MEPS 545:109-121 (2016)  -  DOI:

Flow velocity and light level drive non-linear response of seagrass Zostera noltei to ammonium enrichment

Beatriz Villazán1,*, Fernando G. Brun1, Vanessa González-Ortiz1, Francisco Moreno-Marín1, Tjeerd J. Bouma2, Juan J. Vergara1

1Departamento de Biología (Área de Ecología), Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR), Puerto Real 11510 Cádiz, Spain
2Netherlands Institute for Sea Research (NIOZ), PO Box 140, 4400 AC Yerseke, The Netherlands
*Corresponding author:

ABSTRACT: We investigated the interactive effects of light (low and high light doses) and flow velocity (low, medium and high levels) under NH4+ enriched conditions on dynamic and morphological variables of Zostera noltei plants in a 5 wk flume experiment. Our results showed a non-linear response of Z. noltei in this factorial design, with the strongest negative effect of NH4+ enrichment recorded at intermediate flow velocities for almost all the dynamic response variables (i.e. survival, net production, shoot appearance rate). This negative effect of NH4+ enrichment was intensified under low light conditions, where net production was only positive in plants growing at high flow velocity. This positive effect of flow velocity was ascribed to the more horizontal position of the leaves, which allows for higher levels of light capture than under lower flow velocities. However, enhancing current velocity may increase NH4+ uptake rates until they reach adverse levels, which can potentially trigger NH4+ toxicity. This negative effect of flow velocity seems to be neutralized by the higher light capture at high flow, resulting in intermediate current velocities being more harmful for plants. In summary, our results highlight the importance of studying the complexity of interactions among multiple stressors that frequently co-occur in nature to improve our ability to forecast the response of seagrass populations to possible interaction effects in future global change scenarios.

KEY WORDS: Ammonium toxicity · Flume tank · Hydrodynamics · Light reduction · Multiple stressors · Seagrass · Zostera noltei

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Cite this article as: Villazán B, Brun FG, González‑Ortiz V, Moreno‑Marín F, Bouma TJ, Vergara JJ (2016) Flow velocity and light level drive non-linear response of seagrass Zostera noltei to ammonium enrichment. Mar Ecol Prog Ser 545:109-121.

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