Patterns and Trends in Secchi Disk Depth over Three Decades in the Chesapeake Bay Estuarine Complex
Patterns and Trends in Secchi Disk Depth over Three Decades in the Chesapeake Bay Estuarine Complex
复制标题
切萨皮克湾河口复合体三十年来塞基盘深度的模式和趋势
DOI：
10.1007/s12237-019-00547-9
复制
发表时间：
2019
影响因子：
2.7
通讯作者：
Qian Zhang
中科院分区：
文献类型：
--
作者：
J. Testa;V. Lyubchich;Qian Zhang
水体透明度是切萨皮克湾和地球仪其他海岸和河口系统富营养化的重要生态系统指标。虽然有各种各样的措施可用于量化水的光可用性，Secchi磁盘深度一直是最一致和最频繁的措施，在水监测计划。由于光的可用性是由多个变量，如浮游植物生物量，非生命悬浮颗粒，和有色溶解有机物（CDOM）的影响，了解驱动长期变化的因素和趋势的水清晰度是针对与富营养化相关的流域管理行动的关键。因此，我们进行了一个全面的统计分析的空间和时间变化的塞奇盘深度和关键的内部和外部变量，影响其变化在切萨皮克湾及其潮汐支流在过去的30年。我们的研究结果表明，虽然流域营养盐，沉积物和淡水输入没有相关性与Secchi深度在每月的时间尺度以外的低盐度地区附近的河流流出，水柱变量，代表这些输入（CDOM，叶绿素a，和总悬浮固体[TSS]）的后果与Secchi深度变化强烈相关。这两个调查结果的不一致性可以解释为控制叶绿素a和TSS没有直接关系到流域输入，如放牧和再悬浮，流域输入和相关的水柱浓度之间的滞后几个月。虽然盐度（CDOM的代理）是一个占主导地位的空间协变量与Secchi深度湾宽，TSS浓度与时间变化密切相关的Secchi深度在低盐度地区和浮游植物生物量的指标更重要的中盐和多盐地区。这些研究结果与空间相关的控制Secchi深度增强了我们的理解河口光的可用性的长期变化，并建议特定区域的响应Secchi深度的变量（TSS和叶绿素a）有针对性的流域恢复行动，旨在限制养分和沉积物输入到切萨皮克湾。
Water clarity is an important ecosystem indicator of eutrophication in Chesapeake Bay and other coastal and estuarine systems across the globe. Although a variety of measures are available to quantify light availability in water, Secchi disk depths have been the most consistent and frequent measure employed in water monitoring programs. Because light availability is influenced by multiple variables, such as phytoplankton biomass, non-living suspended particles, and colored dissolved organic matter (CDOM), understanding the factors driving long-term variability and trends in water clarity is critical for targeting watershed management actions related to eutrophication. Thus, we conducted a comprehensive statistical analysis of spatial and temporal variations in Secchi disk depth and the key internal and external variables that influence its variability in Chesapeake Bay and its tidal tributaries over the past 30 years. Our results indicate that although watershed nutrient, sediment, and freshwater inputs did not correlate with Secchi depth on a monthly timescale outside of low-salinity regions near river outflows, water-column variables that represent the consequences of those inputs (CDOM, chlorophyll-a, and total suspended solids [TSS]) were strongly associated with Secchi depth variability. The inconsistency of these two findings may be explained by controls on chlorophyll-a and TSS that are not directly related to watershed input, such as grazing and resuspension, and by lags of several months between watershed inputs and the associated water-column concentrations. While salinity (a proxy for CDOM) was a dominant spatial covariate with Secchi depth bay-wide, TSS concentrations were strongly associated with temporal changes in Secchi depths in low-salinity regions and indicators of phytoplankton biomass were more important in mesohaline and polyhaline regions. These findings related to spatially dependent controls on Secchi depth enhance our understanding of long-term changes in estuarine light availability and suggest a region-specific response of Secchi depth to variables (TSS and chlorophyll-a) targeted by watershed restoration actions designed to limit nutrient and sediment inputs to Chesapeake Bay.