Effects of chronic nitrite exposure on gonad growth in green sea urchin Strongylocentrotus droebachiensis

The effects of nitrite concentration on Gonad growth and feed intake in green sea urchin Strongylocentrotus droebachiensis were examined. In the first experiment, adult sea urchins with a mean [standard deviation (S.D.)] live weight of 52.0 (17.2) Q were exposed to four concentrations of nitrite [0, (control), 0.6 (low), 1.0 (medium) and 2.0 mg N-NO2 1(-1) (high)] for 21 days at 9.0 degreesC. salinity 33 ppt and pH 8.0. In the second experiment. adult sea urchins with a mean (S.D.) live weight of 57.6 (16.2) g were exposed to four concentrations of nitrite [0. (control). 2.0 (low). 4-8 (medium) and 10.0 mg N-NO2 1(-1) (high)] for 42 days at 9.2 degreesC: 33 ppt and pH 8.0. No mortality occurred in any of the experimental groups throughout the study. Gonad growth was significantly reduced by increased nitrite concentrations, with reduced gonadal indices already being apparent at 0.5 mg N-NO2 1(-1). No significant difference in feed intake was observed between treatment groups. The reduction in gonad growth was not attributed to a decrease in feed intake but rather to impaired food conversion efficiency. The present study demonstrates that adult green sea urchins show low tolerance to nitrite and are unable to maintain high gonad growth facing such conditions. (C) 2004 Elsevier B.V. All rights reserved.