Hebei spirit 사고 2년후, 유류유출 지역에 서식하는 개울타리고둥 (Monodonta labio confusa)의 생리와 번식에 관한 연구

Abstract

In an attempt to understand effects of the Hebei spirit oil spill on benthic invertebrate animals 2 years after the accident, the annual reproductive cycle of the toothed top shell, Monodontalabioconfusa (Tapparone-Canefri, 1874) occurring at a rocky intertidal in Taean oil spill site was investigated using histology. For histological analysis, the top shells at the oil spill site were collected monthly from April 2010 to April 2011. As a control, the annual reproductive cycle of the same population distributed in Incheon bay was also collected and analyzed monthly. Size of the toothed top shells in terms of shell height from the oil spill site was significantly smaller (p<0.05) than the top shells at the control site. It was believed that the top shell collected from the spill site was 1-2 years old, possibly recruited in 2009 summer or fall. Monthly means of the condition index of top shell at the control site were significantly higher (p<0.05) than the oil spill area. Histology revealed that the female at the control site initiated gametogenesis in February, which was a month earlier that the spill site. At the control site, the top shell was ripe and ready for spawning in July and first spawning females observed in August. In contrast, sexual maturation and subsequent spawning of the toothed top shell at the oil spill area occurred in July and September respectively. The percent gonad area (PGA) of the top shell at the control site in Incheon bay peaked in June and the PGA declined linearly from June to August, suggesting that the spawning occurred during June and August. The PGA at the control site increased from August to September then declined from September to October, suggesting a second spawning pulse at the control site. In contrast, PGA of the top shell at the spill site peaked in July and it declined gradually from July to October, indicating that the top shell spawned from July to October. The student t-test indicated that PGA of the top shell at the control site during spawning peak was significantly higher than PGA measured from the oil spill site (p<0.05), suggesting that the top shell at the control site produced more eggs compared to the quantity of egg produced from the top shell at the spill site. The observed slow gonad maturation and spawning at the oil spill area 2 years after the accident was in part, explained by the lower water temperature at the spilled area since the surface water temperature at the spill site during the spring and the early summer was 3-4 degree lower than the control site. It was also believed that the difference in the gonad maturation and spawning observed between the control and the oil spill sites was due to the age of the top shell, since the toothed top shell collected from the oil spill area was believed to be 2-3 years younger that the top shells at the control site.