Arula Timo, Gröger Joachim, Ojaveer Henn, Simm Mart
Estonian Marine Institute, University of Tartu, Pärnu, Estonia.
Thünen Institute of Sea Fisheries, Hamburg, Germany; Institute for Biosciences, University of Rostock, Germany.
PLoS One. 2014 Mar 17;9(3):e91304. doi: 10.1371/journal.pone.0091304. eCollection 2014.
Because of the high management relevance, commercial fish related aspects have often been central in marine ecosystem investigations. The iterative shiftogram method was applied to detect occurrence, type and timing of shifts in the single and multivariate time series linked to the spring spawning herring larvae in the Gulf of Riga (Baltic Sea). Altogether nineteen larval herring and related environmental variables were utilized during the period of 1957-2010. All the time series investigated, either single or multivariate, exhibited one or more shifts with variable type and timing. Multivariate shiftogram based on all time series identified two distinct states (1957-1983 and 1992-2010) in studied variables, separated by a smooth transition period lasting almost ten years. The observed shift was mainly related to hydroclimate and not to phenology or biota. Significantly increased variability was found in larval herring and recruitment abundances after the shift. While the shift in hydroclimate (1985-1991) was followed by the shift in phenology (1991-1997), the shift in biota occurred remarkably later (2003). It is likely that the dynamics in biota were affected by other drivers than those investigated in the current paper.
由于具有高度的管理相关性，与商业鱼类相关的方面在海洋生态系统调查中常常处于核心地位。采用迭代移位图法来检测与里加湾（波罗的海）春季产卵鲱鱼幼体相关的单变量和多变量时间序列中的变化发生情况、类型和时间。在1957年至2010年期间，总共使用了19个鲱鱼幼体及相关环境变量。所有调查的时间序列，无论是单变量还是多变量，都表现出一个或多个具有不同类型和时间的变化。基于所有时间序列构建的多变量移位图在研究变量中识别出两个不同的状态（1957 - 1983年和1992 - 2010年），中间由一个持续近十年的平稳过渡期隔开。观察到的变化主要与水文气候有关，而非物候或生物群。变化之后，鲱鱼幼体和补充量的变异性显著增加。水文气候的变化（1985 - 1991年）之后是物候的变化（199(1 - 1997年)，而生物群的变化则显著更晚（2003年）。生物群的动态变化很可能受到了本文所研究驱动因素之外的其他因素影响。
