MEPS 398:127-135 (2010)  -  DOI:

Acclimation of seagrass Zostera noltii to co-occurring hydrodynamic and light stresses

Carmen B. de los Santos1,*, Fernando G. Brun1,2, Tjeerd J. Bouma2, Juan J. Vergara1, J. Lucas Pérez-Lloréns1

1Department of Biology, University of Cádiz, PO Box 40, 11510 Puerto Real (Cádiz), Spain
2Netherlands Institute of Ecology (NIOO-KNAW), Centre for Estuarine and Marine Ecology, PO Box 140, 4400 AC Yerseke, The Netherlands

ABSTRACT: Seagrasses may frequently experience a combination of velocity and light stresses, as elevated hydrodynamics often enhances turbidity and the subsequent light reduction. The objective of this study was to investigate the effects that these stressors induce on morphometric and dynamic seagrass features depending on the initial biomass partitioning. For this purpose, a factorial mesocosm experiment was conducted on plants of Zostera noltii subjected to combinations of 2 contrasting light levels (2.5 ± 0.6 and 15.6 ± 2.5 mol photons m–2 d–1) and 3 unidirectional flow velocities (0.35, 0.10 and 0.01 m s–1). No interactive effects between the 2 variables were recorded, except on plant survival and leaf length, and generally, light effects prevailed over hydrodynamic ones. Plants responded to light reduction regardless of the flow velocity treatments, showing low survival rates (which improved at high velocity), high aboveground/belowground biomass ratios (AG/BG) and a poorly developed root-rhizome system compared to plants under saturating light conditions. Plant morphometry only responded to hydrodynamic stress under saturating light: at high current velocity, plants preferentially allocated biomass into BG structures, bearing short leaves and displaying high internode and root appearance rates. Overall, light reduction promoted similar responses in plants with different AG/BG biomass ratios, but dissimilarities were recorded for current velocity. Thus, it can be concluded that, under simultaneous light and hydrodynamic stresses, light effects prevailed over hydrodynamic ones in Z. noltii, while acclimation to hydrodynamics only occurred under saturating light.

KEY WORDS: Aboveground/belowground biomass ratio · Acclimation · Hydrodynamics · Light reduction · Flume tank · Multiple stressors · Phenotypic plasticity · Zostera noltii

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Cite this article as: de los Santos CB, Brun FG, Bouma TJ, Vergara JJ, Pérez-Lloréns JL (2010) Acclimation of seagrass Zostera noltii to co-occurring hydrodynamic and light stresses. Mar Ecol Prog Ser 398:127-135.

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