Boulianne Jean-Simon, Kivilä E Henriikka, Beisner Beatrix E, Rautio Milla
Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 Boulevard de l'Université, Chicoutimi, Québec G7H 2B1, Canada.
Groupe de Recherche Interuniversitaire en Limnologie, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada.
J Plankton Res. 2025 Aug 17;47(5):fbaf035. doi: 10.1093/plankt/fbaf035. eCollection 2025 Sep-Oct.
Lakes are understudied during ice-covered periods; yet physical, hydrodynamical and biological processes continue under the ice. Ice cover reorganizes lake ecosystems by altering thermal stratification and solar radiation, creating conditions that support different organisms, food webs, and potential trophic cascades. We investigated seasonal shifts in biomass and vertical distribution of heterotrophic and autotrophic micro-organisms (heterotrophic bacteria, picoautotrophs, colorless and pigmented nanoflagellates) and zooplankton across winter in relation to limnological characteristics and hydrodynamics. Boreal Lake Simoncouche was sampled at five depths on six dates between autumn overturn (November 2020) and spring overturn (April 2021) for temperature, dissolved oxygen, chlorophyll-, and plankton. Low chlorophyll- and high heterotroph-to-autotroph biomass ratios indicated dominance of the heterotrophic energy pathway under ice. Heterotrophic micro-organisms also dominated during well-lit overturns, emphasizing the role of the microbial loop in all seasons. Zooplankton richness remained high under ice (18-22 taxa), with most species favoring deeper, warmer layers. Several species of rotifer and cladoceran sustained egg production through winter, ceasing only briefly in February. These findings highlight strong vertical and seasonal heterogeneity in winter-active plankton communities, shaped by stratification, light, and resources, and support the view that winter is biologically dynamic, with consequences for the subsequent open-water season.
在湖泊被冰层覆盖期间，相关研究较少；然而，物理、流体动力学和生物过程在冰层下仍在继续。冰盖通过改变热分层和太阳辐射来重组湖泊生态系统，创造出有利于不同生物、食物网和潜在营养级联反应的条件。我们研究了冬季异养和自养微生物（异养细菌、微微型自养生物、无色和有色纳米鞭毛虫）以及浮游动物的生物量和垂直分布的季节性变化，及其与湖沼学特征和流体动力学的关系。在西蒙库什寒温带湖泊，于秋季水体循环期（2020年11月）至春季水体循环期（2021年4月）之间的六个日期，在五个深度采集了温度、溶解氧、叶绿素以及浮游生物样本。低叶绿素含量和高异养生物与自养生物量比表明在冰层下异养能量途径占主导地位。在光照充足的水体循环期，异养微生物也占主导，这凸显了微生物环在所有季节中的作用。冰层下浮游动物的丰富度依然很高（18 - 22个分类单元），大多数物种偏好更深、更温暖的水层。几种轮虫和枝角类动物在冬季持续产卵，仅在2月短暂停止。这些发现突出了冬季活跃的浮游生物群落存在强烈的垂直和季节性异质性，这种异质性由分层、光照和资源所塑造，并支持了冬季具有生物动态性这一观点，且这对随后的敞水区季节会产生影响。
