Werba Jo A, Stucy Alexandra L, Peralta Ariane L, McCoy Michael W
Department of Biology, McMaster University, Hamilton, Ontario, Canada.
Department of Biology, East Carolina University, Greenville, NC, United States of America.
PeerJ. 2020 Mar 9;8:e8608. doi: 10.7717/peerj.8608. eCollection 2020.
Sea level rise is mixing formerly isolated freshwater communities with saltwater communities. The structure of these new aquatic communities is jointly controlled by pre- and post-colonization processes. Similarly, since salinity is a strong abiotic determinant of post-colonization survival in coastal systems, changes in salinity will likely impact community composition. In this study, we examine how a strong abiotic gradient affects the diversity and structure of bacterial and zooplankton communities and associated ecosystem functions (decomposition and carbon mineralization). We ran a six week dispersal experiment using mesocosm ponds with four distinct salinity profiles (0, 5, 9, and 13 psu). We find that salinity is the primary driver of both bacterial and zooplankton community composition. We find evidence that as bacterial richness increases so does the amount of decomposition. A phenomenological model suggests carbon mineralization may decrease at mid-salinities; this warrants future work into possible mechanisms for this apparent loss of function. Understanding how salinization changes community structure and ecosystem function may be paramount for managing and conserving coastal plain ecosystems where salinity is increasing due to sea level rise, saltwater intrusion, storm surges, and drought.
海平面上升正在使以前孤立的淡水群落与咸水群落混合。这些新的水生群落的结构由定殖前和定殖后的过程共同控制。同样，由于盐度是沿海系统定殖后生存的一个重要非生物决定因素，盐度的变化可能会影响群落组成。在本研究中，我们研究了一个强烈的非生物梯度如何影响细菌和浮游动物群落的多样性和结构以及相关的生态系统功能（分解和碳矿化）。我们使用具有四种不同盐度剖面（0、5、9和13 psu）的中型池塘进行了为期六周的扩散实验。我们发现盐度是细菌和浮游动物群落组成的主要驱动因素。我们发现有证据表明，随着细菌丰富度的增加，分解量也会增加。一个现象学模型表明，在中等盐度下碳矿化可能会减少；这值得未来对这种明显的功能丧失的可能机制进行研究。了解盐渍化如何改变群落结构和生态系统功能对于管理和保护沿海平原生态系统可能至关重要，因为由于海平面上升、海水入侵、风暴潮和干旱，这些地区的盐度正在增加。
