ABSTRACT: The El Niño-Southern Oscillation (ENSO), which includes El Niño and La Niña phases, affects oceanographic conditions and primary productivity of marine ecosystems at a global scale. During El Niño events, warm temperatures in the central and eastern tropical Pacific decrease primary productivity, affecting the biology of many species including sea turtles. We aimed to determine the effect of ENSO (as a global index) and primary productivity in the foraging areas (as a local index) on remigration intervals (number of years between nesting seasons) and seasonal reproductive output (clutch size and number of clutches in a season) of green turtles Chelonia mydas in the North Pacific off Costa Rica, an area highly influenced by ENSO. We used the Multivariate ENSO Index (MEI) and mean values of chlorophyll a from previously identified feeding areas for this population over different time periods (up to 3 yr before the nesting season). Chlorophyll a levels in foraging areas and MEI strongly influenced the reproductive frequency of green turtles. Variability in the remigration intervals was better explained by models that included MEI conditions 2 and 3 yr before the onset of the nesting season and chlorophyll levels in the previous 3 yr. Models using global and local indexes were equally good at predicting changes in the remigration intervals. Positive values of MEI (El Niño phase) and lower levels of chlorophyll a corresponded to longer remigration intervals. No statistically significant relationships were found between seasonal reproductive output and MEI or chlorophyll a levels. As El Niño events may become more frequent and last longer due to climate change, the lifetime reproductive output of green turtles in this area may be compromised in the future.

中文翻译：

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厄尔尼诺事件和叶绿素水平影响东太平洋绿海龟的繁殖频率，但不影响其季节性繁殖产量

摘要：厄尔尼诺-南方涛动（ENSO），包括厄尔尼诺和拉尼娜阶段，在全球范围内影响海洋条件和海洋生态系统的初级生产力。在厄尔尼诺事件期间，中部和东部热带太平洋的温暖温度降低了初级生产力，影响了包括海龟在内的许多物种的生物学。我们旨在确定ENSO（作为全球指数）和觅食区的初级生产力（作为本地指数）对移民间隔（筑巢季节之间的年数）和季节性繁殖产量（离合器的大小和离合器的数量）的影响。一个季节）绿海龟Chelonia mydas位于哥斯达黎加附近的北太平洋，该地区受到ENSO的强烈影响。我们使用了多元ENSO指数（MEI）和先前确定的该人群在不同时间段（筑巢季节之前3年）的摄食区域的叶绿素a平均值。觅食区和MEI中的叶绿素a水平强烈影响绿海龟的繁殖频率。通过包括筑巢季节开始前2年和3年的MEI条件以及前3年中的叶绿素水平在内的模型，可以更好地解释迁移间隔的变化。使用全局和局部索引的模型同样擅长预测迁移间隔的变化。MEI（厄尔尼诺期）的正值和较低的叶绿素a水平对应于更长的迁移间隔。在季节性繁殖产量与MEI或叶绿素a水平之间未发现统计学上的显着关系。由于气候变化，厄尔尼诺事件可能会变得更加频繁且持续时间更长，因此未来该地区绿海龟的终生繁殖产量可能会受到影响。