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Brady, V. J., and T. M. Burton, 1996. Changes in a Coastal Marsh Invertebrate Community Following Zebra Mussel Colonization, Michigan State University Abstract from The Sixth International Zebra Mussel and Other Aquatic Nuisance Species Conference, Dearborn, Michigan, March 1996 Changes in a Coastal Marsh Invertebrate Community Following Zebra Mussel ColonizationEffects of zebra mussels on benthic invertebrate communities have been documented in various open water areas around the Great Lakes. We have been investigating zebra mussel effects on the invertebrate community of a Saginaw Bay (Lake Huron) coastal marsh. The mussels did not colonize the shoreward half (250 m) of the emergent zone, but became seasonally abundant in the bayward 250 m of the marsh. Here they attached to the stems of emergent vegetation, predominantly the bulrush Scirpus americanus. Mussel densities fluctuated dramatically, with the highest densities (75/stem or 30,000/m2) in the late summer due to recruitment of 0+ mussels. By the following spring, mussel densities were low (300/m2) and remained low until several weeks following spawning. The marsh invertebrate community was characterized prior to a significant zebra mussel presence, and was again sampled following mussel colonization. Because mussels did not colonize the shoreward half of the marsh, this community was considered unimpacted and was used as a comparison to the "exposed" community in the bayward area. The invertebrate community as a whole was dominated by oligochaetes, chironomid larvae, and Caenis (Ephemeroptera) larvae. Due to the high variability of the samples, there was very little power to detect differences. However, tubificid oligochaete densities were higher in the sediments throughout the whole marsh after zebra mussel colonization, with the increase significant (p<0.01) in the area settled by the mussels. In addition, there was a decrease in tanytarsid chironomid larvae in the sediment in this area, with a concomitant increase in larval numbers on bulrush stems (p<0.05).
Keywords: Zebra_mussel, Ecological_interactions, Basic_biology |