Feeding Guild and Ontogenetic Diet Shifts of Tidepool Fish Assemblages in North and South Taiwan
| Autor: | Kuo-Chang Wen, 溫國彰 |
|---|---|
| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 Tidepool is a specific marine ecological habitat, and effected by human beings increase daily. Thus, the ecological studies of tidepool have been noticed recently. However, the ecological investigations of intertidal fishes are few in these twenty years. The diet studies of intertidal fishes are also not enough. The aims of this study are to understand the trophic structure and dynamics of tidepool fishes. Feeding guild is defined as a group of species uses the same or similar resource in a similar way. Food partition among intertidal fish assemblage is the main process to divide community structure. Hence, The identification and analysis of the feeding guild is important fundamental method to understand how the community organize and structure. Tidal pool fishes were collected with anesthetic-clove oil, and then the diet shift and feeding guild of fishes was analyzed with both gut contents and stable isotope. Fishes were collected from the tidal pools of Patotz, Yehliu, Aoti of northern Taiwan and Checheng, Hsiangchiaowan, Jiupeng of southern Taiwan during January and October 2001. We collected 17 families, 52 species of tidepool fishes, and the dominant families, Blennidae, Gobiidae and Pomacentridae are the main investigative fishes. This study is the one of the fewresearches on intertidal fishes in tropical east Pacific Ocean, and also the few research of the diets of tidal pool fishes in Taiwan (tropical area). The main trophic structure of tidal pool fish assemblages in Taiwan was herbivores (33~52%). Comparing with the proportion of herbivores (4~16%) in temperate area, herbivores are morn dominant and important in Taiwan. Comparison between north and south Taiwan might be considered as the comparison between tropical and subtropical area. The results show that there is tendency of difference, but not significant. Spatial variations in the diets of tidal pool fishes show no significance, and the result is the same with the identical family or genus of fishes in other area. Seasonal changes in diet are discovered in herbivorous fishes of tidal pool. After comparing with abundance of food resource, seasonal diet shift pattern are relative with resource abundance was suggested. Most of tidal pool fishes in Taiwan have ontogenetic diet change. The food categories are changed and prey sizes are increasing during their growth. Feeding guild structure is determinately changing with ontogenetic diet shift existing. Hence using ontogenetic trophic unit as a feeding guild unit is more suitable. Stable isotope analysis is used to avoid the mistake of gut contents analysis, but also shows the same result with gut contents analysis. However, stable isotope analysis can not have high resolution as gut contents analysis. Another possibility is that food items are over partitioned in gut contents analysis, and not consist with the natural condition. Stable isotope analysis can not built the feeding guild with statistical significant as gut contents analysis is our unsolved problem. The feeding guilds built from gut contents analysis are not significant different in stable isotope analysis, too. Finally, we suggest that when feeding guild was built by gut contents analysis, assisted by the result of stable isotope analysis to make choices of food items. We believe the result of feeding guild will more consist with nature. |
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