Seasonal succession of phytoplankton pigment and its composition in Fei-Tsui reservoir
Date Issued
2009
Date
2009
Author(s)
Lin, Chih-Hsien
Abstract
To understand the annual variation of phytoplankton pigment and community composition as well as the relative importance of different phyla in oligotrophic freshwater ecosystem, pigment analysis via HPLC method was conducted on a weekly basis in the Fei-Tsui reservoir from Oct 2007 to Dec 2008. Epilimnion (20 m deep) integrated averaged chlorophyll-a concentrations (IChl) ranged 0.51~5.55 mg Chl m-3 with a bloom occurring in autumn. Overall, crytophytes, cyanobateria and diatoms were the three most dominant phyla accounting for 25, 24 and 20% of total IChl, respectively. Green algae (chlorophytes and prasinophytes, 12%) and dinoflagellates (10%) ranked the 4th and 5th in term of relative contribution. The analysis between phyla and environmental factors including temperature, light and mixed layer depth (a proxy of nutrient supply) was performed to understand potential controlling mechanisms. Cyanobacteria biomass did not change much during the studied period. Cryptophytes, prasinophytes and chlorophytes prevailed in the cold, low light level and high nutrient supply seasons. On the other hand, dinoflagellates could be categorized as warm water and low nutrient required species. Diatom biomass showed no significant relationships with environmental factors. It is notable that depletion of diatom bloom in turn was replaced by growing dinoflagellates in warm season. Furthermore, dinoflagellates occupied the light-rich surface waters in comparison with diatoms of similar size. Manipulation experiments suggested that plentiful nutrient stimulated the growth of dinoflagellate more than that of diatoms in high light level and phosphorus-enrichment conditions. Additionally, we found that zeaxanthin pigment concentrations showed a good correlation with cyanobacteria abundance with a slope of 1.06 ± 0.04 fg cell-1, which can be used empirically in converting diagnostic pigment concentrations to cyanobacteria abundance in the study area.
Subjects
Fei-Tsui reservoir
phytoplankton community composition
chlorophyll
zeaxanthin
cyanobacteria
SDGs
Type
thesis
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