THESIS
2016
xx leaves, 195 pages : illustrations (some color) ; 30 cm
Abstract
Noctiluca scintillans is a cosmopolitan red tide forming heterotrophic
dinoflagellate, which plays a crucial role in marine food web. My thesis study is to
qualify and quantify the ecological significance of N. scintillans as a predator, nutrient
regenerator and atypical “prey” (of which a newly described marine ciliate
Strombidium hongkongense, within its prey size range, becomes the predator) in
marine food web. To achieve these goals, both field studies and laboratory
observation and experiments were conducted.
A case study in Port Shelter, Hong Kong showed that the population dynamics of
N. scintillans in this semi-enclosed bay was mainly governed by hydrographical
(temperature and water stability), meterological (favorable wind) and biological
factors (phytoplankton f...[
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Noctiluca scintillans is a cosmopolitan red tide forming heterotrophic
dinoflagellate, which plays a crucial role in marine food web. My thesis study is to
qualify and quantify the ecological significance of N. scintillans as a predator, nutrient
regenerator and atypical “prey” (of which a newly described marine ciliate
Strombidium hongkongense, within its prey size range, becomes the predator) in
marine food web. To achieve these goals, both field studies and laboratory
observation and experiments were conducted.
A case study in Port Shelter, Hong Kong showed that the population dynamics of
N. scintillans in this semi-enclosed bay was mainly governed by hydrographical
(temperature and water stability), meterological (favorable wind) and biological
factors (phytoplankton food supply). N. scintillans actively interacted with other
trophic compartments in the existing ecosystem, but its population growth was more
directly and largely related to the abundance and composition of phytoplankton
assemblages, especially diatoms. Laboratory experiments further showed that growth and grazing of N. scintillans were mainly constrained by prey quantity, quality and
composition. Its feeding strategy, i.e. preferential feeding and better growth on
organisms containing sufficient phosphorous (P), eicosapentaneoic acid (EPA) and/or
α- linolenic acid (ALA), and physiological characteristics, i.e. almost homeostasis but
susceptible to P-limitation, and multiple releasing pathways of metabolic products,
are of great importance in determining the energy transfer and nutrient flux in its
existing environment, and shaping the food web structure. Our laboratory results are
applicable to the real field situation and able to explain at least part of the biological
processes that lead to the formation and decline of N. scintillans blooms.
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