Coral Reefs of the Southern Gulf of Mexico

Chapter 9. Reef Fish

2 Reef Fish Ernesto A. Chávez and Carl r. Beaver Coral reefs are among the most biologically diverse ecosystems on the planet. Nowhere on the reef is this diversity as conspicuously displayed as in the reef’s fish community. Between 66% and 89% of all marine fish species are found on coral reefs and reef-associated habitats (Moyle and Cech 1988). The tremendous diversity of reef-fish species is generally thought to be the result of a diversity of habitats found on the reef. The complexity of the reef provides fishes with a multitude of microhabitats or niches to populate. Although diversity is generally high in undisturbed reef communities, reef-fish distribution is not homogeneous and, in fact, can be quite patchy. The heterogeneity of reef-fish distribution may be attributed to habitat characteristics (Hixon and Beets 1993), spatial distribution of food (González-Gándara et a1.1999), and topographic complexity (Risk 1972; Nuñez-Lara and Arias-González 1998) among other factors. Although diverse reef-fish communities exist throughout much of the western Gulf of Mexico, much work has concentrated on the commercially important fish and fishing grounds along the Campeche Bank (Hildebrand et al. 1964; H. Chávez 1966; Reséndez-Medina 1971; Garduño-Andrade 1988, 1989; Gardu ño and Chávez 2000; González-Gándara and Arias-González 2001a, 2001b). Despite being commercially important in their own right, the reef fishes off the states of Veracruz and Tamaulipas in the western Gulf of Mexico have received little quantitative analysis. Because of the paucity of quantitative studies, the analysis presented here is based on three contributions. Two of these represent recent quantitative studies in the area (Garduño-Andrade 1988; Choucair 1992), and the other (Castro-Aguirre and Márquez-Espinoza 1981) is the only source paper written on the subject. Because an in-depth description of all species is beyond the scope of this project, the analysis presented herein is based on dominant elements of the fish community within each reef area. For the reader requiring more information, a complete list of fish species observed at each reef is provided at www.gulfbase .org (Nipper et al. 2004). In the Veracruz Reef System (VRS), quantitative data are available only for the reefs around Isla de Enmedio. However, because the Isla de Enmedio Reef is centrally located, and because the VRS reefs are concentrated within a relatively small geographic region, these data can be considered representative of the VRS as a whole. In all cases, observations were made in several habitats and from several depths, including zones in the windward reef areas, in protected or leeward reef areas, and in reef lagoonal areas. Reef-fish distribution within the reefs of the southern Gulf of Mexico raises questions related to physiography. Is fish community structure the same in all reef areas? If not, how are the resources allocated among communities, popula9 A4339.indb 102 A4339.indb 102 7/6/07 11:19:20 AM 7/6/07 11:19:20 AM Reef Fish 103 tions, or guilds? If environmental driving forces are responsible for the differences in reef-fish distribution, do the physiographic features impose differences on reef-fish fauna, and do these driving forces lead to significantly different faunal components in an area? For answers to these questions, we review the abundance and distribution of dominant fish species on each reef in an attempt to describe the differences in these reef-fish assemblages. Although a number of qualitative studies of southern Gulf of Mexico reef fishes have been done, few quantitative studies pertaining to the abundance of reef fish exist, and consequently, data are scarce. Despite this limitation, the information presented herein comes from only quantitative surveys. Fish records of Isla de Lobos Reef include the work of Castro-Aguirre and Márquez-Espinoza (1981), who used diverse methods of collection, such as beach seine, gill nets, hook and lines, by hand and using a jar, and rotenone. Data from Isla de Enmedio Reef were reported by Choucair (1992), whose methodology included diving and counting fish within a virtual cylindrical area. Coral reefs of the Campeche Bank were sampled using rapid, timed visual-survey techniques conducted while diving (Garduño-Andrade 1988; Garduño and Chávez 2000). Isla de Lobos Reef The fish assemblage of this reef has approximately 76% of reef-fish species known to occur in the western Atlantic along the coast of Florida. Species richness recorded at Isla...