Marine Research Institute, Klaipėda University, Universiteto Ave. 17, 92294 Klaipėda, Lithuania.
Institute for Electromagnetic Sensing of the Environment (IREA), National Research Council (CNR) of Italy, 20133 Milan, Italy.
Sci Total Environ. 2021 May 15;769:145053. doi: 10.1016/j.scitotenv.2021.145053. Epub 2021 Jan 9.
A temporally and spatially detailed historical (1985-2018) analysis of cyanobacteria blooms was performed in the Curonian Lagoon (Lithuania, Russia), the largest coastal lagoon in the Baltic Sea. Satellite data allowed the mapping of cyanobacteria surface accumulations, so-called "scums", and of chlorophyll-a concentration. The 34-year time series shows a tendency towards later occurrence (October-November) of the cyanobacteria scum presence, whereas the period of its onset (June-July) remains relatively constant. The periods when scums are present, "hot moments", have been consistently increasing in duration since 2008. The differences in the starting, ending and annual duration of cyanobacteria blooms have been significantly altered by hydro-meteorological conditions (river discharge, water temperature, and wind conditions) and their year-round patterns. The most important environmental factors that determined the temporal changes of the scum presence and area were the standing stock of cyanobacteria and the ambient wind conditions. The "hotspots", the areas where the blooms most likely occur, were distributed in the south-southwestern and central parts of the lagoon. The least affected areas were the northern part, which is connected to the coastal waters of the Baltic Sea, and the Nemunas River delta region. The longstanding, well-established spatial patterns of cyanobacteria blooms were linked to hydrodynamic features, namely water renewal time and current patterns, and to potential nutrient sources that included muddy sediments and the locations of colonies of piscivorous birds. Our findings confirmed that the annual and seasonal variations of cyanobacteria blooms and their regulation are a complex issue due to interactions between multiple factors over spatially and temporally broad scales. Despite great progress in the prevention and control of eutrophication and cyanobacteria blooms, the lagoon is still considered to be in a poor ecological status. This work provides a new and missing understanding on the spatial and temporal extent of cyanobacteria blooms and the factors that govern them. Such an understanding can help in planning management strategies, forecasting the magnitude and severity of blooms under changing nutrient loads and potential climate scenarios.
对库尔斯沙嘴泻湖（立陶宛、俄罗斯，波罗的海中最大的沿海泻湖）的蓝藻水华进行了时空详细的历史（1985-2018 年）分析。卫星数据可以对蓝藻的表面积聚，即所谓的“浮渣”，以及叶绿素-a 浓度进行测绘。34 年的时间序列显示出蓝藻浮渣存在的时间有推迟的趋势（10 月至 11 月），而其开始的时间（6 月至 7 月）则相对稳定。自 2008 年以来，浮渣存在的“热点”时间持续增加。水文学气象条件（河流量、水温、风和条件）及其全年模式显著改变了蓝藻水华开始、结束和全年持续时间的差异。决定浮渣存在和面积时间变化的最重要环境因素是蓝藻的现存量和环境风条件。最有可能发生水华的“热点”区域分布在泻湖的西南和中部地区。受影响最小的区域是与波罗的海沿海水域相连的北部地区以及内穆纳斯河三角洲地区。蓝藻水华长期存在的、既定的空间模式与水动力特征有关，即水的更新时间和水流模式，以及包括泥泞沉积物和食鱼鸟类聚居地在内的潜在营养源。我们的研究结果证实，由于多种因素在广阔的时空范围内相互作用，蓝藻水华的年际和季节性变化及其调控是一个复杂的问题。尽管在防治富营养化和蓝藻水华方面取得了巨大进展，但泻湖仍被认为处于较差的生态状态。这项工作为蓝藻水华的时空范围及其控制因素提供了新的、缺失的认识。这种理解有助于规划管理策略，根据不断变化的营养负荷和潜在的气候情景预测水华的规模和严重程度。
