Effects of food-particle size and pelletization on individual growth and larval settlement of the deposit feeding polychaete

Three size classes of Capitella capitata (Type I ) were fed 4 size ranges of detritus particles derived from red seaweed Gracilaria foliifera. Growth was generally reduced when only the largest particle-size range (150 to 250 pm) was available, and the effect was most pronounced for small worms. Worms lost weight when fed fecal pellets comparable in size to the largest particles of seaweed detritus. They also lost weight when fed sonically-disrupted fecal pellets, even though most worms consumed disaggregated fecal pellets and some ingested intact pellets. Larval settlement rates were positively correlated with food-particle size for seaweed detritus, but settlement was poor on fecal pellets. Fecal pellets did not inhibit settlement on an attractive substrate (cereal flakes). Thus, the effects of pelletization of ingested materials on growth and larval settlement probably reflect nutritional limitations rather than particle size effects.