Browsing by Author "Harren, Steven"
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Item The Effects of Fish Presence and Mixing Patterns on Water Clarity in Lakes: Arco, Deming, and Itasca(2010-04-12) Harren, Steven; Kartak, Jacob; Knight, Jonathan; Lehman, JustinIn the summer of 2009, in Itasca State Park, MN, samples of zooplankton, chlorophyll a concentrations, and Secchi disk readings were studied in three lakes with differing characteristics. Our study sites were Deming Lake (fish, meromictic), Arco Lake (fishless, meromictic), and Lake Itasca (fish, dimictic). Our variables of interest were the presence or absence of fish, and whether the lake was dimictic or meromictic. Our study showed that Arco Lake, a small meromictic fishless lake, had the highest Secchi disk reading. Along with a high level of water clarity there was an abundance of large zooplankton. We contributed this high level of clarity with the absence of fish, and its meromictic stratification. Lake Itasca showed its true dimictic characteristics in our data, showing relatively low fluctuations in temperature and dissolved oxygen levels.Item Quantitative and qualitative effects of Plains Pocket Gopher (Geomys bursarius) mound building on grassland vegetation in northwestern Minnesota.(2010-11-30) Harren, Steven; Gasteiger, Autumn; Kalmoe, MollyIt has been shown from previous studies that Geomys bursarius (plains pocket gopher) can have both short and long term affects on vegetation associated with their mounds. Our goal was to observe some of the effects of the plains pocket gophers on vegetation in their habitat. To see the effects of gopher mounds we took random samples of unique vegetative patches, surveyed random transects for mounds, and assessed plant diversity on gopher mounds compared to control plots in an abandoned farm field near Itasca Stat Park, MN. Our data was compared to findings of previous studies of the same area. We found that 77% of unique vegetation was associated with mounds while 23% was not. Mounds covered 9.8% of the field and had an average of 6.7 different species of plants compared with 3.18 in control plots. From our data and a comparative analysis of the previous research, we concluded that mounding by gophers does have both short and long term effects on prairie vegetation and its diversity.Item Small Mammal Diversity in Prairie and Forested Habitats In and Near Itasca State Park(2010-12-01) Harren, StevenIn Minnesota, small mammal diversity differs by habitat. The goal of the study was to examine small mammal diversity in forested and prairie habitats near Itasca State Park. We conducted a live trap study to determine animal diversity at each site. Between the sites, 11 different species were captured. The maximum number of different species on any one grid was four. We concluded that small mammal diversity differs by site and grid factors such as succession following a disturbance (e.g. fire) or moisture. Small mammals of Minnesota inhabit a wide variety of habitats throughout the state (Hazard, 1982). Because habitats differ, small mammal diversity will differ from one location to another. Often times, mammal diversity and populations will differ even within similar habitats due to disturbances and successional patterns following a disturbance (Huntly and Inouye, 1987). To study the diversity of small mammals within a community, trapping is the most practical way of establishing the presence and abundance of most small mammals (Williams and Braun, 1983). In this study, we examine the diversity of small mammals within different forest and prairie communities in and near Itasca State Park by live capture method. We expect to find some similar species in each of the different habitats (forest and prairie) because of the wide variety of niches that many small mammals occupy. We also expect to find that many of the species captured will be unique to one type of habitat or the other.