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Effects of light availability on growth, architecture and nutrient content of the seagrass Zostera noltii Hornem.

Peralta, G. and Perez-Llorens, J.L. and Hernandez, I. and Vergara, J.J. (2002) Effects of light availability on growth, architecture and nutrient content of the seagrass Zostera noltii Hornem. Journal of Experimental Marine Biology and Ecology, 269, 9-26. ISSN 0022-0981.

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Official URL: http://dx.doi.org/10.1016/S0022-0981(01)00393-8

Abstract

The growth vs. irradiance response of the seagrass Zostera noltii from Cadiz Bay Natural Park (southwestern Spain) was characterised. Plants were exposed along 14 days to different light treatments (1%, 7%, 42% and 100% surface irradiance, SI), using shade screens in an outdoor mesocosm. Growth at 100% SI (1.6 mg DW plant(-1) day(-1)) was lower than that at 42% SI (2.4 mg DW plant(-1) day(-1)), suggesting photo inhibition. The minimum light requirement estimated was 0.8 mol photons m(-2) day(-1) (2% SI). Light availability affected the pattern of plant development and the overall plant growth. The contribution of the apical shoots to the aboveground production was nearly constant (c.a. 1.13 cm plant(-1) day(-1)) regardless of the light level (except at 1% SI). In contrast, recruitment and growth of lateral shoots arising from the main rhizome axes accounted for the observed differences in aboveground growth, Rhizome branching was only observed at 42% SI. The possibility of a light threshold for rhizome branching could explain the seasonality of shoot recruitment, as well as the observed decrease in shoot density along depth (or light) gradients in seagrass meadows. Carbon demands at low irradiances (1% and 7% SI) were partially met by mobilization of carbohydrate reserves (sucrose in belowground and starch in aboveground parts). Plant nitrogen content decreased with increasing light, especially in belowground parts, reaching critical levels for growth. [KEYWORDS: branching, C/N ratio, growth rate, light, nonstructural carbohydrates, plant architecture, seagrass]

Item Type:Article
ID Code:11202
Deposited On:24 Nov 2011 01:00
Last Modified:24 Apr 2012 16:35

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