Patterns in fish assemblages from coastal wetland and other littoral habitats in Green Bay, Lake Michigan.

摘要

Because the loss rate of coastal wetland habitat is high, knowledge of the fishes that utilize these habitats is limited, and coastal wetlands may play a key role in Great Lakes ecosystems, I attempted to more completely characterize the fish assemblages associated with coastal wetland and other types of littoral habitats in Green Bay. From May to September in 1990 and 1991, I sampled 24 coastal wetland and beach sites spanning the 193 km length of Green Bay. Because I was also interested in determining the effect of human modifications along the shoreline, half of the sites selected for study represented habitats modified by physical alterations such as dikes, landfills, homes or industry. The other half were relatively undeveloped.; A total of 41,867 primarily immature fishes, representing 20 families and 54 species were captured. Regional differences in the assemblages were the most obvious, but habitat and development related differences were also apparent. Species richness and total fish abundance were highest in the lower bay and in undeveloped wetland habitats. The lower bay was typified by a warmwater, turbidity tolerant assemblage (e.g. gizzard shad, white bass, and drum), while the upper bay had a more cool and clear water assemblage (e.g. golden shiner, centrarchids, and darters). Undeveloped wetlands were characterized by several important sport fish (e.g. yellow perch, bluegills, and northern pike) and were most typically dark-colored, phytophilic, turbidity intolerant, zoobenthivores with periodic or equilibrium life history strategies and maneuvering or lie/wait swimming styles. Sites adjacent to human development had fewer fish and fish species. They were characterized by a more disturbance tolerant assemblage (e.g. bullheads, carpsuckers, and smelt). The most influential environmental factors were turbidity, as a reflection of the trophic gradient in the bay, and a suite of variables associated with macrophyte extent and complexity. Biotic interactions appeared to be relatively unimportant. Because of the high biodiversity and large numbers of ecologically and economically important fishes associated with wetland habitats, the significance of maintaining and restoring these habitats seems quite high and is worthy of heightened priority in plans to rehabilitate Green Bay.