Step-changes in the physical, chemical and biological characteristics of the Gulf of Maine, as documented by the GNATS time series
Step-changes in the physical, chemical and biological characteristics of the Gulf of Maine, as documented by the GNATS time series
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DOI：
10.3354/meps09555
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发表时间：
2012-01-01
影响因子：
2.5
通讯作者：
Huntington, T. G.
中科院分区：
文献类型：
--
作者：
Balch, W. M.;Drapeau, D. T.;Huntington, T. G.
我们使用缅因湾北大西洋时间序列 (GNATS) 来识别缅因湾 (GoM) 物理、化学和生物特征的阶跃变化，GNATS 是 1998 年 9 月至 2010 年 12 月期间沿着缅因湾从缅因州波特兰到新斯科舍省雅茅斯的缅因湾横断面获得的一系列海洋学测量结果。 GNATS 对一段降水和河流流量极端的时期进行了采样（上世纪 8 个最潮湿的年份中的 4 个发生在 2005 年至 2010 年之间）。在降水量增加的同时，我们观察到以下变化：(1) 墨西哥湾西部地表水中的盐度和密度降低； (2) 上部 50 m 的温度梯度和垂直温度梯度均减小； (3) 墨西哥湾西部有色溶解有机物 (CDOM) 浓度和颗粒散射增加； (4) 除东部墨西哥湾以外的所有地区硝酸盐和磷酸盐浓度均有所增加； (5) 硅酸盐增加，特别是在墨西哥湾西部，硅酸盐与溶解无机氮的比例急剧增加； (6)浮游植物固碳急剧下降； (7) 中部地区叶绿素、颗粒有机碳 (POC) 和颗粒无机碳 (PIC) 适度下降，(8) POC 和 PIC 特定增长率下降。海湾范围异常分析表明（1）表面密度变化主要由温度驱动，（2）溶解养分以及 POC/PON 在雷德菲尔德比率中变化，（3）盐度、密度、CDOM、颗粒反向散射和硅酸盐异常与河流流量显着相关。降水和河流排放似乎在控制缅因湾的长期生产力方面发挥着关键作用，因为它们提供了 CDOM 和碎屑物质，最终与浮游植物竞争光吸收。
We identify step-changes in the physical, chemical and biological characteristics of the Gulf of Maine (GoM) using the Gulf of Maine North Atlantic Time Series (GNATS), a series of oceanographic measurements obtained between September 1998 and December 2010 along a transect in the GoM running from Portland, ME, to Yarmouth, NS. GNATS sampled a period of extremes in precipitation and river discharge (4 of the 8 wettest years of the last century occurred between 2005 and 2010). Coincident with increased precipitation, we observed the following shifts: (1) decreased salinity and density within the surface waters of the western GoM; (2) both reduced temperature and vertical temperature gradients in the upper 50 m; (3) increased colored dissolved organic matter (CDOM) concentrations and particle scattering in the western GoM; (4) increased concentrations of nitrate and phosphate across all but the eastern GoM; (5) increased silicate, particularly in the western GoM, with a sharp increase in the ratio of silicate to dissolved inorganic nitrogen; (6) sharply decreased carbon fixation by phytoplankton; (7) moderately decreased chlorophyll, particulate organic carbon (POC) and particulate inorganic carbon (PIC) in the central GoM and (8) decreased POC-and PIC-specific growth rates. Gulf-wide anomaly analyses suggest that (1) the surface density changes were predominantly driven by temperature, (2) dissolved nutrients, as well as POC/PON, varied in Redfield ratios and (3) anomalies for salinity, density, CDOM, particle backscattering and silicate were significantly correlated with river discharge. Precipitation and river discharge appear to be playing a critical role in controlling the long-term productivity of the Gulf of Maine by supplying CDOM and detrital material, which ultimately competes with phytoplankton for light absorption.