潮位和底棲生物對潮間帶底棲環節動物稚生分佈的影響

Abstract

本研究以著生的觀點，探討底棲無脊椎動物在潮間帶的帶狀分佈（ zonation ）。自 1 995 年 4 月開始，分別在高、低潮位設置去除底質生物的“去生物”樣區，對底質中的稚生進行連續四週的採樣，與同潮位“未處理”底質中的稚生數量比較，以瞭解潮位與底質中生物，對環節動物稚生分佈的影響；並以初著生數量在高、低潮位間比例，與各別覆水時數比例的符合性，探討各種多毛類著生屬於主動或被動性。 底質環境因數的調查中發現，高、低潮位間在粒徑大小、粉泥/黏土含量、含水量上都有差異，覆水時數的比例約為 2 : 3 ，日均溫和降雨量在實驗期間的第 3 週前後有很大的差異。貧毛類在低潮位的數量較多，在“去生物”樣區中密度增加的速率在低潮位元比高潮位快。海稚蟲 Prionospio japonicus Okuda 稚生多出現在低潮位，但高、低潮位間數量與覆水時數的比例不符合，推測為主動性著生的種類 。纓鰓蟲 Laonome albicingillum Hsieh 的稚生數量在“未處理”樣區較“去生物”樣區多，推測其著生受底棲生物誘引。小頭蟲（Capitella sp．稚生密集地出現在高潮位的原因不明。沙蠶 Neanthes glandicincta ( Southern ）稚生的數量在高潮位較低潮位少，其比例符合高、低潮位的覆水時數，推測為被動性著生的種類。四種多毛類的初著生稚生數量皆在實驗期間的第 4 週同時大幅增加，推測受相同因數影響而皆於春末著生。各種多毛類的初著生稚生，在潮間帶各有其分佈的特徵，顯示著生時即因潮間帶高異質性的環境，區隔出不同的空間分佈。

This research was observing the zonaation of esturary Annelide, by “settlement view”. One month weekly meiofauna sampling was beginning at 1995 April, in two tidal level’s “defauna” and “untreated” site. The influence of tidal level and benthos to the Annelide juvenile distribution was by comparing the abundance of different site. The ratio of juveniles appearing in the high and low tidal level was matching the rinse time ratio, to realize whether the settlement is active or passive. High tidal level had different particle size, silt/clay content, water content with low, and the rinse-time ratio was about 2:3. Daily average temperature and precipitation changed before and after 3rd week. Most of Oligochaeta found in low tidal zone. Both juvenile Prionospio japonicus Okuda and Neanthes glandicincta was more abundant in low tidal zone than high, the ratio was the same with rinse time ratio only in N glandicincta, suggest that settlement of N. glandicincta was passive, and P. japonicus was active. Juvenile Laonome albicingillum Hsieh was more abundant in “untreated” than “defauna” site, suggest settlement attracted by benthos. Juvenile Capitella sp. was abundant in high tidal zone. The distribution of newly settled juvenile Polychaeta in intertidal zone shows different space allocation between species.