University of Maryland Center for Environmental Science, Horn Point Laboratory, PO Box 775, Cambridge, MD 21613, USA.
University of Maryland Center for Environmental Science, Horn Point Laboratory, PO Box 775, Cambridge, MD 21613, USA.
Sci Total Environ. 2021 May 15;769:144528. doi: 10.1016/j.scitotenv.2020.144528. Epub 2021 Jan 7.
Planktonic Prorocentrum, common harmful dinoflagellate, are increasing in frequency, duration, and magnitude globally, as exemplified by the number of blooms of P. minimum in Chesapeake Bay that have nearly doubled over the past 3 decades. Although the dynamics of transport and seasonal occurrence of this species have been previously described, it has been challenging to predict the timing and location of P. minimum blooms in Chesapeake Bay. We developed a new three-dimensional mechanistic model of this species that integrates physics, nutrient cycling and plankton physiology and embedded it within a coupled hydrodynamic-biogeochemical model originally developed for simulating water quality in eutrophic estuarine and coastal waters. Hindcast simulations reproduced the observed time series and spatial distribution of cell density, in particular capturing well its peak in May in the mid-to-upper part of the estuary. Timing and duration of the blooms were mostly determined by the temperature-dependent growth function, while mortality due to grazing and respiration played a minor role. The model also reproduced the pattern of overwintering populations, which are located in bottom waters of the lower Bay, and are transported upstream in spring by estuarine flow. Blooms develop in the mid-upper parts of the estuary when these transported cells encounter high nutrient concentrations from the Susquehanna River and favorable light conditions. Diagnostic analysis and model-sensitivity experiments of nutrient conditions showed that high nitrogen:phosphorus conditions favor bloom development. The model also captured the observed interannual variations in the magnitude and spatial distribution of P. minimum blooms.
浮游性原甲藻是一种常见的有害甲藻，其在全球范围内的出现频率、持续时间和规模都在增加，以切萨皮克湾中最小原甲藻的爆发数量为例，在过去的 30 年中几乎翻了一番。尽管该物种的迁移动力学和季节性出现已经得到了先前的描述，但预测切萨皮克湾中最小原甲藻的爆发时间和地点一直具有挑战性。我们开发了一个新的三维机制模型，该模型集成了物理、营养循环和浮游生物生理学，并将其嵌入到一个最初为模拟富营养河口和沿海水域水质而开发的耦合水动力-生物地球化学模型中。回溯模拟再现了细胞密度的观测时间序列和空间分布，特别是很好地捕捉到了其在 5 月中旬到上游的峰值。爆发的时间和持续时间主要取决于温度相关的生长函数，而摄食和呼吸引起的死亡率则起次要作用。该模型还再现了越冬种群的模式，这些种群位于湾底的下部水域，在春季通过河口流被输送到上游。当这些输送的细胞遇到来自萨斯奎哈纳河的高营养浓度和有利的光照条件时，就会在河口的中上部发育成浮游生物。诊断分析和模型敏感性实验表明，高氮磷条件有利于浮游生物的爆发。该模型还捕捉到了观测到的最小原甲藻爆发的规模和空间分布的年际变化。
