Processes governing phytoplankton blooms in estuaries. II: The role of horizontal transport

Marine Ecology Progress Series
By: , and 



The development and distribution of phytoplankton blooms in estuaries are functions of both local conditions (i.e. the production-loss balance for a water column at a particular spatial location) and large-scale horizontal transport. In this study, the second of a 2-paper series, we use a depth-averaged hydrodynamic-biological model to identify transport-related mechanisms impacting phytoplankton biomass accumulation and distribution on a system level. We chose South San Francisco Bay as a model domain, since its combination of a deep channel surrounded by broad shoals is typical of drowned-river estuaries. Five general mechanisms involving interaction of horizontal transport with variability in local conditions are discussed. Residual (on the order of days to weeks) transport mechanisms affecting bloom development and location include residence time/export, import, and the role of deep channel regions as conduits for mass transport. Interactions occurring on tidal time scales, i.e. on the order of hours) include the phasing of lateral oscillatory tidal flow relative to temporal changes in local net phytoplankton growth rates, as well as lateral sloshing of shoal-derived biomass into deep channel regions during ebb and back into shallow regions during flood tide. Based on these results, we conclude that: (1) while local conditions control whether a bloom is possible, the combination of transport and spatial-temporal variability in local conditions determines if and where a bloom will actually occur; (2) tidal-time-scale physical-biological interactions provide important mechanisms for bloom development and evolution. As a result of both subtidal and tidal-time-scale transport processes, peak biomass may not be observed where local conditions are most favorable to phytoplankton production, and inherently unproductive areas may be regions of high biomass accumulation.

Publication type Article
Publication Subtype Journal Article
Title Processes governing phytoplankton blooms in estuaries. II: The role of horizontal transport
Series title Marine Ecology Progress Series
DOI 10.3354/meps187017
Volume 187
Year Published 1999
Language English
Publisher Inter-Research
Contributing office(s) California Water Science Center, San Francisco Bay-Delta, Toxic Substances Hydrology Program, Pacific Regional Director's Office
Description 14 p.
First page 17
Last page 30
Online Only (Y/N) N
Additional Online Files (Y/N) N
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