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Dissertation
Metaphyton mat conditions and their effects on filamentous algal communities and their diatom epiphytes
Doctor of Philosophy (Ph.D.), Drexel University
May 2009
DOI:
https://doi.org/10.17918/etd-3080
Abstract
Floating filamentous algal mats known as metaphyton form nuisance blooms in lentic waters and affect the use of these waters as well as nutrient cycling and food webs. Metaphyton initially form as benthic mats when water clarity and solar radiation are sufficient to produce buoyant oxygen bubbles that float the algae to the surface. At the surface the floating mats may experience high solar radiation, temperature, and water loss, but lower nutrients. I investigated the conditions and changes over 57 days within layers of floating filamentous mats by making measurements, with micoprobes every 2, 4, and 6 cm down through mats held in floating nets. Mats were then collected, filamentous algae and their diatom epiphytes were identified, enumerated, and analyzed for N, P, C, Si, AFDM and chlorophyll-a. Light intensity, temperature, dissolved oxygen, dry mass, and AFDM all dropped significantly with increasing depth in the mat. The dominant filament, Pithophora did not change over the sampling period, and there was almost no difference in dominance in the different layers, or at the center versus the edge of the mats. There was a decline in the condition of the filaments over time with the 2 cm layer showing the greatest decline. The 6 cm layer had the lowest biomass and concentrations of N, P, C, and Si over the sampling period but the highest chlorophyll-a:AFDM ratio. The diatom coverage per filament was significantly higher at the edge versus the center of the mat. The 2 cm layer showed the greatest downward trend in diatom coverage over the sampling period. The density of the diatoms Gomphonema, Cocconeis, and Fragilaria were significantly correlated with lower light intensity and layers of the mat. Cymbella/Encyonema density was significantly correlated with higher light intensity. Gomphonema, Cocconeis, and Nitzschia were positively correlated with filaments with higher chlorophyll-a content. Achnanthidium, Cymbella/Encyonema, and Nitzschia required higher levels of Si. Diatoms with different growth habits responded similarly to measured variables. Stalk-forming Gomphonema and adnate Cocconeis both occurred in lower light areas and grew well under low N and P conditions. Location within a mat affected filament condition and epiphyte genera.
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Details
- Title
- Metaphyton mat conditions and their effects on filamentous algal communities and their diatom epiphytes
- Creators
- Lynnette Lavery Saunders - DU
- Contributors
- Susan Soltau Kilham (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Bioscience and Biotechnology [Historical]; College of Arts and Sciences; Drexel University
- Other Identifier
- 3080; 991014632401504721