Title

The Response of Gastric pH and Motility to Fasting and Feeding in Free Swimming Blacktip Reef Sharks, Carcharhinus melanopterus

Document Type

Article

Publication Date

7-13-2007

Publication Title

Journal of Experimental Marine Biology and Ecology

Keywords

Data-loggers, Foraging ecology, Gastric digestion, Motility, Optimal foraging, pH, Sharks

ISSN

0022-0981

Volume

345

Issue/No.

2

First Page

129

Last Page

140

Abstract

In many fish and reptiles, gastric digestion is responsible for the complete breakdown of prey items into semi-liquid chyme. The responses of the stomach to feeding and to periods of fasting are, however, unknown for many lower vertebrates. We inserted data loggers into the stomachs of free-swimming captive adult blacktip reef sharks (Carcharhinus melanopterus) to quantify gastric pH, motility and temperature during fasting and following ingestion of food. Gastric acid secretion was continuous, even during long periods of fasting, with a mean pH of 1.66 ± 0.40 (± 1 SD) when the stomach was empty. Stomach contractions were greater following meals of mackerel than for those of squid. Gastric motility following feeding on mackerel, was positively influenced by ambient temperature, and followed a quadratic relationship with meal size, with maximum motility occurring after meals of 0.8–1.0% body weight. Diel changes in gastric motility were apparent, and were most likely caused by diel changes in ambient temperature. Gastric digestion in blacktip reef sharks is affected by both biotic and abiotic variables. We hypothesize that behavioral strategies adopted by sharks in the field may be an attempt to optimize digestion by selecting for appropriate environmental conditions.

Comments

©2007 Elsevier B.V. All rights reserved.

ResearcherID

B-8552-2013

DOI

10.1016/j.jembe.2007.02.006

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Peer Reviewed

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