{"id":{"repo_id":"umn","oai_identifier":"oai:conservancy.umn.edu:11299/260109"},"canonical_url":"https://search.dev.ndltd.org/etd/umn/oai:conservancy.umn.edu:11299/260109","repository":{"repo_id":"umn","name":"University of Minnesota","base_url":"https://conservancy.umn.edu/server/oai/request"},"display":{"title":"Diel and horizontal patterns in the densities of Bythotrephes, Chaoborus, and Leptodora in a Minnesota Reservoir","abstract":"Understanding the simultaneous distributions of three invertebrate planktonic predators—Bythotrephes cederstroemii, Chaoborus punctipennis, and Leptodora kindtii—in one system can help describe food web dynamics and inform management decisions. The population densities of these three species were examined in a tannin-stained lake (Island Lake Reservoir, Duluth, MN, USA) on eight dates in 2020 and 2021. Four shallow to deep (nearshore to offshore) sites, ranging from 2-16 m, were sampled during the day and the same night to target diel movement and nearshore to offshore population density differences across seasons. Night population densities increased on average by 364% (Bythotrephes), 129% (Chaoborus), and 493% (Leptodora) compared to daytime densities. Increases were likely driven by reduced water column net avoidance and nighttime diel vertical migration from a daytime refuge. Differences in nearshore to offshore density were variable, with marginally significant differences in the Bythotrephes distribution during the night (larger nearshore) and significant differences in the Chaoborus distribution during the day (larger offshore). The nearshore to offshore densities at night may be controlled by food and predator avoidance. Contemporary zooplankton sampling practices that focus on daytime, pelagic collections may underestimate invertebrate predator densities, thus misrepresenting the roles of predatory invertebrates in food webs. Further analysis of day-to-night and nearshore-to-offshore distributions of Bythotrephes, Chaoborus, and Leptodora are necessary to explain the extent of these differences and how they may differ between tannin-stained and clear-water ecosystems.","abstract_html":"Understanding the simultaneous distributions of three invertebrate planktonic predators—Bythotrephes cederstroemii, Chaoborus punctipennis, and Leptodora kindtii—in one system can help describe food web dynamics and inform management decisions. The population densities of these three species were examined in a tannin-stained lake (Island Lake Reservoir, Duluth, MN, USA) on eight dates in 2020 and 2021. Four shallow to deep (nearshore to offshore) sites, ranging from 2-16 m, were sampled during the day and the same night to target diel movement and nearshore to offshore population density differences across seasons. Night population densities increased on average by 364% (Bythotrephes), 129% (Chaoborus), and 493% (Leptodora) compared to daytime densities. Increases were likely driven by reduced water column net avoidance and nighttime diel vertical migration from a daytime refuge. Differences in nearshore to offshore density were variable, with marginally significant differences in the Bythotrephes distribution during the night (larger nearshore) and significant differences in the Chaoborus distribution during the day (larger offshore). The nearshore to offshore densities at night may be controlled by food and predator avoidance. Contemporary zooplankton sampling practices that focus on daytime, pelagic collections may underestimate invertebrate predator densities, thus misrepresenting the roles of predatory invertebrates in food webs. Further analysis of day-to-night and nearshore-to-offshore distributions of Bythotrephes, Chaoborus, and Leptodora are necessary to explain the extent of these differences and how they may differ between tannin-stained and clear-water ecosystems.","abstract_has_math":false,"creators":["Corum, Megan"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2023,"date_issued":"2023-11","date_published":"2023-11","updated_at":"2026-07-24T05:19:54Z","subjects":["aquatic invasive species","bythotrephes","chaoborus","leptodora","Plan As (thesis-based master's degrees)","Master of Science","Master of Science in Water Resources Science","Swenson College of Science and Engineering","University of Minnesota Duluth"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/11299/260109","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Corum, Megan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2024-01-19T12:15:16Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2024-01-19T12:15:16Z"]},{"key":"dc:date.issued","label":"Date","values":["2023-11"]},{"key":"dc:type","label":"Dc Type","values":["Thesis or Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["aquatic invasive species","bythotrephes","chaoborus","leptodora","Plan As (thesis-based master's degrees)","Master of Science","Master of Science in Water Resources Science","Swenson College of Science and Engineering","University of Minnesota Duluth"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/11299/260109"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["University of Minnesota M.S. thesis. November 2023. Major: Water Resources Science. Advisor: Donn Branstrator. 1 computer file (PDF); vi, 34 pages."]},{"key":"dc:description.abstract","label":"Abstract","values":["Understanding the simultaneous distributions of three invertebrate planktonic predators—Bythotrephes cederstroemii, Chaoborus punctipennis, and Leptodora kindtii—in one system can help describe food web dynamics and inform management decisions. The population densities of these three species were examined in a tannin-stained lake (Island Lake Reservoir, Duluth, MN, USA) on eight dates in 2020 and 2021. Four shallow to deep (nearshore to offshore) sites, ranging from 2-16 m, were sampled during the day and the same night to target diel movement and nearshore to offshore population density differences across seasons. Night population densities increased on average by 364% (Bythotrephes), 129% (Chaoborus), and 493% (Leptodora) compared to daytime densities. Increases were likely driven by reduced water column net avoidance and nighttime diel vertical migration from a daytime refuge. Differences in nearshore to offshore density were variable, with marginally significant differences in the Bythotrephes distribution during the night (larger nearshore) and significant differences in the Chaoborus distribution during the day (larger offshore). The nearshore to offshore densities at night may be controlled by food and predator avoidance. Contemporary zooplankton sampling practices that focus on daytime, pelagic collections may underestimate invertebrate predator densities, thus misrepresenting the roles of predatory invertebrates in food webs. Further analysis of day-to-night and nearshore-to-offshore distributions of Bythotrephes, Chaoborus, and Leptodora are necessary to explain the extent of these differences and how they may differ between tannin-stained and clear-water ecosystems."]},{"key":"dc:title","label":"Title","values":["Diel and horizontal patterns in the densities of Bythotrephes, Chaoborus, and Leptodora in a Minnesota Reservoir"]}]}],"canonical_facts":{"dc:creator":["Corum, Megan"],"dc:date.accessioned":["2024-01-19T12:15:16Z"],"dc:date.available":["2024-01-19T12:15:16Z"],"dc:date.issued":["2023-11"],"dc:description":["University of Minnesota M.S. thesis. November 2023. Major: Water Resources Science. Advisor: Donn Branstrator. 1 computer file (PDF); vi, 34 pages."],"dc:description.abstract":["Understanding the simultaneous distributions of three invertebrate planktonic predators—Bythotrephes cederstroemii, Chaoborus punctipennis, and Leptodora kindtii—in one system can help describe food web dynamics and inform management decisions. The population densities of these three species were examined in a tannin-stained lake (Island Lake Reservoir, Duluth, MN, USA) on eight dates in 2020 and 2021. Four shallow to deep (nearshore to offshore) sites, ranging from 2-16 m, were sampled during the day and the same night to target diel movement and nearshore to offshore population density differences across seasons. Night population densities increased on average by 364% (Bythotrephes), 129% (Chaoborus), and 493% (Leptodora) compared to daytime densities. Increases were likely driven by reduced water column net avoidance and nighttime diel vertical migration from a daytime refuge. Differences in nearshore to offshore density were variable, with marginally significant differences in the Bythotrephes distribution during the night (larger nearshore) and significant differences in the Chaoborus distribution during the day (larger offshore). The nearshore to offshore densities at night may be controlled by food and predator avoidance. Contemporary zooplankton sampling practices that focus on daytime, pelagic collections may underestimate invertebrate predator densities, thus misrepresenting the roles of predatory invertebrates in food webs. Further analysis of day-to-night and nearshore-to-offshore distributions of Bythotrephes, Chaoborus, and Leptodora are necessary to explain the extent of these differences and how they may differ between tannin-stained and clear-water ecosystems."],"dc:identifier.uri":["https://hdl.handle.net/11299/260109"],"dc:language.iso":["en"],"dc:subject":["aquatic invasive species","bythotrephes","chaoborus","leptodora","Plan As (thesis-based master's degrees)","Master of Science","Master of Science in Water Resources Science","Swenson College of Science and Engineering","University of Minnesota Duluth"],"dc:title":["Diel and horizontal patterns in the densities of Bythotrephes, Chaoborus, and Leptodora in a Minnesota Reservoir"],"dc:type":["Thesis or Dissertation"]},"updated_at":"2026-07-24T05:19:54Z"}