IS KELP DETRITUS A GOOD FOOD FOR SUSPENSION FEEDERS - EFFECTS OF KELPSPECIES, AGE AND SECONDARY METABOLITES

The food quality of detrital particles derived from three species of k elps was. evaluated in a laboratory feeding experiment utilizing two s pecies of suspension feeders, the serpulid polychaete Pseudochitanopom a occidentalis and the mussel Mytilus trossulus. Fresh and aged kelp p articles were also evaluated, and growth in all treatments was compare d to growth on ad libidum phytoplankton rations. Fresh particles from Laminaria groenlandica, aged particles from Agarum fimbriatum and Alar ia marginata, and mixed phytoplankton promoted the highest growth rate s in both consumers. Growth was inversely related to total polyphenoli c concentration in the fresh kelp particles. The increase in quality o f both Agarum fimbriatum and Alaria marginata particles with age corre sponded with a rapid loss of polyphenolic secondary metabolites and an increase in total nitrogen.