UC San Diego

Cryptobenthic fishes are small-bodied, short-lived species that live in near constant contact with the reef surface and generally rely on crypsis as their main means of escaping predation. They constitute an important part of the reef fish community that is often not well understood. For this work, I investigated cryptobenthic fishes in the Gulf of California, Mexico, a basin noted for high productivity, high diversity of fishes, and heterogeneity of local environments. Specifically, I present the results of several studies designed to better understand the role of cryptobenthic fishes in the rocky reef fish community. In Chapter 1, I place all subsequent results in a local, environmental context by quantifying the temperature variability at several sites across the Gulf. Chapter 2 concentrates on the biogeography of these fishes and details a quantitative analysis of the community dynamics of this group. In Chapter 3, I define the contribution of cryptobenthic fishes to the wider fish community. In Chapter 4, I use historical samples to examine possible differences between the community structure of these fishes in 2010 and in the 1970s. Finally, in the Appendix, I report several novel natural history observations that I documented while conducting the research reported here. Each of these chapters builds toward a more complete understanding of cryptobenthic fish community ecology, in the Gulf and in general, than has previously been documented. My results indicate that cryptobenthic fishes are a vital component of the reef fish community and may account for as much as 50% of the total energy requirements of and total species richness of reef fishes at sites in the Gulf. Furthermore, I confirm that the Gulf is, biogeographically, a particularly important region to new world cryptobenthic lineages and that endemism is high among cryptobenthic communities there. Finally, I quantitatively demonstrate, using Canonical Analysis of Principal Coordinates, that this component of the reef fish community was different in 2010 than in the 1970s, in both total and relative abundance, with some species represented by more than a 90% reduction in numbers, while others increased significantly. Prior to this work, the long-term stability of cryptobenthic communities had not been tested. The research presented here provides several new data sets to a growing field and may contribute to the understanding of marine community dynamics