Sahoo Subhashree, Baliarsingh S K, Lotliker Aneesh A, Pradhan Umesh K, Thomas C S, Sahu K C
Department of Marine Sciences, Berhampur University, Brahmapur, Odisha, 760 007, India.
Indian National Centre for Ocean Information Services, Hyderabad, 500 090, India.
Environ Monit Assess. 2017 Apr;189(4):153. doi: 10.1007/s10661-017-5850-5. Epub 2017 Mar 9.
A comprehensive analysis on spatiotemporal variation in physico-chemical variables and their control on chlorophyll-a during 2013-14 was carried out in the Chilika Lagoon. Spatiotemporal variation in physico-chemical regimes significantly controlled the phytoplankton biomass of the lagoon. Further, precipitation-induced river/terrestrial freshwater influx and marine influence controlled the physico-chemical regimes of the Chilika Lagoon, such as nutrients (NH, NO, NO, PO and Si(OH)), temperature, salinity, total suspended matter and dissolved oxygen. This study revealed significant effects of tropical cyclones Phailin (2013) and Hudhud (2014) on physico-chemical regimes and in turn the phytoplankton biomass of the lagoon. Although both cyclones Phailin (2013) and Hudhud (2014) were intense, Phailin (2013) had a greater impact on the Chilika Lagoon due to the proximity of its landfall. Heavy precipitation caused an influx of nutrient-rich freshwater, both during each cyclone's passage, through rainfall, and after, through increased river flow and terrestrial run-off. The increase in nutrients, carried by the run-off, promoted phytoplankton growth, albeit in lag phase. In general, phytoplankton growth was controlled by nitrogenous nutrients. However, the addition of SiO through terrigenous run-off fuelled preferential growth of diatoms. The salinity pattern (which can be considered a proxy for fresh and marine water influx) indicated injection of freshwater nutrients into the northern, southern and central sectors of the lagoon through riverine/terrestrial freshwater run-off; marine influx was restricted to the mouth of the lagoon. Present and past magnitudes of salinity and chlorophyll-a were also compared to better understand the pattern of variability. A significant change in salinity pattern was noticed after the opening of an artificial inlet, because of the resulting higher influx of marine water. The overall phytoplankton biomass (using chlorophyll-a concentration as a proxy) remained consistent in the lagoon pre- and post-restoration. Due to the wide range of salinity and temperature tolerance, diatoms remained dominant in both pre- and post-restoration periods, but the overall phytoplankton diversity increased after the artificial inlet was dredged.
2013 - 2014年期间，对奇利卡泻湖的物理化学变量的时空变化及其对叶绿素a的控制进行了全面分析。物理化学状况的时空变化显著控制了泻湖的浮游植物生物量。此外，降水引发的河流/陆地淡水流入以及海洋影响控制了奇利卡泻湖的物理化学状况，如营养物质（NH、NO、NO、PO和Si(OH)）、温度、盐度、总悬浮物和溶解氧。本研究揭示了热带气旋“费林”（2013年）和“胡德胡德”（2014年）对物理化学状况进而对泻湖浮游植物生物量的显著影响。尽管“费林”（2013年）和“胡德胡德”（2014年）这两个气旋都很强，但由于“费林”（2013年）登陆地点较近，对奇利卡泻湖的影响更大。强降水导致在每个气旋经过期间通过降雨以及之后通过河流流量增加和陆地径流带来了富含营养的淡水流入。径流携带的营养物质增加促进了浮游植物的生长，尽管处于滞后阶段。一般来说，浮游植物的生长受含氮营养物质控制。然而，通过陆源径流添加的SiO促进了硅藻的优先生长。盐度模式（可被视为淡水和海水流入的指标）表明通过河流/陆地淡水径流将淡水营养物质注入泻湖的北部、南部和中部区域；海洋流入仅限于泻湖口。还比较了当前和过去的盐度及叶绿素a值，以更好地了解变化模式。在人工入口开通后，盐度模式出现了显著变化，这是由于海水流入增加所致。在恢复前后，泻湖中的浮游植物总生物量（以叶绿素a浓度为指标）保持一致。由于对盐度和温度的耐受性范围较广，硅藻在恢复前后均占主导地位，但在人工入口疏浚后，浮游植物的总体多样性增加了。
