Local and Systemic Controls on Fish and Fish Habitat in South Dakota Rivers and Streams: Implications for Management

Assessments of the health of rivers and streams in prairie environments would improve if the role of systemic patterns and processes among geologic-climatic settings in controlling physical habitat and fish communities were better defined. My research approach was based on a premise that assessments of the health of rivers and streams in prairie environments would benefit from studies that 1) examine the moderating effects of systemic patterns and processes by comparing physical habitat continua and fish communities among geologic-climatic settings, 2) determine the relative influence of locally interacting variables (e .g., channel shape and riparian vegetation) and systemic processes in structuring physical habitat and fish communities among a range of streams sizes, and 3) test the effects of biotic and abiotic controls on habitat partitioning by fish during critical periods of low flows common in prairie streams. My research had three complementary parts: two field studies and a laboratory study. The first field study tested the hypothesis that systemic processes moderate physical riverine environments, and thus biological communities, in distinct ways between a semi-arid region and a subhumid region. The second field study tested the hypothesis that in a subhumid region the interactions of local variables have greater influence on physical habitat and fish communities in small streams than in rivers. The laboratory study tested the influence of predators, large woody debris, and turbidity on habitat use by common minnow species under simulated low flow conditions. In the first study, longitudinal trends in channel morphometry, bankfull dimensions, stream bank and riparian traits, substrate, and fish community attributes were compared between the Bad River in a semi-arid region of western South Dakota and the Big Sioux River in the sub-humid region in eastern South Dakota. Findings suggest that along the Big Sioux River, the longitudinal changes in physical characteristics are gradual and continuous. Bankfull dimensions, channel bottom width, sand substrate, and streambank as deposition increased longitudinally while silt substrate, and percent of bank with vegetation decreased. In contrast, in the Bad River, longitudinal changes in these physical characteristics showed either a random pattern or a pattern of no change. In the Bad River, vertical channel dimensions (i.e., bank length and bank height) did increase with watershed size but not uniformly as they did in the Big Sioux River. Relationships of fish community attributes with watershed size were similar to the physical patterns. For example, in the Big Sioux River, most fish community attributes showed a continuous pattern of change either upward or downward with watershed size. In contrast, in the Bad River, most attributes show no discrete changes with watershed. My findings show that while prairie streams in sub-humid regions exhibit a truncation of the river continuum concept (RCC), physically and biologically, in semiarid regions, further truncation of the upper part of the RCC occurs. While both rivers had similarities in pioneering species in the upper parts of each river, only the Big Sioux River had a headwater component in the upper part. Also, a general randomness or lack of pattern in the physical and biological structure in the Bad River can be conceptualized as a longitudinal stretching of a reach of river into a longer segment of river. This would account for the seemingly lack of pattern in fishes. In the second study, findings indicate that variation in channel morphometry, physical habitat, and riparian-r1elated habitat decreases with watershed size in a subhumid prairie stream. Variation in channel morphometry, physical habitat, and riparian related habitat in tributaries could not be explained by local riparian conditions or adjacent land use. In fact, land use was or had been pasture, which limited comparison with other adjacent land use types (e.g., cropland). Furthermore, within pastures the level of animal vegetation use could not account for variation in riparian-related cover types among tributary sites. In this study the range of physical conditions among tributaries was coupled with a range of biological attributes. However, very few significant correlations were found between the biological and physical attributes. This suggests that the systemic controls even among small watersheds do have an influence on site-specific physical habitat and biological attributes. Several phenomena are probably responsible for this variation: hydrologic alterations caused by upland conversion to agriculture, cumulative loss of riparian buffering capacity, subtle differences in sub-watershed hydrology and geology, and flow fluctuations. In the laboratory study, low flow conditions were simulated in three experimental streams. Two suites of trials were performed: low and high turbidity trials

Evaluation of Smallmouth Bass Introductions in South Dakota Lakes

In 1989, electrofishing gear and modified-fyke (trap) nets were used to sample smallmouth bass Micropterus dolomieui during the spring from five lakes of varying environmental characteristics in eastern South Dakota. The\ mean length of smallmouth bass caught by electrofishing was significantly smaller (P=0.0001) than those caught in fyke nets. Highly significant correlations were found between paired mean electrofishing and mean fyke net catch rates among lakes, both for stock- length (18 cm) fish (r=0.973, P=0.005) and all fish ( r = 0.948, P=0.014). These correlations suggest that both gears were not seriously affected by environmental conditions within the ranges encountered. An s posteriori analysis indicated that mean electrofishing catch rates among lakes were 50.1/h over rock/boulder substrates, 7.0/h over sand/gravel substrates, and 0.0/h over silt/organic substrates. Delineation of catch rate data by habitat type indicated habitat use and the influence of habitat differences on overall catch rates. Thus, population density was partially related to available habitat and that standardized sampling programs must consider habitat at sampling stations. In 1990, smallmouth bass were again sampled in the spring from two East River lakes, the mainstem Missouri River reservoirs, and three West River reservoirs. Mean electrofishing catch rates, age and growth, recruitment, size and age structure, and fish body condition from 1989 and 1990 samples were summarized and used to assess stocking efforts, and to provide a preliminary assessment of the need for harvest regulations . Stocking efforts were successful in most waters where rock/boulder habitats were available. Dominant year classes in the samples were not entirely dependent upon the stocking of fingerlings. Differences in growth, variability in recruitment, and a range in total annual mortality could affect size structure and density of smallmouth bass. Hypothetical proportional stock densities (PSD) and densities of quality-length (�180 mm) smallmouth bass were generated from simple modelling to help illustrate these interactions and provide a basis for further assessment of harvest regulations. Limnological data were collected from five eastern South Dakota lakes in 1989 and were examined in relation to smallmouth bass population characteristics. Rock/boulder habitats were a definite prerequisite to the successful establishment of smallmouth bass. Lake morphometry appeared to be related to reproductive success. Lakes with low shoreline development tended to have less potential for reproductive success. However, shoreline development may not be a limiting factor if rock/boulder substrates are already minimal. Potential competition for food may exist between young-of-year smallmouth bass and yellow perch as indicated by age-0 smallmouth bass growth, age-0 and age-1 yellow perch density, and changes in mean length of Daphnia spp. Crayfish densities were low to non-existent where structural complexity of habitat (i.e., interspersion of substrate types) was low and smallmouth bass populations were concentrated

An Environmental History of Lower St. Regis: Lake Degradation and the Path to Ecological Redemption

This paper examines the environmental history of Lower St. Regis Lake (Franklin County, NY), the historic location of the Paul Smith’s Hotel and the present day site of Paul Smith’s College. Using water quality and fiisheries data collected by students, faculty, and environmental professionals, this article examines ecological changes that have taken place in the lake during the last 50 years. An analysis of lake-bottom sediments also reaches farther back in time to show what Lower St. Regis might have been like long before Paul Smith arrived. The story illustrates the effects of massive loading of phosphorus on water quality, places the lake within the context of the environmental awakening of the late 1960s and early 1970s, and chronicles steps that have been taken move Lower St. Regis Lake from a state of degradation toward “ecological redemption

Reliability of MRI interpretation of Discoid Lateral Meniscus: A multicenter study

BACKGROUND: Discoid lateral meniscus (DLM) has a varied and complex morphology that can be challenging to assess and treat. Preoperative magnetic resonance imaging (MRI) is frequently used for diagnosis and surgical planning; however, it is not known whether surgeons are reliable and accurate in their interpretation of MRI findings when defining the pathomorphology of DLM. HYPOTHESIS: Surgeons experienced in treating DLM are able to reliably interpret DLM pathology using MRI. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Knee MRI scans from 44 patients (45 knees) were selected from a pool of surgically treated patients with DLM. Five reviewers (fellowship-trained pediatric sports medicine surgeons) performed independent review of each MRI scan using the PRiSM Discoid Meniscus Classification. Inter- and intraobserver reliability of the rating factors-primary (width, height, presence of peripheral instability or tear) and secondary (location of instability or tear, tear type)-was assessed using the Fleiss κ coefficient, designed for multiple readers with nominal variables (fair reliability, 0.21-0.40; moderate, 0.41-0.60; substantial, 0.61-0.80; excellent, 0.81-1.00). Reliability is reported as κ (95% CI). RESULTS: Interobserver reliability in assessing most primary and secondary characteristics ranged from substantial (meniscal width) to moderate (peripheral instability, anterior instability, posterior instability, and posterior tear). Intraobserver reliability for most characteristics ranged from substantial (peripheral instability, presence of tear, anterior instability, posterior instability, and posterior tear) to moderate (meniscal width, anterior tear, and tear type). Notable exceptions were presence of tear, anterior tear, and tear type-all with fair interobserver reliability. Height had poor interobserver reliability and fair intraobserver reliability. CONCLUSION: Orthopaedic surgeons reliably interpret MRI scans using the PRiSM Discoid Meniscus Classification for the majority of DLM characteristics but vary in their assessment of height and presence and type of tear. MRI evaluation may be helpful to diagnose discoid by width and identify the presence of instability: 2 major factors in the decision to proceed with surgery. Arthroscopic evaluation should be used in conjunction with MRI findings for complete DLM diagnosis