Seasonal to Inter-Annual Variability of Primary Production in Chesapeake Bay: Prospects to Reverse Eutrophication and Change Trophic Classification
Seasonal to Inter-Annual Variability of Primary Production in Chesapeake Bay: Prospects to Reverse Eutrophication and Change Trophic Classification
复制标题
切萨皮克湾初级生产的季节到年际变化：扭转富营养化和改变营养分类的前景
DOI：
10.1038/s41598-020-58702-3
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发表时间：
2020
影响因子：
4.6
通讯作者：
H. Paerl
中科院分区：
文献类型：
--
作者：
L. Harding;M. E. Mallonee;E. Perry;W. David Miller;J. Adolf;C. Gallegos;H. Paerl
河口-沿海生态系统是全球海洋资源丰富的地区，其有机物产量较高，支持着主要渔业。净初级生产和总初级生产（NPP、GPP）是这些生态系统的基本属性，其特征是与气候对水文的影响相关的高空间、季节和年际变率。20多年前，Nixon根据浮游植物年初级产量（APPP）定义了海洋生态系统的营养分类，分类范围从“贫营养”到“肥养”。源数据包括1982年至2004年美国大西洋中部切萨皮克湾NPP和GPP的船载测量数据，支持APPP在300至500 g C m−2 yr−1之间的估计，对应于“富营养化”到“肥厚化”类别。在此，我们开发了广义加性模型（GAM）来插值源数据有限的时空分辨率。主要目标是：(1)建立基于源数据（1982 - 2004）校准的NPP和GPP预测模型；(2)将模型应用于历史（20世纪60、70年代）和监测（1985 ~ 2015年）数据，并对养分负荷和气候效应进行调整；(3)利用NPP的模型预测值估算APPP；(4)考察模拟浮游植物生物量减少或养分负荷减少对基于APPP的营养分类的影响。模拟显示，富氧层chl-a或TN和NO2 + NO3负荷减少40%，导致APPP下降，足以使海湾低盐（OH）和多盐（PH）盐度区从“富营养化”变为“中营养化”，中盐（MH）盐度区从“肥厚”变为“富营养化”。这些结果表明，通过持续逆转足以降低浮游植物生物量和APPP的养分过度富集，可以实现水质的改善。
Estuarine-coastal ecosystems are rich areas of the global ocean with elevated rates of organic matter production supporting major fisheries. Net and gross primary production (NPP, GPP) are essential properties of these ecosystems, characterized by high spatial, seasonal, and inter-annual variability associated with climatic effects on hydrology. Over 20 years ago, Nixon defined the trophic classification of marine ecosystems based on annual phytoplankton primary production (APPP), with categories ranging from “oligotrophic” to “hypertrophic”. Source data consisting of shipboard measurements of NPP and GPP from 1982 to 2004 for Chesapeake Bay in the mid-Atlantic region of the United States supported estimates of APPP from 300 to 500 g C m−2 yr−1, corresponding to “eutrophic” to “hypertrophic” categories. Here, we developed generalized additive models (GAM) to interpolate the limited spatio-temporal resolution of source data. Principal goals were: (1) to develop predictive models of NPP and GPP calibrated to source data (1982 to 2004); (2) to apply the models to historical (1960s, 1970s) and monitoring (1985 to 2015) data with adjustments for nutrient loadings and climatic effects; (3) to estimate APPP from model predictions of NPP; (4) to test effects of simulated reductions of phytoplankton biomass or nutrient loadings on trophic classification based on APPP. Simulated 40% decreases of euphotic-layer chl-a or TN and NO2 + NO3 loadings led to decreasing APPP sufficient to change trophic classification from “eutrophic’ to “mesotrophic” for oligohaline (OH) and polyhaline (PH) salinity zones, and from “hypertrophic” to “eutrophic” for the mesohaline (MH) salinity zone of the bay. These findings show that improved water quality is attainable with sustained reversal of nutrient over-enrichment sufficient to decrease phytoplankton biomass and APPP.