Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA.
Appl Environ Microbiol. 2022 Jun 28;88(12):e0251821. doi: 10.1128/aem.02518-21. Epub 2022 May 23.
Blooms of many dinoflagellates, including several harmful algal bloom (HAB) species, are seeded and revived through the germination of benthic resting cysts. Temperature is a key determinant of cysts' germination rate, and temperature-germination rate relationships are therefore fundamental to understanding species' germling cell production, cyst bed persistence, and resilience to climate warming. This study measured germination by cysts of the HAB dinoflagellate Alexandrium catenella using a growing degree-day () approach that accounts for the time and intensity of warming above a critical temperature. Time courses of germination at different temperatures were fit to lognormal cumulative distribution functions for the estimation of the median days to germination. As temperature increased, germination times decreased hyperbolically. scaling collapsed variability in germination times between temperatures after cysts were oxygenated. A parallel experiment demonstrated stable temperature-rate relationships in cysts collected during different phases of seasonal temperature cycles over three years. scaling of the results from prior A. catenella germination studies showed consistent differences between populations across a wide range of temperatures and suggests selective pressure for different germination rates. The model provides an elegant approach to quantify and compare the temperature dependency of germination among populations, between species, and in response to changing environmental conditions. Germination by benthic life history stages is the first step of bloom initiation in many, diverse phytoplankton species. This study outlines a growing degree-day () approach for comparing the temperature dependence of germination rates measured in different populations. Germination by cysts of Alexandrium catenella, a harmful algal bloom dinoflagellate that causes paralytic shellfish poisoning, is shown to require a defined amount of warming, measured in after cysts are aerated. Scaling by , the time integral of temperature difference from a critical threshold, enabled direct comparison of rates measured at different temperatures and in different studies.
许多甲藻的水华，包括几种有害藻类（HAB）物种，是通过底栖休眠孢的萌发而产生和恢复的。温度是孢萌发率的关键决定因素，因此温度-萌发率关系是理解物种萌发细胞产生、孢床持久性和对气候变暖的恢复能力的基础。本研究使用度日（）方法测量了 HAB 甲藻亚历山大藻（Alexandrium catenella）孢的萌发，该方法考虑了临界温度以上升温的时间和强度。在不同温度下的萌发时间历程被拟合到对数正态累积分布函数中，以估计萌发的中位数天数。随着温度的升高，萌发时间呈双曲线减少。在氧合后， 缩放消除了不同温度下萌发时间的变异性。一项平行实验表明，在三年的时间里，在不同的季节性温度周期阶段收集的孢中，温度-速率关系稳定。对来自先前亚历山大藻萌发研究的结果进行 缩放表明，在广泛的温度范围内，不同种群之间存在一致的差异，表明存在不同萌发率的选择压力。该模型提供了一种优雅的方法来量化和比较不同种群之间、不同物种之间以及在环境条件变化时萌发的温度依赖性。底栖生活史阶段的萌发是许多不同浮游植物物种爆发的第一步。本研究概述了一种度日（）方法，用于比较不同种群测量的萌发率的温度依赖性。亚历山大藻（Alexandrium catenella）的孢萌发需要一定量的升温，在孢充气后以度日（）来衡量，这是一种导致麻痹性贝类中毒的有害藻类甲藻。通过 缩放，即从临界阈值的温度差的时间积分，可以直接比较在不同温度和不同研究中测量的速率。
