large to be swallowed whole (Biljlsma & de Roder, 1991; Jayne et al, 2002) or (d) incapacitate or kill crabs to minimise the risk of injury from struggling and dangerous prey (Wall & Shine, 2007). It is possible that only a few individuals in the population use anvils as a handling mechanism (Dunn, 2015).…”