Meeting Abstract

29.1  Friday, Jan. 4  Measuring the palatability of marine invertebrate embryos in the field ALLEN, JD; Bowdoin College jallen@bowdoin.edu

The dispersive larval stages of marine invertebrates likely suffer high rates of mortality due to predation. Several studies have clearly demonstrated that the larval stages of marine invertebrates possess chemical defenses that effectively deter predation during planktonic development. It has also been suggested that brooded larvae and large lecithotrophic larvae are more likely to be chemically defended against consumers than are planktotrophic larvae. However, there are only a few laboratory studies that have tested this hypothesis and even fewer studies that have done so in a field setting. In a series of field experiments I tested the hypothesis that planktotrophic larvae are more palatable to predators than lecithotrophic or brooded larvae, by measuring predation on tethered baits flavored with the eggs, embryos or larvae of more than 20 species of invertebrates common to the waters of coastal southern Maine. Of the species tested, 10 were broadcast spawners: 8 exhibiting planktotrophic development and 2 exhibiting lecithotrophic development. Five species developed in benthic egg masses or capsules and the embryos of three of these species hatched as planktotrophic larvae while the embryos of the remaining two species hatched as benthic juveniles. Six species brooded embryos that were released as planktotrophic larvae and two species brooded embryos that were released as lecithotrophic larvae. Contrary to previous studies, there was no clear evidence that planktotrophic larvae were more palatable to predators than lecithotrophic or brooded larvae. Tests of palatability were also performed in the laboratory and supported the field results, suggesting that levels of chemical defense may not be correlated with mode of development in marine invertebrates.