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

冰盖对我们理解北温带生态系统构成了后勤障碍。反映这一点的是，生态系统模型经常忽视或低估与冰盖相关的生物参数，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关注冰盖环境的必要性。面对气候变暖，我们对这些环境中导致水华发展的因素的预测越来越有信心。然而，确定导致水华衰退的因素并确定这些生物量的命运变得更加困难，因为后勤方面的考虑挑战了我们研究这些水华从上升到下降的能力。与包括海岸警卫队及其破冰资产在内的两国机构现有的合作关系，再加上我离这个研究地点很近，为研究伊利湖大规模冰下硅藻水华的兴衰提供了一个可行的方法。这一假设驱动的提议的核心是解决伊利湖冬季硅藻水华的发展、命运和食物网相互作用的问题。总的来说，该提案强调了在一个研究较少的季节，寄生在调节浮游生物动态方面的作用，超越了营养物质供应和放牧等常规控制。显微镜和转录分析发现的潜在寄生虫中，包括合胞真菌和卵菌，它们是在农业和水产养殖中引起疾病的众所周知的病原体。对新的宿主-寄生虫相互作用的其他见解来自于观察到，从BLOW偏转录组中挖掘出的最丰富的病毒序列与dsRNA Partitiviridae家族一致，其自然宿主是真菌和植物。鉴于裂卵虫是已知的硅藻寄生虫，很容易推测这些病毒可能有助于控制裂卵虫，而裂卵虫又寄生在冰下的伊利湖硅藻群落。这些初步发现的意义是多方面的，并提供了框架，以假设不同的微生物相互作用在调节水华命运中的作用，寄生虫实现分流，减少直接输出到底栖生物的碳量。在这样做的过程中，寄生虫将大量的生物量转化为池塘，更容易被远洋食物网的不同成员消费。

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.