MEPS 550:101-110 (2016)  -  DOI: https://doi.org/10.3354/meps11726

Cordgrass canopy elicits weak effects on sediment properties and microphytobenthic abundance in a harsh environment

Fausto N. Firstater1,*, Maite Narvarte1, M. Fernanda Alvarez2, M. Eugenia Fanjul3, Oscar O. Iribarne3

1Instituto de Biología Marina y Pesquera Almirante Storni, Escuela Superior de Ciencias Marinas, Universidad Nacional del Comahue – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Güemes 1030, 8520 San Antonio Oeste, Rio Negro, Argentina
2Laboratorio Cuenca del Salado Instituto de Limnología ‘Dr. Raul A. Ringuelet’ (ILPLA-CONICET), Universidad Nacional de La Plata (UNLP), 1900 La Plata, Argentina
3Laboratorio de Ecología, Instituto de Investigaciones Marinas y Costeras (IIMyC), CONICET - FCEyN, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
*Corresponding author:

ABSTRACT: The magnitude of the outcome of ecosystem engineering is context-dependent; as environmental stresses increase, habitat amelioration by ecosystem engineers becomes more relevant. Moreover, the individual- and population-level traits of ecosystem engineers can affect their ability to reduce environmental stress. On the Patagonian shores of Argentina (SW Atlantic, 41°S), the intertidal community is exposed to harsh conditions. We predicted that in this severe environment, variation in the above-ground structure of the smooth cordgrass Spartina alterniflora should buffer the physical stress on the substrate through shading and reduction of wind and water flow energy, ultimately affecting the sediment properties and microphytobenthic biomass. To test this hypothesis, we experimentally manipulated cordgrass density at the edge and inner marsh of a S. alterniflora meadow during both summer and winter. In summer, evaporation and temperature were higher in clipped plots, while in winter, evaporation varied across densities and location treatments, with higher sediment water content in the inner marsh. No effect of S. alterniflora density or location were observed on sediment organic matter or chl a concentration, and mean sediment grain size was always smaller inside the marsh. In summer, extracellular polymeric substance (EPS) content was higher in clipped plots inside the marsh, however this did not differ from the other density treatments at this location. Overall, shading had weak effects on sediment properties and microphytobenthic biomass, and most observed differences were attributable to grain size. We speculate that the harsh conditions of this system overwhelm the ecosystem engineering effects of S. alterniflora, probably because of its relatively small aboveground biomass.


KEY WORDS: Ecosystem engineering · Environmental stress · Patagonia · Salt marsh · Spartina


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Cite this article as: Firstater FN, Narvarte M, Alvarez MF, Fanjul ME, Iribarne OO (2016) Cordgrass canopy elicits weak effects on sediment properties and microphytobenthic abundance in a harsh environment. Mar Ecol Prog Ser 550:101-110. https://doi.org/10.3354/meps11726

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