Impacts of detrital enrichment on estuarine assemblages: disentangling effects of frequency and intensity of disturbance

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 341:25-36 (2007) - doi:10.3354/meps341025 Impacts of detrital enrichment on estuarine assemblages: disentangling effects of frequency and intensity of disturbance Melanie J. Bishop*, Brendan P. Kelaher Department of Environmental Sciences and Institute for Water and Environmental Resource Management, University of Technology Sydney, PO Box 123, Broadway, New South Wales 2007, Australia *Email: Melanie.Bishop-1@uts.edu.au ABSTRACT: Under climate change, enhanced storminess may increase the magnitude and rate of detrital loading to the benthos, potentially altering sediment chemistry and/or physical disturbance of sediments. To assess whether the impact of detrital loading on invertebrates in intertidal sediment sparsely vegetated by seagrass is negatively affected by increasing the frequency and/or intensity of the disturbance, high (90 g dry weight) or low (30 g dry weight) quantities of shredded Zostera capricornii were added to experimental plots at high (intervals of 8 wk, on a total of 3 occasions) or low (added once) frequency. Macroinvertebrate assemblages were sampled 8, 16 and 24 wk after the first detrital enrichment. Plots subjected to frequent detrital addition contained up to 50% fewer macroinvertebrates, representing 50% fewer taxa than plots disturbed only once. This pattern was independent of disturbance intensity and emerged after only 2 detrital additions. Only at the low frequency of addition did the increased quantity of detritus influence macroinvertebrate assemblage composition, halving the number of animals by Week 24. Physical disturbance, not sediment chemistry, drove the frequency effect. Generally negative impacts of frequent detrital enrichment on infaunal populations occurred despite small positive effects of high detrital enrichment on the biomass of microphytobenthos, the food source of many sediment-dwelling invertebrates. These results suggest that, even though climate warming may increase the amount of detritus that is washed up onto intertidal sediments, its greater effect on soft-sediment communities is likely to come through increasing the frequency of storms. KEY WORDS: Detrital enrichment · Frequency · Intensity · Macroinvertebrate · Zostera capricornii Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 341. Online publication date: July 04, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.