A COMPARISON OF EASTERN AND WESTERN HONG KONG PHYTOPLANKTON FROM WEEKLY SAMPLES (1997-1999) |
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摘 要: |
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关 键 词: | 浮游植物 硅藻类 赤潮 香港特别行政区 标本 中国南海 |
收稿时间: | 13 July 2000 |
修稿时间: | 26 June 2001 |
A comparison of eastern and western Hong Kong phytoplankton from weekly samples (1997–1999) |
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Authors: | Mike Dickman Tang Sen-ming Jessie Lai |
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Institution: | (1) 221 South 12th Ave., 59715 Bozeman, Montana, USA;(2) Institute of Geography and Limnology, Chinese Academy of Sciences, 210008 Nanjing, China;(3) Ecology and Biodiversity Dept., The University of Hong Kong, Pokfulam Rd., Hong Kong |
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Abstract: | Weekly phytoplankton samples were taken from western Hong Kong (Lamma) from Jan. 1997 to Dec. 1999 and from Port Shelter in
Eastern Hong Kong from January 1998 to December 1999. During that time diatom blooms occurred repeatedly at both sites but
never in synchrony. One species would bloom at one site and then weeks later it or another species would bloom at the other
site; while the 1998 red tide of the mucus producing dinoflagellateGymnodinium mikimotoi occurred at both sites. It first occurred at the Port Shelter site in March and did not appear at the Lamma site until April.
With the single exception of this species, no other dinoflagellate reached bloom concentrations at the Lamma site. In addition,
dinoflagellate abundance at the Lamma site was significantly lower (P<0.05) than that at the Port Shelter site. This was correlated
with a significantly higher turbidity (i. e. low Secchi transparency) and higher turbulence (stronger currents) at the Lamma
site.
Annual variation in surface temperature correlated with total surface phytoplankton abundance at both our sample sites. Phytoplankton
abundance increased in spring as water temperatures warmed. In fall, as surface water temperatures began to decline and the
monsoon rains became less frequent there was a reduction in phytoplankton abundance associated with the reduction in temperature
and light. Because so many variables co-occur with temperature (e. g. the amount of rainfall light intensity and light duration
etc.) it is not possible to cite temperature as the causal factor associated weth controlling phytoplankton abundance at our
two sample sites.
Our data support the rather controversial notion that percentage-wise, there are relatively more harmful bloom forming species
in nutrient-rich coastal waters than there are in the world's oceans. 16% of the dinoflagellate species and 10.3% of the diatom
species observed at our two sample sites were classed as harmful. These percentages were higher than those cited by Sournia
(1995) for the worlds oceans (9.6% and 6.8% respectively). This raises the possibility that there are relatively more toxic
species in the nutrient-rich coastal waters of the world than there are in the mid ocean nutrient-poor areas of the world.
Some reasons for this are briefly discussed. |
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Keywords: | red tides phytoplankton periodicity South China Sea harmful algal blooms |
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