Distributional Control of Seagrasses by Light Availability, Twin Cays, Belize, Central America

Calem, J. A. and Pierce, J. W. (1993) Distributional Control of Seagrasses by Light Availability, Twin Cays, Belize, Central America. Atoll Research Bulletin (387). pp. 1-13.

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    Abstract

    Twin Cays are two mangl~ovei slands in the lagoon behind the barrier reef of Belize, Central America with radically different aquatic environments in close juxtaposition. These environments range from open lagoon, with very clear water, to channels with high turbidity, and to creeks inlmediately adjacent to the mangrove swamps with reddish-brown water. Thirty-eight measurements of beam transmission of blue and green light were made at 11 stations in the channels and creeks of Twin Cays and a few at 2 stations in the open lagoon. Seagrasses, primarily Thalassia testudinum, occur only where blue wavelengths of light can penetrate to the bottom. Loss of blue light is due to either absorption by tannin or backscattering out of the water by suspended particles. Seagrasses are absent in the upper reaches of the tributary channels and creeks because the reddish-brown water, emanating from the mangrove swamps, effectively absorbs blue light. Such plants also are absent from areas that have high turbidity, resulting in scattering of the light and reflection back out of the water. This high turbidity is the result of high concentrations of suspended mineral particles, transported into the major channel between the islands by wind drift, after resuspension of bottom sediments by waves in the main lagoon. Elsewhere, seagrasses are common in Main Channel and lower reaches of the tributary channels.

    Item Type: Peer-reviewed Journal Article
    Related URLs:
      Publisher: Smithsonian Institute
      Keywords: seagrasses, light, distributional control
      Subjects: (C) Ecosystems > (CB) Marine > (CBH) Seagrasses
      Publication Sources: (3) Other Source > (3D) Other or Unspecified
      Date Deposited: 31 Jan 2011 15:45
      Last Modified: 31 Jan 2011 15:45
      URI: http://eprints.uberibz.org/id/eprint/1254

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