Population dynamics of the sea snake Emydocephalus annulatus

For sea snakes as for many types of animals, long-term studies on population biology are rare and hence, we do not understand the degree to which annual variation in population sizes is driven by density-dependent regulation versus by stochastic abiotic factors. We monitored three populations of turtle-headed sea snakes (Emydocephalus annulatus) in New Caledonia over an 18-year period. Annual recruitment (% change in numbers) showed negative density-dependence: that is, recruitment increased when population densities were low, and decreased when densities were high. Windy weather during winter increased survival of neonates, perhaps by shielding them from predation; but those same weather conditions reduced body condition and the reproductive output of adult snakes. The role for density-dependence in annual dynamics of these populations is consistent with the slow, K-selected life-history attributes of the species; and the influence of weather conditions on reproductive output suggests ...与诸多动物类群一致，海蛇类的种群生物学长期研究仍较为匮乏，因此我们尚无法明确，种群规模的年度波动在多大程度上受密度制约调控，又或是受随机非生物因子驱动。我们在18年的周期内，对新喀里多尼亚海域的3个龟首海蛇（Emydocephalus annulatus）种群开展了监测工作。年度补充量（种群数量变化百分比）呈现负密度制约效应：即当种群密度较低时，补充量上升；而当密度升高时，补充量则下降。冬季的大风天气提升了新生幼体的存活率，这可能是因为大风为幼体规避了捕食压力；但这类天气条件同时也会降低成体海蛇的身体状况与繁殖产出。密度制约在该类群种群年度动态中的作用，与该物种缓慢的、K-选择（K-selected）型生活史特征相符；而天气条件对繁殖产出的影响则表明……