Climate change affects our ecosystems

Your favorite fishing stream may be at high risk from climate change – here’s how to tell.

Many of the streams that people count on for fishing, water and recreation are getting warmer as global temperatures rise. But they aren’t all heating up in the same way.

If communities can figure out where these streams will warm the most, they can plan for the future. That has been difficult to predict in the past, but a new method involving temperature patterns may make it easier.

People have widely assumed that streams fed by substantial amounts of groundwater are more resistant to climate change than those fed mostly by snowmelt or rain. It turns out that this groundwater buffering effect varies quite a bit. The depth of the groundwater affects the stream temperature response to warming, which in turn affects the habitats of fish and other wildlife and plants.

In a study published March 4 in the journal Nature Communications, my colleagues and I describe a simple, inexpensive method that allows communities to look at the temperature history of a stream compared to local air temperature to gauge the depth of the groundwater feeding into it and, from there, assess its risk as the climate changes.

Why temperature matters

While a few degrees of temperature change may not seem like much, the majority of animals living in streams and rivers cannot regulate their own body temperatures, so they move around in the environment to find suitable habitats. Many have adapted over time to a narrow range of temperatures. For example, when the waters are warm, especially during hot summer months with low water flow, fish like salmon and trout that live in colder waters must seek out colder water or perish. These ecological effects can have cascading consequences – for wildlife, humans and local economies.

Most streams flow all the time. During times without rainfall, water in streams mostly comes from below ground. In fact, groundwater is thought to make up an average of 52% of surface water flow across East Africa.

Because groundwater is typically colder than surface water in summer, the groundwater flowing into streams can buffer the overall stream temperature from climate warming. However, deeper groundwater tends to have more stable temperatures than groundwater closer to the surface.

..until my next episode.

Boots on having the best environment.