Browsing by Subject "Chironomidae"

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    Cumulative Effects of Coastal Watershed Land Use on Chironomidae (Insecta: Diptera) Communities of Neotropical Estuaries in Costa Rica
    (2017-07) Kranzfelder, Petra
    Chironomidae 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.
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    Emergence, survival, and longevity of adult Diamesa mendotae Muttkowski (Diptera: Chironomidae) in groundwater-fed streams
    (2013-06) Mazack, Jane Elizabeth
    Groundwater-fed streams, which remain cold in summer but ice-free in winter, provide ideal habitat for ultra-cold stenotherm insects. Diamesa mendotae Muttkowski (Diptera: Chironomidae) is a winter-active species common to groundwater-fed streams in Minnesota. In order to improve the understanding of the winter dynamics of this species, we studied the influence of temperature on its emergence, survival, and longevity. The winter emergence dynamics of D. mendotae and other winter-active chironomids were documented by collecting surface-floating pupal exuviae samples from 24 groundwater-fed streams in southeastern Minnesota. Early, mid, and late winter samples were collected from each stream, and mean water temperatures during the week preceding sample collection were estimated using air-water temperature regressions. The results of this assessment indicate that D. mendotae are influenced by both thermal stability and water temperature. Abundance of D. mendotae was positively related to air-water temperature regression slope in early and mid-winter; emergence was negatively related to water temperature in late-winter. Emergence patterns of other genera were related to estimated water temperatures, showing significant thermal partitioning within the chironomid community. Field collections of adult D. mendotae were used to determine survivorship under long-term exposure to controlled sub-freezing conditions. Batches of specimens were placed into a controlled treatment chamber at -5°C for between 7 and 70 days. Survivorship at constant sub-freezing temperatures was negatively related to treatment length, although some individuals survived sub-freezing temperatures for 70 days. Additionally, male D. mendotae had a significantly higher rate of survivorship than females within the same treatment. Post-treatment longevity decreased with increased exposure to sub-freezing temperatures; however, total longevity increased with treatment time. These studies indicate that D. mendotae is well adapted to the cold winter-weather conditions across southeastern Minnesota, suggesting that adults may be able to survive long periods of extreme temperature conditions in the winter to increase their ability to successfully reproduce. Groundwater inputs not only influence the thermal regime of streams in southeastern Minnesota's karst landscape, but also significantly impact chironomid community dynamics, which may play a significant role in the broader invertebrate and fish communities of these streams.
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    Exploring the hidden diversity of winter-emerging Chironomidae (Insecta: Diptera)
    (2021-12) Durnin, Tessa
    Chironomidae are a diverse family of flies found on every continent, including Antarctica. As immatures they occupy streams, rivers, lakes, and wetlands and emerge as terrestrial adults. They are biological indicators of water quality and have species-specific tolerance to pollution and disturbances. At least 5,000 species are described, however, projections estimate 20,000 chironomids when including cryptic and yet to be defined species. Cryptic species are one of two or more biological groups that are morphologically identical to one another, are incapable of interbreeding, and are genetically distinct. Driftless Area groundwater-dominated trout streams of southeastern Minnesota provide perfect habitat for cryptic chironomid diversity. During winter, these streams remain open and ice-free all season long because of constant inputs of relatively warm groundwater (~9° C), providing a stable environment in favor of morphological stasis, making the identification of closely related species difficult. Diamesa mendotae Muttkowski and D. nivoriunda Fitch are two commonly encountered winter-emerging chironomids of the Driftless Area. I used molecular methods to explore genetic diversity of these two winter-emerging flies. Cryptic winter-emerging chironomid identification will help sustain trout habitat conservation, create more accurate freshwater management practices, and advance our knowledge of Dipteran evolution.
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    Winter invertebrate dynamics in groundwater-fed streams in southeastern Minnesota, USA
    (2018-01) Mazack, Jane
    Southeastern Minnesota is characterized by Karst geology and trout streams. These groundwater-fed streams remain cool in summer and ice-free in winter, providing ideal habitat for trout and cold-adapted insects. Previous studies of winter-active insects have been localized or laboratory-based; however, the broader winter invertebrate community and its relationships to groundwater input are not well established. The goals of this research were to (1) assess the emergence patterns of winter-active chironomids (Diptera); (2) evaluate the effect of groundwater on the voltinism of the chironomid species Diamesa mendotae Muttkowski; (3) assess overall winter invertebrate community composition and abundance; and (4) describe the winter benthic chironomid community. Invertebrates were collected from 36 groundwater-fed streams over three winters (2010 - 2013). Surface-floating pupal exuviae (SFPE) collections were used to study the emergence patterns of cold-adapted chironomids, and Hess samples were used to evaluate winter benthic invertebrate composition and abundance. A total of 14 chironomid genera emerged from December through February; an additional 16 genera emerged in March. D. mendotae was the most commonly encountered and abundant winter-emerging chironomid, and emerged throughout the winter. Analysis of stream thermal regime indicated that D. mendotae complete multiple generations in a single winter in most streams. Benthic invertebrate communities were dominated by few taxa, with three chironomid genera (Diamesa, Orthocladius (Orthocladius), and Pagastia), two mayfly genera (Baetis and Ephemerella) and one caddisfly genus (Hydropsyche) comprising over 60% of individuals collected. Overall abundance was highest in thermally stable streams. Chironomids were abundant and diverse, with the winter-active species Diamesa mendotae dominating the community. We conclude that groundwater-fed streams (sensu Krider et al. 2013) in southeastern Minnesota support large, winter-active invertebrate communities, which are ecologically important to brown trout.
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    Winter warm spikes reduce cold-adapted insect longevity and reproduction
    (2022) Bodmer, Hannah; Nyquist, Corrie; Vondracek, Bruce; Ferrington, Len
    The aquatic fly family Chironomidae contains many cold-adapted, winter-active species in the Northern Hemisphere. Cold-adapted chironomid larvae develop underwater but emerge in winter as terrestrial adults to reproduce. Climate change will likely impact these winter-active adults as winter air temperatures increase. Previous studies have found constant exposure to high temperatures reduces survivorship of adult Diamesa mendotae, a cold-adapted chironomid in Minnesota. My research sought to understand how climate change could affect D. mendotae and other cold-adapted chironomids by exposing D. mendotae to high temperatures for short intervals. Here I show short-term exposure to high temperatures decreased adult D. mendotae longevity, reduced egg laying, and increased larval hatch success, but did not noticeably alter adult behaviors. Mean longevity of adult D. mendotae ranged from 14.7-24.3 days at constant 6°C, 12.3-16.8 days after exposure to 22°C for 24h, and 10.5-17.4 days after exposure to 22°C for 48h. D. mendotae eggs were also more likely to complete embryogenesis and hatch as larvae at constant 6°C than after 22°C exposure. However, D. mendotae exhibited similar behaviors over their lifespan in constant 6°C and 22°C exposure treatment groups. Taken together, I found impacts of winter short-term high temperature spikes on D. mendotae. Disruptions in D. mendotae and cold-adapted insect populations by winter warming may have broad ramifications f0r groundwater-fed stream ecosystems. This study highlights the need for further research on cold-adapted insect survivorship after short-term temperature spikes to understand seasonal impacts of climate change beyond mean annual temperature increases.
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    Winter-emerging chironomidae (Insecta: Diptera) in Minnesota trout streams
    (2012-12) Anderson, Alyssa Mae
    The Chironomidae (Diptera) is among the few aquatic insect families with species that are reliably able to grow, develop, and emerge as fully functional adults throughout the cold winter months that characterize the midwestern United States. However, few studies document their role in trout streams during this time of year. The intent of this dissertation is to enhance the field of Chironomidae research by focusing on the winter dynamics of these insects, including their response to severe flood events, their incorporation in the winter diet of trout, and the morphological and molecular description of three new cold-adapted Chironomidae species. The resistance and resilience of the winter chironomid community was assessed following a severe flood that impacted many streams in southeast Minnesota during the late summer of 2007. Methodology included collections of chironomid surface-floating pupal exuviae from 18 southeast Minnesota streams; streams were selected to include representation of localities that incurred moderate to extreme levels of flooding disturbance. These data were compared to data from the same localities during prior winters. Significantly more taxa emerged during the winter after late-summer flooding as compared to historic collections, and the number of species emerging in winter was positively correlated with rainfall severity, indicating the winter-active Chironomidae are resistant to late summer spates. This indicates that chironomids are an available winter food resource to stream trout recovering from devastating floods. In attempt to examine the importance of Chironomidae and other winter-active aquatic insects to the winter diet of brown trout (Salmo trutta L.), stomach contents were collected from trout inhabiting three southeast Minnesota streams; these data were compared to organisms collected in the stream drift and benthos. Results indicated that trout diets differ by stream and by fish size, with larger trout feeding heavily on Trichoptera and Physella, and smaller fish relying more on Gammarus and Chironomidae larvae. Stomach contents were more similar to the benthos than the drift, indicating a greater reliance on benthic feeding during winter. Trout in all streams selected Trichoptera and Chironomidae over other prey, and appeared to maintain sizeselective predation throughout winter. Winter-emerging Chironomidae appear to enhance the trout diet in all streams, and chironomid larvae were particularly dominant in the diet of one trout population. Three new chironomid species within the genus Micropsectra, a genus commonly found in the winter trout diet, were discovered from a study of five Minnesota streams. These species, Micropsectra neoappendica, n. sp., Micropsectra penicillata, n. sp., and Micropsectra subletteorum, n. sp., were described using morphological and molecular methods, along with one additional species, Micropsectra xantha Roback, which was redescribed. Two of the new species initially appeared identical to species known from the Palearctic, however molecular data indicated they are genetically distinct. Subsequently, reexamination of morphological characters revealed slight, but consistent diagnostic differences. These results emphasize the importance of using molecular tools in conjunction with traditional morphological techniques when studying Chironomidae diversity, especially when relying on diagnoses from other regions. The culmination of these studies sheds light on the dynamics of winter-emerging Chironomidae in southeastern Minnesota trout streams, their distribution and abundance, and the larger role they play in stream communities.