AUSABLE WATER WISE: Changing leaves and spawning brook trout

Every autumn in the Adirondacks, we look forward to majestic fall foliage on display in our watersheds. Leaves are not the only thing changing this time of year, however, as our region prepares for winter. Many species of wildlife are breeding, birds and insects migrate to warmer climates, and reptiles, amphibians and mammals prepare to weather the frigid northeast winters. Trees also prepare for winter and in so doing, give us a lovely display of colors.

To avoid expending large amounts of energy during the winter, trees shed their leaves and transfer nutrients to their twigs and branches for the winter. This allows them to re-absorb up to half of these nutrients in their system and save them for the spring growth cycle. But why do the leaves change color during this process? In the summer months, trees use carbon dioxide and sunlight to produce a byproduct of oxygen and glucose, which they use for food — the process known as photosynthesis. Chlorophyll, the pigment most active during this process, is what gives leaves their green color. As trees prepare for winter, the photosynthesis process slows and chlorophyl production nearly stops. Underlying pigment colors then become more prevalent: carotenoids are the yellow and orange pigments and anthocyanins are the red pigments.

Beyond trees and terrestrial wildlife, our native fish species, including brook trout, are also preparing for winter. Late September through mid-October is the spawning season for these beautiful salmonids. Brook trout in rivers or ponds will swim upstream or into inflowing tributaries to cooler water, often cold springs or upwelling groundwater. Females use their tails to construct round nests of gravel called redds. Once completed, the female waits in her redd for a male to arrive, at which point she will lay her eggs and the male will fertilize them. Once fertilized, the female will cover the eggs with small pebbles to protect them until hatching season in late winter or early spring.

Fish, trees, and the rest of our biotic communities exist in an interconnected system, and researchers study their relationships from a scientific perspective. Phenology is the branch of science that examines cyclic and seasonal changes in the natural world, especially in relation to climate and plant and animal life. In 2013, a phenological study conducted in Quebec, compared brook trout spawning season to the apex of autumn leaf change. The data from this study suggest that brook trout spawning may synchronize with fall leaf color change. This connection, and other interconnections between terrestrial and aquatic processes, are important because they can help us predict how animals and plants are affected by altered weather patterns due to climate change.

It is critical to understand how spawning patterns earlier or later in the year, due to climate change, affect brook trout populations. Various studies have identified climate change as the top threat to brook trout survival in the northeastern United States. Within this region, Adirondack watersheds provide extensive areas of intact brook trout habitat — ample opportunity for this special species to flourish, even with rising water temperatures. Because of this, the Ausable River Association works hard to improve habitat connectivity for brook trout by replacing undersized culverts and restoring reaches of streams and rivers compromised by past industrial practices or lacking access to their floodplains.

As we work cooperatively with municipalities, government agencies, nonprofit partners, landowners, and other community members, one of our long-term goals is to understand, predict, and conserve the future of the brook trout in our Adirondack watersheds. We know that protecting and restoring the form and self-sustaining function of our waterways and creating habitat for native species also creates resilience for our communities — the place where we live, work, and play.

If you want to learn more about how our work is making a difference in this region, and how it fits into larger conservation efforts nationally and globally, please join us virtually on Friday, Oct. 29 for our third annual Wild & Scenic Film Festival. Learn more at www.ausableriver.org/events.

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(Carrianne Pershyn is the biodiversity research manager for the Ausable River Association.)

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