Romano, Nicholas, and Zeng, Chaoshu (2009) Evaluating the newly proposed protocol of incorporated potassium in nitrate toxicity experiments at different salinities: a case study with the tiger prawn, Penaeus monodon, juveniles. Aquaculture, 289 (3). pp. 304-309.

PDF (Published Version) Restricted to Repository staff only

 

31

2

Abstract

Many aquaculture species may be cultured in a wide range of salinities and therefore determining their acute nitrate tolerance at different salinities can benefit the industry. Recently a new protocol of incorporating K+ in the NaNO3-N stock solution was proposed to help balance the Na+/K+ ratio of the test solutions to provide more accurate nitrate toxicity results for marine animals. However, the relative effectiveness of this protocol at different salinities is unclear. This protocol was hence tested by comparing the NaNO3-N LC50 values of the euryhaline tiger prawn, Penaeus monodon, juveniles at different salinities when K+ was either added or not added to the NaNO3-N stock solution. Experiments were carried out at 3 salinity levels of 15, 25 and 35‰. At each salinity level, 6 nitrate concentrations of, 1000, 1500, 2000, 2500, 3000 and 3500 mg L-1 NaNO3-N were prepared with or without added K+ to the stock solution. Each treatment and control were triplicated and mortality observations were made at 12-h intervals for 96-h to determine the LC50 values. Comparing the respective past and new protocol, K+ additions significantly increased the LC50 values in the 15‰ (1411 mg L-1 vs. 1878 mg L-1) although no significant differences were detected at 25‰ (2020 mg L-1 vs. 2297 mg L-1) or 35‰ (2213 mg L-1 vs. 2337 mg L-1). This result was likely due to the added K+ preventing exponential increase to the Na+/K+ ratios at 15 ‰, however this new protocol was less effective to these ratios at salinities of 25 and 35 %«.. The results of current experiments, together with previous experiments on marine crabs,suggestthat while the addition of K+ to the NaNO3-N stock solution should be viewed as standard protocol for future acute nitrate toxicity test on marine animals, it is more crucial at low salinities and/or high NaNO3-N concentrations.

Actions (Repository Staff Only)

Item Control Page