Arula T, Ojaveer H, Klais R
Estonian Marine Institute, University of Tartu, Pärnu, Estonia.
Estonian Marine Institute, University of Tartu, Pärnu, Estonia.
Mar Environ Res. 2014 Dec;102:102-9. doi: 10.1016/j.marenvres.2014.05.001. Epub 2014 May 20.
We used weekly observational data from mid-May to end of July in 1958-2012 in Gulf of Riga to investigate temporal coupling between spring herring larvae and their first prey - copepod nauplii, under the extreme hydroclimatic conditions. We focused on a small shallow estuary that is important nursery ground for larvae of the Gulf of Riga (Baltic Sea) herring population. We quantified the effect of extreme values of the winter air temperatures, time of ice retreat and spring water temperatures on the timing of peak abundance of herring larvae and copepod nauplii. We also assessed whether the invasion of the non-native cladoceran Cercopagis pengoi had notable effect on timing and abundance of copepod nauplii during the peak occurrence of herring larvae. In the years of earliest ice retreat the peak abundance of herring larvae was five weeks earlier than in the years of latest ice retreat, while the timing of nauplii remained unchanged. Abundant presence of the C. pengoi affected neither timing nor maximum abundance of copepod nauplii during the herring larvae first feeding period. Thus, we conclude that processes induced by climate variability are superior to invasion of C. pengoi in determining the timing and coupling of larval herring and copepod nauplii.
我们利用1958年至2012年5月中旬至7月底里加湾的每周观测数据，在极端水文气候条件下，研究春季鲱鱼幼体与其第一种猎物——桡足类无节幼体之间的时间耦合关系。我们聚焦于一个小型浅河口，它是里加湾（波罗的海）鲱鱼种群幼体的重要育幼场。我们量化了冬季气温极值、融冰时间和春季水温对鲱鱼幼体和桡足类无节幼体丰度峰值时间的影响。我们还评估了非本地枝角类彭氏哲水蚤的入侵在鲱鱼幼体出现高峰期对桡足类无节幼体的时间和丰度是否有显著影响。在最早融冰的年份，鲱鱼幼体的丰度峰值比最晚融冰的年份提前了五周，而无节幼体的时间保持不变。在鲱鱼幼体首次摄食期，彭氏哲水蚤的大量存在对桡足类无节幼体的时间和最大丰度均无影响。因此，我们得出结论，在决定鲱鱼幼体和桡足类无节幼体的时间和耦合关系方面，气候变率引发的过程比彭氏哲水蚤的入侵更为重要。
