Scholarship & Research
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/1
Browse
13 results
Search Results
Item Long-term and over winter phytoplankton community dynamics in Lake Bonney, Antarctica(Montana State University - Bozeman, College of Agriculture, 2017) Patriarche, Jeffrey Dennis; Chairperson, Graduate Committee: John C. PriscuLake Bonney is a hypersaline permanently ice-covered lake in the Taylor Valley, Antarctica that hosts simplified microbial food-webs. Studied since the 1960s, there are many aspects which are poorly understood. Logistical constraints have prevented sampling during the austral winter, a 4-month period of 24-hour darkness. Our knowledge of how the resident photosynthetic microorganisms respond during this period is limited. With inputs from ephemeral glacial-melt streams the lake level (stage) of Bonney has risen more than 3 m since 2004. With no outflow streams, the only known water loss is via ablation of the permanent ice-cover. A study of the spatial and temporal changes in the phytoplankton community structure during this period of rapid lake level rise is lacking. During the summers (November-January) from 2004-05 to 2014-15 an in situ submersible spectrofluorometer was deployed in Lake Bonney to quantify the chlorophyll-a concentrations (microgram L -1) of four functional groups of microalgae (green algae, brown/mixed algae, cryptophytes, cyanobacteria) using known excitation/emission spectra. During the 2013-14 field season this same instrument was mounted on autonomous cable-crawling profilers deployed in both east and west lobes of Lake Bonney, obtaining the first ever daily profiles of chlorophyll-a concentration at an annual scale. Following a summer of rapid lake level rise (2010-11), an increasing trend in depth integrated chlorophyll-a concentration was observed in Lake Bonney. During the same period, the nutrient poor surface water has become increasingly dominated by green algae. Dramatic shifts were also observed in the phytoplankton communities during the polar night. The highest concentrations of mean chlorophyll-a were measured during the 24-hour darkness. Algal spectral groups containing species capable of a mixotrophic metabolism (brown/mixed and cryptophytes) increased in concentration and relative abundance when photosynthetically active radiation was unavailable. This work provides valuable contributions to our knowledge of long-term and year-round phytoplankton community dynamics in Lake Bonney, and improves our understanding of the metabolic strategies employed by organisms in this high latitude permanently ice-covered lake.Item Canyon Ferry Reservoir zooplankton population dynamics(Montana State University - Bozeman, College of Agriculture, 1975) Martin, Chadwick LeeItem An investigation into the trophic status of Canyon Ferry Reservoir, Montana(Montana State University - Bozeman, College of Agriculture, 1974) Rada, Ronald GeorgeItem Effects of toxaphene upon plankton and aquatic invertebrates in North Dakota lakes(Montana State University - Bozeman, College of Letters & Science, 1962) Needham, Robert G.Item Changes in zooplankton species composition in newly filled Bighorn Lake, Montana and Wyoming(Montana State University - Bozeman, College of Agriculture, 1977) Horpestad, Abraham AndrewItem Spatial and temporal variations of phytoplankton populations in Lake Bonney, Antarctica(Montana State University - Bozeman, College of Agriculture, 2003) Tursich, Nicole LeaItem Biological cycling of nitrogen in a Rocky Mountain alpine lake, with emphasis on the physiological and ecological effects of acidification(Montana State University - Bozeman, College of Letters & Science, 1989) Angelo, Robert ThomasItem The population dynamics and production of the net zooplankton in Georgetown Lake, Montana in 1974(Montana State University - Bozeman, College of Agriculture, 1977) Geer, William HerbertItem Population dynamics of rotifers and some factors affecting their populations in Canyon Ferry Reservoir, Montana(Montana State University - Bozeman, College of Agriculture, 1971) Kaiser, Gerald LynnItem Some limnological effects of Tiber Reservoir on the Marias River(Montana State University - Bozeman, College of Letters & Science, 1962) Stober, Quentin J.