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Changes in macroinvertebrate assemblages in lower Green Bay, Lake Michigan,.
Fettes, Amy1, Reed-Andersen, Tara1, 1
ABSTRACT- Green Bay is a unique system that is highly impacted by agricultural and industrial pollutants. Benthic macroinvertebrate data from 4 years (1978, 1983, 1987, 1994) and 14 sites located in the mid and lower Green Bay were analyzed to determine if the benthic macroinvertebrate populations have changed since the mid 1970s. Benthic macroinvertebrates are excellent indicators of water and sediment quality and their population density and diversity can indicate overall water quality of the system. Almost all of the sediment and nutrient input into Green Bay arises from the Fox River and, as a result, the lower bay is highly impacted. Over the past 30 years, there has been an effort to reduce the nutrient and sediment load from the Fox River into Green Bay. Zebra mussels were also first found in the bay beginning in 1991. A reduction of pollutants over the last 3 decades, as well as the presence of zebra mussels, have resulted in changes in the benthic macroinvertebrate populations over that time period. Zebra mussels are found at one site in the 1994 data set. Diversity of the benthic macroinvertebrates has increased through time although Hexagenia, which was historically present in the system, has not yet reappeared.
KEY WORDS: benthic macroinvertebrate, Green Bay, zebra mussel