Barramundi Stocks Clive Keenan data

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Effects of Tributyltin on the Chlorophyll
Contents of microalgae Tetraselmis tetrathele,
Nannochloropsis and Dunaliella sp
Natalie D. Rumampuk and Inneke F. M.
Rumengan Sam Ratulangi University
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Background

• Environmental concern about the utilization of
  TBT as antifouling biocide and plastic stabilizer
• The role of phytoplankton in both primary
  production and nutrient recycling.
• Any adverse effects of TBT on phytoplankton may
  potentially lead to food chain transfer or
  biomagnification

An acute toxicity test of TBT to microalgae was
conducted with emphasis on the chlorophyll a and
b contents
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TBT in water
Soluble up to concentrations of tens to
hundreds of mg.l-1, depending on the compound
used and on salinity and content of particulate
matter of the medium. Once dissolved, the
tributyltin cation is in equilibrium with the
neutral hydroxytributyltin TBTOH, and, in
seawater, with the neutral unpolar TBTCl species,
which will tend to sorb to particles.  
TBTCl
TBTOH
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TBT exposure

• Standard TBT solution purchased by Kanto Chemical
  Co.Inc. Japan

• Tested concentrations
• 0.1 ug.l-1
• 0.5 ug.l-1
• 1.0 ug.l-1

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Mircoalgae

• Three representative species of microalgae

• Tetraselmis tetrathele
• (Chlorophyta Prasinophyceae, 170 pg/cell,
  8x16 ?m)
• Nannochloropsis oculata (10 pg/cell)
• (Chlorophyta-Eustigmatophycea, 10 pg/cell,
  1,8x1.2 ?m)
• Dunaliella sp
• (Chlorophyta-Chlorophyceae)

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Algal preparation
Hirata Medium
6h-TBT Exposure
Determination of Chlorophyll a and b
200 ml
0.5
1.0
?g.L-1
0.1
0
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Chlorophyll a and b
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Chlorophyll Absorbance
b
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Chlorophyll determination
Culture of Microalga
TBT exposure
Filtration
Calculation of Chlorophyll a and b in ug.ml-1 (
90 Acetone) Chl a (11.93OD664)-(1.93OD647)
Chl b (20.36OD647)-(5.5OD664)
Debris
Filtrate
Precipitate
Supernatant
Extract
Spectrophotometer (Chlorophyll a ?664
Chlorophyll b ?647)
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Results Chl a contents
T. tetrathele
N. oculata
Chl. a (µg.ml-1)
Dunaliella
0.1
0
0.5
1.0
TBT concentration (µg.l-1)
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Results Chl b contents
T. tetrathele
N. oculata
Chl. b (µg.ml-1)
Dunaliella
0.1
1.0
0
0.5
TBT concentration (µg.l-1)
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Effects of TBT
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Conclusions

• No adverse effects of TBT (from 0.1 to 1 ?g.l-1)
  on the chlorophyll contents of T. tetrathele
  after very short exposure time, but for N.
  oculata and Dunaliella sp 0.5 ?g.ml-1 of TBT had
  been a critical level.
• Exposure to TBT induces species-specific
  responses. N. oculata and Dunaliella sp are more
  sensitive than T. tetrathele
• TBT concentration and exposure time are the major
  determinants

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Recommendation

• Further studies required are
• Acute and chronic toxicity tests of TBT to a wide
  variety of phytoplankton with respect in
  chlorophyll synthesis and other biological
  parameters.
• Possible alternative assay that would allow
  detection of effects of more range of TBT in
  different exposure periods
• Biodegradation, biotransformation and successive
  biomagnifications of TBT in microalgae would
  provide valuable information for assessing
  toxicant-transferring along trophic levels from
  the basic level.