Community structure of an assemblage of tidepool fishes on a tropical eastern Pacific rocky shore, Colombia G. A. C ASTELLANOS -G ALINDO *†, A. G IRALDO ‡§ AND E. A. R UBIO * *Universidad del Valle, Departamento de Biologı´a, Seccio ´n de Biologı´a Marina, Laboratorio de Ictiologı´a. A.A. 25360, Cali, Colombia,†INCIVA, Museo Departamental de Ciencias Naturales, Laboratorio de Zoologı´a, Calle 6 # 24-80, Cali, Colombia and ‡Universidad del Valle, Departamento de Biologı´a, Seccio ´n de Zoologı´a, Grupo de Investigacio ´n en Ecologı´a Animal Aplicada, A.A. 25360, Cali, Colombia (Received 23 July 2004, Accepted 16 February 2005) The composition, abundance, species richness and diversity of a rocky intertidal fish assemblage in the central zone of the Pacific coast of Colombia were determined. From July to December 2002, 10 tidepools with volumes ranging from 0087 to 1350 m 3 were surveyed. A total of 893 fishes belonging to 14 species and 12 families were found. The most abundant species were Bathygobius ramosus and Abudefduf concolor, representing 71% of all fishes collected. Bathy gobius ramosus, Malacoctenus zonifer and Gobiesox adustus were residents, Abudefduf concolor, Abudefduf troschelii, Microsphatodon bairdii, Chaenomugil proboscideus, Halichoeres aestuari- cola and Echidna nocturna were transients, and Apogon dovii, Sargocentron suborbitalis, Cerdale sp, Rypticus nigripinnis and Ctenochaetus marginatus were considered as accidental visitors. The temporal and spatial variation of assemblage structure was tested. The fish assemblage struc- ture did not differ between months and there was not a clear relationship between tidepool surface area and depth, and community variables. Diversity and species richness were nega- tively correlated with tidepool height. It is suggested that the tidepool assemblage was stable and resilient in time on short (annual) scales. The constancy in time and space could have been a consequence of eurytopic features of the organisms and the lack of drastic seasonal changes in the tropics. # 2005 The Fisheries Society of the British Isles Key words: community structure; intertidal fishes; rocky shore; stability; tropical eastern Pacific. INTRODUCTION The rocky intertidal shore is an environment of extreme environmental sever- ity, where physical and biological factors act together in order to determine the community structure of inhabiting organisms (Lewis, 1964; Paine & Levin, 1981; Denny, 1988; Little & Kitching, 1996). The pools formed by tide cycles on the rocky shore, however, serve as a refuge for the marine communities, which live §Author to whom correspondence should be addressed. Tel.: þ57 2 3212171; fax: þ57 2 3393243; email: agiraldo@univalle.edu.co Journal of Fish Biology (2005) 67, 392—408 doi:10.1111/j.1095-8649.2005.00735.x, available online at http://www.blackwell-synergy.com 392 # 2005 The Fisheries Society of the British Isles