Author : Edward J. C. Baker
Publisher :
ISBN 13 :
Total Pages : 206 pages
Book Rating : 4.:/5 (747 download)
Book Synopsis The Nutritional Ecology of Odax Pullus (Odacidae) by : Edward J. C. Baker
Download or read book The Nutritional Ecology of Odax Pullus (Odacidae) written by Edward J. C. Baker and published by . This book was released on 2011 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Herbivorous fishes are important to reef ecology because as primary consumers they influence the flux of nutrients through reef ecosystems. Relatively little is known of the feeding habits and digestive physiology of marine herbivorous fishes. The temperate odacine Odax pullus inhabit shallow reef environments in New Zealand waters and are unusual in being one of a very small number of fish species to subsist on phaeophytes in cool water. O. pullus are currently harvested from the wild on a limited commercial scale and have recently been spawned in captivity with a view to future aquaculture. This study is the first of its kind to analyse the nutritional ecology via feeding behavior, throughput time and assimilation efficiency of captive O. pullus, and provides a framework for the formulation of an optimal diet. Feeding behavior was evaluated through a series of experiments in which O. pullus was offered either no choice of diet or multiple algal species from which to feed. O. pullus consumed more of the algae with the higher nitrogen content (Undaria pinnatifida) when this alga was offered as a monospecific diet and also when offered as choice between Ecklonia radiata, Carpophyllum maschalocarpum and Macrocystis pyrifera. Throughput time and assimilation efficiency (of nitrogen and organic matter) for each of these algae was determined to provide an estimate of their relative values to O. pullus. U. pinnatifida and M. pyrifera tended to have shorter throughput times and higher assimilation efficiencies than E. radiata and C. maschalocarpum. A radiographic bead technique was used to measure throughput time which, to my knowledge, is the first time this technique has been used for an herbivorous fish. Un-assimilable ash was used as a marker to determine assimilation efficiency, which also to my knowledge, is the first time insoluble ash has been used as a marker for a fish with a basic gut pH. The results produced by these techniques are therefore more accurate when compared to other indirect methods used to estimate throughput time and assimilation efficiency in other fishes. The aquaculture perspective taken by this thesis provides a practical example of the importance of integrative nutritional approaches that examine plant-herbivore interactions from the perspective of both post-ingestive processes and consumer behaviour"--Abstract.