|Capello, H - UNIV. OF MISSISSIPPI|
|Ochs, C - UNIV. OF MISSISSIPPI|
Submitted to: American Society of Limnology and Oceanography
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2007
Publication Date: February 1, 2008
Citation: Capello, H.E., Ochs, C., Zimba, P.V. 2008. Phytoplankton Pigment Degradation Patterns in the Oxic and Hypoxic Regions of a Lake Water-Column. American Society of Limnology and Oceanography. Technical Abstract: Degradation of senescent phytoplankton occurs as cells sink through the water-column. Once below the photic zone or buried in the sediments, pigment degradation products may be used in paleolimnological studies to elucidate past phytoplankton community composition. Interpretation of the sediment pigment record can be problematic because decomposition processes of different kinds of pigments are not uniform. This research project tested the rates and patterns of degradation of four phytoplankton accessory pigments suspended in the oxic and hypoxic regions of a lake. Genera chosen for this experiment and their diagnostic pigments were: a centric diatom Cyclotella, fucoxanthin; a colonial chlorophyte Scenedesmus, lutein; a colonial cyanophyte Microcystis, myxoxanthophyll; and a filamentous cyanophyte Anabaena, aphanizophyll. Cultures were concentrated onto filters and deployed in 20-micrometer Nitex bags at two depths in a 4.5-m deep lake. The 1-m depth was always oxygenated whereas the 3.5-m depth was hypoxic from May to September. Pigment samples were collected at 2-6 week intervals for a year. Rates and patterns of degradation of each pigment were determined by analyzing changes in pigment spectral profiles using high-performance liquid chromatography.