Wikström Sofia A, Carstensen Jacob, Blomqvist Mats, Krause-Jensen Dorte
Baltic Sea Centre, Stockholm University, 10691 Stockholm, Sweden.
Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
Mar Biol. 2016;163(12):257. doi: 10.1007/s00227-016-3032-6. Epub 2016 Nov 21.
Coastal vegetation communities are important for primary production, biodiversity, coastal protection, carbon and nutrient cycling which, in combination with their sensitivity to eutrophication, render them potential indicators of environmental status for environmental policies like the EU Water and Marine Strategy Framework Directives. We evaluated one potential indicator for coastal vegetation, the cumulative cover at depths where the vegetation is light limited, by investigating its response to eutrophication along gradients in natural conditions. We used a large data set covering the Swedish coastline, spanning broad gradients in nutrient level, water clarity, seabed substrate, physical exposure and climate in addition to a salinity gradient from 0.5 to 30.5. Macroalgal cover increased significantly along gradients of declining nutrient concentration and increasing water clarity when we had accounted for diver effects, spatio-temporal sampling variability, salinity gradients, wave exposure and latitude. The developed empirical model explained 79% of the variation in algal cover across 130 areas. Based on this, we identified macroalgal cover as a promising indicator across the Baltic Sea, Kattegat and Skagerrak. A parallel analysis of soft-substrate macrophytes similarly identified significant increases in cover with decreasing concentrations of total nitrogen and increasing salinity, but the resulting empirical model explained only 52% of the variation in cover, probably due to the spatially more variable nature of soft-substrate vegetation. The identified general responses of vegetation cover to gradients of eutrophication across wide ranges in environmental settings may be useful for monitoring and management of marine vegetation in areas with strong environmental gradients.
沿海植被群落对于初级生产、生物多样性、海岸保护、碳和养分循环至关重要，再加上它们对富营养化的敏感性，使其成为欧盟水和海洋战略框架指令等环境政策中环境状况的潜在指标。我们通过研究其在自然条件下沿梯度对富营养化的响应，评估了一种沿海植被的潜在指标，即植被受光照限制深度处的累积覆盖率。我们使用了一个覆盖瑞典海岸线的大型数据集，该数据集除了涵盖从0.5到30.5的盐度梯度外，还涵盖了营养水平、水体透明度、海底基质、物理暴露和气候等广泛梯度。在考虑潜水员效应、时空采样变异性、盐度梯度、波浪暴露和纬度后，大型海藻覆盖率随着营养浓度下降和水体透明度增加的梯度而显著增加。所建立的经验模型解释了130个区域藻类覆盖率变化的79%。基于此，我们确定大型海藻覆盖率是波罗的海、卡特加特海峡和斯卡格拉克海峡的一个有前景的指标。对软底大型植物的平行分析同样发现，随着总氮浓度降低和盐度增加，覆盖率显著增加，但所得经验模型仅解释了覆盖率变化的52%，这可能是由于软底植被在空间上更具变异性。在广泛的环境背景下确定的植被覆盖率对富营养化梯度的一般响应，可能有助于在具有强烈环境梯度的区域对海洋植被进行监测和管理。
