ScienceAsia 20 (1994): 085-099 |doi: 10.2306/scienceasia1513-1874.1994.20.085

EFFECTS OF SALINITY ON ACUTE TOXICITY OF LEAD NITRATE TO LARVAL STAGES OF GIANT FRESHWATER PRAWN, MACROBRACHIUM ROSENBERGII(DE MAN)

PIANSIRI PIYATIRATITNORAKUL^a, SOMKIAT PIYATIRATITNORAKUL^b THANAWAN PANICHPAT^a

ABSTRACT: An exploratory test for the acute toxicity of lead nitrate on early larval stages of Macrobrachium rosenbergii was carried out at salinity 15 ppt in a static water system. The median lethal concentrations (LD₅₀) of lead nitrate at 24, 48, 72 and 96 h were 35, 25, 15 and 1 ppm, respectively. These median lethal concentrations were then used as starting concentrations for determining combined effects of salinity and lead nitrate on survival of 4-day-old larvae (larval stage II), 14 day-old larvae (larval stage V), and 24 day-old larvae (larval stage VIII) of M. rosenbergii. The combined test was run under similar conditions to the exploratory test but at different salinities (from 5 to 25 ppt). For all stages of larvae, salinity showed a strong influence on larval survival. At salinities closed to 15 ppt, the larvae were more tolerant to lead nitrate toxicity than at other salinities. Toxicity of lead nitrate increased with increasing salinity and LD₅₀ varied with larval stages. The 14-day-old larvae were the most resistant to lead nitrate.

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a Department of Chemistry, Faculty of Science, Burapha University (Bang-saen), Amphoe Muang, Chon-buri 20131.
b National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Ministry of Science, Technology and Environment, Rama VI Road, Bangkok 10400.
c Department of Chemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand.

Received March 18, 1994