Shaw, E. C., A. J. Gabric, A. J. Miller and G. A. Tularam, 2012:
Chlorophyll variability in Hong Kong coastal waters: Spatial coherencies and relations to large-scale
climate variability
Journal of Geophysical Research-Oceans, sub judice.
Abstract.
Discerning the influence of climatic variability on phytoplankton dynamics within coastal
ecosystems is complex due to anthropogenic influences that also impact phytoplankton
growth. We analyzed a 17-year time series of water quality monitoring data from 1988-2004
in the coastal waters of Hong Kong to determine if climatic variability was an important
process driving phytoplankton variability. The relationship between chlorophyll a
concentration (CHL) and three major climatic modes (El Nino/Southern Oscillation, Pacific
Decadal Oscillation and North Pacific Gyre Oscillation (NPGO)) was examined using
empirical orthogonal function and correlation analyses. CHL variability was dominated by an
in-phase pattern across the whole study area suggesting that a large-scale forcing, such as
climate, that acts on the entire area may be driving CHL variability. CHL was strongly
correlated with the NPGO index (NPGOI), however a much longer time series will be
required to unequivocally determine if the NPGO is driving phytoplankton dynamics in Hong
Kong coastal waters. We suggest that the negative relationship between wind speed and
NPGOI may be a mechanism driving the positive relationship between the NPGOI and CHL.
Our findings show that climatic variability can be an important factor in determining
phytoplankton dynamics in coastal waters, even where they have been strongly influenced by
anthropogenic factors, such as cultural eutrophication.
Preprint (pdf)