Dahms Hans-Uwe, Tseng Li-Chun, Hwang Jiang-Shiou
Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.
Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan.
PLoS One. 2017 Sep 7;12(9):e0182649. doi: 10.1371/journal.pone.0182649. eCollection 2017.
Hydrothermal vent organisms are adapted to their extreme and patchily distributed habitats. They are expected to have evolved mechanisms that keep them in their specific habitation. Since little is known about the recruitment or habitat selection of HV organisms such as brachyurans, we examined the properties of several hydrothermal vent-associated cues on the behavior of the hydrothermal vent (HV) crab Xenograpsus testudinatus in the laboratory that were contrasted by the offering of non-vent cues. This crab species is endemic and dominates the vent fauna of Turtle Island off the NE coast of Taiwan. HV crabs were separately and in combination offered the following vent-specific cues: (1) sulfuric sediment, (3) air-bubbling, (4) elevated temperature, (5) dead settled zooplankton, (7) other crabs, and (8) shade. The non-vent-specific cues were: (2) quarz sediment, (6) dead fish, (8) light. These cues were provided on either side of a two-choice chamber. The movement of individual crabs was monitored: as initial and final choices, and as the proportion of time the crabs spent in each compartment (resident time). Cues were offered alone and no such cue as a control in the same set-up. Sulfuric sediments and dead fish were significantly more attractive to females, and other crabs irrespective of gender were significantly more attractive to males. When compared to expected distributions, crabs, irrespective of gender, significantly avoided light and tended to select other crabs, air-bubbling, sulfuric sediment, elevated temperature, dead fish, dead zooplankton, and quarz sediments in the order of decreasing importance. Data do not support the hypothesis that dead settled zooplankton was particularly attractive nor that the other gender was selected. A combination of several vent-associated cues (sulfuric sediment, elevated temperature, air-bubbling) facilitated the strongest attraction to the crabs as reflected by all response variables. The 'first choice' responses were always consistent with the side of the choice compartment in which they spent the longest amount of time (resident time), but not with the 'final choice' of crabs, suggesting that the 'resident time' in addition to their 'first choice' is more reliable than just the 'final choice'. The present results provide the first indication that several vent-associated habitat cues function as attractors for HV crabs. Habitat choice is also reflected by crab larval distribution in the field which tend to stay near the bottom not to be carried away from their specific habitat.
热液喷口生物适应了其极端且分布零散的栖息地。预计它们已经进化出能使其留在特定栖息地的机制。由于对诸如短尾类等热液喷口生物的补充或栖息地选择了解甚少，我们在实验室中研究了几种与热液喷口相关的线索对热液喷口（HV）蟹——龟纹蟹（Xenograpsus testudinatus）行为的影响，并通过提供非喷口线索进行对比。这种蟹是台湾东北海岸龟山岛的特有物种，在该喷口动物群中占主导地位。分别或组合向HV蟹提供以下特定于喷口的线索：（1）含硫沉积物，（3）冒泡，（4）温度升高，（5）死亡沉降的浮游动物，（7）其他螃蟹，以及（8）阴影。非特定于喷口的线索有：（2）石英沉积物，（6）死鱼，（8）光照。这些线索在二选一试验箱的两侧提供。监测个体螃蟹的移动情况：作为初始选择和最终选择，以及螃蟹在每个隔室中停留的时间比例（停留时间）。线索单独提供，在相同设置中不提供此类线索作为对照。含硫沉积物和死鱼对雌性螃蟹的吸引力明显更大，而其他螃蟹对雄性螃蟹的吸引力明显更大，无论性别如何。与预期分布相比，螃蟹无论性别都明显避开光照，并倾向于选择其他螃蟹、冒泡、含硫沉积物、温度升高、死鱼、死亡浮游动物和石英沉积物，其重要性依次降低。数据不支持死亡沉降的浮游动物特别有吸引力这一假设，也不支持存在性别选择的假设。几种与喷口相关的线索（含硫沉积物、温度升高、冒泡）的组合对螃蟹的吸引力最强，这一点在所有反应变量中都有体现。“第一选择”反应始终与它们停留时间最长的选择隔室一侧一致，但与螃蟹的“最终选择”不一致，这表明除了“第一选择”外，“停留时间”比“最终选择”更可靠。目前的结果首次表明，几种与喷口相关的栖息地线索对HV蟹起到吸引作用。螃蟹幼体在野外的分布也反映了栖息地选择，它们往往停留在靠近底部的位置，以免被带离其特定栖息地。
