Exploring the behavioral and reproductive ecology of fishes on coral reefs

The 'lab rat' of coral reef fish research:

Thalassoma bifasciatum

Much of my research for the last decade has focused on herbivorous coral-reef fishes, particularly the Caribbean striped parrotfish, Scarus iserti. These relatively small, sex-changing, herbivores display a remarkably complex social organization (including group territories with dominance hierarchies, roving "satellite" individuals, and non-territorial schools that invade territories). Their range of mating tactics and alternative life-history strategies, coupled with their quantifiable food resources make them, in many ways, an ideal study organism. Additionally, the ability of these fish to respond quickly to changing environmental and demographic conditions makes them especially well-suited for both comparative and experimental field studies. By combining data on resource availability with experimental and comparative data on their behavior and demography my studies explore how physical and social environmental effects determine where animals are found and how they interact.

Back to the Clifton biology home page
The Striped Parrotfish

         Scarus iserti
My research to date includes studies of the economics of group-territorial behavior by non-kin (Clifton 1989, 1990), the effects of seasonal changes in resource levels upon social organization and the timing of reproduction (Clifton 1995), the determinants of group size inside and out of territories (Clifton, submitted), and tests of "ideal despotic" models of dispersion under variable regimes of resource renewal (in prep). Social behaviors such as dominance (Clifton 1991) and territoriality play a particularly important role in determining the dispersion and life history of these fish because they modify both individual food intakes and underlying patterns of food availability.
The Beaugregory Damselfish 

            Stegastes leucostictus
(with white paint tag on its back)
More recently, my studies of reef-fish reproductive phenology, in collaboration with Dr. Ross Robertson of the Smithsonian Tropical Research Institute, have investigated how food limitation constrains the life history, parental care, and reproductive ecology of the Caribbean damselfish (Stegastes leucostictus), a territorial herbivore with male parental care of eggs. In a series of field experiments, we supplemented the diet of wild adult fish over extended periods of time to judge how food availability influenced adult life history. Simultaneously, we monitored unmanipulated populations on a variety of spatial scales to establish the extent and relative importance of these effects. After almost two years of field work, we have clearly documented how food availability drives seasonal, but not lunar, patterns of reproduction, growth, and survival for this tropical species. This link between aspects of the adult environment and their expression of various life history traits challenges current thinking about the seasonality of reproduction on coral reefs and emphasizes the need to include adult biology within current models of reef fish population ecology. Plans to extend this work to other fishes with different life history and ecology (e.g. planktivores and detritivores without parental care) are currently underway.
 




      

         
            
 Other
               Studies of Reef Fish
               
               
Phylogenetic, ecological, and biogeographic
               relationships among Labroid coral reef
               fishes

               
               
Although relatively recently derived, parrotfishes
               and wrasses have rapidly evolved into one of the most
               diverse and influential guilds of fishes on modern
               coral reefs. Similarities in morphology, fin
               structure, and scale pattern have traditionally
               obscured the phylogenetic relationships within these
               important groups. In collaboration with a molecular
               population biologist (G.
               Bernardi at UCSC) we have recently established a
               molecular phylogeny for both the Atlantic parrotfish
               genus Sparisoma (Bernardi et al., submitted)
               and the pan-tropically distributed wrasse genus,
               Thalassoma (Bernardi et al., in prep). Levels
               of genetic similarity within Sparisoma provide
               intriguing insights into their molecular, ecological,
               and biogeographic divergence. Similarly, our on going
               analysis of Thalassoma phylogeny is revealing
               unexpected relationships that both challenge and
               support current perceptions of speciation within the
               group. Our success thus far prompts further study, and
               we are currently working toward a complete phylogeny
               of the Scaridae that examines patterns of evolution,
               ecology, and biogeography.

               
               
 Diel feeding cycles by herbivorous
               fishes.

               
               
Many herbivorous fishes show marked daily cycles in
               their feeding rate. Many are also territorial. As a
               result, several workers have suggested that feeding
               periodicity is a response to predictable changes in
               food quality (i.e. nutritive value) and the ability to
               control access to that food. A simple model I have
               developed, however, predicts that food quantity (i.e.
               standing crop) and competition for resources, may also
               generate feeding cycles. Ross Robertson and I are
               discriminating among these possibilities using a
               comparative and experimental approach. To date, we
               have characterized the diel feeding behavior of 13
               species of herbivorous fish (damselfish, surgeonfish,
               and parrotfish). Together, these fish show a range of
               feeding patterns, express different levels of
               territorial behavior, and eat different types of algae
               and sea grass. A preliminary analysis indicates that
               various factors drive feeding cycles in different
               species, depending on resource type, demography, and
               digestive physiology. Experimental manipulations of
               food quality, food quantity, and population density
               will test the models further.

               
               

         		
      

   

   
   

      

         
            
Relevant
               publications

               
               
Clifton, K.E. &
               Robertson, D.R. (in prep). Diet and reproduction of
               the Caribbean Yellow jack, Carangoides
               bartholomaei in the near-shore waters of San Blas,
               Panama.

               
               
Robertson, D.R. &
               Clifton, K.E. (in prep). Patterns of mortality in the
               herbivorous Caribbean damselfish, Stegastes
               leucostictus.

               
Clifton,
                     K.E. & Rogers, L. 2008. Sex-specific mortality explains
                     non-sex-change by large female Sparisoma radians,
                     a protogynous Caribbean parrotfish. Animal
               Behavior, 75:e1-10.

               
Bernardi,
                     G., Clifton, K.E., Robertson, D.R. & Azzurro. E., 2000               Molecular sytematics, zoogeopraphy, and evolutionary
               ecology of the Atlantic parrotfish genus
               Sparisoma. Mol. Phyl Evol
               15:292-300.

               
               
Clifton,
                     K.E. &
               Clifton, L.M. 1998 A survey of fishes from various
               habitats within the Cayos Cochinos Marine Preserve,
               Honduras. Rev Biol. Trop. 46:
               109-124.

               
               
Clifton,
                     K.E., Kim, K. & Wulff, J.L. 1997 A field guide to the reefs of
               Caribbean Panama emphasizing western San Blas, Panama.
               Proc. 8th Int. Coral Reef Symp. 1:
               167-184.

               
               
Clifton,
                     K.E. 1996.               Field methods for the behavioral study of foraging
               ecology and life history of herbivorous coral reef
               fishes. Proc.
               Am. Acad. Und. Sci.
               16: 75-82.

               
               
Clifton,
                     K.E. 1995.
               Asynchronous food availability on neighboring
               Caribbean coral reefs determines seasonal patterns of
               growth and reproduction for an herbivorous parrotfish.               Mar.
               Ecol. Prog. Ser.
               116:39-46.

               
               
Clifton,
                     K.E. &
               Robertson, D.R. 1993. Risks of alternative mating
               tactics. Nature
               366:520.

               
               
Clifton,
                     K.E. 1991.               Subordinate group members act as food finders within
               striped parrotfish territories. J.
               Ex. Mar. Bio. Ecol.
               145:141-148.

               
               
Clifton,
                     K.E. 1990.               The costs and benefits of territory sharing for the
               Caribbean coral reef fish, Scarus iserti.
               Behav.
               Ecol. Soc.
               26:139-147.

               
               
Clifton,
                     K.E. 1989.               Territory sharing by the Caribbean striped parrotfish,
               Scarus iserti, patterns of resource
               distribution, group size, and behaviour.
               Anim.
               Behav.
               37:90-103.

            

            
            
home