Kaitlin L. Reinl

Long‐term research and monitoring programs are critical to our understanding of ecosystem processes. Although short‐term studies are one effective method for scientific investigations, they cannot elucidate the role of medium to long‐term cycles and lag effects in ecosystem processes, limiting our ability to interpret trends and interactions among processes. Because funding for environmental sciences is inherently limited, and work that addresses current societal needs is often prioritized over basic research and monitoring efforts, the design of long‐term studies needs to be creative and intentional. This will allow it to address relevant and pressing issues to remain competitive for funding while also being useful for conducting basic and applied research across a broad range of topics. We use prior studies from the U.S. National Estuarine Research Reserve System's System‐Wide Monitoring Program to illustrate the value of long‐term studies and demonstrate how they can be designed to directly address management needs, advance our fundamental ecological understanding of aquatic ecosystems, and better serve our communities.

Climate change is predicted to intensify lake algal blooms globally and result in regime shifts. However, observed increases in algal biomass do not consistently correlate with air temperature or precipitation, and evidence is lacking for a causal effect of climate or the nonlinear dynamics needed to demonstrate regime shifts. We modeled the causal effects of climate on annual lake chlorophyll (a measure of algal biomass) over 34 y for 24,452 lakes across broad ecoclimatic zones of the United States and evaluated the potential for regime shifts. We found that algal biomass was causally related to climate in 34% of lakes. In these cases, 71% exhibited abrupt but mostly temporary shifts as opposed to persistent changes, 13% had the potential for regime shifts. Climate was causally related to algal biomass in lakes experiencing all levels of human disturbance, but with different likelihood. Climate causality was most likely to be observed in lakes with minimal human disturbance and cooler summer temperatures that have increased over the 34 y studied. Climate causality was variable in lakes with low to moderate human disturbance, and least likely in lakes with high human disturbance, which may mask climate causality. Our results explain some of the previously observed heterogeneous climate responses of lake algal biomass globally and they can be used to predict future climate effects on lakes.

The objective of this viewpoint is to highlight the importance of long-term research and monitoring programs that are designed to address both basic science and applied management questions. Because funding for environmental sciences is inherently limited, and work that addresses current societal needs can be prioritized over basic research and monitoring efforts, design of long-term studies needs to be creative and intentional to address relevant and pressing issues, remain competitive for funding, and can also be used to conduct basic research across a broad range of topics. We use the U.S. National Estuarine Research Reserve System (NERRS) System-Wide Monitoring Program (SWMP) to illustrate the value of long-term studies and demonstrate how they can be designed to directly address management needs while also advancing our fundamental ecological understanding of coastal ecosystems.

Cyanobacterial blooms have substantial direct and indirect negative impacts on freshwater ecosystems including releasing toxins, blocking light needed by other organisms, and depleting oxygen. There is growing concern over the potential for climate change to promote cyanobacterial blooms, as the positive effects of increasing lake surface temperature on cyanobacterial growth are well documented in the literature; however, there is increasing evidence that cyanobacterial blooms are also being initiated and persisting in relatively cold‐water temperatures (< 15°C), including ice‐covered conditions. In this work, we provide evidence of freshwater cold‐water cyanobacterial blooms, review abiotic drivers and physiological adaptations leading to these blooms, offer a typology of these lesser‐studied cold‐water cyanobacterial blooms, and discuss their occurrence under changing climate conditions.

Freshwater cyanobacterial blooms have become ubiquitous, posing major threats to ecological and public health. Decades of research have focused on understanding drivers of these blooms with a primary focus on eutrophic systems; however, cyanobacterial blooms also occur in oligotrophic systems, but have received far less attention, resulting in a gap in our understanding of cyanobacterial blooms overall. In this review, we explore evidence of cyanobacterial blooms in oligotrophic freshwater systems and provide explanations for those occurrences. We show that through their unique physiological adaptations, cyanobacteria are able to thrive under a wide range of environmental conditions, including low‐nutrient waterbodies. We contend that to fully understand cyanobacterial blooms, and thereby mitigate and manage them, we must expand our inquiries to consider systems along the trophic gradient, and not solely focus on eutrophic systems, thus shifting the high‐nutrient paradigm to a trophic‐gradient paradigm.