Sunday, March 22, 2009

Warblers of the Underwater World

When I first began my career, I had the good fortune to make many trips afield with Ted Cavender and Dan Rice, two of the top fish guys in Ohio. Once they saw I was truly interested in stream ecology and fish, they let me serve as labor on fields trip far and wide. In the process, I got to see nearly all of Ohio's fish, and learn them pretty well.

But that's been a while, and circumstances haven't let me look for fish in a serious way for a long time. For a few years, though, I've been threatening to make concrete plans with Mac Albin, another true fish guru, to work some riffles in Big Darby Creek. Finally, today was the day, and we couldn't have picked a better one. Warm air temperatures and low water levels made conditions for catching fish just perfect. And we're not talking Smallmouth Bass or Bluegill - oh, no, much more interesting piscine targets than those were our goal.

Our main quarry were darters. These are tiny members of the perch family, and they mostly lack air bladders and thus can't float. So one doesn't often notice darters, and you've pretty much got to make a special effort to find them. And darters truly are the warblers of the depths. At this time of year, males brighten up and their colors rival just about anything one might find in aquaria. Reds, oranges, blues, greens, you name it - darters are a rainbow palette of showiness.

Big Darby Creek, in Battelle-Darby Metropark. This 8,000-acre park protects large swaths of the Big and Little Darby Creeks, one of North America's standout river systems, and one of Ohio's most significant natural resources. More species of fish occur in these waters than any other Ohio stream, including many very rare ones.

For our subjects, we're going to have to go underwater, into rapidly flowing riffles like the one above. You see, most darters are torrent specialists, uniquely equipped to negotiate the unending rush of chutes and rapids. In some places, it is nearly impossible to find purchase and remain erect and holding a seine, so forceful is the sweep of the water. But if you can, there will be darters down there.
Mac Albin, left, aquatic ecologist for Franklin County Metroparks, and Anthony Sasson, freshwater conservation coordinator for The Nature Conservancy. They may be the two most knowledgeable people around whan it comes to the Darby Creeks, and it was a treat to spend time in the water with them. We spent about three hours working just one riffle and some assoicated habitats, and scored big time. In all, we got ten species of darters, most in good numbers. This would be like finding 30 species of warblers in one day in Ohio. For those darter listers among you, we had: Rainbow Darter, Bluebreast Darter, Spotted Darter, Tippecanoe Darter, Greenside Darter, Orangethroat Darter, Banded Darter, Johnny Darter, Variegate Darter, and Logperch.

Of course, a healthy stream has much more than darters. We dredged up this robust hellgrammite, which is the larval form of the dobsonfly. Fishermen love 'em for bait. They've got a decent pair of pinchers, and this one gave Anthony a good nip. Wish I had caught that on film!

Stonerollers, Campostoma anomalum. Fish are not easy to observe, and concerted efforts have to be made to check them out. Thus, most people don't know much about what lurks under water. These Stonerollers are males in their breeding finery. Just like birds, the males of many fish take on brighter colors and a gaudier appearance for a short while during the breeding period, which for many stream species is right now. Stonerollers are bottom-dwelling minnows, and normally don't look like much. But for a few weeks, the male's dorsal fin becomes infused with bright color, bluish-white warts known as tubercles appear on the head, and even the eye color seems to get brighter. In essence, they become real showstoppers.

Darters are aptly named. This is a Rainbow Darter, Etheostoma caeruleum, in habitat. They lack air bladders, and thus don't float. But this serves them well, and helps darters to anchor themselves to the cobble of stream bottoms in swiftly flowing riffles. There, they dart about with quick, abrupt movements, capturing an array of tiny macroinvertebrates and other stream life. Their stiff pectoral fins - fanned out to the sides in the above shot - are used as props, and help to hold the darter in place.

It isn't difficult to see how this species got the name Rainbow Darter. Breeding males are absolutely striking, enriched with bold greens, blues, and reddish-orange.

Although they appear exotic, like something that should be in a saltwater aquarium, Rainbow Darters can be quite common in appropriate habitat. Mac and Anthony seined up about 400 of them today.

Part of a male Variegate Darter, Etheostoma variatum, in breeding condition. The transition to breeding condition is triggered by water temperature. I think Mac told me that Variegates come into color when water temperatures hit about 48 degrees. This is another common species, and one that gets fairly large by Etheostoma darters standards. A whopper might stretch the tape to three or four inches. This is an extremely colorful darter; almost makes you blink and rub your eyes! Variegates are found only in Ohio River drainages in Ohio.

Variegate Darter on stream bottom cobble. Darters are especially sensitive to degradation of stream systems, as they require clear waters and clean substrates. Muck the stream up with too much sediment, and darters will vanish. Big Darby remains fairly pristine, in no small measure due to the hard work of Franklin County Metroparks and The Nature Conservancy. As Columbus and surrounding areas continue to grow, it will be increasingly difficult to protect the Darby, though. Hopefully we are up to it, and decision-makers can recognize the global significance of the stream, and its value to central Ohio.
I shot off 345 photos today, and a fair number were keepers. I'll share other underwater warblers as the week progresses, including a few of the real rarities.

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6 comments:

Lisa at Greenbow said...

WOW, I didn't realize there were such colorful fish inland. I bet they are even more beautiful seen in person. I always learn so much from your blog. Thank you for making it so intersting.

Anonymous said...

Jim
Great post. Very informative.
Gary Wayne

Jim McCormac said...

Thank you both, and I am glad you have enjoyed the darter show!

Jim

dAwN said...

Thanks for sharing this world that most of us never get to see..
very cool.

Jenn Jilks said...

Great blog. JMS sent me from My Muskoka!
Great photos and information.

Gail said...

I just discovered these in our spring. I had always seen the brown darters but never this colorful.

Thanks for helping me find the answers.