Top-down and bottom-up control of infauna varies across the saltmarsh landscape
Fleeger, John W.
Johnson, David S.
Galvan, Kari A.
Deegan, Linda A.
MetadataShow full item record
KeywordSaltmarsh gradient; Fertilization; Predator removal; Fundulus heteroclitus; Macroinfauna; Meiofauna; Impact assessment; Indirect effects
Responses of infaunal saltmarsh benthic invertebrates to whole-ecosystem fertilization and predator removal were quantified in Plum Island Estuary, Massachusetts, USA. Throughout a growing season, we enriched an experimental creek on each flooding tide to 70 mM NO3 - and 4 mM PO4 -3 (a 10 x increase in loading above background), and we reduced Fundulus heteroclitus density by 60% in a branch of the fertilized and a reference creek. Macroinfauna and meiofauna were sampled in creek (mudflat and creek wall), marsh edge (tall form Spartina alterniflora) and marsh platform (Spartina patens and stunted S. alterniflora) habitats before and after treatments were begun; responses were tested with BACI-design statistics. Treatment effects were most common in the mid-range of the inundation gradient. Most fertilization effects were on creek wall where ostracod abundance increased, indices of copepod reproduction increased and copepod and annelid communities were altered. These taxa may use epiphytes (that respond rapidly to fertilization) of filamentous algae as a food source. Killifish reduction effects on meiobenthic copepod abundance were detected at the marsh edge and suggest predator limitation. Fish reduction effects on annelids did not suggest top-down regulation in any habitat; however, fish reduction may have stimulated an increased predation rate on annelids by grass shrimp. Interactions between fertilization and fish reduction occurred under S. patens canopy where indirect predator reduction effects on annelids were indicated. No effects were observed in mudflat or stunted S. alterniflora habitats. Although the responses of infauna to fertilization and predator removal were largely independent and of similar mild intensity, our data suggests that the effects of ecological stressors vary across the marsh landscape.
Author Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Experimental Marine Biology and Ecology 357 (2008): 20-34, doi:10.1016/j.jembe.2007.12.003.
Showing items related by title, author, creator and subject.
Complexity of the flooding/drying process in an estuarine tidal-creek salt-marsh system : an application of FVCOM Chen, Changsheng; Qi, Jianhua; Li, Chunyan; Beardsley, Robert C.; Lin, Huichan; Walker, Randy; Gates, Keith (American Geophysical Union, 2008-07-30)The tidal flooding/drying process in the Satilla River Estuary was examined using an unstructured-grid finite-volume coastal ocean model (FVCOM). Driven by tidal forcing at the open boundary and river discharge at the ...
Johnson, David S.; Warren, R. Scott; Deegan, Linda A.; Mozdzer, Thomas J. (John Wiley & Sons, 2016-10-20)In saltmarsh plant communities, bottom-up pressure from nutrient enrichment is predicted to increase productivity, alter community structure, decrease biodiversity, and alter ecosystem functioning. Previous work supporting ...
Response of the benthic food web to short- and long-term nutrient 1 enrichment in saltmarsh mudflats Pascal, Pierre-Yves; Fleeger, John W.; Boschker, Henricus T. S.; Mitwally, Hanan M.; Johnson, David S. (2013-01)We examined the responses of biota at or near the base of the benthic food web to nutrient enrichment in salt marsh mudflats in Plum Island estuary (Massachusetts, USA). To simulate eutrophication, nitrate and phosphate ...