Trophic ecology of coral reef gobies: interspecific, ontogenetic, and seasonal comparison of diet and feeding intensity
- PDF / 558,751 Bytes
- 14 Pages / 595 x 791 pts Page_size
- 12 Downloads / 167 Views
ORIGINAL PAPER
Trophic ecology of coral reef gobies: interspeciWc, ontogenetic, and seasonal comparison of diet and feeding intensity V. Hernaman · P. K. Probert · W. D. Robbins
Received: 27 April 2007 / Accepted: 3 November 2008 / Published online: 6 December 2008 © Springer-Verlag 2008
Abstract In Wshes, a small body size may facilitate costeVective exploitation of various primary and secondary food resources, but may pose diYculties associated with digestion of plant material and Wnding suYcient food in a foraging area potentially restricted by a high risk of predation. We examined the trophic ecology of Wve common, small-bodied coral reef Wsh from the family Gobiidae. For each species, we determined diet composition, feeding bite rate, foraging substrate, and feeding behaviour, and examined whether diet composition and feeding bite rate changed ontogenetically and seasonally. The Wve species showed a diverse range of trophic modes: Amblygobius bynoensis and Amblygobius phalaena were herbivores, Valenciennea muralis was a carnivore, Asterropteryx semipunctatus a detritivore, and Istigobius goldmanni an omnivore. Both the herbivores and detritivore supplemented their diet with animal material. The consumption of a wide range of dietary resources by the two smallest species with the most restricted mobility (A. semipunctatus and
Communicated by U. Sommer. V. Hernaman · P. K. Probert Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand W. D. Robbins School of Marine and Tropical Biology, James Cook University, Townsville, QLD, Australia Present Address: V. Hernaman (&) Centre for Marine Studies, University of Queensland, St Lucia, QLD 4072, Australia e-mail: [email protected]
I. goldmanni) may ensure energy requirements are met within a restricted foraging area. There was a signiWcant diVerence in mean feeding bite rate among species, with carnivore > herbivore > omnivore > detritivore. None of the species exhibited an ontogenetic shift in diet composition or increase in feeding bite rate, indicating that (1) postmaturation growth is not facilitated by a higher quality diet or increased feeding intensity following maturation, and (2) their small body size does not preclude herbivory. The herbivores had the highest gut:Wsh length ratio, which may facilitate plant digestion. While diet did not change seasonally, the mean feeding bite rate was signiWcantly lower in winter than summer for four of the study species.
Introduction Small species of Wshes form a large component of the total Wsh community on coral reefs in terms of species richness, population abundance, and biomass (Munday and Jones 1998; Ackerman and Bellwood 2000). Small coral reef Wshes play an important role in coral reef trophodynamics and energy transfer through the reef because of their high numerical abundance, short life-spans and rapid turnover rates, relatively high mass speciWc metabolic rates, and trophic modes (Ackerman and Bellwood 2000; Kritzer 2002; Depczynski and Bellwood 2003; Wilson et al. 2003). Whil
Data Loading...
