| Summary: | 碩士 === 南華大學 === 環境管理研究所 === 97 === The recovery and composition of algal assemblages affected the primary production of freshwater ecosystems. The goal of this research was to understand the effects of dispersal and colonization on algal diversity, algal growth, and early succession of algal assemblages. The study site is located at the Huo-Bei-Keng Creek in Lian-Hua-Chi area of Nantou County. I used tiles to study dispersal and colonization of algae in natural and artificial streams. The duration of the experiment was 41 days and the transfer of tiles from natural to artificial streams was on day 8. Algae were collected on 9 dates and analyzed.
Results showed that algal densities increased with time in both natural and artificial streams. Algal diversity reached the highest value in early days, then decreased with time, and dominance increased with time. Algal biomass and AFDM were higher on tiles of natural streams than in artificial streams through time, indicating higher algal growth rates in natural streams than artificial streams. Some diatom species had different growth rates in natural and artificial streams. Most diatom species increased with time in the natural system, some increased in the artificial system, while some decreased with time in either of two systems. Most dominant species belonged to Achnathes because small sizes rendered them high growth, dispersal, and colonization rates. Multivariate analyses showed that diatom assemblages of natural and artificial systems belonged to different clusters and had different development routes. Diatom species composition in the natural system was similar to that in the drift assemblage. The succession of diatom assemblages in the natural system was driven by the dispersal and colonization of drift algae, while the succession of diatom assemblages in the artificial system was driven by the growth rate and competition capacity.
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