Arendt Michael D, Schwenter Jeffrey A, Witherington Blair E, Meylan Anne B, Saba Vincent S
Marine Resources Division, South Carolina Department of Natural Resources, Charleston, South Carolina, United States of America ; Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America.
PLoS One. 2013 Dec 5;8(12):e81097. doi: 10.1371/journal.pone.0081097. eCollection 2013.
A recent analysis suggested that historical climate forcing on the oceanic habitat of neonate sea turtles explained two-thirds of interannual variability in contemporary loggerhead (Caretta caretta) sea turtle nest counts in Florida, where nearly 90% of all nesting by this species in the Northwest Atlantic Ocean occurs. Here, we show that associations between annual nest counts and climate conditions decades prior to nest counts and those conditions one year prior to nest counts were not significantly different. Examination of annual nest count and climate data revealed that statistical artifacts influenced the reported 31-year lag association with nest counts. The projected importance of age 31 neophytes to annual nest counts between 2020 and 2043 was modeled using observed nest counts between 1989 and 2012. Assuming consistent survival rates among cohorts for a 5% population growth trajectory and that one third of the mature female population nests annually, the 41% decline in annual nest counts observed during 1998-2007 was not projected for 2029-2038. This finding suggests that annual nest count trends are more influenced by remigrants than neophytes. Projections under the 5% population growth scenario also suggest that the Peninsular Recovery Unit could attain the demographic recovery criteria of 106,100 annual nests by 2027 if nest counts in 2019 are at least comparable to 2012. Because the first year of life represents only 4% of the time elapsed through age 31, cumulative survival at sea across decades explains most cohort variability, and thus, remigrant population size. Pursuant to the U.S. Endangered Species Act, staggered implementation of protection measures for all loggerhead life stages has taken place since the 1970s. We suggest that the 1998-2007 nesting decline represented a lagged perturbation response to historical anthropogenic impacts, and that subsequent nest count increases since 2008 reflect a potential recovery response.
最近的一项分析表明，历史气候对新生海龟海洋栖息地的影响，解释了佛罗里达州当代蠵龟（Caretta caretta）海龟巢穴数量年际变化的三分之二，在西北大西洋，该物种近90%的筑巢活动都发生在佛罗里达州。在此，我们表明，巢穴数量年度计数与筑巢前几十年的气候条件以及筑巢前一年的气候条件之间的关联并无显著差异。对年度巢穴计数和气候数据的检查显示，统计假象影响了所报告的与巢穴计数的31年滞后关联。利用1989年至2012年观察到的巢穴计数，对2020年至2043年31岁新生海龟对年度巢穴计数的预计重要性进行了建模。假设各年龄段海龟的存活率一致，种群增长轨迹为5%，且每年有三分之一的成年雌性海龟筑巢，那么在1998 - 2007年期间观察到的年度巢穴计数41%的下降，预计在2029 - 2038年不会出现。这一发现表明，年度巢穴计数趋势受回迁海龟的影响大于新生海龟。在5%的种群增长情景下的预测还表明，如果2019年的巢穴计数至少与2012年相当，半岛恢复单元到2027年可能达到每年106,100个巢穴的种群恢复标准。由于生命的第一年仅占31岁时所经历时间的4%，几十年来在海上的累积存活率解释了大多数年龄段的变异性，进而解释了回迁种群的规模。根据美国《濒危物种法》，自20世纪70年代以来，已对蠵龟所有生命阶段的保护措施进行了分阶段实施。我们认为，1998 - 2007年筑巢数量的下降代表了对历史人为影响的滞后扰动反应，而自2008年以来巢穴计数的后续增加反映了潜在的恢复反应。
