Sulfide tolerance and detoxification of the vent crab, Xenograpsus testudinatus

• Main Authors: Cheng-Mao Chang, 張誠茂
• Other Authors: 戴昌鳳
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/05249650848974766466

碩士 === 國立臺灣大學 === 海洋研究所 === 95 === The study aims to investigate the marine macro fauna associated with the shallow-water hydrothermal vents off Kueishan Island. Six species representing 4 phyla were recorded, including a hexacoral Tubastraea aurea, an unidentified sea anemone, two species of mollusks (a snail Nassarius sp., an unidentified chiton), one serpulid polychaete, and the vent crab Xenograpsus testudinatus. The crab is the dominant species and often swarms in enormous populations at venting areas, while other species occur at the peripheral areas of the hydrothermal vents. Sulfide is highly toxic to aquatic animals due to the inhibition of cytochrome-c oxidase, a critical enzyme for mitochondrial respiration. Seawater samples collected near the vents showed the highest concentration of sulfide as 2405.5 µM. The median lethal time（LT50）of X. testudinatus exposed to 1000 µM and 2000 µM of sulfide were 136 h and 102 h, respectively. Elevated levels of thiosulfate（S2O3-2）in the tissues of the crabs after exposure of sulfide showed that oxidation of sulfide to non-toxic thiosulfate is possibly the major detoxification mechanism. This mechanism enables X. testudinatus to tolerate to the high sulfide concentration in the environment. The hydrothermal fluid not only provides abundant food supply for the crabs by killing zooplankton and descent as ‘marine snow’ to the bottom, but also precludes the possible competitors and predators. The special adaptation of X. testudinatus to the toxicity of sulfide enables them to colonize successfully and become dominate in the shallow-water hydrothermal vent ecosystem off Kueishan Island.