Biology Department, Mount Holyoke College, South Hadley, MA, 01075, United States.
Biology Department, Mount Holyoke College, South Hadley, MA, 01075, United States.
J Therm Biol. 2023 Aug;116:103639. doi: 10.1016/j.jtherbio.2023.103639. Epub 2023 Jul 7.
The fiddler crab Minuca pugnax occupies thermally unstable mudflat habitats along the eastern United States coastline, where it uses behavioral thermoregulation, including burrow retreats, to manage body temperature (T). We explored the relationship between frequency of burrow use and environmental conditions, including burrow and surface temperatures, relative tidal height, and time of day, by twenty male M. pugnax in breeding areas around Flax Pond, New York, USA. We found a highly significant positive correlation between burrow use and surface temperature, with a clear shift to longer times underground above 32 °C degrees. We also experimentally heated live crabs in the laboratory and allowed them to retreat into cooled artificial burrows while continuously measuring T. Laboratory data on cooling times were compared to field observations of burrow retreat durations. The median burrow duration in the field of 2.74 min was enough time for our laboratory crabs to capture over 70% of the cooling potential of artificial burrows 10 or 15 °C below T. Because crab bodies in burrows experience exponential declines in T due to Newton's law of cooling, there are diminishing returns to remaining in a burrow, and many crabs probably leave before coming to equilibrium. For M. pugnax, burrow retreats reduce time spent feeding and courting, activities that only occur on the surface. Current concerns about the impacts of climate change on animals include whether compensatory mechanisms, like more frequent and longer burrow retreats, will come at the cost of other behaviors necessary for survival and reproduction.
招潮蟹 Minuca pugnax 占据着美国东海岸不稳定的热泥滩栖息地，它利用行为体温调节，包括洞穴撤退，来管理体温（T）。我们通过在美国纽约州弗拉克斯池塘周围的繁殖区对 20 只雄性 M. pugnax 进行研究，探索了洞穴使用频率与环境条件之间的关系，包括洞穴和表面温度、相对潮汐高度和一天中的时间。我们发现，洞穴使用频率与表面温度之间存在高度显著的正相关关系，当表面温度超过 32°C 时，明显会有更长时间的地下活动。我们还在实验室中对活体螃蟹进行了加热实验，让它们在进入冷却后的人工洞穴时撤退，并持续测量 T。将实验室中冷却时间的数据与实地观察到的洞穴撤退持续时间进行比较。在野外，洞穴持续时间的中位数为 2.74 分钟，这足以让我们实验室中的螃蟹在 10°C 或 15°C 的温度下，捕获人工洞穴冷却潜力的 70%以上。由于螃蟹身体在洞穴中会因牛顿冷却定律而导致 T 呈指数下降，因此留在洞穴中的回报会逐渐减少，许多螃蟹可能在达到平衡之前就离开洞穴。对于 M. pugnax 来说，洞穴撤退减少了觅食和求偶的时间，这些活动仅在表面发生。目前人们对气候变化对动物的影响表示担忧，其中包括补偿机制，如更频繁和更长时间的洞穴撤退，是否会以牺牲生存和繁殖所必需的其他行为为代价。
