Science Inventory

Geographic Analysis of the Vulnerability of U.S. Lakes to Cyanobacterial Blooms under Future Climate

Citation:

Butcher, J., M. Fernandez, T. Johnson, A. Shabani, AND S. Lee. Geographic Analysis of the Vulnerability of U.S. Lakes to Cyanobacterial Blooms under Future Climate. Earth Interactions. American Meteorological Society, Boston, MA, 27(1):e230004, (2023). https://doi.org/10.1175/EI-D-23-0004.1

Impact/Purpose:

Climate change has been linked to an increased risk of HAB events. The long-term (e.g., multi-decadal) effects of climate change on HABs risk in different geographic and bio-physical settings are not well understood. While many authors have identified risk factors related to cyanobacteria blooms, the relationship between future cyanobacterial blooms and physical and chemical drivers is complex and variable. This article describes a national-scale, qualitative evidence synthesis of potential future changes in cyanobacterial HAB risk for inland lakes in the conterminous U.S. Estimates of future HAB risk is based on estimates of how different lake types in different regions of the U.S. are likely to respond, e.g., based on a set of lake “archetypes” defined by depth, surface area, water clarity and/or other physical characteristics for each region. Results help build the capacity of EPA, State, and local partners to understand and respond to future changes in HAB risk in different U.S. regions and lake types.

Description:

Cyanobacteria blooms are an increasing concern in U.S. freshwaters. Such blooms can produce nuisance conditions, deplete oxygen, and alter the food chain, and in some cases they may produce potent toxins, although many factors may modulate the relationships between biomass and toxin production. Cyanobacterial blooms are in turn associated with nutrient enrichment and warm water temperatures. Climate change is expected to increase water temperatures and, in many areas, surface runoff that can transport nutrient loads to lakes. While some progress has been made in short-term prediction of cyanobacterial bloom and toxin risk, the long-term projections of which lakes will become more vulnerable to such events as a result of climate change is less clear because of the complex interaction of multiple factors that affect bloom probability. We address this question by reviewing the literature to identify risk factors that increase lake vulnerability to cyanobacterial blooms and evaluating how climate change may alter these factors across the sample of conterminous U.S. lakes contained in the 2007 National Lakes Assessment. Results provide a national-scale assessment of where and in which types of lakes climate change will likely increase the overall risk of cyanobacterial blooms, rather than finer-scale prediction of expected cyanobacterial and toxin levels in individual lakes. This information can be used to guide climate change adaptation planning, including monitoring and management efforts to minimize the effects of increased cyanobacterial prevalence.