Seasonal Growth Responses of the Seagrass Zostera marina under Severely Diminished Light Conditions

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Date: Mar. 2015
From: Estuaries and Coasts(Vol. 38, Issue 2)
Publisher: Springer
Document Type: Report
Length: 283 words

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Abstract :

Byline: Young Kyun Kim (1), Seung Hyeon Kim (1), Kun-Seop Lee (1) Keywords: Growth; Light attenuation events; Light reduction; Red tide; Seagrass; Temperature; Zostera marina Abstract: Acute light attenuation events, such as those caused by red tide algal blooms or inflows of turbid plumes during monsoonal rains, are occurring with increased frequency in coastal waters. To explore seasonal growth responses of the seagrass Zostera marina to such severe light reduction events, we reduced radiation reaching Z. marina shoots by in situ shading with neutral density screens over 6-week periods in each of four seasons. Underwater photon flux densities (PFDs) in the shaded cages were reduced to 4.0--17.2 % of unshaded control values. Water temperatures ranged from 8.2 [degrees]C in the winter to 23.2 [degrees]C in the summer over the experimental period. Under reduced light, the aboveground biomass of Z. marina usually decreased more rapidly than belowground biomass. By the end of each experiment, total biomass had decreased to ~10 % of the control biomass in the summer, fall, and winter periods but to ~50 % of controls during spring. Detrimental effects of light reduction on seagrass growth were most severe in summer and least severe in spring. Thus, Z. marina is more susceptible to the negative effects of light reduction when water temperatures are high. Since red tide algal bloom events and turbid plumes usually occur during high water temperature periods in summer, these light attenuation events are likely major drivers of observed Z. marina declines in coastal areas. Author Affiliation: (1) Department of Biological Sciences, Pusan National University, Busan, 609-735, Korea Article History: Registration Date: 15/05/2014 Received Date: 06/03/2013 Accepted Date: 13/05/2014 Online Date: 28/05/2014 Article note: Communicated by Iris C. Anderson

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Gale Document Number: GALE|A398972341