The Twin Cays Mangrove Ecosystem, Belize: Biodiversity, Geological History, and Two Decades of Change

Anon., (2003) The Twin Cays Mangrove Ecosystem, Belize: Biodiversity, Geological History, and Two Decades of Change. Technical Report.

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    The tidal channels of mangrove islands such as Twin Cays, Belize support a productive and diverse microplankton assemblage. In turn, this microplankton community supports large populations of endemic mesozooplankton species that form dense aggregations in the prop-root environment along the margins of these channels. The growth rate of the phytoplankton community and the grazing rate of the heterotrophic microzooplankton community were measured during the seawater dilution method. In separate experiments, the grazing rate of the swarm-forming copepod Dioithona oculata on natural microplanton assemblages was measured during both 24 h and 12 h (day/night) incubations. Chlorophyll concentrations in the natural plankton assemblages used in this experiment ranged from ca.1 to 11 ug Chl a/l. Dinoflagellate populations typically ranged from ca.17 to 50 cells/ml, with heterotrophic dinoflagellates generally exceeding autotrophic forms in abundance. Ciliates were the second most abundant form of heterotrophic microzooplantons, with populations ranging from 1-15 cells/ml. Results of the dilution experiments indicate that during the study period, phytoplankton growth exceeded microzooplankton grazing in all experiments. Grazing experiments with Dioithona oculata carried out over a 24 h period indicated that copepod ingestion were highest on ciliates and autotrophic dinoflagellates, and that copepod populations are capable of grazing a large fraction of the protozoan population each day. These experiments suggests that protozoan populations in mangrove channels are under "top-down" control by copepod grazing, rather than being limited from the "bottom-up" by food availability. The 12 h incubation experiments indicated that there were no consistent diurnal changes in feeding rates. Since these copepods from high-density swarms during the day , competition for food within swarms must be intense.

    Item Type: Technical Reports (Technical Report)
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      Keywords: mangroves, Twin Cays, biodiversity,
      Subjects: (A) Biodiversity > (AH) Plants
      (C) Ecosystems > (CB) Marine > (CBE) Mangroves
      Publication Sources: (3) Other Source > (3D) Other or Unspecified
      Date Deposited: 06 Jan 2011 16:35
      Last Modified: 06 Jan 2011 16:35

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