University of Athens, Faculty of Biology, Department of Ecology and Systematics, Panepistimiopolis, Athens 15784, Greece; Department of Fisheries and Marine Research, 1416 Nicosia, Cyprus.
Hellenic Centre for Marine Research, Institute of Marine Biological Resources & Inland Waters, 46.7 km Athens-Souniou Av., 19013, Anavissos, Attica, Greece.
Sci Total Environ. 2019 Dec 1;694:133773. doi: 10.1016/j.scitotenv.2019.133773. Epub 2019 Aug 5.
Phytoplankton is the main indicator group for eutrophication in coastal ecosystems, however its high dispersal potential does not enable the assessment of localized effects of coastal nutrient enrichment. Benthic diatoms are sessile microalgae associated with sandy substrates and have the potential to reflect more localized pollution impacts. Although benthic diatoms are widely used bioindicators in freshwater systems, they have rarely been used for assessing the eutrophication status of oligotrophic environments such as the eastern Mediterranean Sea. In the present study, we assess the efficiency of benthic diatoms as bioindicators of nutrient enrichment in oligotrophic coastal systems, by investigating the effect of different physicochemical conditions and nutrient concentrations on the assemblage composition, diversity and individual species populations. To do this, we sampled along a eutrophication gradient formed by anthropogenic nutrient inputs from a metropolitan area. The main driver of assemblage composition, diversity and biomass of diatoms was nitrogen concentration and its temporal and spatial changes. Nitrogen loadings were positively correlated with increased biomass of Cocconeis spp. and negatively correlated with Mastogloia spp. Our findings suggest that in coastal ecosystems of oligotrophic marine ecoregions, benthic diatom assemblage structure and specific taxonomic groups can be reliable predictors of coastal eutrophication offering higher spatial resolution compared to phytoplankton.
浮游植物是沿海生态系统富营养化的主要指示生物群，但由于其具有较强的扩散能力，因此无法评估沿海富营养化的局部影响。底栖硅藻是与沙质基底相关的固着微藻，具有反映更局部污染影响的潜力。尽管底栖硅藻在淡水系统中被广泛用作生物指标，但它们很少用于评估贫营养环境（如地中海东部）的富营养化状况。在本研究中，我们通过研究不同理化条件和营养浓度对组合组成、多样性和个体物种种群的影响，评估了底栖硅藻作为贫营养沿海系统营养富化生物指标的效率。为此，我们沿着由大都市人为营养输入形成的富营养化梯度进行采样。硅藻组合组成、多样性和生物量的主要驱动因素是氮浓度及其时空变化。氮负荷与 Cocconeis spp.的生物量增加呈正相关，与 Mastogloia spp.呈负相关。我们的研究结果表明，在贫营养海洋生态区的沿海生态系统中，与浮游植物相比，底栖硅藻组合结构和特定分类群可以成为沿海富营养化的可靠预测因子，提供更高的空间分辨率。
