| Abstract: | Female green razorfish, Xyrichtys splendens, were studied in the field in three shallow tropical marine habitats: sandbed, Thalassia grassbed, and coral rubble bottom. Individuals showed varying degrees of home range overlap (one measure of territoriality) in each habitat, due to differences in predator pressure, the availability of refuges, and water turbidity. In a large scale field manipulation, a 68 m2 bed of artificial seagrass (300 'grass' blades per m2) was planted at one site with low turbidity, thereby increasing the availability of refuges. The females' home ranges overlapped more, whereas control fish did not change their home range use, indicating that home range exclusivity in this species is a function of refuge distribution. Female X. splendens apparently have the phenotypic plasticity to adapt their social behavior to local conditions; in this case, the availability of economically inexpensive refuges, and the risk of predation as a function of the turbidity of the water. |
