Shorebirds affect ecosystem functioning on an intertidal mudflat

Booty, James M. ORCID:, Underwood, Graham J. C., Parris, Amie, Davies, Richard G. ORCID: and Tolhurst, Trevor ORCID: (2020) Shorebirds affect ecosystem functioning on an intertidal mudflat. Frontiers in Marine Science, 7 (685). ISSN 2296-7745

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Ecosystem functioning and services have provided a rationale for conservation over the past decades. Intertidal muddy sediments, and the microphytobenthic biofilms that inhabit them, perform crucial ecosystem functions including erosion protection, nutrient cycling and carbon sequestration. It has been suggested that predation on sediment macrofauna by shorebirds may impact biofilms, and shorebirds are known to consume biofilm, potentially causing significant top-down effects on mudflat ecosystem functioning. We carried out an exclusion experiment on the Colne Estuary, Essex, UK to examine whether shorebird presence significantly affects sediment erodibility measured with a Cohesive Strength Meter (CSM) and microphytobenthos biomass measured using PAM fluorescence (Fo) and chlorophyll a content. We also tested for treatment effects on sediment-water nutrient fluxes (nitrate, nitrite, ammonia, phosphate and dissolved organic carbon (DOC)) during periods of both dark and light incubation. Excluding shorebirds caused statistically significant changes in regulating and provisioning ecosystem functions, including mudflat erodibility and nutrient fluxes. The presence of shorebirds lowered the sediment critical erosion threshold, reduced nitrate fluxes into the sediment under illumination, lowered nitrate efflux, and reduced phosphate uptake, compared to sediments where birds were excluded. There were no significant differences in macrofauna community composition within the sediment between treatments after 45 days of bird exclusion, suggesting a direct link between shorebird presence or absence and the significant differences in biofilm-related variables. This study introduces previously unknown effects of shorebird presence on ecosystem functions within this system and highlights an area of shorebird science that could aid joint conservation and human provisioning action.

Item Type: Article
Additional Information: Correction at 10.3389/fmars.2020.619563: In the original article, there was a mistake in the legend for Table 2 as published. Estimated bird days are presented as total for the survey area, not per hectare. The correct legend appears below. Table 2. Bird-days estimated for each species recorded foraging within the survey area between the 20th of January and the 3rd of April 2017 on the mudflat adjacent to Geedon Saltings at Fingringhoe Wick Essex Wildlife Trust Nature Reserve, Essex, United Kingdom (grid reference TM 05065 19030). The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.
Uncontrolled Keywords: shorebirds,ecosystem function,microphytobenthos,biofilm,sediment,erosion,nutrient cycling,sediment erosion,microphytobenthos biofilm,nutrient flux,environmental science(all),water science and technology,environmental science (miscellaneous),ocean engineering,aquatic science,oceanography,global and planetary change ,/dk/atira/pure/subjectarea/asjc/2300
Faculty \ School: Faculty of Science > School of Environmental Sciences
Faculty of Science > School of Biological Sciences
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Geosciences
Faculty of Science > Research Groups > Organisms and the Environment
Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation
Faculty of Science > Research Groups > Marine Knowledge Exchange Network
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Depositing User: LivePure Connector
Date Deposited: 17 Aug 2020 23:55
Last Modified: 14 May 2023 00:32
DOI: 10.3389/fmars.2020.00685


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