Environmental Studies of Macrozoobenthos, Aquatic Macrophytes, and Juvenile Fishes in the St. Clair-Detroit River System, 1983-1984: Ponar Sampling Record for Macrozoobenthos

This ponar sampling record for macrozoobenthos data set was collected for use in the administrative report entitled "Environmental Studies of Macrozoobenthos, Aquatic Macrophytes, and Juvenile Fishes in the St. Clair-Detroit River System, 1983-1984". It is a portion of the data collected for this administrative report, which provided information needed by the U.S. Army Corps of Engineers for preparation of a Supplemental Environmental Impact Statement addressing the winter operation of the lock facilities at Sault Ste. Marie, Michigan, and the subsequent extension of the navigation season in the St. Clair-Detroit River system (SCDRS) to January-February. The following is excerpted from the original report\'s abstract: We describe the distribution and abundance of macrozoobenthos, aquatic macrophytes and juvenile fishes during the 1983 and 1984 open water season, and attempt to predict or evaluate the potential environmental impact of an extended navigation season on the biota of SCDRS. Fauna and flora were diverse and abundant; we identified more than 300 taxa of macrozoobenthos, 30 taxa of submergent and emergent macrophytes, and 36 species of fish. The diversity and abundance of macrozoobenthos were generally highest in the St. Clair River. Abundance and diversity of submersed macrophytes were similar in the two rivers, but Chara dominated in the St. Clair River and Vallisneria americana in the Detroit River. We collected more total fish in the Detroit River but more species in the St. Clair River. Yellow perch and rock bass dominated most catches in both rivers. An ice jam in the St. Clair River in spring 1984 appeared to affect two of the three groups studied--macroinvertebrates and submersed macrophytes. Of the 24 abundant taxa of macroinvertebrates, 9 were seemingly less abundant in spring in 1984 than in 1983 in the St. Clair River; however the densities of 6 of these taxa had recovered by fall 1984 to levels equal to or exceeding those in fall 1983 and the other 3 were within 30% of those in 1983. Cover of the bottom with submersed macrophytes was somewhat reduced in spring of 1984--particularly in the St. Clair River--but recovered to 1983 levels by fall 1984. Plant biomass levels varied between years and locations; no consistent differences could be attributed to the ice jam. Catches of fish were lower in 1984 than in 1983 but differences between locations and months were inconsistent. Observed differences in the plant community could be attributed to reduced temperatures, and ice-scour may have reduced the density of several taxa of macrozoobenthos. Evaluation of the potential environmental impacts of an extended navigation season on the biota of SCDRS was not attempted.

本大型底栖无脊椎动物（macrozoobenthos）采样记录数据集，是为撰写题为《1983-1984年圣克莱尔-底特律河水系大型底栖无脊椎动物、水生维管植物（aquatic macrophytes）及幼鱼（juvenile fishes）环境研究》的行政报告而采集的。该数据集属于为上述行政报告采集的部分数据，当时美国陆军工程兵团（U.S. Army Corps of Engineers）正筹备一份补充环境影响报告书（Supplemental Environmental Impact Statement），以评估密歇根州苏圣玛丽（Sault Ste. Marie）船闸设施的冬季运行，以及将圣克莱尔-底特律河水系（St. Clair-Detroit River System, 简称SCDRS）通航季延长至1-2月可能带来的环境影响，本数据集即为此提供所需支撑信息。

以下内容摘录自原报告的摘要：
我们对1983、1984年开阔水域季的大型底栖无脊椎动物、水生维管植物及幼鱼的分布与丰度进行了系统描述，并尝试预测或评估延长通航季对SCDRS生物群落的潜在环境影响。
本次调查覆盖的动植物类群丰富多样、种群体量可观：共鉴定出300余种大型底栖无脊椎动物类群、30余种沉水与挺水维管植物类群，以及36种鱼类。
大型底栖无脊椎动物的多样性与丰度整体上以圣克莱尔河最高。沉水维管植物的丰度与多样性在两条河流中相近，但圣克莱尔河以轮藻属（Chara）为绝对优势类群，底特律河则以美洲苦草（Vallisneria americana）占据主导地位。
底特律河的鱼类总捕获量更高，而圣克莱尔河捕获的鱼类物种数更多。在两条河流的多数渔获样本中，黄鲈（Yellow perch）与岩鲈（rock bass）为优势物种。
1984年春季圣克莱尔河发生的冰塞似乎对本次研究的三个类群中的两类——大型底栖无脊椎动物与沉水维管植物——造成了显著影响。在24种丰度较高的大型底栖无脊椎动物类群中，有9类在1984年春季的丰度较1983年同期有所下降；不过其中6类的种群密度在1984年秋季已恢复至1983年秋季的水平甚至更高，剩余3类的密度也与1983年同期偏差不超过30%。
1984年春季，沉水维管植物的底床覆盖率有所下降，尤以圣克莱尔河为甚，但到1984年秋季已恢复至1983年的水平。植物生物量在不同年份与采样点位间存在自然波动，未发现可明确归因于冰塞的一致性差异。
1984年的鱼类捕获量较1983年更低，但不同采样点位与月份间的差异并不具备一致性。观测到的植物群落差异可归因于水温降低，而冰蚀作用可能降低了部分大型底栖无脊椎动物类群的种群密度。
本次研究未尝试评估延长通航季对SCDRS生物群落的潜在环境影响。