Effects of sewage effluent on 'pulse' infaunal assemblages.

This experiment tested the effects of secondary treated sewage effluent on infauna assemblages that were taken from a 'reference' site immediately after a large dump of macroalgae had cleared from the mudflat. Macroalgae cover can have severe effects on infaunal assemblages so it was expected that the recent macroalgae dump would affect the responses of infauna to the effluent dosing. Twelve intact sediment cores were collected from this site on the Western Treatment Plant foreshore (Port Phillip Bay, Victoria) and brought back to the laboratory. Four cores were assigned to each of the two treatments, which were high dose (7mls effluent per minute) or no dose of effluent. The experiment ran for 13 days in October 1999. Throughout the experimental period, dissolved oxygen levels were measured and animals that migrated from the sediment were collected, counted and identified. At the end of the experiment, sediment chlorophyll levels were measured and infauna remaining in the sediment were counted and identified.本实验旨在探究二级处理污水出水（secondary treated sewage effluent）对底内动物（infauna）群落的影响，实验所用的底内动物样本采自某“参照位点”——该位点的潮间带泥滩刚完成一次大型藻类（macroalgae）倾倒事件后的清理工作。鉴于大型藻类覆盖可对底内动物群落产生显著负面影响，因此推测本次近期发生的大型藻类倾倒事件会影响底内动物对污水投加的响应效果。研究人员从位于澳大利亚维多利亚州菲利普港湾的西污水处理厂前滨的该位点，采集了12根完整沉积物柱样（sediment cores）并带回实验室。将12根柱样随机分为两组处理，每组各4根，分别为高剂量投加组（7毫升污水/分钟）与空白对照组（无污水投加）。本实验于1999年10月开展，持续时长13天。实验全程均监测水体溶解氧（dissolved oxygen）水平，并收集、计数及鉴定从沉积物中迁移出的底内动物个体。实验结束后，测定沉积物叶绿素（chlorophyll）含量，并计数、鉴定沉积物中残留的底内动物。