Monday, September 27, 2010

Banded Darters In The Flint River

Five of us went out to the Flint River east of Huntsville, AL, on Saturday just as the rain started. But it was reasonably warm, with no lightning, so we worked in the rain for four hours and got soaking wet. The Flint has a beautiful riffle system at this point, about 30 meters wide. We measured three transects at four meter intervals along the shore, measuring depth and benthic current flow at one meter marks from shore to shore. And there was certainly a measureable current this time. On each of the three transects we made six seine hauls from shore to shore at equal intervals, using darter dancing to drive fish into the net. The amazing find was banded darters, Etheostoma zonale, as the most common darter in this riffle. It's amazing because neither of the "Fishes of Alabama" books reports bandeds as present in the Flint. We found that about 30 of the 74 darters we netted were bandeds, with black snubnoses the second most common. Bandeds like fast flowing water over cobble and boulders with aquatic vegetation and aquatic mosses, which describes the Flint site. So I guess we're reporting a range extension? It's not an uncommon species to the north of us so I'm perplexed that no one else has recorded their presence in the Flint.

Thursday, September 23, 2010

Fundulus diaphanus Photo From Tony Terceira

I want to thank Tony Terceira for sending me this beautiful photo of a banded killifish, Fundulus diaphanus. He sent me some preserved in ethanol last month and rightly felt that a photograph is a better representation of the species. So, enjoy:

Friday, September 17, 2010

Stream Ecology, More DNA Extractions

Eric almost has the data from last Saturday at Estill Fork entered into Excel in correct form. Even the first take shows some interesting trends - rainbow and redline darters are overwhelmingly found in areas with measurable current, the logperch and greenside darters are entirely found in areas with deeper, stiller water. The tennessee snubnoses are pretty much found everywhere.

I submitted an order to Forestry Suppliers for two items: a 100 m tape on a retractable reel for defining transects across the Flint River, and an old-fashioned compass. They should be here by next weekend, in time for our first survey trip to the Flint River at Winchester Road. There's no rain in the forecast between now and then so the river should be very low.

And finally, we started extracting DNA from the New England fundulids that Tony sent me a month ago. Valerie hadn't used fresh fish for this before and was struck at the difference in cutting the tissue out, and the visibly larger pellet yield at the end. I'm still waiting to hear from IXG about what I gave them last week.

Sunday, September 12, 2010

A New Way To Study Estill Fork

We spent most of the day yesterday at Estill Fork characterizing a 60 meter strip of riffle as darter habitat. The exact site we worked is mostly downstream from where we've usually gone to collect shiners. The water level was the lowest I've seen there. If you look at the photo below, you don't see much of the stream, which pretty much tells the story. What we did was to mark off every 4 meters on a 60 meter stretch (16 stations) and make depth and current flow measuresments at every quarter meter in a transect at each station. We used the default depth setting for measuring flow, at about 5 cm. Most of our measurements (and there were lots of them!) showed no or very little flow. This is kind of what I expected, since there are benthic boundary layers just above the sediment where frictional drag between the water and sediments slows down the current. This is where most darters spend most of their time so it's directly interesting to us.

Most of our time was taken up doing these current measurements, each for a minute, which adds up fast. The latter part of our visit we were rained on and threatened with thunder storms that never directly hit us, running just to our south. We did a "darter dance" seine haul at each station to census darters, characterizing them to species and sex, or just juvenile status if they're YOY. Our richest seines came up from the deepest water pockets near a tree's roots, where we measured no flow. In particular we found some beautiful, big greenside darters that surprised the students who had never seen big greensides before. The stations that were characterized by shallow, fast-flowing water contained tennessee snubnoses, rainbows, fantails and stripetails; the latter three were much less likely to be found in the deep pools, and tennessees were everywhere. Finally, we characterized sediment composition to percentage boulder, cobble, sand, etc. All in all a fun day.

Wednesday, September 08, 2010

The Flint At Winchester Road Looks Good

I've been reconsidering the use of Lick Fork of the Paint Rock as a second site to study darter habitat partitioning. The site might be too low flow, and not "riffley" enough, as well as flowing through more disturbed farm lands than I had thought. And then I drove out Winchester Road from Huntsville two weeks ago, into the NE corner of the county, crossing the Flint River. When I saw that site I realized that it would probably be good for our purposes. It's accessible from the bridges over the Flint and Brier Fork, and it's also very much a riffle system. The latter makes sense since roads historically crossed rivers at shallow fords, and that's what this site was historically. What iced the deal in my mind today was talking to Brian. He said that some years ago he was there with his uncle Charles collecting fish and they caught some banded darters, Etheostoma zonale. This species is at the southern edge of its range here, and is found in high energy riffle systems with clean water. So, this means we can study the two different rivers, close to each other, and compare how the same basic group of darter species utilize available riffle habitats. The Flint is a bigger stream, but that might be an interesting variable for comparative purposes.

Saturday, September 04, 2010

New Current Flow Meter

I just received a new, fun toy: a current flow meter for stream work, sold by Forestry Suppliers. It's made in England with a nice booklet with helpful hints how to best describe stream flow. Basically, it's a propeller rotor mounted on a collapsible meter pole with a handheld meter that tells you fast it's rotating and you can convert that into flow rate. More expensive models (hundreds or thousands of dollars more) will tell you that information directly. It has attachments so that the rotor can be raised off the sediment to various heights (the default height is 10 cm). We'll use it at Estill Fork next Saturday in our first work-up of darter habitat micropartitioning. Today, I mow the lawn...

Wednesday, September 01, 2010

A First Intact Gill Parasite From A Darter

Robert found, removed and mounted on a slide our first intact gill parasite from a rainbow darter on Tuesday. It's obviously a Dactylogyrid, but I have no idea as to genus even. The haptor hooks are obvious at one end, and the eye spots at the other. We took a digital image at 40X with a digital dissecting 'scope but the thing is only 65 micrometers long, so at that magnification it's just a pinkish blimp in the image. It could well be a juvenile. Once this week's intro biology labs are over I'll bring one of the digital compound 'scopes up so that we can make a better image of it. Ultimately we'll have to prepare whole parasites for imaging in the new confocal microscope which has huge potential for this work, but we're not there yet.

Today I hope to contact Lance at IXG and arrange for the ultimate sequencing of our latest batch of Fundulus bifax DNA, along with a few other samples. From here we'll go on to extracting DNA from F. majalis from Charleston, SC, and from the fishes that Tony from RI sent me recently. I think I even have money in an account to pay for all of this, amazingly enough!