Matt Dickerson: Yes, jellyfish can be found in area waters

For over two decades I’ve been writing an outdoor column with a special emphasis on fishing. I never thought I’d be writing about jellyfish, though. One reason is that they aren’t even fish; they are more accurately referred to as “jellies.” Another reason is that Vermont, by virtue of not having any ocean coastline, doesn’t have any jellies. Or so I thought.
Last week my good friend Dave stopped by for a visit. Dave graduated from Middlebury College at the end of my second year teaching there, and for most of the next decade he stayed in the state. He and I spent a lot of time outdoors together, mostly fishing. We got to know each other exploring trout streams all over Vermont. Eventually we wrote three books together, one of which was an exploration of environmental issues in literature, and another was about trout, fly-fishing and ecology. We’ve even talked about a fourth book and begun to research it. Those books have also led us to streams and rivers in Maine, North Carolina, Tennessee, Kentucky, Oregon and even Alaska where we co-taught a class on narrative non-fiction writing about nature, ecology and trout.
Dave lives and teaches in South Dakota now, so we don’t get to fish together very often. However, a philosophy conference across the lake in the Adirondacks brought him close enough to Vermont to pop in for an afternoon visit before catching an early flight home from BTV. Dave loves to learn. He’s an avid reader, and also a careful observer of nature, so I like to pay attention to what he writes and says. I learn a lot from him. On his visit, Dave told me a story of when he was growing up near the Vermont corner of New York, how on a trip with his father into the Adirondacks he saw a jelly in a freshwater pond. It was quite a surprise since New England and New York aren’t supposed to have freshwater jellies. Or so he also thought. Fortunately, his dad saw it too, and made a note in his journal, so Dave had at least one eyewitness.
That story from Dave was the first I’d ever heard of freshwater jellies in the Northeast. The second I heard of them was also from Dave, a few sentences later. He told of recently learning about a particular lake in the Adirondacks that had been one of the last — perhaps the last — “pristine” water body in the Adirondacks, meaning not only that it had no development around the lake, but also that there was no evidence of any introduced non-native species, and because of the local calcium-rich geology it had escaped the ravages of acid rain that did so much damage to so many other lakes and ponds in Vermont and upstate New York. But recently a satellite photo showed that the lake had suddenly turned a peculiar unnatural shade of green. A visit from biologist showed that invasive freshwater jellies had invaded the lake, likely in the feathers of a waterfowl, and had reproduced abundantly. Jellies eat small fish and also zooplankton. Though these jellies were not dangerous to humans, their consumption of zooplankton apparently led in turn to a bloom of phytoplankton (which includes algae) which is what had turned the water green.
Remembering his own sighting years earlier, Dave felt vindicated by the discovery. He also learned more about the species — Craspedacusta sowerbii, as it turned out — and submitted his father’s journal entry to scientists trying to track the species’ invasive progress around New England. Within the next week I would read yet another article about the presence of these invasive jellies in Vermont and New Hampshire.
There doesn’t seem to be a consensus about how much of a threat these jellies are to native fish. Though they might consume very small fish, they might actually be a food supply to larger fish. Certainly causing a crash in zooplankton and corresponding algae bloom could prove problematic, but the actual risk of that is still unknown. From what I’ve read, there isn’t even a consensus for how long they have been here, though they seem to have come from Asia and to travel on waterfowl. The one thing that does seem to be consensus is that, with the impacts of climate change and in particular longer hotter summers, we should expect a significant increase in these invasive species in the waters of Vermont.
I have yet to see one. But I might start preparing for the invasion by tying a few jelly flies. Maybe my third decade of writing this outdoor column will see my first story of catching a trout on a C.Sowerbii fly.

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