UC Santa Cruz

Consistent pressures from overfishing and extirpation have led to the study and conservation of many of the apex consumers within kelp forest ecosystems. Among kelp forests, those of Southern California have been described as the most diverse in the world. Yet, despite the large body of data on species interactions within these ecosystems, information on the ecology for many of the top predators is lacking. This paucity of information may be because of predator declines (e.g., giant sea bass) or simply the elusiveness of some species. One example of a large elusive predator about which little is known is the California moray (Gymnothorax mordax). The combination of a cryptic lifestyle and lack of a commercial fishery has enabled morays, in general, to have remained virtually undetected in standard species surveys. Moreover, basic biological information on morays is scarce. I use field methods, laboratory measurements, and metabolic experiments, to investigate the functional ecology of the California moray to answer questions pertaining to its dispersal, habitat preference, diet, and physiology. Data from my studies reveal that California moray dispersal is primarily driven by changes in oceanic currents caused by El Niño events. Larvae then settle to shallow Santa Catalina Island habitats consisting mainly of boulder and cobble substrates in densities ≤100x greater than previously estimated. The California moray is a piscivorous predator, consuming kelp bass, but also preying upon a wide range of fish and invertebrate species. Lastly, I discovered that the California moray has a relatively low standard metabolic rate (SMR) compared to non-anguilliform fish taxa of similar mass and that the SMRs of larger individuals do not respond to chronic changes in temperature as strongly as smaller individuals. The California moray has a subcutaneous adipose layer that increases in thickness as morays increase in mass. The adipose layer may be a physiological mechanism underlying the lower response in SMR of larger individuals at decreasing temperatures. Cumulatively, the results of this research suggest that the California moray is an apex consumer, with the potential to influence Southern California kelp forest community structure similar to patterns observed of morays in tropical communities.