A time-dependent model of Margalefidinium polykrikoides, a mixotrophic dinoflagellate, cell growth was implemented to assess controls on blooms in the Lafayette River, a shallow, tidal sub-tributary of the lower Chesapeake Bay. Simulated cell growth included autotrophic and heterotrophic contributions. Autotrophic cell growth with no nutrient limitation resulted in a bloom but produced chlorophyll concentrations that were 45% less than observed bloom concentrations (~80 mg Chl m⁻³ vs. 145 mg Chl m⁻³) and a bloom progression that did not match observations. Excystment (cyst germination) was important for bloom initiation, but did not influence the development of algal biomass or bloom duration. Encystment (cyst formation) resulted in small losses of biomass throughout the bloom but similarly, did not influence M. polykrikoides cell density or the duration of blooms. In contrast, the degree of heterotrophy significantly impacted cell densities achieved and bloom duration. When heterotrophy contributed a constant 30% to cell growth, and dissolved inorganic nitrogen was not limiting, simulated chlorophyll concentrations were within those observed during blooms (maximum ~140 mg Chl m⁻³). However, nitrogen limitation quenched the maximum chlorophyll concentration by a factor of three. Specifying heterotrophy as an increasing function of nutrient limitation, allowing it to contribute up to 50% and 70% of total growth, resulted in simulated maximum chlorophyll concentrations of 90 mg Chl m⁻³ and 180 mg Chl m⁻³, respectively. This suggested that blooms of M. polykrikoides in the Lafayette River are fortified and maintained by substantial heterotrophic nutritional inputs. The timing and progression of the simulated bloom was controlled by the temperature range, 23 °C to 28 °C, that supports M. polykrikoides growth. Temperature increases of 0.5 °C and 1.0 °C, consistent with current warming trends in the lower Chesapeake Bay due to climate change, shifted the timing of bloom initiation to be earlier and extended the duration of blooms; maximum bloom magnitude was reduced by 50% and 65%, respectively. Warming by 5 °C suppressed the summer bloom. The simulations suggested that the timing of M. polykrikoides blooms in the Lafayette River is controlled by temperature and the bloom magnitude is determined by trade-offs between the severity of nutrient limitation and the relative contribution of mixotrophy to cell growth.

实施了Margalefidinium polykrikoides（一种混合营养型鞭毛藻）细胞生长的时间依赖模型，以评估对拉斐特河（切萨皮克湾下游的浅潮次支流）中水华的控制。模拟细胞生长包括自养和异养贡献。没有营养限制的自养细胞生长导致水华，但产生的叶绿素浓度比观察到的水华浓度低 45%（~80 mg Chl m ^-3与 145 mg Chl m ^-3) 和与观察结果不匹配的绽放进程。脱囊（囊肿萌发）对于藻华开始很重要，但不影响藻类生物量的发育或藻华持续时间。包囊（包囊形成）导致整个开花期间生物量的少量损失，但同样地，不会影响M. polykrikoides细胞密度或开花持续时间。相比之下，异养程度显着影响达到的细胞密度和开花持续时间。当异养对细胞生长的贡献恒定为 30% 并且溶解的无机氮不受限制时，模拟的叶绿素浓度在开花期间观察到的浓度范围内（最大 ~140 mg Chl m ^-3）。然而，氮限制使最大叶绿素浓度降低了三倍。将异养指定为营养限制的递增函数，允许其贡献高达总生长的 50% 和 70%，导致模拟的最大叶绿素浓度分别为 90 mg Chl m ^-3和 180 mg Chl m ^-3。这表明拉斐特河中M. polykrikoides 的大量繁殖得到了大量异养营养投入的强化和维持。模拟水华的时间和进程由支持M. polykrikoides的温度范围控制，23 °C 到 28 °C生长。温度升高 0.5 °C 和 1.0 °C，与当前切萨皮克湾下游由于气候变化而变暖的趋势一致，使开花开始的时间提前并延长了开花持续时间；最大绽放幅度分别降低了 50% 和 65%。升温 5 °C 抑制了夏季开花。模拟表明，拉斐特河中M. polykrikoides开花的时间受温度控制，而开花程度取决于养分限制的严重程度和混合营养对细胞生长的相对贡献之间的权衡。