We conducted a study to examine the relationship between common carp (Cyprinus carpio) exclusion, water quality, zooplankton, and submergent macrophytes. Twelve 50-m2 in situ experimental enclosures were installed in degraded Cootes Paradise Marsh during the carp spawning period in 1995. Enclosures were stocked with two or three carp of similar size, ranging from 13 to 59 cm and in total biomass from 23 to 2100 kg/ha. Turbidity, total phosphorus, and total ammonia concentrations increased predictably with total carp biomass in the enclosures. Although carp had no direct effect on zooplankton community structure, increased turbidity and nutrient load associated with carp activity resulted in reduced total zooplankton biomass. We developed a relationship between species richness and water turbidity for 19 wetlands in the Great Lakes basin which indicated that above an apparent threshold of 20 NTU, there were less than five species of submergent plants, while a more diverse community existed in less turbid systems. We predict that water turbidity in Cootes Paradise Marsh may not be reduced below this threshold value of 20 NTU following carp exclusion. We emphasize the need to consider other factors that may contribute to increases in water turbidity and nutrient concentrations, including wind resuspension and substrate characteristics.

We collected water quality, land use, and aquatic macrophyte information from 62 coastal and inland wetlands in the Great Lakes basin and found that species richness and community structure of macrophytes were a function of geographic location and water quality. For inland wetlands, the primary source of water quality degradation was inputs of nutrients and sediment associated with altered land use, whereas for coastal wetlands, water quality was also influenced by exposure and mixing with the respective Great Lakes. Wetlands within the subbasins of the less developed, more exposed upper Great Lakes had unique physical and ecological characteristics compared with the more developed, less sheltered wetlands of the lower Great Lakes and those located inland. Turbid, nutrient-rich wetlands were characterized by a fringe of emergent vegetation, with a few sparsely distributed submergent plant species. Highquality wetlands had clearer water and lower nutrient levels and contained a mix of emergent and floating-leaf taxa with a diverse and dense submergent plant community. Certain macrophyte taxa were identified as intolerant of turbid, nutrient-rich conditions (e.g., Pontederia cordata, Najas flaxilis), while others were tolerant of a wide range of conditions (e.g., Typha spp., Potamogeton pectinatus) occurring in both degraded and pristine wetlands. Résumé : Des données recueillies sur la qualité de l'eau, l'utilisation des terres et les macrophytes aquatiques dans 62 terres humides des régions côtières et intérieures du bassin des Grands Lacs indiquent que la richesse spécifique et la structure des communautés de macrophytes dépendent de la situation géographique et de la qualité de l'eau. Dans les terres humides intérieures, la source principale de dégradation de la qualité de l'eau est l'apport de nutriments et de sédiments causé par les changements dans l'utilisation des terres, alors que, dans les terres humides côtières, la qualité de l'eau est aussi influencée par le contact avec le Grand Lac adjacent et les mélanges d'eau qui s'y produisent. Les terres humides des sous-bassins des Grands Lacs d'amont, qui ont subi moins de développement et qui sont plus exposés, possèdent des caractéristiques physiques et écologiques tout à fait particulières, par comparaison avec les terres humides des Grands Lacs d'aval qui sont plus développés et moins protégés, et les terres humides intérieures. Les terres humides turbides et riches en nutriments sont caractérisées par le développement d'une ceinture de végétation émergente et la présence sporadique de quelques plantes submergées. Les terres humides de grande qualité possèdent une eau plus claire, des concentrations plus faibles de nutriments et une combinaison de taxons de plantes émergentes et de plantes à feuilles flottantes, d'une part, et d'une communauté diversifiée et dense de plantes submergées, d'autre part. Certains taxons de macrophytes se sont révélés intolérants aux conditions de turbidité et de richesse en éléments nutritifs élevées (e.g., Pontederia cordata...

We collected water quality, land use, and aquatic macrophyte information from 62 coastal and inland wetlands in the Great Lakes basin and found that species richness and community structure of macrophytes were a function of geographic location and water quality. For inland wetlands, the primary source of water quality degradation was inputs of nutrients and sediment associated with altered land use, whereas for coastal wetlands, water quality was also influenced by exposure and mixing with the respective Great Lakes. Wetlands within the subbasins of the less developed, more exposed upper Great Lakes had unique physical and ecological characteristics compared with the more developed, less sheltered wetlands of the lower Great Lakes and those located inland. Turbid, nutrient-rich wetlands were characterized by a fringe of emergent vegetation, with a few sparsely distributed submergent plant species. High-quality wetlands had clearer water and lower nutrient levels and contained a mix of emergent and floating-leaf taxa with a diverse and dense submergent plant community. Certain macrophyte taxa were identified as intolerant of turbid, nutrient-rich conditions (e.g., Pontederia cordata, Najas flaxilis), while others were tolerant of a wide range of conditions (e.g., Typha spp., Potamogeton pectinatus) occurring in both degraded and pristine wetlands.

No abstract

Abstract:We use fish and environmental data from 40 wetlands of the Laurentian Great Lakes to develop the Wetland Fish Index (WFI), a tool that can be used to assess the quality of coastal marshes. A partial canonical correspondence analysis was used to ordinate fish species along multidimensional environmental axes that accounted for anthropogenic disturbance based on temperature, conductivity, and the presence of pollutants (e.g., suspended solids and primary nutrients). Compared with other measures of fish habitat quality (e.g., Shannon-Wiener diversity index and species richness), the WFI was the only index that was significantly related to the degree of water quality degradation and wetlands condition, as indicated by an independent index of wetland quality, the Water Quality Index (WQI). WQI ranks sites according to deterioration in water quality and is statistically related to the degree of land-use alteration in wetland watersheds. We demonstrate the usefulness of the WFI for detecting intrawetland variation between two sites in a degraded urban wetland, Frenchman's Bay, Lake Ontario, and to distinguish the heavily impacted wetlands in lower Green Bay from the less-impacted marshes in middle and upper Green Bay, Lake Michigan. This was accomplished by using only published fish data without corresponding environmental variables.Résumé : Nous avons utilisé des données sur les poissons et sur le milieu provenant de 40 terres humides des Grands Lacs laurentiens afin de mettre au point un indice ichtyologique des terres humides (WFI, Wetland Fish Index), un outil qui peut permettre d'évaluer la qualité des marais côtiers. Une analyse partielle des correspondances canoniques a servi à ordonner les espèces de poissons le long d'axes environnementaux multidimensionnels qui expliquent les perturbations anthropiques d'après la température, la conductivité et la présence de polluants (par exemple, de solides en suspension et de nutriments primaires). Par comparaison à d'autres mesures de la qualité de l'habitat des poissons (par exemple, l'indice de diversité de Shannon-Wiener et la richesse spécifique), le WFI est le seul qui soit relié significativement à l'importance de la dégradation de la qualité de l'eau et à l'état des terres humides, tel qu'indiqué par un indice indépendant de la qualité des terres humides, l'indice de qualité de l'eau (WQI, Water Quality Index). Le WQI ordonne les sites d'après la détérioration de la qualité de leur eau et montre une corrélation significative avec les modifications associées à l'utilisation des terres dans le bassin versant des terres humides. Nous montrons l'utilité de WFI pour détecter la variation dans un même système entre deux sites dans Frenchman's Bay, lac Ontario, une terre humide urbaine et dégradée; il peut aussi distinguer les terres humides fortement modifiées de la partie inférieure de Green Bay. lac Michigan, des régions moins affectées des parties moyennes et supérieures de la baie. Cela a pu être réalisé à partir seulement des données publiées sur les poiss...