Unraveling novel microbial community interactions involved in the decline and fate of an under-ice diatom bloom

冰盖对我们了解北温带生态系统构成了一个逻辑障碍。反映这一点的生态系统模型经常忽视或低估与冰盖有关的生物参数，包括潜在的高初级生产力。然而，目前全球气候变暖的趋势正在加强对冰雪覆盖环境的关注。面对气候变暖，我们对在这些环境中促进开花发展的因素的预测越来越有信心。然而，由于后勤方面的考虑，确定导致水华减少的因素和确定这些生物量的命运更加困难，这挑战了我们研究这些水华从“上升到下降”的能力。现有的双边合作关系，包括海岸警卫队和他们的破冰资产，再加上我离这个研究地点很近，为研究伊利湖冰下硅藻华的兴衰提供了一种可行的方法。这个假设驱动的提议的核心是解决伊利湖冬季硅藻华的发展，命运和食物网相互作用的问题。总的来说，该提案强调了寄生在常规控制（如营养供应和放牧）之外的新作用，在一个研究不足的季节调节浮游生物的动态。显微镜和转录组学分析鉴定的潜在寄生虫包括壶菌和卵菌，真菌样原生生物是农业和水产养殖中众所周知的致病菌。对新型宿主-寄生虫相互作用的其他见解来自于观察，从开花亚转录组中提取的最丰富的病毒序列与dsRNA Partitiviridae家族一致，其天然宿主是真菌和植物。鉴于壶菌是已知的硅藻寄生虫，人们很容易推测这些病毒可能有助于控制壶菌，而壶菌又寄生在伊利湖冰下的硅藻群落上。这些初步发现的意义是多方面的，并提供了一个框架来假设各种微生物相互作用在调节开花命运中的作用，其中寄生虫影响分流，减少直接出口到底栖动物的碳量。在这样做的过程中，寄生虫将藻华生物量转化为更容易被远洋食物网的各种成员消耗的水池。

Ice cover presents a logistical obstacle to our understanding of north temperate ecosystems. Reflecting this, ecosystem models frequently neglect or underestimate biological parameters associated with ice cover including potentially high rates of primary productivity. Yet current warming trends in global climate are reinforcing the need to focus attention on ice covered environments. We are growing more confident in our predictions of factors contributing to bloom development in these environments in the face of climate warming. However, identifying factors that lead to bloom decline and determining the fate of this biomass is more difficult owing to logistical considerations that challenge our abilities to study these blooms from 'rise to fall'. Existing collaborative relationships with binational agencies including Coast Guards and their ice-breaking assets combined with my close proximity to this study site offer a feasible approach to study the rise and decline of an expansive under-ice diatom bloom in Lake Erie. Central to this hypothesis-driven proposal are questions addressing the development, fate and foodweb interactions of Lake Erie's winter diatom bloom. Broadly, the proposal highlights the emerging role of parasitism beyond conventional controls such as nutrient supply and grazing, in regulating plankton dynamics during a poorly studied season. Amongst potential parasites identified by microscopy and transcriptomic analysis were chytrid fungi and oomycetes, fungal-like protists that are well-known pathogens causing disease in agriculture and aquaculture. Additional insights into novel host-parasite interactions came from the observation that the most abundant viral sequences mined from a bloom metatranscriptome aligned with the dsRNA Partitiviridae family whose natural hosts are fungi and plants. Given that chytrids are known parasites of diatoms, it is tempting to speculate that these viruses may help control chytrids which in turn are parasitic on the under-ice Lake Erie diatom community. The implications of these preliminary findings are manifold and provide the framework to hypothesize roles for diverse microbial interactions in regulating bloom fate whereby parasites effectuate a shunt reducing the amount of carbon that is directly exported to the benthos. In doing so, parasites transform bloom biomass into pools more readily consumed by diverse members of the pelagic food web.