|
|||||
|
|
Diel Activity Patterns and Foraging Dynamics of the Sea Urchin Tripneustes ventricosus in a Tropical Seagrass Community and a Reef Environment (Virgin Islands) |
|
| Authors: | Wolfram P Tertschnig |
| Institution: | University of Vienna, Institute of Zoology, Dept. of Marine Biology;Althanstr. 14, A-1090 Vienna, Austria |
| Abstract: | Abstract. Feeding and movement activity patterns and the foraging behavior of the sea urchin Tripneustes ventricosus were investigated in a Thalassia testudinum seagrass bed and on a patch reef at St. Croix, U.S. Virgin Islands. Most of T. ventricosus in the seagrass bed fed during both the day and night. Consumption of seagrass blades amounted to 1.4 g dw · individual The movement of T. ventricosus was diel with high nocturnal activity levels and rates of locomotion, and little activity during daylight hours. Foraging activity was reduced under turbulent conditions. Movement rates were not governed by food availability. T. ventricosus travelled 3.7 m · d The high rate of movement in seagrass beds may represent an innate behavioral adaptation to predation by night-active helmet conchs ( Cassis spp.). Fitness optimization by T. ventricosus may have been achieved by minimizing the predation risk during night hours. In an evolutionary context, survival by means of an increased energy expenditure for locomotion may compensate for the lower net energy gain from foraging. |
| Keywords: | Tripneustes ventricosus seagrass beds patch reefs herbivores activity pattern movement rate predator avoidance foraging strategy fitness optimization |