Aquaculture International

, Volume 22, Issue 2, pp 321–338

Environmental persistence of chlorine from prawn farm discharge monitored by measuring the light reactions of photosynthesis of phytoplankton

  • Panthida Saetae
  • Sakshin Bunthawin
  • Raymond J. Ritchie
Article
  • 313 Downloads

Abstract

Chlorine (reactive chlorine: Cl2+OCl) is used as a disinfectant on prawn farms but the environmental effects of discharged chlorine is of environmental concern. Toxicity of chlorine on prawn farm phytoplankton populations was monitored using the pulse amplitude fluorometer technique to measure phytoplankton photosynthesis. The dominant phytoplankton species found in the ponds of a prawn farm in Pang-Nga Province (Thailand) were Chlorella sp. (>95 %), with some Tetraselmis and Chaetoceros. Cells were suspended in clean sea water with (chlorine) of 15, 30, 45, 60, 75 and 90 ppm, respectively, in short-term experiments for 10 min (ST) and for long-term (24 h) exposure. Photosynthesis of Chlorella, Tetraselmis and Chaetoceros in clean sea water was inhibited by 50 % at (chlorine) of 4.68 ± 0.6, 7.26 ± 1.14 and 7.81 ± 0.78 ppm (mean ± SEM), respectively, in ST experiments. The chlorine consuming reactions with the large amounts of dissolved organic matter and ammonia in prawn farm pond water decreases toxicity but would form organochlorines and chloramine. Thiosulphate, often used to neutralise chlorine, was found to be of very limited toxicity to Chlorella in both short-term 1-h and 24-h experiments (up to ≈500 mmol m−3, 124 ppm). Environmental effects of Chlorine in discharges from ponds are short term. Chlorine quickly disappears in the environment, particularly during daylight and so only has effects close to effluent points. Standard practice was to discharge on a falling tide in daylight. The long effluent channel (1 km) also ensured that very little reactive chlorine reached the estuary.

Keywords

Gross photosynthesis ETR Light curves Pond phytoplankton PAM fluorometry Chlorine toxicity Iodine toxicity Aquaculture Environmental effects 

Abbreviations

ΦPSII

is the effective quantum yield (Fv/Fm)

E

Irradiance (mol m−2 s−1) PPFD

ETR

Electron transport rate

PAM

Pulse amplitude modulation fluorometry

PPFD

Photosynthetic photon fluence density (400–700 nm)

Pg

Gross photosynthesis

PSII

Photosystem II

Supplementary material

10499_2013_9642_MOESM1_ESM.docx (21 kb)
Supplementary material 1 (DOCX 21 kb)
10499_2013_9642_MOESM2_ESM.pptx (85 kb)
Supplementary material 2 (PPTX 84 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Panthida Saetae
    • 1
  • Sakshin Bunthawin
    • 1
  • Raymond J. Ritchie
    • 1
  1. 1.Tropical Plant Biology, Faculty of Technology and EnvironmentPrince of Songkla UniversityPhuketThailand

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