Detrital production in Nova Scotian kelp beds: patterns and processes

Connectivity via the transport of detrital material from areas of high to low productivity may be an important determinant of secondary productivity and biodiversity in receiving communities. On the Atlantic coast of Nova Scotia, detritus exported from subtidal kelp beds contributes to food webs in communities inhabiting deeper waters offshore. To estimate the amount of energy available via this pathway, we measured rates of detrital production via erosion of kelp blades in kelp beds at 5 sites varying in wave exposure. Specifically, we measured productivity and erosion of the 2 dominant species of kelp, Laminaria digitata and Saccharina longicruris, over 16 mo. We also examined the effect of environmental and biological factors on erosion rates, including temperature, wave exposure, grazing by snails and cover by the invasive bryozoan Membranipora membranacea. We observed clear seasonal and spatial patterns in productivity, with the highest production in spring. Erosion rate was high...