MP3 Chronic and Sublethal Sediment Toxicity
254 Portland Ballroom
1:20 PM - 4:40 PM, Monday
() Establishment of a monoxenic free living marine nematoda culture and its availability for toxicity tests.
Oshima, Y1, Karmal, E2, Yomura, T1, Isobe, T1, Nagatake, M1, Shimasaki, Y1, Honjo, T1, 1 Kyushu University, Fac. of Agriculture, Fukuoka, Japan2 The Islamic University of Gaza, Gaza, Palestine
ABSTRACT- We successfully isolated a free marine nematoda, Prochromadorella sp.1, from seaweed collected along the coast of Japan, and established monoxenic and synchronized cultivation fed the diatom, Cylindrotheca closterium. (Patent submitted in Japan). This nematoda was identified according to Platt and Warwick′s (part II, 1988) pictorial keys, as Prochromadorella sp.1 (Chromadoridae, Adenophorea) and confirmed upon comparison to the 28S rDNA and 18S rDNA sequences of this nematoda, with its conspecific marine nematoda sequences obtained from the GenBank. Prochromadorella sp.1 attained their shortest generation times of 6 days in cultures of 25 ‰ and 30 °C. After egg hatching, Prochromadorella sp.1 underwent only three molts before maturing into adults. At 25 °C and 25‰ salinity, the average number of eggs deposited per female was approximately 250. Of the hatched eggs 82 % developed to the adult stage and the sex ratio (male:female) of the offspring was 2:3. The median lethal concentration (LC50) of Cd (96h), Cu (96h), and Zn (96h) and tributyltin (72h) were assessed as 2.2, 0.45, 2.0 and 0.26 mg/L, respectively. Chronic toxicities (50% inhibition of generation time) of Cu and Cd were estimated to 0.35 and 2.1 mg/L, respectively. Toxicity was also assessed in sediments collected from heavily contaminated coastal sites in Japan. These results demonstrate that Prochromadorella sp.1 is a suitable organism for toxicity testing in sediment and water.
Key words: diatom, marine nematoda, sediment, toxicity