Small streams beloved by hikers, anglers and nature enthusiasts alike are also crucial for our ecosystems

Headwater streams are the sources of lakes, large rivers, and estuaries. Even though they are smaller and generally cooler than the rivers into which they flow, they are important for feeding fresh water, nutrients, and sediment into the larger bodies of water. Being as though they are so small, streams are highly sensitive to drought and changes in water availability. Thus, the increasing temperatures, particularly in the winter, and shifts in precipitation resulting from climate change have begun to threaten these systems. A greater portion of coldwater habitats (>60%) is likely to be lost in the Northeast than in the rest of the United States by 2100 because regional air temperatures are expected to rise at a faster rate.

Headwater streams support key life stages of important Massachusetts wildlife species

For example, Brook Trout, an economically important game species, are increasingly restricted to cold, clean headwater streams in Massachusetts (Climate Action Tool).

The U.S. Geological Survey Eastern Ecological Science Center’s S.O. Conte Fish Research Center in Turners Falls, Massachusetts, aims to identify streams that will support native fish long-term. Incorporating expertise from several disciplines including hydrogeology, stream temperature, and ecology, the team works collaboratively to research how fish interact with cold-water habitats, and uses interactive visualizations and tools to empower decision-makers to incorporate the latest science into on-the-ground management. 

The work done by members of the team, including Dr. Benjamin Letcher, a USGS population ecologist, Dr. Jennifer Fair, a USGS ecohydrologist, and Josie Pilchik, a Ph.D student in Organismic & Evolutionary Biology at the University of Massachusetts, Amherst, is crucial to expanding knowledge of interactions between streamflow, stream temperature, and fish behavior. These dynamics aggregate to improved understanding of current and future climate refugia for native cold water fishes. The specifics matter; in Massachusetts, streams are assigned to different categories according to thermal conditions, which correspond to differing levels of protection. 

New Brook Trout Discoveries with USGS Flow Photo Explorer

The USGS team seeks to integrate different scales of conservation efforts, particularly research and resource management, to make conservation efforts more impactful with the necessary research and technology needed to make these decisions. For example, the USGS Flow Photo Explorer combines time-lapse imagery of small streams taken by low-cost game cameras with a machine-learning model to rank images in terms of streamflow (developed in partnership with Microsoft’s AI For Good Lab). The Flow Photo Explorer is a collaborative effort in that anyone can contribute to the research being done. Anyone can place a camera on a small stream and upload image data, annotate that data, and create a relative flow hydrograph. The tool is working to make data processes easier by creating a stable, explorable database for people to view data in one place. AI is also being adapted to integrate stream flow into these analyses

Results provide new information on streamflow and temperature dynamics, which in turn supports decisions made by municipalities across the region. The project has revealed previously undocumented effects of storms, stream drying, and other impacts of hydrologic extremes on the habitat. New technology like the Flow Photo Explorer is changing the way researchers think about and map refugia.

Brook trout (Salvelinus fontinalis), a coldwater-adapted species that is important to ecology and recreation in the northeastern U.S., has been the focus of recent refugia research. Warming stream temperatures and changing flow conditions pose a threat to the species. Pilchik and Matt O’Donnell, a research ecologist, are part of a team of researchers from the University of Massachusetts and USGS partly funded by the Northeast Climate Adaptation Science Center (CASC) that worked to discover how the varying flow and temperature conditions in streams were impacting brook trout movements, behavioral decisions, and overall growth and survival. Using radio telemetry and thermal tags in fish, the team tracked brook trout movements throughout the summer to characterize their habitats and the temperatures they were experiencing. They also track their growth and compare them to fish both undisturbed and laboratory settings. Through this study, researchers discovered that fish were defying previous understanding of warm temperature tolerance, and finding cold microclimates that had not previously been identified with traditional stream monitoring equipment.  

The Flow Photo Explorer Tracking Streams After Hurricane Helene

Hurricanes often take out traditional stream monitoring approaches, but when Hurricane Helene hit in November, many of the cameras installed as part of the Flow Photo Explorer remained operative and captured the effect of the hurricane. The compilation of still images captured became GIFs demonstrating the impact that a hurricane can have, in this case, on streamflow in Shenandoah National Park. This noncontact form of monitoring allowed for an understanding of the timing and relative magnitude of the impact of the hurricane on the small streams and aquatic ecology in the park.

Stream flow data are crucial to furthering the understanding of these ecosystems. Areas with too much or too little flow make them difficult places for fish—these factors are caused by drought and floods. The team is working to identify places that are more susceptible to these conditions and learn how they work, and pictures like the ones the Flow Photo Explorer captures are fundamental to furthering the understanding of stream flow diversity.

Collaborations Across the Northeast

The team at Conte Fish Research Center collaborates and works with many organizations across the region, including but not limited to:

Angie Reed, a Water Resources Planner with the Penobscot Nation, has been setting up cameras in Maine to monitor streams. She is excited about how easy and cost-effective this monitoring can be. Cameras are an important aspect of the USGS Remote Sensing Division, where Marty Briggs has pioneered thinking in the space of cold water, groundwater, and surface water interactions as a hydrogeologist. He thinks about it all as a mechanism with a mechanistic approach and emphasizes the importance of cameras in efforts to understand sources of cold water in streams.  

The Deerfield River Watershed Chapter of Trout Unlimited works with the center as a project partner and helps with centering the work around trout, asking central questions like how the field equipment supports species. As a USGS fish biologist and head of the Massachusetts Cooperative Research Unit, Allison Roy works with Pilchik on cold water patch mapping. They work to understand how water seeps that come up from the ground into streams may or may not cause cold water patches and the extent to which these are important for fish refugia during low flow or warm temperatures. 

Streams are a large percentage of the landscape, many stream miles composed of smaller streams that are often difficult to access. Tools like the USGS Flow Photo Explorer provide the necessary monitoring aspects that are the key to understanding the current and future situation of these landscapes, regardless of their traditional aspects of accessibility. Understanding the flow of these streams and the subsequent impact one component has will lead to a further understanding of other stream characteristics in conjunction with one another, such as the effect flow and temperature together have on populations. The research and work of the S.O. Conte Fish Research Center team is fundamental to furthering this understanding and to building the necessary instruments to continue to change the landscape of the research in this evolving ecosystem. 

Our brightly colored, forest log dwelling Spring Salamander, a species of conservation concern, also frequents the clean, cool, well oxygenated waters of headwater streams. Their larvae as strictly aquatic, so strictly in fact that they live in the stream on average four years before metamorphizing into an adult. Adults are also highly aquatic but are known to leave from time to time in order to forage in riparian zones. Therefore, these salamanders are highly susceptible to changing water temperatures. In MA, spring salamanders do not persist within streams that have been warmed, muddied, or degraded. Since these species are so susceptible to habitat change, it has been suggested that warming of streams as a result from climate change has the potential to reduce and fragment populations of this species.

Another stream-dependent species is the state-listed brook floater, one of the most endangered mussels in northeastern North America; declines may be related to climate and land use change but may also be related to the decline of their host fish brook trout. These guys not only are responsible for keeping the water from being overrun by algae, but also filter feed bacteria, zooplankton, and sediment from the water. These silent super heroes keep our streams turbidity low and oxygenation high in order to support other organisms that rely on high levels of oxygen to grow.

Despite stream vulnerability, there are options for conserving these ecosystems in the face of climate change

MassWildlife is teaming with federal, state, and university partners to map areas of climate change refugia, streams that are most resistant to increases in temperature that can increase persistence of wildlife and fish populations, to prioritize for protection and restoration. For example, brook trout are able to persist in surprisingly small, isolated populations above barriers in headwater streams so there is potential to protect and connect these places to bolster declining populations. Alternatively, areas that are projected to warm but are still well connected could be protected for warmer water species of conservation concern.

Restorations of stream crossings have made impacts

 In Nash Stream Forest in New Hampshire, crossings were restored from 2007-2016 and other instream work was done from 2008-2017 by Trout Unlimited, NH Fish and Game Department, NH Division of Forests and Lands. This project aimed to restore the natural fluvial processes, such as the natural flow of the water and removing excess sediment in order to increase oxygenation of the water. Streams that had low summer temperatures and good habitat upstream of the culvert were prioritized. Culverts were either removed or replaced with geomorphically compatible crossings that didn't impede an organism's ability to cross, with an emphasis on the native brook trout. Another project was done in the Indian Stream watershed in New Hampshire from 2013 to 2017 for the crossings and 2015-2017 for instream work by Trout Unlimited, NH Fish and Game Department, The Forestland Group, NH Department of Natural and Cultural Resources with the same goals in mind.

     A dam removal was also done at Hamant Brookin Massachusetts funded by Millennium Power, The Eastern Brook Trout Joint Venture, and The Massachusetts Environmental Trust. This dam removal aimed to reconnect ¾ of a mile of coldwater habitat for native Eastern Brook Trout and Wood Turtles. It accomplished this by restoring stream and riparian habitat and habitat connectivity, improving water quality. Another example is the collaborative monitoring and mapping efforts led by Dan Isaak of the U.S. Forest Service in the Pacific Northwest. The Cold-Water Climate Shield research project now provides user-friendly digital maps and GIS databases showing which streams throughout the Northwest are most likely to serve as climate change refugia for salmonids this century.

Current efforts to identify and map coldwater climate change refugia for wildlife and people

Massachusetts Climate Action Tool Ecology and Vulnerability Rivers and streams: Coldwater fisheries resources streams

MassGIS Data - MA DFW Coldwater Fisheries Resources (1:25,000)

Mass.gov Coldwater Fish Resources List