In situ and laboratory feeding trials coupled with stomach content analysis of largemouth bass (Micropterus salmoides) were performed to examine how turbidity influences the size selectivity and capture rates of prey. No significant differences in the capture success of adult largemouth bass preying on northern redbelly dace (Phoxinus eos) were observed during in situ feeding trials in two Lake Ontario coastal wetlands differing in turbidity level (2.3 and 20 nephlometric turbity units (NTU)). During 1-h laboratory feeding trials, the overall number of fathead minnows (Pimephales promelas) captured was not significantly different among 1-, 18-, and 37-NTU treatments. However, at 70 NTU, the number of fathead minnows captured was significantly lower than that at the lowest turbidity treatment. Selection by juvenile largemouth bass of the smallest size-class of fathead minnow decreased as turbidity increased. No significant differences in piscivory were apparent between juvenile largemouth bass collected from turbid and clear habitats. Stomach content comparisons of juvenile largemouth bass seined from six clear and turbid habitats suggest that piscivory is primarily regulated by the availability of vulnerable size-classes of prey fish, as opposed to water clarity.

A long history of human-induced degradation of Great Lakes wetlands has made restoration a necessity, but the practice of wetland restoration is relatively new, especially in large lake systems. Therefore, we compiled tested methods and developed additional potential methods based on scientific understanding of Great Lakes wetland ecosytems to provide an overview of approaches for restoration. We addressed this challenge by focusing on four general fields of science: hydrology, sedimentology, chemistry, and biology. Hydrologic remediation methods include restoring hydrologic connections between diked and hydrologically altered wetlands and the lakes, restoring water tables lowered by ditching, and restoring natural variation in lake levels of rcgulated lakes Superior and Ontario. Sedimentologieal remediation methods include management of sediment input from uplands, removal or proper management of darns on tributary rivers, and restoration of protective barrier beaches and sand spits. Chemical remediation methods include reducing or eliminating inputs of contaminants from point and non-point sources, natural sediment remediation by biodegradation and chemical degradation, and active sediment remediation by removal or by in situ treatment.Biological remediation methods include control of non-target organisms, enhancing populations of target organisms, and enhancing habitat for target organisms. Some of these methods were used in three major restoration projects (Metzger Marsh on Lake Erie and Cootes Paradise and Oshawa Second Marsh on Lake Ontario), which are described as case studies to show practical applications of wetland restoration in the Great Lakes. Successful restoration techniques that do not require continued manipulation must be founded in the basic tenets of ecology and should mimic natural processes. Success is demonstrated by the sustainability, productivity, nutrient retention ability, invasibility, and biotic interactions within a restored wetland,

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In this study, we investigated the impact of carp and turbidity on the growth of macrophytes from propagules in four Lake Ontario marshes with low submersed macrophyte abundance. A healthy propagule bank was transplanted into 4 m z carp exclosures (5-cm-mesh cages), turbidity exclosures (enclosed in plastic), and open control sites, with four replicates per treatment used in each marsh. Carp exclosures were intended to protect the transplanted propagule banks from carp and other large aquatic organisms; turbidity exclosures were intended to also reduce wind exposure and inflowing suspended sediments, thus increasing the amount of light reaching bottom sediments. The mean density of shoots produced in the turbidity exclosures (256 4-46 shoots.m -2) was significantly higher than that produced in carp enclosures (20 ± 7 shoots.m -z) and open controls (10 + 5 shoots.m--'); above-ground biomass (AGB) was also significantly greater in turbidity exclosures. The difference in protection afforded the developing submersed macrophyte shoots can be attributed to the lower concentration of total suspended solids and greater level of light penetration in the turbidity exctosures. There was a strong linear relationship between photosynthetically active radiation (PAR) reaching the substrate surface and shoot growth in terms of both shoot density and AGB. The growth response was more sensitive to PAR in the field than it was in a growth chamber, suggesting that light levels are more critical to shoot development when multiple stressors are involved. The two marshes exposed to high wave energy had very high levels of suspended solids, and the introduced propagule bank was eroded away in controls and carp exclosures. In such marshes, both turbidity and exposure would have to be addressed for macrophyte recovery.

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The issue of over-fishing has spawned controversy in the Laurentian Great Lakes since the early 1800s. Aboriginal, domestic, commercial food, aquacultural and recreational fisheries have experienced a number of different types of over-fishing that have contributed to the fishing-up sequence in the lakes. Some effects of fish habitat destruction by many environmental abuses interacted synergistically with inappropriate fishing practices. The fish communities near larger settled areas ‘hit the wall’ ecologically beginning in the late 1800s. The fisheries of the whole basin ‘hit the wall’ politically in the period 1955–1968. Since 1968, a managerial transformation to an ecosystem approach has occurred, from a modern progressive approach to a new self-organizing redevelopment approach in which biotic and abiotic interests are more balanced than previously. Controversy continues as emergent grass-roots regimes seek alternatives to remnant and senescent institutional arrangements or seek partnership arrangements with new governance institutions.

The seed banks of six Lake Ontario shoreline marshes were investigated to assess the potential for natural regeneration of sparse submerged macrophyte populations in marshes subjected to anthropogenic disturbance. Twenty-six core samples were taken in each of three disturbed marshes with sparse submerged vegetation, and the number of seeds was compared with samples from three reference marshes containing abundant submerged vegetation. Six cores from each of six marshes were examined to determine whether there was a difference between disturbed and reference marshes in seed density or seed distribution, and germination assays were used to assess differences in seed viability. Seeds of five submerged macrophyte taxa were identified in substrate samples of the six marshes. Mean seed density was significantly higher in the three reference marshes (4082 – 47 623 seeds/m2) than in the three disturbed marshes (0–2041 seeds/m2). The density of seedlings of submerged macrophytes germinating in reference marsh samples ranged from 333 to 2406 seedlings/m2, whereas no seedlings germinated from disturbed marsh samples. The deeper sediments (7–14 cm sediment depth) in the reference marshes had comparable seed densities to those in the shallower sediments, whereas seeds were found in only the deeper sediments of the disturbed marshes. These data suggest that regeneration from buried seeds is unlikely in the disturbed marshes, even if improvements occur in the environmental conditions that have historically inhibited the growth of submerged macrophytes. Key words: submerged macrophytes, anthropogenic disturbance, Lake Ontario, seed banks, natural regeneration.