Browsing by Subject "Bioassessment"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Cumulative Effects of Coastal Watershed Land Use on Chironomidae (Insecta: Diptera) Communities of Neotropical Estuaries in Costa Rica(2017-07) Kranzfelder, PetraChironomidae assemblages are likely to provide a useful measure of biotic integrity in Neotropical estuaries of Costa Rica, which lack an intensive estuarine bioassessment tool to support environmental monitoring. However, little is known about chironomid communities in these estuaries and the cumulative effects of watershed land use on chironomid communities have not been studied. The purpose of this dissertation was to (1) quantify land cover change of six watersheds on the Caribbean coast of Costa Rica between 2001 and 2014, (2) describe all steps of the Chironomidae surface-floating pupal exuviae method in detail, including sample collection, laboratory processing, slide mounting, and genus identification, (3) investigate Chironomidae species diversity of nine estuaries across a land use gradient on the Caribbean coast of Costa Rica, (4) compare the relative effectiveness of five different DNA extraction protocols and direct PCR in isolation of DNA from chironomid pupal exuviae, and (5) assess the efficiency of using standard DNA barcoding for species identification of chironomid pupal exuviae. I found that watershed-scale land use analyses showed agricultural expansion and deforestation in watersheds on the northeastern coast and secondary forest regrowth on the southeastern coast of Costa Rica. I identified 228 morphospecies and 70 genera from 17,071 Chironomidae surface-floating pupal exuviae collected from nine Neotropical estuaries and that a Chironomidae Index of Biotic Integrity successfully discriminated estuaries with differing degrees of stress across a land use gradient. I extracted genomic DNA from 61.2% of 570 sampled pupal exuviae. The NucleoSpin® Tissue XS Kit, DNeasy® Blood and Tissue kit, and QuickExtract™ DNA Extraction Solution provided the best results in isolating DNA from single pupal exuviae. A total of 36.3% of 190 sampled pupal exuviae resulted in high-quality sequences for Costa Rica, but none matched known species. This knowledge is important if these aquatic communities are to be used more effectively in future biological monitoring, conservation, and integrated water resource management of Neotropical estuaries.Item Minnesota macrophytes: linking aquatic plants, lake health, and human activities(2013-06) Beck, Marcus W.Aquatic plants (macrophytes) are an undervalued but critically important component of Minnesota's lakes. The macrophyte Index of Biotic Integrity (IBI) was developed to evaluate lake health using metrics that describe the condition of the aquatic plants. However, a detailed evaluation to determine whether the index can explicitly link lake condition with activities that negatively impact lake resources has not been conducted. This information is necessary before the IBI can be used to develop biological standards required under the federal Clean Water Act. The goal of this dissertation was to develop and implement a framework for identifying the strengths and weaknesses of the index to inform biological assessment. Four chapters describe research to fulfill this goal. The first chapter identifies comparable groups of lakes using a set of environmental variables that influence macrophyte community composition. The second chapter describes the development and application of semi-automated techniques for quantifying potential stressors of aquatic macrophytes in nearshore areas of lakes, such as docks and boat lifts. The third chapter provides a complementary analysis to chapter two by examining the relationships of shoreline development at different spatial scales with metrics describing macrophyte richness. The fourth and final chapter develops modeling techniques to quantify the relative effects of multiple stressors on the IBI. Specifically, I have used artificial neural network models that can 'learn' inherent data structures and are especially useful for modeling noisy data with non-linear relationships. Outcomes from my dissertation will inform management agencies on the most appropriate use of the index, which will ultimately facilitate the protection and restoration of Minnesota's lakes.