Cooperation in a cleaner fish mutualism and its ecological implications
Ecology, Evolution and Marine Biology
Many organisms are capable of changing their behavior (or other phenotypic traits) in response to cues in their environment, and this can affect their interactions with other species. Here I investigate interactions between the bluestreak cleaner wrasse, Labroides dimidiatus, and its client fish in Moorea, French Polynesia, and demonstrate that the mutualism can have wide ranging impacts on coral reef communities by influencing the behavior of the participants. Before investigating the ecological consequences of the interaction, I explored factors that influence cooperation between cleaners and their clients. I found that when ornate butterflyfish, Chaetodon ornatissimus, have multiple cleaner stations in their territory, cleaners compete for access to these preferred clients and give them higher quality service (Chapter 1). Next, I documented a pattern indicating that juvenile bluestreak cleaner wrasse may preferentially settle near adults, and I used a field experiment to explore the potential impact of this settlement pattern on the performance (growth and survivorship) of new settlers (Chapter 2). Despite evidence for a direct negative effect of resident adults on new settlers, settlers grew at a faster rate at established cleaner stations. This occurred because adult cleaners were strongly associated with high quality habitat that harbored a high density of potential client fishes, and adult cleaners attracted additional clients seeking cleaning to these reefs. Finally, I found that cleaners increase the local predation pressure on corals at cleaner stations by attracting corallivorous butterflyfish (Chaetodontidae) to their territories (Chapter 3). Ornate butterflyfish foraged at lower rates and shifted their diet to include a greater proportion of less preferred prey items while at cleaner stations suggesting a trade-off between seeking cleaning and foraging. Nonetheless, predation pressure on corals was higher at cleaner stations because the spatial response of butterflyfish to cleaners more than compensated for their lower foraging rates. Furthermore, the results of a field experiment suggest that the greater predation pressure observed at cleaner stations is sufficient to reduce the growth rate of an unpreferred coral, Porites rus.
Thesis or Dissertation
University of California