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Processes governing phytoplankton blooms in estuaries. I: The local production-loss balance

Marine Ecology Progress Series

By:
, , , , and
DOI: 10.3354/meps187001

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Abstract

The formation and spatial distribution of phytoplankton blooms in estuaries are controlled by (1) local mechanisms, which determine the production-loss balance for a water column at a particular spatial location (i.e. control if a bloom is possible), and (2) transport-related mechanisms, which govern biomass distribution (i.e. control if and where a bloom actually occurs). In this study, the first of a 2-paper series, we use a depth-averaged numerical model as a theoretical tool to describe how interacting local conditions (water column height, light availability, benthic grazing) influence the local balance between phytoplankton sources and sinks. We also explore trends in the spatial variability of the production-loss balance across the topographic gradients between deep channels and lateral shoals which are characteristic of shallow estuaries. For example, under conditions of high turbidity and slow benthic grazing the highest rates of phytoplankton population growth are found in the shallowest regions. On the other hand, with low turbidity and rapid benthic grazing the highest growth rates occur in the deeper areas. We also explore the effects of semidiurnal tidal variation in water column height, as well as spring-neap variability. Local population growth in the shallowest regions is very sensitive to tidal-scale shallowing and deepening of the water column, especially in the presence of benthic grazing. A spring-neap signal in population growth rate is also prominent in the shallow areas. Population growth in deeper regions is less sensitive to temporal variations in tidal elevation. These results show that both shallow and deep regions of estuaries can act as sources or sinks for phytoplankton biomass, depending on the local conditions of mean water column height, tidal amplitude, light-limited growth rate, and consumption by grazers.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Processes governing phytoplankton blooms in estuaries. I: The local production-loss balance
Series title:
Marine Ecology Progress Series
DOI:
10.3354/meps187001
Volume
187
Year Published:
1999
Language:
English
Publisher:
Inter-Research
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Marine Ecology Progress Series
First page:
1
Last page:
15