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.

浅水湖泊从以大型水生植物为主的清水稳态，向以浮游植物为主的浊水稳态的生态稳态转换，以往普遍被认为是短期快速的过渡过程。北美草原坑洼区域（Prairie Pothole Region）浅水湖泊沉积记录中的硅藻残体，为这类湖泊的长期生态稳定性由大规模稳态转换遗留效应所决定这一论点提供了新的实证。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。当前，其中4个湖泊处于清水稳态，3个始终维持浊水稳态，另有4个湖泊的生态状态逐年发生变化（过渡态）。
跨越过去150至200年的湖泊沉积记录显示：1）硅藻群落的组成特征与清水或浊水湖泊的典型特征高度匹配；2）在大规模景观改造发生之前，所有湖泊均处于稳定的清水稳态；3）当前被归类为浊水态或过渡态的湖泊，在过去150至200年间均经历过一次剧烈的稳态转换，自此之后便长期维持以浊水为主的生态系统；4）鱼类引种对湖泊食物网产生的下行控制效应，是引发剧烈稳态转换的主导驱动因素，而非营养盐浓度的升高。
基于本研究结果，我们提出了一套可用于湖泊管理者识别生态历史接近清水-浊水稳态转换阈值的湖泊的方法；这类湖泊可通过生物操纵手段更高效地恢复至清水稳态。但令人遗憾的是，当前这类湖泊大多已纳入人工管理的景观体系中，大概率需要持续的人为干预才能维持其生态状态。