Long-term changes in hydrography, nutrients and phytoplankton in Tolo Harbour, Hong Kong

Yung, Y.-K.; Wong, Carmen; Broom, Mark; Ogden, John A.; Chan, Sze Wa; Leung, Yiu-Wing

doi:10.1007/978-94-011-5234-1_12

Cited by 17 publications

(29 citation statements)

References 3 publications

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“…Increased eutrophication led to changes in the characteristics of the phytoplankton community. Hodgkiss and Chan (1983) reported a trend of gradual replacement of diatoms by dinoflagellates, although a longterm survey carried out between 1982 and 1992 showed that the phytoplankton in Tolo Harbour was still dominated by diatoms (Yung et al, 1997). Information on the abundance and species composition of the phytoplankton populations is important because long-term changes can serve as indicators of water quality and eutrophication (Lam and Ho, 1989).…”

Section: Introductionmentioning

confidence: 98%

Study of phytoplankton characteristics in Tolo Harbour, Hong Kong, by HPLC analysis of chemotaxonomic pigments

Wong

2004

J Appl Phycol

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Spatial and seasonal characteristics of phytoplankton in Tolo Harbour, Hong Kong, were studied by microscopic observation of phytoplankton samples and HPLC analysis of chemotaxonomic pigments. Diatoms dominated the phytoplankton. Common diatoms included Skeletonema costatum and species of Cerataulina, Leptocylindrus, Pseudo-nitzschia and Thalassiosira. Dinoflagellates occurred sporadically and mainly in the inner part of the harbour. The dinoflagellate Scrippsiella trochoidea was the causative organism for the red tide occurrences in March, April and September 2001. Significant positive correlations between fucoxanthin and diatoms and between peridinin and dinoflagellates suggested that fucoxanthin and peridinin were valuable chemotaxonomic markers for diatoms and dinoflagellates, respectively. Analysis of pigment ratios revealed that red tide events caused by dinoflagellates were marked by increase in the value of PERI:chl a and decrease in the value of FUCO:chl a. Increase in the value of FUCO:chl a also revealed the presence of a dense population of Pseudo-nitzschia that was not indicated by increase in chlorophyll a and fucoxanthin concentrations. Pigment analysis also revealed the presence of cyanobacteria, silicoflagellates, cryptophytes and green algae in the surface waters of Tolo Harbour.

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Section: Introductionmentioning

confidence: 98%

Study of phytoplankton characteristics in Tolo Harbour, Hong Kong, by HPLC analysis of chemotaxonomic pigments

Wong

2004

J Appl Phycol

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“…It is relatively unpolluted and contains 2 marine parks and most of the coral beds in Hong Kong. The availability of long-term data on phytoplankton composition and physio-chemical variables (Yung et al 1997) makes the 2 sites good candidates for studying the diversity of picoeukaryotes.…”

Section: Introductionmentioning

confidence: 99%

Genetic diversity of picoeukaryotes in a semi-enclosed harbour in the subtropical western Pacific Ocean

Cheung¹,

Chu²,

Li³

et al. 2008

Aquat. Microb. Ecol.

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Picoeukaryotes (< 2 to 3 µm) are important components of aquatic ecosystems. The genetic diversity and seasonal variability of marine picoeukaryotes were compared between a semienclosed harbour and the adjacent open sea off the subtropical coast in the western Pacific Ocean based on 18S rRNA clone library analysis. Examination of 733 clones revealed 186 different restriction fragment length polymorphism (RFLP) patterns, representing 186 operational taxonomic units (OTUs). At least 19 high-level taxonomic groups of picoeukaryotes were recorded. Alveolates group II, ciliates and stramenopiles comprising 37, 17 and 11% of the picoeukaryotes, respectively, were the most dominant groups. Phototrophs such as prasinophytes, cryptophytes and haptophytes were retrieved occasionally. Members from the 2 newly defined phyla, picobiliphytes and Telonemia, were also obtained. A differential spatial distribution of OTUs was observed between samples collected from the 2 sampling sites. Seasonal variations in picoeukaryote composition were more pronounced in the open sea libraries than in the semi-enclosed harbour libraries. MATERIALS AND METHODSSample collection. Surface seawater samples (~2.5 l) were collected from stations in Tolo Harbour (22°26' N, 114°13' E) and Mirs Bay (22°30' N, 114°21' E) in January, April, July and October 2006 (Fig. 1). Immediately after collection, the water samples were filtered through a 200 µm mesh sieve to remove most of the mesozooplankton and large particles. Water temperatures, salinities and dissolved oxygen (DO) levels were measured on board ship using a HydroLab sensor. In the laboratory, chlorophyll a (chl a) concentrations were determined using a Turner Designs 10-AU fluorometer as described in Wong & Wong (2003). Diatom and dinoflagellate concentrations were determined by counting them under an inverted microscope. Two litres of water were prefiltered through 3 µm pore size Nuclepore ® membranes (Whatman) and the microbial biomass was then collected onto a GF/F filter (Whatman). A gentle vacuum (< 20 cm Hg) created by a hand pump was used to facilitate the filtration processes. The filter was then immersed in DNA lysis buffer (0.75 M sucrose, 40 mM EDTA, 50 mM Tris-HCl, pH 8), immediately frozen in liquid nitrogen and stored at -80°C until DNA extraction.DNA extraction and PCR. DNA was extracted using a cetyltrimethylammonium bromide (CTAB) extraction procedure (Doyle & Doyle 1990). Extracts were purified with the Geneclean ® II Kit (Q-BIOgene) and then stored at -20°C until use. The 18S rRNA gene was amplified by PCR using the eukaryotic primers Euk328f (5'-ACC TGG TTG ATC CTG CCA G-3') and Euk329r (5'-TGA TCC TTC YGC AGG TTC AC-3') complementary to regions of conserved sequences proximal to the 5' and 3' termini of the 18S rRNA gene (Moon-van der Staay et al. 2000, Romari & Vaulot 2004. Each PCR mixture (50 µl) contained 2 µl of DNA template, 5 µl of 10× PCR buffer (50 mM KCl, 10 mM Tris-HCl and 1.5 mM MgCl 2 ), 200 µM of dNTP, 0.2 µM of each primer and 2.5 U Taq polymerase ...

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“…The frequency of red tides in these waters has been suggested to be related to an increase in the human population (Lam & Ho 1989), nutrient inputs (Holmes 1988, Wong 1989 and N:P ratios (Hodgkiss & Ho 1997). However, the cause of red tides is still controversial (Yung et al 1997). In Hong Kong, there has been a monitoring program for red tides since the 1980s and water quality has also been monitored since the 1990s.…”

Section: Introductionmentioning

confidence: 99%

Influence of monsoons and oceanographic processes on red tides in Hong Kong waters

Yin¹

2003

Mar. Ecol. Prog. Ser.

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Long-term changes in hydrography, nutrients and phytoplankton in Tolo Harbour, Hong Kong

Cited by 17 publications

References 3 publications

Study of phytoplankton characteristics in Tolo Harbour, Hong Kong, by HPLC analysis of chemotaxonomic pigments

Study of phytoplankton characteristics in Tolo Harbour, Hong Kong, by HPLC analysis of chemotaxonomic pigments

Genetic diversity of picoeukaryotes in a semi-enclosed harbour in the subtropical western Pacific Ocean

Influence of monsoons and oceanographic processes on red tides in Hong Kong waters

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