Relative Importance of Grazing and Nutrient Controls of Macroalgal Biomass in Three Temperate Shallow Estuaries

Hauxwell, Jennifer; McClelland, J. W.; Behr, Peter J.; Valiela, Iván

doi:10.2307/1352481

Cited by 148 publications

(122 citation statements)

References 63 publications

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“…Gammarus is a grazer of microalgae, detritus, and associated microbes (Zimmerman et al 1979, Smith et al 1982, and often reaches very high densities in shallow habitats in Chesapeake Bay during spring (Fredette and Diaz 1986). Idotea baltica is a characteristic member of vegetated marine and estuarine habitats on both sides of the North Atlantic, grazing on microalgae, macroalgae, and seagrasses (Robertson and Mann 1980, Shacklock and Doyle 1983, Salemaa 1987, Hauxwell et al 1998, Worm et al 2000. Erichsonella attenuata occurs along the East and Gulf coasts of North America and appears to feed primarily on microalgae Short 1986, Boströ m andMattila 1999).…”

Section: Natural History Of the Systemmentioning

confidence: 99%

Grazer Diversity, Functional Redundancy, and Productivity in Seagrass Beds: An Experimental Test

Duffy

Macdonald

Rhode

et al. 2001

Ecology

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Abstract. Concern over the accelerating loss of biodiversity has stimulated renewed interest in relationships among species richness, species composition, and the functional properties of ecosystems. Mechanistically, the degree of functional differentiation or complementarity among individual species determines the form of such relationships and is thus important to distinguishing among alternative hypotheses for the effects of diversity on ecosystem processes. Although a growing number of studies have reported relationships between plant diversity and ecosystem processes, few have explicitly addressed how functional diversity at higher trophic levels influences ecosystem processes. We used mesocosm experiments to test the impacts of three herbivorous crustacean species (Gammarus mucronatus, Idotea baltica, and Erichsonella attenuata) on plant biomass accumulation, relative dominance of plant functional groups, and herbivore secondary production in beds of eelgrass (Zostera marina), a dominant feature of naturally low-diversity estuaries throughout the northern hemisphere. By establishing treatments with all possible combinations of the three grazer species, we tested the degree of functional redundancy among grazers and their relative impacts on productivity.Grazer species composition strongly influenced eelgrass biomass accumulation and grazer secondary production, whereas none of the processes we studied was clearly related to grazer species richness over the narrow range (0-3 species) studied. In fact, all three measured ecosystem processes-epiphyte grazing, and eelgrass and grazer biomass accumulation-reached highest values in particular single-species treatments. Experimental deletions of individual species from the otherwise-intact assemblage confirmed that the three grazer species were functionally redundant in impacting epiphyte accumulation, whereas secondary production was sensitive to deletion of G. mucronatus, indicating its unique, nonredundant role in influencing this variable. In the field, seasonal abundance patterns differed markedly among the dominant grazer species, suggesting that complementary grazer phenologies may reduce total variance in grazing pressure on an annual basis. Our results show that even superficially similar grazer species can differ in both sign and magnitude of impacts on ecosystem processes and emphasize that one must be cautious in assuming redundancy when assigning species to functional groups.

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Section: Natural History Of the Systemmentioning

confidence: 99%

Grazer Diversity, Functional Redundancy, and Productivity in Seagrass Beds: An Experimental Test

Duffy

Macdonald

Rhode

et al. 2001

Ecology

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“…This range of nitrogen loads encompasses approximately 75% of the range of reported values to estuaries worldwide (Nixon 1992). Although there were differences among the Waquoit Bay subestuaries, previous publications showed that the differences in nitrogen loading received from land overwhelm the influence of other potential controls on water Fox et al 5 chemistry, primary production, and trophic interactions McClelland et al 1997;Hauxwell et al 1998;Thompson and Valiela 1999).…”

Section: Introductionmentioning

confidence: 97%

“…Increased primary production owing to increased nutrient supply can control higher trophic levels in both benthic and pelagic food webs (Rafaelli et al 1998;Ware and Thompson 2005). Macroalgal blooms, in particular, have had further consequences, often shading and replacing seagrass meadows (McGlathery 2001;Hauxwell et al 2001), as well as fostering of hypoxic conditions (D'Avanzo and Kremer 1994;Diaz 2001) that decrease abundance of invertebrates (Hauxwell et al 1998;Oesterling and Pihl 2001) and fish (Baden et al 1990;Deegan et al 2002).…”

Section: Introductionmentioning

confidence: 99%

“…Macrophyte biomass may be controlled by temperature, light availability, nutrients, and grazers (Lapointe and Duke 1984;Geertz-Hansen et al 1993;Duarte 1995;Peckol and Rivers 1995;Hauxwell et al 1998). Opportunistic species of macroalgae, such as Cladophora vagabunda and Gracilaria tikvahiae, are better able to take advantage of light and nutrients than other non-blooming species (Lapointe and O'Connell 1989;Peckol and Rivers 1995;Borum and Sand-Jensen 1996;Hauxwell et al 2001).…”

Section: Introductionmentioning

confidence: 99%

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Macrophyte Abundance in Waquoit Bay: Effects of Land-Derived Nitrogen Loads on Seasonal and Multi-Year Biomass Patterns

Fox

Stieve

Valiela

et al. 2008

Estuaries and Coasts

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Anthropogenic inputs of nutrients to coastal waters have rapidly restructured coastal ecosystems.To examine the response of macrophyte communities to land-derived nitrogen loading, we measured macrophyte biomass monthly for six years in three estuaries subject to different nitrogen loads owing to different land uses on the watersheds. The set of estuaries sampled had nitrogen loads over the broad range of 12 to 601 kg N ha -1 y -1 . Macrophyte biomass increased as nitrogen loads increased, but the response of individual taxa varied. Specifically, biomass of Cladophora vagabunda and Gracilaria tikvahiae increased significantly as nitrogen loads increased. The biomass of other macroalgal taxa tended to decrease with increasing load, and the relative proportion of these taxa to total macrophyte biomass also decreased. The seagrass, Zostera marina, disappeared from the higher loaded estuaries, but remained abundant in the estuary with the lowest load. Seasonal changes in macroalgal standing stock were also affected by nitrogen load, with larger fluctuations in biomass across the year and higher minimum biomass of macroalgae in the higher loaded estuaries. There were no significant changes in macrophyte biomass over the six years of this study, but there was a slight trend of increasing macroalgal biomass in the latter years. Macroalgal biomass was not related to irradiance or temperature, but Z. marina biomass was highest during the summer months when light and temperatures peak. Irradiance might, however, be a secondary limiting factor controlling macroalgal biomass in the higher loaded estuaries by restricting the depth of the macroalgal canopy. The relationship between the bloom-forming macroalgal species, C. vagabunda and G. tikvahiae, and nitrogen loads suggested a strong connection between development on watersheds and macroalgal blooms and loss of seagrasses. The influence of watershed land uses largely Fox et al. 3 overwhelmed seasonal and inter-annual differences in standing stock of macrophytes in these temperate estuaries.

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“…Benthic algal primary producers contribute to subtidal and marsh carbon and nutrient cycling (Osgood and Zieman 1993;Valiela et al 1997;Piehler et al 1998;Boyer and Fong 2005;Sundback and McGlathery 2005); primary production by benthic micro-algae in this zone typically ranges from 50 to 300 mg C m -2 year -1 , which is of the same magnitude as phytoplankton production in estuarine waters, and both macro-and micro-algae contribute significantly to total primary production in shallow estuarine waters (Sundback and McGlathery 2005). Benthic algae are vulnerable to changes in marsh elevation, hydrology and associated soil properties, and changes in the location and abundance of macroalgae could have cascading effects on secondary productivity (Hauxwell et al 1998) and nutrient supply to low marsh plants (Boyer and Fong 2005).…”

Section: Introductionmentioning

confidence: 99%

Salt marsh stabilization affects algal primary producers at the marsh edge

O’Connor

Violin

Antón

et al. 2011

Wetlands Ecol Manage

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As sea level rise and human activities erode coastal wetlands, managers rebuild or preserve wetlands that can perform the ecosystem services of a natural system. One increasingly common mitigation activity is the construction of rock sills in the low marsh zone to stabilize marsh elevation. Sills dramatically alter the physical structure of marshes by changing elevation, adding hard substrate and potentially altering the spatial structure of benthic algal communities in and adjacent to the low marsh. We documented differences in benthic algal abundance at the seaward marsh edge in silled and unsilled marshes in North Carolina. We found that sills were associated with reduced standing stocks of benthic algal primary production and reduced macroalgal taxonomic richness, and this difference was driven primarily by differences in macroalgal abundance. We experimentally tested the effect of macroalgal abundance on cordgrass (Spartina alterniflora) growth in the low zone of an unmanipulated marsh, and found that macroalgal removal had no effect on final cordgrass abundance. Our study suggests that salt marsh management through the construction of sills in low marsh zones impacts benthic primary production in the low marsh zone, but that benthic algal production does not affect cordgrass growth over a growing season.

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Relative Importance of Grazing and Nutrient Controls of Macroalgal Biomass in Three Temperate Shallow Estuaries

Cited by 148 publications

References 63 publications

Grazer Diversity, Functional Redundancy, and Productivity in Seagrass Beds: An Experimental Test

Grazer Diversity, Functional Redundancy, and Productivity in Seagrass Beds: An Experimental Test

Macrophyte Abundance in Waquoit Bay: Effects of Land-Derived Nitrogen Loads on Seasonal and Multi-Year Biomass Patterns

Salt marsh stabilization affects algal primary producers at the marsh edge

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