The occurrence of regime shifts in marine ecosystems has important implications for environmental legislation that requires setting reference levels and targets of quantitative restoration outcomes. The Baltic Sea ecosystem has undergone large changes in the 20^th century related to anthropogenic pressures and climate variability, which have caused ecosystem reorganization. Here, we compiled historical information and identified relationships in our dataset using multivariate statistics and modeling across 31 biotic and abiotic variables from 1925 to 2005 in the Central Baltic Sea. We identified a series of ecosystem regime shifts in the 1930s, 1970s, and at the end of the 1980s/beginning of the 1990s. In the long term, the Central Baltic Sea showed a regime shift from a benthic to pelagic-dominated state. Historically, benthic components played a significant role in trophic transfer, while in the more recent productive system pelagic–benthic coupling was weak and pelagic components dominated. Our analysis shows that for the entire time period, productivity, climate, and hydrography mainly affected the functioning of the food web, whereas fishing became important more recently. Eutrophication had far-reaching direct and indirect impacts from a long-term perspective and changed not only the trophic state of the system but also affected higher trophic levels. Our study also suggests a switch in regulatory drivers from salinity to oxygen. The “reference ecosystem” identified in our analysis may guide the establishment of an ecosystem state baseline and threshold values for ecosystem state indicators of the Central Baltic Sea.

中文翻译：

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参考上个世纪沿海海域的状态、结构、制度转变和监管驱动因素：波罗的海中部案例

海洋生态系统发生制度转变对环境立法具有重要意义，环境立法需要设定定量恢复结果的参考水平和目标。波罗的海生态系统在 20^{世纪发生了巨大变化}世纪与人为压力和气候变化有关，这导致了生态系统重组。在这里，我们使用 1925 年至 2005 年波罗的海中部 31 个生物和非生物变量的多元统计和建模，汇编了历史信息并确定了数据集中的关系。我们确定了 1930 年代、1970 年代和 1980 年代末/1990 年代初的一系列生态系统制度转变。从长远来看，波罗的海中部地区出现了从底栖动物为主向远洋为主的政权转变。从历史上看，底栖生物成分在营养转移中发挥了重要作用，而在最近的生产系统中，远洋-底栖生物耦合较弱，远洋成分占主导地位。我们的分析表明，在整个时间段内，生产力、气候、和水文学主要影响食物网的功能，而捕鱼最近变得很重要。从长远来看，富营养化具有深远的直接和间接影响，不仅改变了系统的营养状态，而且影响了更高的营养水平。我们的研究还表明监管驱动因素从盐度转向氧气。我们分析中确定的“参考生态系统”可以指导波罗的海中部生态系统状态指标的生态系统状态基线和阈值的建立。我们的研究还表明监管驱动因素从盐度转向氧气。我们分析中确定的“参考生态系统”可以指导波罗的海中部生态系统状态指标的生态系统状态基线和阈值的建立。我们的研究还表明监管驱动因素从盐度转向氧气。我们分析中确定的“参考生态系统”可以指导波罗的海中部生态系统状态指标的生态系统状态基线和阈值的建立。