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

Melanie J. Bishop, Brendan P. Kelaher

Research output: Contribution to journalArticleResearchpeer-review

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.

LanguageEnglish
Pages25-36
Number of pages12
JournalMarine Ecology Progress Series
Volume341
DOIs
Publication statusPublished - 4 Jul 2007
Externally publishedYes

Fingerprint

disturbance
sediments
macroinvertebrate
sediment chemistry
physical disturbance
sediment
macroinvertebrates
detritus
invertebrate
chemistry
invertebrates
seagrass
benthos
Zostera
warming
effect
benthic organisms
global warming
climate change
food

Keywords

  • Detrital enrichment
  • Frequency
  • Intensity
  • Macroinvertebrate
  • Zostera capricornii

Cite this

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title = "Impacts of detrital enrichment on estuarine assemblages: Disentangling effects of frequency and intensity of disturbance",
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.",
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Impacts of detrital enrichment on estuarine assemblages : Disentangling effects of frequency and intensity of disturbance. / Bishop, Melanie J.; Kelaher, Brendan P.

In: Marine Ecology Progress Series, Vol. 341, 04.07.2007, p. 25-36.

Research output: Contribution to journalArticleResearchpeer-review

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