Data from: The legacy of large regime shifts in shallow lakes

Ecological shifts in shallow lakes from clear-water macrophyte-dominated to turbid-water phytoplankton-dominated are generally thought of as rapid short-term transitions. Diatom remains in sediment records from shallow lakes in the Prairie Pothole Region of North America provide new evidence that the long-term ecological stability of these lakes is defined by the legacy of large regime shifts. Here we examine the modern and historical stability of eleven shallow lakes. Currently, four of the lakes are in a clear-water state, three are consistently turbid-water, and four have been observed to change state from year to year (transitional). Lake sediment records spanning the past 150-200 years suggest that: 1) the diatom assemblage is characteristic of either clear or turbid lakes; 2) prior to significant landscape alteration, all of the lakes existed in a regime of a stable clear-water state; 3) lakes that are currently classified as turbid or transitional have experienced one strong regime shift over the past 150-200 years, and have since remained in a regime where turbid-water predominates; and 4) top-down impacts to the lake food web from fish introductions appear to be the dominant driver of strong regime shifts, and not increased nutrient availability. Based on our findings we demonstrate a method that could be used by lake managers to identify lakes that have an ecological history close to the clear-turbid regime threshold; such lakes might more easily be returned to a clear-water state through biomanipulation. The unfortunate reality is that many of these lakes are now part of a managed landscape and will likely require continued intervention.学界普遍认为，浅水湖泊从以大型植物为主的清水态（clear-water macrophyte-dominated）向以浮游植物为主的浊水态（turbid-water phytoplankton-dominated）的生态转型，多为快速的短期过程。北美草原坑洼区域（Prairie Pothole Region）浅水湖泊的沉积记录（sediment records）中的硅藻遗体（diatom remains），为这类湖泊的长期生态稳定性由大型稳态转换（regime shifts）遗留效应所决定这一论断提供了新的实证依据。本研究针对11个浅水湖泊的现代与历史生态稳定性展开分析。目前，其中4个湖泊处于清水态，3个长期维持浊水态，另有4个被观测到在年度间发生状态转换（过渡态）。对涵盖过去150至200年的湖泊沉积记录的分析结果显示：1) 硅藻群落（diatom assemblage）的组成特征可作为判别清水或浊水湖泊的依据；2) 在显著景观改造（landscape alteration）发生之前，所有湖泊均处于稳定清水态；3) 当前归类为浊水态或过渡态的湖泊，在过去150至200年间均经历过一次强烈的稳态转换，此后长期维持以浊水为主的状态；4) 鱼类引种（fish introductions）对湖泊食物网产生的下行控制效应（top-down impacts），似乎是引发强烈稳态转换的主导驱动因素，而非营养盐负荷的升高。基于本研究结果，我们提出了一种可供湖泊管理者使用的方法，用于识别生态历史接近清水-浊水稳态转换阈值的湖泊；这类湖泊可通过生物操纵（biomanipulation）更高效地恢复为清水态。但遗憾的是，这类湖泊如今大多已纳入人工管理景观，大概率需要持续的人工干预才能维持其健康状态。