On a razor’s edge: Maintaining lake ecosystem services and functions in an extreme world

The delineation of the current geological epoch as the “Anthropocene,” derived from the prefix “anthro-” meaning “human,” aptly summarizes the sheer magnitude in which humans have affected the biosphere. For many ecosystems, these pressures have caused long-term degradations to their health and functions. Freshwater systems such as lakes are particularly susceptible as these lentic water bodies act as sentinels of change in the region by accumulating information from the whole catchment. With pressures from anthropogenic actions and climatic scenarios projected to continue, if not intensify, in the coming decades, there is concern regarding the impairment of lake ecosystems.

Of the climatic projections, one of the more recent concerns is the intensifying frequency and severity of extreme climatic events (“ECEs”), or a climatic event such as a heatwave or precipitation that is in the tail ends (e.g. 99th percentile) of the distribution curve for that region or time of year. The potential for these events to instigate disproportionate disruptions within freshwater systems worldwide can be significant. Paired with other, non-climatic pressures derived from human actions, such as wide-spread land use change and pandemic outbreaks, there can be multiple pressures affecting the biosphere sequentially or in tandem. Depending upon the nature of the pressure, these can be categorized as “pulse” stressors which are generally short-lived events, such as heatwaves or extreme precipitation, and “press” stressors which have a long-lasting or chronic duration, such as ecosystem alterations (e.g. urbanization, dam construction, etc.) or climate change.  

Degradation of systems presents challenges not only for the biosphere itself but for human communities as our livelihoods are tied to and built upon the functions and values that the biosphere provides. If the trend of increasing pressures is permitted to continue without intervention, human health, well-being and economies could be impacted just as much as the ecosystem inhabitants. With lakes being the abundantly utilized and vulnerable systems that they are, approaching these multifaceted problems will require looking beyond just the science sector to address present and future challenges.

In this thesis, the research traces the cause-effect relationship from 1) the occurrence of extreme event(s) to 2) their implications on ecosystem functions to 3) the effect on ecosystem service provisioning and 4) the implications that intersectoral collaborations could have on ecosystem remediation. This is conducted through an interdisciplinary approach with each chapter tackling various aspects of this cause-effect chain. 

The research projects comprising this thesis built an intersectoral bridging of knowledge for tracing the impacts of extreme events and of anthropogenic actions. For example, chapter two investigated the implications of individual and coinciding climatic stressors through a full-factorial microcosm experiment (cause-effect chains aspects 1 and 2). The applications of a warming event (press pressure), a precipitation event (pulse pressure) and a combination of both were measured against the reactions of a phytoplankton community comprised of Anabaena flos-aquae (cyanobacterium), Chlorella vulgaris (green alga) and Synedra (diatom). While the subsequent results from this experiment cannot be directly translated into similar lake systems, the outcome provides insights into mechanisms wherein lake systems experience mitigating effects when coinciding pressures were applied. It has hypothesized that the resilience intrinsic to complex systems are capable of decreasing the impact of pressures.

Chapter three assessed the impacts that the coronavirus pandemic (“COVID-19”) has had on human interactions with lake systems in select highly urbanized regions (cause-effect chains aspects 1 to 3). Based on the sudden and wide-spread shift in human behaviors due to health regulations, there were distinct changes in the interactions occurring with aquatic systems (both increasing and decreasing depending upon the local mobility regulations that were applied). Shifting human demand for ecosystem services and uses during this anthropause period can inform lessons on management in a future full of lake degradation, climate change and more pandemics.

Chapter four details the creation and applications of the serious game “Flipping Lakes,” which is a tool wherein the content and uses trace the entirety of the thesis cause-effect chain (aspects 1 to 4). Through interacting with the game, players were engaged with the cause-effect components by acting as a “catchment manager” tasked with preserving the clear state of the game’s lakes, thus maintaining the capacity of these water bodies to provide ecosystem services. From a theoretical standpoint, this game permits players to view the full cause-effect interactions as they play out, even when in real life the implications could occur over long time periods or be challenging to decipher. Customizability of the game for “build your own catchments” further permits abundant opportunity for players to simulate a specific system, observe ecological concepts in-action or to explore various management approaches.

Chapter five investigated the extent of (dis)connection between lake scientists and managers along with methods to further bridge the sectors (emphasis on cause-effect chain aspect 4 in relation to aspects 1 to 3). Given the extent of influence that extreme events can have on lakes and subsequently on both the biosphere and anthropogenic communities, being able to mitigate or avoid the negative effects will require intersectoral knowledge and planning. In recognition of the survey findings, these methods should be adapted to the regional situation that managers are working within. Co-creation of collaboration frameworks and knowledge development could make strides towards achieving lake management goals, especially in an extreme world

Maintaining status quo approaches to utilizing, studying and managing lakes will not be sufficient for improving or preserving ecosystem health and functions in the future. Navigating the razor’s edge of maintained lake functions and services in an extreme world requires informed, proactive, inclusive and holistic methods. By recognizing the urgency of the situation and adapting the approaches used for this new reality, the biosphere and dependent anthropogenic communities may be able to weather the extremes.