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Full-Text Articles in Terrestrial and Aquatic Ecology
Urea As An Effective Nitrogen Source For Cyanobacteria, Kevin J. Erratt
Urea As An Effective Nitrogen Source For Cyanobacteria, Kevin J. Erratt
Electronic Thesis and Dissertation Repository
Urea use has grown substantially in the past half-century, with urea now accounting for > 50% of nitrogen fertilizer applications worldwide. The shift from inorganic nitrogen fertilizers to urea-based sources has coincided with the reappearance of cyanobacteria blooms in freshwaters. Here, we examined urea as a nitrogen source for three bloom-forming cyanobacteria species. We found that (1) urea was consumed more rapidly relative to inorganic nitrogen substrates, suggesting that cyanobacteria exhibit a preference for urea; (2) urea was consumed in excess of cellular requirements; and (3) urea may offer cyanobacteria a competitive edge over eukaryotic algae by enhancing light absorption capabilities. …
The Mixed Source Chinook Salmon Fishery In Lake Huron: A Comparison Of Spawning And Foraging Habitat Use By Naturalized And Hatchery Fish, Stephen A.C. Marklevitz
The Mixed Source Chinook Salmon Fishery In Lake Huron: A Comparison Of Spawning And Foraging Habitat Use By Naturalized And Hatchery Fish, Stephen A.C. Marklevitz
Electronic Thesis and Dissertation Repository
Chinook salmon (Oncorhynchus tshawytscha) were introduced into the Great Lakes to restore top-down control of the food web and create new recreational fisheries. Soon after introduction, naturalized spawning populations became established, and with continued stocking of hatchery fish, created a mixed source fishery. My research provides new ecological information about the contributions of naturalized fish to the mixed source Chinook salmon fishery in Lake Huron. I examined spawning and foraging habitat use by naturalized and hatchery Chinook salmon using multiple methods to identify sources of individual fish (external tags, hatchery fin clips, and otolith microchemistry). In the Sydenham …