The role of kelp detritus in the growth of benthic suspension feeders in an understory kelp forest

Abstract

Stands of understory kelps greatly alter the physical and biological environment within the algal canopy. In some regions, kelps can also contribute significantly to suspension feeder nutrition through detrital pathways. In a field experiment utilizing artificial kelps, we attempted to decouple and evaluate the physical versus nutritional mechanisms by which understory kelps affect the growth rates of benthic suspension feeders. Suspension feeding organisms were translocated to patches of real and artificial kelps at two subtidal sites, and growth rates measured. Physical parameters were not significantly different between treatments (real versus artificial kelp) and thus any differences in growth rate should be attributable to differences in detrital contribution between real and plastic plants. Of six taxa of suspension feeders examined, only one showed a significant treatment effect and that species grew faster in the artificial kelp treatment. The difference between our result and those of previously published studies may relate to issues of scale and species-specific plant secondary substances.