Factors influencing the partitioning of food resources among six fish species in a large embayment with juxtaposing bare sand and seagrass habitats

• Published in: Journal of Experimental Marine Biology and Ecology
• Main Authors: Linke, T.E., Platell, M.E., Potter, I.C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier BV 2001
• Subjects: Antarc*; Antarctica
• Online Access: https://doi.org/10.1016/S0022-0981(01)00356-2; https://researchportal.murdoch.edu.au/esploro/outputs/journalArticle/Factors-influencing-the-partitioning-of-food/991005540941107891

Six abundant fish species were collected from a large embayment during both day and night and at bimonthly intervals for a year. Gerres subfasciatus and Upeneus tragula occurred mainly over bare sand, while Psammoperca waigiensis, Centrogenys vaigiensis and Apogon victoriae lived mainly in seagrass (Amphibolis antarctica) and A. rueppellii often migrated from seagrass to over bare sand at night. All species except U. tragula fed at night, as well as during the day. The overall dietary compositions of the six species were significantly different from each other, even when the species occurred in the same habitat. G. subfasciatus and U. tragula consumed greater volumes of errant polychaetes, which could be readily targeted in a substrate that does not contain dense rhizome mats. In contrast, P. waigiensis, C. vaigiensis and A. victoriae ingested greater volumes of carid decapods, which are particularly abundant in seagrass and, thus, within the water column. Furthermore, when A. rueppellii moved at night from seagrass to over sand, the consumption of carid decapods declined, whereas that of polychaetes and particularly mysids, which are very abundant over bare sand, increased. However, the composition of the prey consumed by different species within the same habitat also often varied markedly. For example, unlike U. tragula, G. subfasciatus ingested not only sedentary polychaetes, but also considerable volumes of errant polychaetes, reflecting its ability to use a combination of vision and its highly protrusible mouth to target prey both on and just below the substrate surface. Differences in the types and range of prey ingested by the six species could often be related to differences in the overall size, width and/or protrusibility of the mouth. Furthermore, dietary breadth was greatest in species with the largest mouth dimensions. The diets of three species underwent diel changes that could be related to differences in foraging mode and/or prey availability. Thus, a use of vision to detect prey would account for ...