An individual-based model of pigment flux in lakes: implications for organic biogeochemistry and paleoecology

Authored by K Cuddington, PR Leavitt

Date Published: 1999

DOI: 10.1139/cjfas-56-10-1964

Sponsors: National Science and Engineering Research Council of Canada (NSERC)

Platforms: No platforms listed

Model Documentation: Other Narrative Flow charts

Model Code URLs: Model code not found

Abstract

Vertical fluxes of pigments are used in limnology to monitor phytoplankton abundance, herbivore grazing, ecosystem efficiency, and historical changes in production. However, significant pigment degradation can occur during algal sedimentation. We used an individual-based model of pigment flux to quantify the relative importance of production and degradation as controls of pigment sedimentation. Pigment deposition increased with production, sinking rate, and phytoplankton depth and declined as lake depth and the depth of oxygen penetration increased. Unexpectedly, pigment sedimentation rate was not sensitive to variation in photooxidation rates, even though bleaching accounted for the second greatest amount of pigment loss. Digestion by zooplankton caused the most pigment degradation, but grazing increased pigment deposition when digestive losses were less than those due to oxidation of pigments in ungrazed cells. The model suggests that algal production may be underestimated in sedimentation studies that do not consider variability in water column depth. Further, comparisons with paleoecological analyses suggest that some inferred increases in production during lake ontogeny may arise from changes in regulation of pigment fluxes rather than from increased algal production.

Tags

Error analysis Fossil pigments Sedimentary pigments Northwestern ontario Sensitivity analysis Chlorophyll budgets Aquatic pigments Computer-models Trophic status Fecal pellets