Habitat patchiness and predation modify the distribution of a coral-dwelling damselfish
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ORIGINAL PAPER
Habitat patchiness and predation modify the distribution of a coral-dwelling damselWsh Jonathan Belmaker · Yaron Ziv · Nadav Shashar
Received: 4 May 2008 / Accepted: 19 November 2008 / Published online: 10 December 2008 © Springer-Verlag 2008
Abstract Fish abundance is often better predicted by microhabitat variables on continuous reefs than on isolated patch reefs. Although this was suggested to stem from reduced post-recruitment relocation, this has not been shown experimentally. We found the relationship between the presence of a coral-dwelling Wsh, Dascyllus marginatus, and the size of its coral host to diVer between corals on continuous reefs and the sparsely distributed corals on sandy bottoms. Empty transplanted corals were colonized exclusively by new recruits when on the sandy bottom, and both by new recruits and post-recruitment dispersal of adults when on the continuous reef. New recruits settled predominantly into small corals, although analyses of recruitment patterns were confounded by low recruitment in the studied years. Both tank experiments and Weld survey data suggest that the presence of recruits in small corals is at least partially driven by predation by the dottyback, Pseudochromis olivaceus, which lives predominantly in large corals within both habitats. Consequently, we suggest that the relationship between Wsh presence and coral size diVers between the habitats due to coral size dependent Communicated by S.A. Poulet. J. Belmaker (&) · Y. Ziv · N. Shashar The Department of Life-Sciences, Ben-Gurion University of the Negev, PO Box 653, 84105 Beer-Sheva, Israel e-mail: [email protected] J. Belmaker The H. Steinitz Marine Biology Laboratory, The Interuniversity Institute for Marine Sciences, PO Box 469, 88103 Eilat, Israel N. Shashar Eilat Campus, Ben-Gurion University of the Negev, Hatmarim St., 88000 Eilat, Israel
predation on recruits and variability in the importance of direct recruitment to replenish Wsh populations.
Introduction Coral reefs can be composed of continuous reef tracks, isolated reef patches, and a variety of intermediate forms. Owing to their small size and the ease of experimental manipulations most research on coral reef Wsh ecology has been limited to isolated reef patches (Ault and Johnson 1998a; but see Webster 2003; Sandin and Pacala 2005). Nevertheless, ecological processes on isolated reefs may diVer from continuous reefs. For example, predictability of Wsh abundance by microhabitat variables on continuous reefs is higher than on patch reefs (Ault and Johnson 1998a) and Wsh abundance is higher and less regular on isolated patches (Nanami and Nishihira 2002, 2003; Belmaker et al. 2007a). It is still unclear what mechanisms cause Wshes on reefs with dissimilar degrees of isolation to respond diVerentially to microhabitat variables. Accumulated evidence suggests that predation by piscivorous Wsh can have a signiWcant eVect on the abundance and the diversity of coral reef Wshes (e.g., Carr and Hixon 1995; Beets 1997; Holbrook and Schmitt 2003; Almany
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