Stefanidou Natassa, Genitsaris Savvas, Lopez-Bautista Juan, Sommer Ulrich, Moustaka-Gouni Maria
Department of Botany, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
School of Economics, Business Administration and Legal Studies, International Hellenic University, Thermi, Greece.
Front Microbiol. 2018 Oct 9;9:2444. doi: 10.3389/fmicb.2018.02444. eCollection 2018.
Climate change has profound impacts on marine biodiversity and biodiversity changes in turn might affect the community sensitivity to impacts of abiotic changes. We used mesocosm experiments and Next Generation Sequencing to study the response of the natural Baltic and Mediterranean unicellular eukaryotic plankton communities (control and +6°C heat shock) to subsequent salinity changes (-5 psu, +5 psu). The impact on Operational Taxonomic Unit (OTU) richness, taxonomic and functional composition and rRNA:rDNA ratios were examined. Our results showed that heat shock leads to lower OTU richness (21% fewer OTUs in the Baltic and 14% fewer in the Mediterranean) and a shift in composition toward pico- and nanophytoplankton and heterotrophic related OTUs. Heat shock also leads to increased rRNA:rDNA ratios for pico- and micrograzers. Less than 18% of shared OTUs were found among the different salinities indicating the crucial role of salinity in shaping communities. The response of rRNA:rDNA ratios varied highly after salinity changes. In both experiments the diversity decrease brought about by heat shock influenced the sensitivity to salinity changes. The heat shock either decreased or increased the sensitivity of the remaining community, depending on whether it removed the more salinity-sensitive or the salinity-tolerant taxa.
气候变化对海洋生物多样性有着深远影响，而生物多样性的变化反过来可能会影响群落对非生物变化影响的敏感性。我们利用中宇宙实验和新一代测序技术，研究了波罗的海和地中海天然单细胞真核浮游生物群落（对照和 +6°C 热休克）对随后盐度变化（-5 个实用盐度单位，+5 个实用盐度单位）的响应。我们检验了对操作分类单元（OTU）丰富度、分类和功能组成以及 rRNA:rDNA 比率的影响。我们的结果表明，热休克导致 OTU 丰富度降低（波罗的海的 OTU 减少 21%，地中海减少 14%），并且组成向微微型和微型浮游植物以及与异养相关的 OTU 转变。热休克还导致微微型和微型食草动物的 rRNA:rDNA 比率增加。在不同盐度中发现的共享 OTU 不到 18%，这表明盐度在塑造群落中起着关键作用。盐度变化后，rRNA:rDNA 比率的响应变化很大。在两个实验中，热休克导致的多样性降低影响了对盐度变化的敏感性。热休克要么降低要么增加了剩余群落的敏感性，这取决于它去除的是对盐度更敏感的分类群还是耐盐分类群。
