Chronic effects of suspended solids on gill structure, osmoregulation, growth, and triiodothyronine in juvenile green grouper Epinephelus coioides

D. W. T. AU, C. A. POLLINO, Shiu Sun Rudolf WU, P. K. S. SHIN, S. T. F. LAU, J. Y. M. TANG

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Abstract

Despite suspended solids being an important water-quality parameter in the regulatory process, very little is known about the risks of prolonged exposure to high concentrations of suspended solids in fish, especially marine species. In this study, the green grouper Epinephelus coioides, an important mariculture species with a wide geographic distribution, was exposed to various concentrations (0, 50, 100, 200, 1000 and 2000 mg l-1) of suspended solids for 6 wk. The results showed that exposure was not lethal at environmentally realistic concentrations, and no changes in food intake, growth and RNA:DNA ratio were observed. However, damages to gill structure, including epithelium lifting, hyperplasia in the pillar system, and reduction of epithelial volume, were clearly evident, and strongly correlated with suspended solid concentration exposure. Despite the observation that serum osmolarity and haematocrit values did not change, Na+, K+-ATPase activities and chloride cells of the gill lamellae were altered, indicating that fish were experiencing osmoregulatory stress. Reduction in levels of free triiodothyronine (T3) in serum further confirmed that fish were experiencing physiological stress with suspended solids exposure. The overall results suggested that prolonged exposures can cause sub-lethal stress and compromise fish health, even though the high suspended solids we delivered were in concentrations that have been reported in coastal environments as not lethal to green grouper. Copyright © 2004 Inter-Research.

Original languageEnglish
Pages (from-to)255-264
JournalMarine Ecology Progress Series
Volume266
DOIs
Publication statusPublished - Jan 2004

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Epinephelus coioides
osmoregulation
grouper
triiodothyronine
long term effects
gills
lethal genes
fish
serum
RNA-DNA ratio
fish health
mariculture
sodium-potassium-exchanging ATPase
osmolarity
food intake
pillar
hyperplasia
marine fish
hematocrit
coastal zone

Citation

Au, D. W. T., Pollino, C. A., Wu, R. S. S., Shin, P. K. S., Lau, S. T. F., & Tang, J. Y. M. (2004). Chronic effects of suspended solids on gill structure, osmoregulation, growth, and triiodothyronine in juvenile green grouper Epinephelus coioides. Marine Ecology Progress Series, 266, 255-264. doi: 10.3354/meps266255

Keywords

  • Suspended solids
  • Grouper
  • Gill structure
  • Triiodothyronine
  • Osmoregulation
  • Growth
  • RNA:DNA ratio