- 期刊
- OpenAccess
Colonization Patterns of Aquatic Instects on Artificial Substrates in a Taiwan Stream
水棲昆蟲在人工底質的拓質型式
摘要
Experiments on colonization patterns of artificial substrates by aquatic insects were conducted in the upper Chingmei Stream, Taiwan. Artificial substrates were colonized by aquatic insects for periods of 3, 6, 12, 21, 30, and 42 days from 15 Dec. 1990 to 26 Jan. 1991 at 2 sites: a polluted site caused by coal mining activities (Site 1) and a recovery site further downstream of the polluted site (Site 2). Total numbers of individuals and taxa were significantly affected by exposure period of experimental substrates and sites, indicating the occurrence of succession and the detrimental effect of coal mining activities on aquatic insect communities. At site 1, only Caenis sp., Euphaea sp., and Chironomidae occurred on all sampling dates and were abundant. The other taxa may have just continued to drift away from the site. The chironomid larvae were most abundant. They accounted for over 90% of the colonizing individuals from day 12 to day 42. At Site 2, Baetis spp. and Chironomidae were most abundant. They accounted for over 80% of individuals during the experiment, execpt on day 21. The relative abundance shifted from Baetis spp. to Chironomidae with an increase in colonization time. A large number of positive correlation was found within the functional groups of filter-feeders and predators at Site 2. Taxa within the two groups tended to overlap in their distribution among baskets. The lognormal distribution was a better fit at Site 1 than at Site 2, suggesting that it is easier for a community to attain a state of equilibrium in a stressed environment than in a less-polluted environment. Mechanisms determining the colonization patterns of aquatic insects were reflected by the susceptibility of organisms to mining activities at Site 1, and the influence of biological interactions and disturbance caused by high discharges at Site 2 during the experimental period.
並列摘要
本研究之目的是在不同的兩採樣站，比較水棲昆蟲在人工底質的拓質情形。試驗地點是在位於景美溪的上游，第一站受到採礦活動的影響，而視為受污染站，第二站則位於第一站的下游，被視為微受污染站。從1990年12月15日到1991年1月26日，人工底質分別被水棲昆蟲拓殖3、6、12、21、30及42天。研究結果發現，水棲昆蟲的個體數及種類數顯著的會受到拓殖時間因素及採樣站的影響，此結果表示水棲昆蟲種類有消長的現象發生，及採礦活動對整個群落有不利的影響。在第一站，只有Caenis sp.、Euphaea sp.、及Chironomidae出現在所有的採樣日，其他種類可能繼續漂移離開此站，Chironomidae是此站最優勢的類群，從拓殖的第12天以後，其佔所有拓殖個體數的90%以上。在第二站，Baetis spp.及Chironomidae是優勢的類群，除了在拓殖的第21天以外，佔所有個體數的80%以上，而且相對的數量，隨著拓殖時間的增長，從Baetis spp.為最優勢，變為Chironomidae最優勢。另外，由指數常態分布模式，來判別群落在拓殖過程中的平衡程度，結果顯示在第一站比在第二站更符合此模式，亦即在一遭受污染的河域比在未受污染或微受污染的河域較易達到平衡狀態。