Estuarine nutrient loading affects phytoplankton growth and microzooplankton grazing at two contrasting sites in Hong Kong coastal waters

Bingzhang Chen, Hongbin Liu, Michael R. Landry, Mianrun Chen, Jun Sun, Loklun Shek, Xihan Chen, Paul J. Harrison

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

To investigate the effects of enhanced nutrient loading in estuarine waters on phytoplankton growth and microzooplankton grazing, we conducted monthly dilution experiments at 2 stations in Hong Kong coastal waters with contrasting trophic conditions. The western estuarine station (WE) near the Pearl River estuary is strongly influenced by freshwater discharge, while the eastern oceanic station (EO) is mostly affected by the South China Sea. Growth rates of phytoplankton were often limited by nutrients at EO, while nutrient limitation of phytoplankton growth seldom occurred at WE due to the high level of nutrients delivered by the Pearl River, especially in the summer rainy season. Higher chlorophyll a, microzooplankton biomass, phytoplankton growth and microzooplankton grazing rates were found at WE than at EO. However, the increase in chlorophyll greatly exceeded the increase in phytoplankton growth rate, reflecting different response relationships to nutrient availability. Strong seasonality was observed at both stations, with temperature being an important factor affecting both phytoplankton growth and microzooplankton grazing rates. Picophytoplankton, especially Synechococcus, also exhibited great seasonality at EO, with summer abundances being 2 or 3 orders of magnitude higher than those during winter. Our results confirm that in eutrophic coastal environments, microzooplankton grazing is a dominant loss pathway for phytoplankton, accounting for the utilization of >50% of primary production on average.

LanguageEnglish
Pages77-90
Number of pages14
JournalMarine Ecology Progress Series
Volume379
DOIs
Publication statusPublished - 30 Mar 2009

Fingerprint

pollution load
coastal water
grazing
phytoplankton
China
nutrient
nutrients
seasonality
chlorophyll
eutrophic environment
Synechococcus
summer
station
trophic conditions
brackish water
nutrient availability
nutrient limitation
primary productivity
wet season
estuaries

Keywords

  • grazing rates
  • microzooplankton
  • Pearl River estuary
  • phytoplankton
  • picoplankton

Cite this

Chen, Bingzhang ; Liu, Hongbin ; Landry, Michael R. ; Chen, Mianrun ; Sun, Jun ; Shek, Loklun ; Chen, Xihan ; Harrison, Paul J. / Estuarine nutrient loading affects phytoplankton growth and microzooplankton grazing at two contrasting sites in Hong Kong coastal waters. In: Marine Ecology Progress Series . 2009 ; Vol. 379. pp. 77-90.
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Estuarine nutrient loading affects phytoplankton growth and microzooplankton grazing at two contrasting sites in Hong Kong coastal waters. / Chen, Bingzhang; Liu, Hongbin; Landry, Michael R.; Chen, Mianrun; Sun, Jun; Shek, Loklun; Chen, Xihan; Harrison, Paul J.

In: Marine Ecology Progress Series , Vol. 379, 30.03.2009, p. 77-90.

Research output: Contribution to journalArticle

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