Pretty substantial decreases: Wildlife scientists estimate impact of floods on aquatic creatures – VTDigger

Vermont Fish & Wildlife Aquatic Habitat Biologist Will Eldridge holds up a brook trout he caught at Pond Brook in Berlin. Photo by Emma Cotton/VTDigger

BERLIN Electric fishing gear in hand, biologist Will Eldridge smiled as he fished a young brown trout from Pond Brook on Thursday afternoon. He and other Vermont Fish & Wildlife officials were surveying the area in the aftermath of the devastating floods, and it was the first young brook trout he had seen all day.

While scientists don’t yet know how fish were affected across the state, fluxes are still too high to conduct large-scale monitoring. Eldridge has estimated that fish populations will decline as much as after Tropical Storm Irene.

So, he said, what we’ve found is that the numbers have dropped considerably. Like 50% to 60% or higher.

That’s probably what we expect here, he said. You’re going to see pretty substantial declines in populations.

Particularly at risk are younger fish that are not yet strong swimmers. Brook trout may be better off than some other species because they mature at a younger age, meaning fewer fish are small, Eldridge said.

As Vermont’s human residents have endured flood impacts that required more than 100 rescue efforts, left homes and businesses in ruins, and destroyed essential infrastructure, the tiny creatures, especially those that live in rivers and streams, have lost homes, habitats, and lives.

The risk of extreme weather events, including floods, has increased in Vermont with a changing climate, and such events cause a variety of dangers to wildlife.

There are more ways, far more ways, these changes can affect wildlife than we could even imagine at this point, said Jim Andrews, who leads the Vermont Reptile and Amphibian Atlas. Wildlife has co-evolved with certain weather patterns and we are changing the rules of the game.

While rising temperatures, northward migration of ticks and new diseases could be considered long-term impacts of climate change, the changes caused by an event like this month’s floods are more direct and rapid.

It could be a decade before we see changes in other species, but it will be immediate short-term changes in some of those streams that were directly affected this time around, he said.

Like fish, salamanders are likely to experience significant population declines after the flood. Both typically spawn in rocks in freshwater streams, which are nearly sterilized by these floods, Andrews said.

At this time of year, bifurcated salamanders and spring salamanders capsize in the water and spawn under rocks.

Those rocks would have been washed downstream and fallen, so their effort to reproduce and reproduce is likely swept away in the first streams where they live and spawn, Andrews said.

As for the adult salamanders, most will have washed upstream, Andrews said, and some of them have been killed. Some leave streams during floods and find refuge in higher ground, while others may survive and return to their habitat, Andrews said.

He recounted the aftermath of a flood in Grafton, where he conducted an investigation once the waters receded. A traffic jam had diverted a river onto a road, and he watched the salamanders skimming up the flowing water.

Even those who survive the flood and return home, however, are likely to return to an unknown location. The base of the food chain has probably been wiped out by leaves, small insects, and other creatures that fish eat.

The move is also likely to harm turtles, according to Luke Groff, a herpetologist at Vermont Fish & Wildlife. He cited a Massachusetts study that showed population declines in turtles that were swept downstream in floods.

The displacement of the turtles is kind of an indirect impact because, if they don’t die, they suddenly find themselves in these new habitats and don’t know where to look for food, where to find mates, where to seek shelter, he said.

He has also seen reports of injured turtles, where their shells are cracked or broken. Infections from these lesions can be fatal. He is particularly concerned about species such as the wood turtle, which are tied to rivers and streams.

But there are also positive knock-on effects: Downstream turtle populations may benefit from the new genetic diversity of surviving turtles that have been washed upriver.

If you have a couple of populations scattered across a watershed or region of the state that don’t really interact because they’re too far away, these turtle-displacing floods could bring together distinct populations, Groff said.

However, not all aquatic species were doomed to population declines due to the flood. Tyler Brown, a wildlife specialist at Vermont Fish & Wildlife who specializes in beavers, said it’s likely some beaver dams were destroyed while others resisted. Dams higher up the watershed are more likely to have held, while those dealing with water accumulation in lower-lying areas may not have been so lucky.

In any case, beaver populations are not expected to decrease due to flooding.

Once those waters have receded, those beavers will return to the very areas where they were, in the places where perhaps their dam has run out; they’ll start rebuilding them very quickly, Brown said.

Vermont Fish & Wildlife Aquatic Habitat Biologist Will Eldridge talks to a reporter near a log jam in Pond Brook. Photo by Emma Cotton/VTDigger

Eldridge, who studies fish with Vermont Fish & Wildlife, said river ecosystems may be more likely to recover quickly if allowed to do so naturally.

Storm jams create new habitat for fish Eldridge calls them fish hotels. They create pouches that protect fish from high flows and predators and make good feeding points.

We’ve really changed our perspective on how to handle them, he said, pointing to a traffic jam in Pond Brook, because historically people would come in, we’d come in and pull it up. This is a mess. But now we realize it, you know what? The river has actually always done it right.


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