Chaoborus prey capture efficiency in the light and dark1

The strike efficiency of fourth‐instar larvae on different size copepods was measured in the light and dark in the laboratory. Dark measurements were made with near‐infrared illumination and a closed circuit television system. There was no significant difference between strike efficiency in the light and dark during either day (0900–1800) or night (2100–0600). Strike efficiency generally increased as the prey size decreased, and the longest prey captured was about 1.4 mm. However, 29% of the larvae which contacted egg‐bearing female copepods longer than 1.4 mm ingested all or part of the female’s egg sac. The lack of a measurable difference in larval strike efficiency in the light and dark suggests that the diel vertical migration pattern followed by larvae is not related to diel changes in prey vulnerability.

Duke Scholars

Author Richard B. Forward Marine Science and Conservation