This study investigates the acute toxicity of sublethal tributyltin (TBT) exposure in the marine polychaetes Perinereis aibuhitensis by measuring changes in mortality, burrowing activity, acetylcholinesterase (AChE) function, and antioxidant defense mechanisms. The 96h-LC50 of TBT was established at 23.7 μg L⁻¹. Following exposure to 1 μg L⁻¹ of TBT led to a dose-dependent reduction in burrowing behavior and AChE activity in polychaetes. Elevated levels of malondialdehyde (MDA) and pronounced reduction of glutathione (GSH) contents explained significant oxidative stress. The major antioxidant enzymes, including GSH peroxidase, GSH reductase, catalase, and superoxide dismutase, were also significantly suppressed following TBT exposure. These findings indicate that TBT-induced acute toxicity compromises physiological functions and undermines antioxidant defense system in polychates.

Introduction
Materials and Methods
    1. Marine polychaete
    2. Acute toxicity test
    3. Measurements of burrowing andacetylcholinesterase activity
    4. Measurement of antioxidant response
    5. Statistical analysis
Results
    1. Mortality
    2. Burrowing and AChE activities
    3. Measurements of oxidative stress andantioxidant response
Discussion
Acknowledgement
References

• Jhee-Yeong Hwang(Department of Marine Science, College of Natural Sciences, Incheon National University, Incheon 22012, Republic of Korea)
• Jae-Sung Rhee(Department of Marine Science, College of Natural Sciences, Incheon National University, Incheon 22012, Republic of Korea, Research Institute of Basic Sciences, Core Research Institute, Incheon National University, Incheon 22012, Republic of Korea, Yellow Sea Research Institute, Incheon 22012, Republic of Korea) Corresponding author
• Eun-Ji Won(Department of Marine Science and Convergent Technology, Hanyang University, Ansan 15588, Republic of Korea, Institute of Marine and Atmospheric Sciences, Hanyang University, Ansan 15588, Republic of Korea) Corresponding author