碩士 / 國立海洋大學 / 海洋生物研究所 / 90 / There are two purposes to this research conducted in the seawaters of Dapon-Bay, a shoal lagoon in Pingtung County, southwest Taiwan. First is to investigate whether the fish assemblages in the area has spatial and temporal variations and correlate the environmental factors with the community structure. The other purpose is to realize feeding habits of different species to find out the ecological niche, in order to construct a simple food web among the fish species, so to establish the relationship between the trophic levels in the lagoon. The research period lasted from July 2000 till December 2001. From the periodically sampling done once every 3 months, 173 species of 51 families were collected in the Dapon-Bay area using gill net, fyt net, and electric fishing, including four new records in Taiwan. The 4 species were Ambassis macracanthus, Apogon amboinensis, Leiognathus fasciata, and Sebastapistes strongia.
Cluster analysis and Analysis of Similarilies (ANOSIM) were used to compare samples collected by different fishing gear (electric fishing, gill net, and fyt net), and ANOSIM showed a significant difference among fish assemblages collected by different fishing gear.
Cluster analysis, Non-metric multi-dimensional scaling (MDS), and ANOSIM were used to inspect the spatial and temporal variations of fish communities by gill net and electric fishing. The results didn’t show any variance among seasons and between tides. However, the samples collected by fyt net showed a significant variance between dry and rainy seasons. ANOSIM showed significant differences among samples which collected by gill and electric fishing, and the results of MDS showed that fish assemblages had spatial variation and species richness tended to decrease as stations were situated farther from the estuary. Canonical correspondence analysis (CCA) and Biota and Environment matching (BIO-ENV) were used to correlate environmental factors with fish assemblages. The gradients of freshwater discharge which mixed with seawater in Dapon bay could be the main factor of spatial variation in fish assemblages by gill net. The samples collected by electric fishing revealed that there was the variation of fish assemblage among microhabitats in the lagoon. Since the spatial and temporal variations of fish assemblages may differ consequently to the sampling methods used, the factor to control the variation of fish assemblages may be different. Therefore, the conclusions we make about the variations of fish assemblage may only suit a samples from a specific sampling method.
For the feeding habits of fishes, Cluster analysis was applied to feeding habits of 16 dominant fishes in the lagoon to realize the ecological niche of the species. The result showed that most species were carnivorous, implying that large amounts of protein sources are being provided in the lagoon. Fish which feed on algae, are mostly marine species with distribution generally ranging from the oyster island to the mouth of river. Comparison between the feeding habits of the same species showed that same species from Tan-sui River and Dapon Bay varies on feeding habits. The comparison was made between 9 identical species from Dapon Bay and Chiku lagoon, revealing that fishes from Chiku lagoon have a wider range of food items than fishes from Dapon bay; indicating that food selectivity of fishes from the Dapon bay was more than that of fishes from Chiku lagoon.
In conclusion, fish assemblages in the lagoon differ consequently to the sampling methods used, and spatial variations are more important than temporal variations for fish assemblages. Large amount of protein sources could be provided for fishes in the lagoon, but the competition among fishes for food may be higher.
| Identifer | oai:union.ndltd.org:TW/090NTOU0270005 |
| Date | January 2002 |
| Creators | Chen Ching-Yi, 陳靜怡 |
| Contributors | kwang-Tsao Shao, 邵廣昭 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 101 |
Page generated in 0.0021 seconds