Toxic Effects of Naphthalene-Spiked Sediment to Freshwater Oligochaete Limnodrilus hoffmeisteri from Chao Phraya Estuary

Abstract

The lethal and sublethal effects of naphthalene-contaminated sediment to Limnodrilus hoffmeisteri were determined using a 96 h, static-toxicity test. It was found that naphthalene was highly toxic to worms with 72 and 96 h LC₅₀ values of 85.11 and 60.26 µg/g wet wt, respectively. The 96 h EC₅₀ values for autotomy and sediment avoidance were 35.48 and 58.88 µg/g wet wt, respectively. The 96 h LOEC reworking activity value was 25 µg/g wet wt which was more than two times lower than the LC₅₀. The results suggested the usefulness of L. hoffmeisteri as a test organism to determine the toxicity of sediment polluted with naphthalene. Changes of morphological features and in behavioral responses of the worm can be used as criteria for sublethal toxicity testing.