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Advisor(s)
Abstract(s)
Alterations of freshwater flow regimes and
increasing eutrophication can lead to alterations
in phytoplankton biomass, composition, and
growth in estuaries and adjacent coastal waters.
Since phytoplankton is the first trophic level of
most aquatic foodwebs, these changes can be
propagated to other biological compartments,
eventually impacting water quality and
ecosystem services. However, phytoplankton
responses to environmental changes in abiotic
variables (e.g., light, nutrients) are additionally
controlled by mortality or removal processes
(e.g., grazing, horizontal advection and viral
lysis). Grazing exerted by microzooplankton,
usually dominated by phagotrophic protists, is
considered the most relevant phytoplankton
mortality factor in most aquatic systems (see
Calbet, Landry 2004). In fact, grazing impact of
microzooplankton can prevent phytoplankton
accumulation in marine systems despite an
overall increase in phytoplankton replication rate.
By consequence, microzooplankton grazing may
minimize problems associated to increased
eutrophication and, ultimately, prevent the
occurrence of harmful phytoplankton blooms.
Thus, microzooplankton grazing on phytoplankton
constitutes a key biological process
required to understand and predict
relationships between hydrological and
biological processes in aquatic ecosystems
and to use ecosystem properties to improve
water quality and enhance ecosystem
services, general principles of the
Ecohydrology Concept (Zalewski 2000).
Description
Keywords
Phytoplankton Microzooplankton grazing Dilution method Top-down control
Citation
Barbosa, AB and RB Domingues, 2009. Grazing impact of microzooplankton upon phytoplankton. In: Practical Experiments Guide for Ecohydrology, Eds.: L Chícharo, I Wagner, M Chícharo, M Lapinska and M Zalewski, UNESCO, 41-46 pp. ISBN: 978-989-20-1702-0.
Publisher
L Chícharo, I Wagner, M Chícharo, M Lapinska and M Zalewski