Now showing items 21-40 of 123

    • Research Opportunities in Interdisciplinary Ground-Water Science

      Sanford, Ward E.; Caine, J. S.; Wilcox, Douglas A.; McWreath, H. C.; Nicholas, J. R.; The College at Brockport; U.S. Geological Survey (2006-01-01)
      The U.S. Geological Survey (USGS) has a long-standing reputation for providing unbiased scientific leadership and excellence in the field of ground-water hydrology and geological research. This report provides a framework for continuing this scientific leadership by describing six interdisciplinary topics for research opportunities in ground-water science in the USGS. These topics build on recommendations of the National Research Council (2000) contained in the report, “Investigating Groundwater Systems on Regional and National Scales,” and emphasize research topics that would benefit from the integrated capabilities of all parts of the USGS. Understanding the relations between ground water and the geological characteristics of aquifers within which ground water resides, and the relation of ground water to surface-water resources and terrestrial and aquatic biota is increasingly important and presents a considerable opportunity to draw on expertise throughout the USGS, including the science disciplines of biology, geography, geology, and hydrology. The National Research Council (2000) also emphasizes that USGS regional and national assessments of ground-water resources should focus on aspects that foster the sustainability of the resource. The need for a comprehensive program addressing the sustainability of ground-water resources can be stated very concisely—we need enough ground water of good quality to sustain our lives, our economy, and our aquatic ecosystems. Although societal needs for high-quality, objective ground-water science are increasing, current funding for USGS regional ground-water programs is about 40 percent of the funding available 20–25 years ago. Given the current challenges of budgetary constraints, however, this report provides a flexible set of interrelated research topics that enhance the ability of the USGS to focus limited fiscal resources on developing ground-water science tools and methods that provide high-quality, objective scientific information.
    • Differences in Sedge Fen Vegetation Upstream and Downstream from a Managed Impoundment

      Kowalski, Kurt P.; Wilcox, Douglas A.; The College at Brockport; U.S. Geological Survey (2003-10-01)
      The U .S. Fish and Wildlife Service proposed the restoration of wetlands impacted by a series of drainage ditches and pools located in an extensive undeveloped peatland in the Seney National Wildlife Refuge, Michigan. This study examined the nature and extent of degradation to the Marsh Creek wetlands caused by alteration of natural hydrology by a water-storage pool (C-3 Pool) that intersects the Marsh Creek channel. We tested the hypothesis that a reduction in moderate-intensity disturbance associated with natural water-level fluctuations below the C-3 dike contributed to lower species richness, reduced floristic quality and a larger tree and shrub component than vegetation upstream from the pool. Wetland plant communities were sampled quantitatively and analyzed for species richness, floristic quality and physiognomy. Aerial photographs, GIS databases and GPS data contributed to the characterization and analysis of the Marsh Creek wetlands. Results showed that there was lower species richness in vegetated areas downstream from the pool, but not the anticipated growth in shrubs. Wetland vegetation upstream and downstream from the pool had similar floristic quality, except for a greater number of weedy taxa above the pool. Seepage through the pool dike and localized ground-water discharge created conditions very similar to those observed around beaver dams in Marsh Creek. In essence, the dike containing the C-3 Pool affected hydrology and wetland plant communities in a manner similar to an enormous beaver dam, except that it did not allow seasonal flooding episodes to occur. Management actions to release water from the pool into the original Marsh Creek channel at certain times and in certain amounts that mimic the natural flow regime would be expected to promote greater plant species richness and minimize the negative impacts of the dike.
    • Structure and Function of the Zooplankton Community of Mirror Lake, New Hampshire

      Makarewicz, Joseph C.; Likens, Gene E.; Cornell University; The College at Brockport (1979-03-01)
      An intensive study of the zooplankton community of Mirror Lake, New Hampshire, was undertaken over a 3-yr period. Our objectives in the lake study have included measurements of a number of attributes of the zooplankton community that integrate structure and function at the ecosystem level; among these are dispersion, biomass, productivity, respiration, and nutrient cycling. Eight species of rotifers and 3 species of cladocerans were successfully cultured. Generation time for planktonic rotifers was -8-10 days (170C). The effect of higher food levels on rotifers was to shorten generation time and to increase brood size. In cladocerans, high food levels caused an increase in length and brood size . A curvilinear relationship existed between zooplankton community respiration and temperature in Mirror Lake. Mean monthly zooplankton community respiration ranged from 96.0 kg C/ha/mo in June of 1969 to a low of 20.5 kg C/ha/mo in April of 1970. Over a 3-yr period, respiration was 79.9% of assimilation. The 0 to 4.5-m strata (;epilimnion) contributed 68.5% and 46.5% of the annual zooplankton production and biomass. Zooplankton community production ranged from 22.3 kg C/ha/yr to 29.3 kg C/ha/yr with a 3-yr mean of 25.2 kg C/ha/yr. The annual zooplankton biomass ranged from 1.4 to 2.6 kg C/ha with a 3-yr mean of 2.0 kg C/ha. A linear relationship was found to exist between net phytoplankton and zooplankton production in various lakes of the world. Ecological efficiency apparently increases with the trophic status of the lake. It is recommended that the term ecological efficiency be refined to include both autochthonous and allochthonous inputs of reduced carbon into the lake. Rotifers assume a major role in intrasystem nutrient cycling and energy transfer within the lake ecosystem. Of the total amount of P incorporated into the organic matter of zooplankton community each year, 33.5% is assimilated in rotifer tissue. The annual turnover rate of P by rotifers is 30.9 and is high compared to crustaceans (10.1). Copepods comprise 55.4% of the total zooplankton biomass. However, the copepods, with their slow growth over an entire year, represent only 19.3% of the zooplankton production, while rotifers account for 39.8% of the zooplankton production annually in Mirror Lake. Also, evidence is presented that rotifers play a major role in energy transfer in lakes of varying trophic status (oligotrophic to eutrophic).
    • Cattails as far as the eye can see

      Wilcox, Douglas A.; The College at Brockport (2011-05-01)
      This SWS Research Brief summarizes recently publicized information regarding the effects of lake-level regulation on wetlands, and the predictive models for evaluating the potential effects of proposed new regulations plans on wetland plant communities.
    • A Paleoecological Test of a Classical Hydrosere in the Lake Michigan Dunes

      Jackson, Stephen T.; Futyma, Richard P.; Wilcox, Douglas A.; The College at Brockport (1988-08-01)
      Aquatic vegetation varies along a chronosequence of dune ponds at Miller Woods, Indiana Dunes National Lakeshore. Submersed and floating-leaved macrophytes dominate the vegetation of the youngest ponds. Older ponds contain mixed assemblages of submersed, floating-leaved, and emergent plant taxa. The oldest ponds are dominated by emergent plants, especially Typha angustifolia. We conducted paleoecological studies at one of the oldest ponds to test the hypothesis that the modern vegetational array along the pond chronosequence represents a hydrarch successional sequence. Macrofossil stratigraphy of the 3000-yr-old pond indicates no significant changes in pond vegetation following early colonization until < 150 BP. Pond vegetation before 150 BP consisted of a diverse assemblage of submersed, floating-leaved, and emergent macrophyte taxa. Pollen and macrofossil data indicate a major, rapid vegetational change at < 150 BP, evidently in response to local human disturbance. Pollen data reveal that the extensive Typha stands in the older ponds have developed recently, following postsettlement disturbance. Modern vegetational differences along the chronosequence reflect differential effects of disturbance rather than autogenic hydrarch succession. This study illustrates a major pitfall in inferring successional trends from spatial sequences of vegetation.
    • A Model For Assessing Interdisciplinary Approaches to Wetland Research

      Wilcox, Douglas A.; The College at Brockport (1987-01-01)
      An interdisciplinary approach to research in wetlands is necessary to avoid incorrect extrapolations and projections about broad wetland functions based on limited knowledge. The values of several lesser-used disciplines or fields of study are often overlooked and therefore not incorporated into study designs. To address this problem, a model was developed that relates ten ecological and environmental science disciplines to each other (geohydrology, surface water hydrology, water chemistry, soil/sediment chemistry, stratigraphy/sedimentology, paleoecology, plant ecology, animal ecology, remote sensing, and seedbank studies). A matrix and compartmentalized model cross-identify each discipline as a research tool and as a type of study for which a given tool can be used in data collection. Use of the model is demonstrated by assessing the research approach utilized in the study of three wetland systems (shallow dune ponds, bog, fen) at Indiana Dunes National Lakeshore and the study of the pocosin wetlands as presented in a comprehensive volume on that subject.
    • Intrapopulation Variation in Egg Lipid and Fatty Acid Composition and Embryo Viability in a Naturally Spawning Walleye Population from an Inland Reservoir

      Czesny, Sergiusz; Rinchard, Jacques; Dabrowski, Konrad; Ohio State University; The College at Brockport (2005-01-01)
      The objective of the study was to evaluate the variation in embryo viability within a population of walleye Sander vitreus from an inland reservoir throughout the spawning season. Egg size, egg lipid content, and fatty acid composition were used as criteria to evaluate egg quality. Additionally, we sought to verify whether any particular size-class of females produces superiorquality eggs or whether the time of spawning (early, middle, or late) has an effect on egg quality. Seventy-seven ovulating walleye females (total length, 465–885 mm) were captured in Salt ForkReservoir, Ohio, throughout the spawning season. Although egg diameter after water hardening varied among females (1.85–2.38 mm), egg size did not correlate with female length (P > 0.05). Average egg lipid content was 12.0 +/- 1.3% (mean +/- SD) of wet weight and was unrelated to egg diameter (P > 0.05). Neutral and phospholipid classes in eggs comprised 77.5 +/- 4.7% and 22.5 +/- 4.7% of total lipids, respectively. Egg diameter was not significantly related to any of the specific fatty acids from neutral or phospholipid fractions (P > 0.05). Moreover, egg fatty acid compositions from both neutral lipids and phospholipids did not change during the spawning season. High survival of embryos (90.0 +/- 8.7%) from females across the observed size range was recorded regardless of the spawning period. We concluded that the quality of walleye eggs was consistently high and thus that the timing of gamete collection would not compromise hatchery programs.
    • Multivariate Analysis of the Lake Michigan Phytoplankton Community at Chicago

      Baybutt, Robert I.; Makarewicz, Joseph C.; The College at Brockport (1981-04-01)
      Ordination techniques were used to analyze phytoplankton and water chemistry data collected between 1927 and 1978 from Lake Michigan at Chicago. Ordination analysis summarized the phytoplankton data and illustrated the progression from oligotrophy to eutrophy and the subsequent reversal of cultural eutrophication after 1970 in the nearshore waters of Lake Michigan at Chicago. The analysis highlighted a significant correlation between blue-green algal biomass and Na+ concentration. The increase in mean annual Na+ concentration in Lake Michigan at Chicago and the experimental evidence implying a Na+ requirement for blue-green algae suggested that the increase in blue-greens, although influenced by P enrichment and by other factors, such as CO2 availability, allelopathic effects and N: P ratios, may also be linked with increases in Na+ concentration.
    • A Chronosequence of Aquatic Macrophyte Communities in Dune Ponds.

      Wilcox, Douglas A.; Simonin, Howard A.; New York State Department of Environmental Conservation; The College at Brockport (1987-01-01)
      Differences in macrophyte community composition in a chronosequence of spatially separated dune ponds near the south shore of Lake Michigan were examined and related to environmental variables. Five ponds from each of five pond rows were sampled. In each pond, the cover of each plant species and water and sediment depth were sampled using a stratified random design. Radiocarbon dates were obtained from selected ponds. Ordination of the vegetation data by detrended correspondence analysis revealed similarities in the plant communities of ponds in the same row and community differences between ponds in different rows. Younger ponds (< 300 years) were dominated by Chara spp. and Najas flexilis, middle-age ponds (2100 years) by Myriophyllum spp. and Nymphaea tuberosa, and older ponds (3000 years) by Typha angustifolia. Distribution of macrophyte communities was most closely correlated with water depth, which generally decreased with increasing age of the pond row. Some sediment chemistry differences were found between pond rows, but there were no significant differences in water chemistry. Although a linear succession pattern is suggested, we think that anthropogenic disturbance played a major role in determining the vegetation differences observed. Thus, a chronosequence of spatially separated ponds can provide valuable information on hydrarch succession, but it may be misleading and actually represent succession affected by disturbance history.
    • Long-Term (1927-1978) Changes in the Phytoplankton Community of Lake Michigan at Chicago

      Baybutt, Robert I.; Makarewicz, Joseph C.; The College at Brockport (1981-04-01)
      Fifty-one years of phytoplankton data from the South District Water Intake of the Chicago Water Filtration Plant were analyzed to determine changes in the phytoplankton community related to the eutrophication of Lake Michigan. From 1930 to 1940, a net biomass (~100 mg C/m3) indicative of oligotrophic-mesotrophic conditions were implied by the net algal biomass. By 1961 net algal biomass was ~600 mg C/m3-a biomass indicative of a eutrophic lake. Much of the biomass increase is due to Tabellaria, Stephanodiscus tenuis and S. binderanus. Since the early 1970's, there has been a consistent general decrease in algal biomass to levels associated with oligotrophic-mesotrophic conditions. The decrease in net algal biomass, the decrease in abundance of eutrophic species, the small but general increase in genera that were decreasing in relative abundance until ~ 1972, and the increase in dissolved reactive silica concentrations in Lake Michigan suggest a reversal of cultural eutrophication of Lake Michigan near Chicago. Only the increase in the relative abundance (22% of the total community biomass in 1978) of blue-green algae, mostly Oscillatoria and Gomphosphaeria, argues for accelerated eutrophication.
    • Burrowing Saves Lake Erie Clams

      Nichols, S. Jerrine; Wilcox, Douglas A.; The College at Brockport; U.S. Geological Survey (1997-10-01)
      Native clams seem to have been protected from zebra mussel infestation at Metzger Marsh by the interaction between warm temperatures and soft sediments. Warm water encourages burrowing, but soft sediments are required to allow encrusted clams to burrow. In support of this conclusion, we have since found live unionids or fresh shells at three other Lake Erie wetlands.
    • A water-budget approach to restoring a sedge fen affected by diking and ditching

      Wilcox, Douglas A.; Sweat, Michael J.; Carlson, Martha L.; Kowalski, Kurt P.; The College at Brockport; U.S. Geological Survey (2005-06-01)
      A vast, ground-water-supported sedge fen in the Upper Peninsula of Michigan, USA was ditched in the early 1900 s in a failed attempt to promote agriculture. Dikes were later constructed to impound seasonal sheet surface flows for waterfowl management. The US Fish and Wildlife Service, which now manages the wetland as part of Seney National Wildlife Refuge, sought to redirect water flows from impounded C-3 Pool to reduce erosion in downstream Walsh Ditch, reduce ground-water losses into the ditch, and restore sheet flows of surface water to the peatland. A water budget was developed for C-3 Pool, which serves as the central receiving and distribution body for water in the affected wetland. Surface-water inflows and outflows were measured in associated ditches and natural creeks, ground-water flows were estimated using a network of wells and piezometers, and precipitation and evaporation/evapotranspiration components were estimated using local meteorological data. Water budgets for the 1999 springtime peak flow period and the 1999 water year were used to estimate required releases of water from C-3 Pool via outlets other than Walsh Ditch and to guide other restoration activities. Refuge managers subsequently used these results to guide restoration efforts, including construction of earthen dams in Walsh Ditch upslope from the pool to stop surface flow, installation of new water-control structures to redirect surface water to sheet flow and natural creek channels, planning seasonal releases from C-3 Pool to avoid erosion in natural channels, stopping flow in downslope Walsh Ditch to reduce erosion, and using constructed earthen dams and natural beaver dams to flood the ditch channel below C-3 Pool. Interactions between ground water and surface water are critical for maintaining ecosystem processes in many wetlands, and management actions directed at restoring either ground- or surface-water flow patterns often affect both of these components of the water budget. This approach could thus prove useful in guiding restoration efforts in many hydrologically altered and managed wetlands worldwide.
    • Reconstructing Paleo Lake Levels from Relict Shorelines along the Upper Great Lakes

      Baedke, Steve J.; Thompson, Todd A.; Johnston, John W.; Wilcox, Douglas A.; Indiana University - Bloomington; James Madison University; The College at Brockport (2004-01-01)
      Shorelines of the upper Great Lakes include many embayments that contain strandplains of beach ridges. These former shoreline positions of the lakes can be used to determine changes in the elevation of the lakes through time, and they also provide information on the warping of the ground surface that is occurring in the Great Lakes after the weight of glacial ice was removed. Relative lake-level hydrographs can be created by coring the beach ridges to determine the elevation of basal foreshore (swash zone) deposits in each ridge and by obtaining radiocarbon dates of basal wetland sediments between ridges to generate an age model for the ridges. Because the relative-level hydrographs are the combination of lake-level change and vertical ground movement (isostatic rebound), the rebound must be removed to produce a graph that shows only the physical limits and timing of past lake-level fluctuations referenced to a common outlet. More than 500 vibracores of beach-ridge sediments were collected at five sites along Lake Michigan and four sites along Lake Superior. The cores showed a sequence of dune deposits overlying foreshore deposits that, in turn, overlie upper shoreface deposits. The base of the foreshore deposits is coarser and more poorly sorted than an overlying and underlying sediment and represents the plunge-point sediments at the base of the swash zone. The plunge-point deposits are a close approximation of the elevation of the lake when the beach ridge formed. More than 150 radiocarbon ages of basal wetland sediments were collected to produce age models for the sites. Currently, age models exist for all Lake Michigan sites and one Lake Superior site. By combining the elevation data with the age models, six relative lake-level hydrographs were created for the upper Great Lakes. An iterative approach was used to remove rebound from the five Lake Michigan relative hydrographs and merge the graphs into a single hydrograph. The resultant hydrograph shows long-term patterns of lake-level change for lakes Michigan and Huron and is referenced to the Port Huron outlet. When the age models are completed for the Lake Superior sites, a hydrograph will be created for the entire lake.
    • Interactions Between Ground Water and Wetlands, Southern Shore of Lake Michigan, USA

      Shedlock, Robert J.; Wilcox, Douglas A.; Thompson, Todd A.; Cohen, David A.; Indiana University - Bloomington; The College at Brockport; U.S. Geological Survey (1993-01-01)
      Wetlands between, and within, dune-beach complexes along the south shore of Lake Michigan are strongly affected by ground water. The hydrogeology of the glacial drift aquifer system in a 26 km2 area was investigated to determine the effects of ground water on the hydrology and hydrochemistry of Cowles Bog and its adjacent wetlands. The investigation showed that ground water from intermediate- and regional-scale flow systems discharges to Cowles Bog from confined aquifers that underlie the wetland. These flow systems are recharged in moraines south of the dune- beach complexes. Water from the confined aquifers discharges into the surficial aquifer mainly by upward leakage through a buried till sheet that serves as the confining layer. However, the till sheet is breached below a raised peat mound in Cowles Bog, allowing direct upward discharge from the confined aquifer into the surficial sand, marl, and peat. The shallow ground and wetland water in the area influenced by this leakage is a calcium magnesium bicarbonate type, with low tritium concentrations consistent with mixing of older ground water and more recent precipitation. Ground water and wetland water from surrounding areas are less mineralized and have higher tritium concentrations characteristic of precipitation in the late 1970s. The results of this study suggest that wetlands in complex hydrogeologic settings may be influenced by multiple ground-water flow systems that are affected by geomorphic features, stratigraphic discontinuities, and changes in sediment types. Discharge and recharge zones may both occur in the same wetland. Multidisciplinary studies incorporating hydrological, hydrochemical, geophysical, and sedimentological data are necessary to identify such complexities in wetland hydrology.
    • Differentiating Climatic And Successional Influences On Long-Term Development Of A Marsh

      Singer, Darren K.; Jackson, Stephen T.; Madsen, Barbara J.; Wilcox, Douglas A.; Northern Arizona University; The College at Brockport; University of Michigan - Ann Arbor (1996-01-01)
      Comparison of long-term records of local wetland vegetation dynamics with regional, climate-forced terrestrial vegetation changes can be used to differentiate the rates and effects of autogenic successional processes and allogenic environmental change on wetland vegetation dynamics. We studied Holocene plant macrofossil and pollen sequences from Portage Marsh, a shallow, 18-ha marsh in northeastern Indiana. Between 10 000 and 5700 yr BP the basin was occupied by a shallow, open lake, while upland vegetation consisted of mesic forests of Pinus, Quercus, Ulmus, and Carya. At 5700 yr BP the open lake was replaced rapidly by a shallow marsh, while simultaneously Quercus savanna developed on the surrounding uplands. The marsh was characterized by periodic drawdowns, and the uplands by periodic fires. Species composition of the marsh underwent further changes between 3000 and 2000 yr BP. Upland pollen spectra at Portage Marsh and other sites in the region shifted towards more mesic vegetation during that period. The consistency and temporal correspondence between the changes in upland vegetation and marsh vegetation indicate that the major vegetational changes in the marsh during the Holocene resulted from hydrologic changes forced by regional climate change. Progressive shallowing of the basin by autogenic accumulation of organic sediment constrained vegetational responses to climate change but did not serve as the direct mechanism of change.
    • Discoloration of Polyvinyl Chloride (PVC) Tape as a Proxy for Water-Table Depth in Peatlands: Validation and Assessment of Seasonal Variability

      Booth, Robert K.; Hotchkiss, S. C.; Wilcox, Douglas A.; Lehigh University; The College at Brockport; University of Wisconsin - Madison (2005-01-01)
      Summary 1. Discoloration of polyvinyl chloride (PVC) tape has been used in peatland ecological and hydrological studies as an inexpensive way to monitor changes in water-table depth and reducing conditions. 2. We investigated the relationship between depth of PVC tape discoloration and measured water-table depth at monthly time steps during the growing season within nine kettle peatlands of northern Wisconsin. Our specific objectives were to: (1) determine if PVC discoloration is an accurate method of inferring water-table depth in Sphagnum -dominated kettle peatlands of the region; (2) assess seasonal variability in the accuracy of the method; and (3) determine if systematic differences in accuracy occurred among microhabitats, PVC tape colour and peatlands. 3. Our results indicated that PVC tape discoloration can be used to describe gradients of water-table depth in kettle peatlands. However, accuracy differed among the peatlands studied, and was systematically biased in early spring and late summer/autumn. Regardless of the month when the tape was installed, the highest elevations of PVC tape discoloration showed the strongest correlation with midsummer (around July) water-table depth and average water-table depth during the growing season. 4. The PVC tape discoloration method should be used cautiously when precise estimates are needed of seasonal changes in the water-table.
    • Caddisflies (Insecta: Trichoptera) of Fringing Wetlands of the Laurentian Great Lakes

      Armitage, Brian J.; Hudson, Patrick L.; Wilcox, Douglas A.; Midwest Biodiversity Institute, Inc.; The College at Brockport; U.S. Geological Survey (2001-09-01)
      Fringing wetlands of the Laurentian Great Lakes are subject to natural processes, such as water-level fluctuation and wave-induced erosion, and to human alterations. In order to evaluate the quality of these wetlands over space and time, biological communities are often examined. Ideally, the groups of organisms selected for these evaluations should be resident in the wetlands themselves. Fish are often sampled, but many species are not truly resident, visiting wetlands on an occasional basis to feed or on a seasonal basis to breed. Aquatic vascular plants are perhaps the most common group selected for evaluation. However, in some cases, aquatic plants give a false impression by providing photosynthetic capabilities and structural infrastructure but having greatly diminished herbivore and carnivore communities.
    • Promoting Species Establishment in a Phragmites-dominated Great Lakes Coastal Wetland

      Carlson, Martha L.; Kowalski, Kurt P.; Wilcox, Douglas A.; The College at Brockport; U.S. Geological Survey (2009-01-01)
      This study examined efforts to promote species establishment and maintain diversity in a Phragmites-dominated wetland where primary control measures were underway. A treatment experiment was performed at Crane Creek, a drowned-river-mouth wetland in Ottawa National Wildlife Refuge along the shore of western Lake Erie. Following initial aerial spraying of Phragmites with glyphosate, this study tested combinations of cutting, raking, and additional hand spraying of Phragmites with glyphosate as methods to promote growth of other wetland species and increase plant diversity. Percent-cover vegetation data were collected in permanent plots before and after treatments, and follow-up sampling was performed the following year. Increased species richness, species emergence, and relative dominance of non-Phragmites taxa were used as measures of treatment success. We also examined treatment effects on Phragmites cover. Dimensionality of seedbank and soil properties was reduced using principal component analysis. With the exception of nitrogen, soil nutrients affected species establishment, non-Phragmites taxa dominance, and Phragmites cover. A more viable seedbank led to greater species emergence. Treatments had differential effects on diversity depending on elevation and resulting degree of hydrologic inundation. Whereas raking to remove dead Phragmites biomass was central to promoting species establishment in dry areas, spraying had a greater impact in continually inundated areas. For treatment success across elevations into the year following treatments, spraying in combination with cutting and raking had the greatest effect. The results of this study suggest that secondary treatments can produce a short-term benefit to the plant community in areas treated for Phragmites.
    • Growth, Survival, and Body Composition of Yellow Perch Juveniles Fed Commercial and Experimental Diets

      Rinchard, Jacques; Becheret, Renaud; Dabrowski, Konrad; Ohio State University; The College at Brockport (2008-01-01)
      Two experiments were carried out to evaluate the efficacy of commercial and experimental diets on the survival, growth, and body composition of juvenile yellow perch Perca flavescens. In both experiments, fish were fed by hand four to five times a day at a restricted ration of up to 90% satiation for 51 d. In experiment 1, fish (initial weight, 87 6 24 mg) were fed three experimental diets (F1, F2, and a casein–gelatin-based diet) and one commercial diet (Kyowa 400B). In experiment 2, fish (initial weight, 174 6 56 mg) were fed four experimental diets (Kyowa 400B, INVE-NRD, a starter diet from BioOregon, and a starter diet from Purina). In both experiments, the growth performance of yellow perch juveniles was significantly affected by dietary treatments. In experiment 1, fish fed Kyowa 400B and the casein–gelatinbased diet grew significantly faster than those fed the F1 and F2 diets. However, survival was significantly lower in fish fed the casein–gelatin-based diet than in those fed the other dietary treatments. In experiment 2, fish fed the INVE-NRD diet exhibited the best growth performance. Survival was not affected by dietary treatments. In both experiments, the proximate composition of fish among dietary treatments reflected the proximate composition of the diet. Our results indicate that satisfactory growth of yellow perch juveniles can be achieved using commercial and experimental diets.
    • Modeling Wetland Plant Community Response to Assess Water-Level Regulation Scenarios in the Lake Ontario – St. Lawrence River Basin

      Hudon, Christiane; Wilcox, Douglas A.; Ingram, Joel; Canadian Wildlife Service; St. Lawrence Centre; The College at Brockport (2006-01-01)
      The International Joint Commission has recently completed a five-year study (2000– 2005) to review the operation of structures controlling the flows and levels of the Lake Ontario – St. Lawrence River system. In addition to addressing the multitude of stakeholder interests, the regulation plan review also considers environmental sustainability and integrity of wetlands and various ecosystem components. The present paper outlines the general approach, scientific methodology and applied management considerations of studies quantifying the relationships between hydrology and wetland plant assemblages (% occurrence, surface area) in Lake Ontario and the Upper and Lower St. Lawrence River. Although similar study designs were used across the study region, different methodologies were required that were specifically adapted to suit the important regional differences between the lake and river systems, range in water-level variations, and confounding factors (geomorphic types, exposure, sediment characteristics, downstream gradient of water quality, origin of water masses in the Lower River). Performance indicators (metrics), such as total area of wetland in meadow marsh vegetation type, that link wetland response to water levels will be used to assess the effects of different regulation plans under current and future (climate change) water-supply scenarios.