Wednesday, September 27, 2006

Flame Chub Presence/Absence Maps

I wanted to post one of the county maps from my flame chub survey of the past 16 months. The maps were created in ArcInfo by Kevin Hammons, a student working with me. They're designed to show sites where flame chubs are known to have been collected since 1966 as represented by collections in the University of Alabama Ichthyology Collection (thanks again Bernie!). Three possibilities exist for these locations: either we found flame chubs there (in green on the map), we visited the location but didn't find flame chubs there (in red on the map), or we didn't visit the site (in black on the map). I'm sure the image below is too small to read well, to enlarge it click on it. Lauderdale County is the northwestern corner of Alabama, with Mississippi to the west and Tennessee to the north.

Lauderdale County is the best of the counties we visited (8 in total) for number of flame chub sites, and percentage of "present" sites. The Cypress Creek system that we visited on three locations is large, rising in Tennessee, and for the most part still in good shape. The big exception to that is the Burcham Creek system, the western arm of this system. These were sites that are now dry, and were bone dry for hundreds of meters up and down stream. Several of those sites showed evidence of being dug up as part of what can only be described as "trailer suburbia".

The Lauderdale County sites also showed evidence of healthier populations of flame chubs, since we could always catch more than one flame chub without a major effort. This is very different from many other sites in other counties we visited and found only a single flame chub in as much as two hours of seining. So the Cypress Creek system appears to be the sweet spot for flame chubs in north Alabama.

Tuesday, September 26, 2006

Flame Chub Talk Yesterday

I gave an invited talk yesterday about my flame chub research to a class run by the Physics Department, "Frontiers In Science". This class is also part of our Honors program. The 40 students were probably about a third physics majors, almost as many biology majors, and scattered engineers and other majors. The point of invited speakers is to expose students to a range of scientific research, and especially the background of the researchers.

So I'm a little weird that way, my undergraduate degree is in Economics and I went to grad school in my early thirties. But the talk went well, explaining why and how I came upon this project of surveying the historic range of flame chubs in north Alabama. The students had some good questions at the end of my 30 minute presentation. This lead into a discussion of how to protect wetlands and streams with me giving a review of the recent Supreme Court decision that narrowly upholds the EPA's work to protect "navigable waters".

At the very least I don't think I bored or confused anyone, possibilities if you don't couch your research in some understandable context. No one volunteered to work with me, but you never know... It was good as a first comprehensive presentation of my research to some kind of informed audience. Now I just have to write it up and get it published somewhere!

Thursday, September 21, 2006

Scarlet Shiner Brain Photo

This morning I was able to sit down and do a dissection on a recently caught scarlet shiner that's been in 10% buffered formaldehyde since last Friday. I wanted to set up a dorsal photo of the brain in situ. And voila, below is the photo. I've labelled the major features of the brain as follows: DM, dorsal medulla; CB, cerebellum; OT, optic tectum; TL, telencephalon; OB, olfactory bulb. The fish's left eye is bisected by the white line descending from OB. For perspective, this fish is 54 mm long (standard length) and weighs 1.865 g. The image was grabbed by a digital dissecting 'scope at 18X magnification.

Wednesday, September 20, 2006

Measuring Fish Brains... The New Game In Town

I've been sucked in to this whole fish brain/neurobiology thing. Maybe I benefit by not having formal training in it? What I've gleaned from reading some relevant papers on fish brain size and apparent function is that there are a wide variety of ways to quantify fish brain size. What we've started in on with scarlet shiners is fairly simple, just to consider brain mass as a function of body mass. This approach doesn't seem to be too common, except with some shark researchers from what I can tell. Many researchers focus on the size of specific regions of the brain, such as the telencephalon or cerebellum. They usually do this by measuring the length and width from a dorsal perspective in a digital image. I was talking to Amy today about this and we both felt that a more precise measure of specific brain regions would be informative. But weighing a shiner cerebellum is a very precise measurement; maybe we could do it with ten individuals of each sex for a reasonable data set? An easier measure might be volume. For such oddly shaped structures maybe we could set up a small cylinder to measure displacement and state that as cubic millimeters. Or, using an ellipsoid volume calculation if one has length, width and depth. One reason to do this would be to see if male fish, especially male fish, have a larger cerebellum relative to body size than females. This would be consistent with alpha males being more active in defending territories, so that their cerebellum is enlarged to handle this coordination of movement in three dimensional space. Some work has been done on this general theme with a range of shiner species, published by Robert Huber and Michael Rylander in 1992. So in principle we could deepen this work and find other correlations. These are all tempting ideas at the moment; in the immediate future I hope we can accumulate a data set based on about 100 scarlet shiner brains. We already have 9 dissected out as of yesterday; my even more immediate task is to make sure that the students keep fresh blades in the scalpels!

Saturday, September 16, 2006

A Pleasant Afternoon At Limestone Creek

I went out yesterday with three students to Limestone Creek both to collect striped and scarlet shiners for various projects, and to do a sampling for diversity purposes. The first part was easy, getting fish for parasite, color and brain structure purposes. The second part was in particular for Jennifer's classwork. She's in a graduate Community Ecology class, and the lab component is independent study. I suggested that she sample fishes at our collecting site and analyze the diversity with various statistics.

I don't have all of the numbers in front of me, but we collected 99 individual fish mostly through seining. We worked a variety of microhabitats, from weedy riffles to gravel riffles to an open pool to a side run almost cut off by low water. Most common by far were scarlet and striped shiners, with reasonable numbers of stonerollers, blackspotted topminnows and black darters. We only netted one YOY largemouth bass, and no other sunfishes which was odd. The most interesting fish was a slender madtom, Noturus exilis, which we'd never encountered before. The madtom came out of the side run and was netted with a pushnet jammed up and under a low overhanging bank. I was hoping we'd find another flame chub, but I haven't found one at this stretch of creek since February. I'll post the numbers and descriptive statistics later when I get them.

Tuesday, September 12, 2006

How To Remove A Shiner Brain

I was hoping to have a photo to illustrate. But I don't, so take my word for it, it's surprisingly easy to remove an entire scarlet shiner brain intact. We started this project last Friday, and as a pilot project dissected out three brains. After weighing the entire fish I did the first one, carefully cutting open the dorsal skull with a new scalpel blade under 12X magnification on a dissecting 'scope. The brain is maybe 10 mm long, in the biggest scarlet shiner we could find in our preserved collection. The trick was to remove the brain proper, trimming off various nerves and cutting the spinal cord just where it becomes part of the brain. Each brain is kept in its own numbered Eppendorf tube in 10% phosphate buffered formaldehyde. We still have to go back and weigh those three brains on an analytical balance. An intact large scarlet shiner weighs about 2.3 grams, and I suspect the brain will weigh about a tenth of that. We hope to do this for a series of scarlets and characterize the brain/body size relationship, checking for any sexual differentiation. I have no idea what to expect; no literature seems to exist on the subject for any species of fish, except possibly chondrichthyans. We'll also examine many of these brains with antibody staining to characterize the nucleus olfactoretinalis, a key area in fish brains for learning and sexual differentiation. Once you have the brains, it should be easy(!).

I went out to Limestone Creek with Enrique yesterday, for the sole purpose of netting some YOY scarlet shiners. Enrique turns out to be really good with a pushnet, snagging small scarlets out of the water column. We came home with about 15, ranging in size from about 12 to 20 mm. When I showed them to Amy she started to laugh at the thought of removing their brains, they're so small. I guess if Enrique and Leigh can do that, we should give them Master's degrees on the spot. We'll see.

Thursday, September 07, 2006

Scarlet Shiner Picture And Fundulus bifax Status

The scarlet shiner image analysis project is moving ahead. Below is one of the images that Jennifer took last weekend. We're putting in paint swatches for color calibration, and of course there's a ruler for size approximation. The Image Tool software is extremely precise at measuring images in a photo; all we have to do now is fully understand the nuances of color analysis.

I've also started to work with Joe Scanlan in Montgomery on the status of Fundulus bifax, the Stippled Studfish. This fish is pretty much a Tallapoosa River endemic, apparently with an historic range extending upstream into Georgia. Efforts to find the fish at the two historic collection sites in Georgia were unsuccessful last summer, so it appears that this is now an Alabama endemic. Joe has been able to spawn the fish in captivity, but with limited success at rearing fry. He also wants to bring the species' plight to broader attention. It's unclear what the species' range was in Alabama, although Joe has some idea of its current range from his own work. This fish seems to be very sensitive to land use changes in stream basins, especially those changes that affect the cleanliness of gravel substrates. The expansion of the cancer known as Atlanta seems to be responsible for altering the few Georgia streams that were home to this species, such that successful reproduction probably failed. Our task is to convince other people to care at least a little about such an obscure, nongame fish.

Friday, September 01, 2006

Getting More Work Started On Scarlet Shiners

This week I picked up another graduate student to work on characterizing scarlet shiner brain structure. Enrique had a bad experience in another research lab on campus, and since I know him from undergraduate classes I agreed to take him in on my work. For his thesis project he'll work on our effort to characterize the nucleus olfactoretinalis (NOR) of scarlet shiners, a key region of fish brains for coordinating sexual development and differentiation. This will involve some fairly slick histological preparations and staining with antibodies, but I think we can do it. Leigh is also working on this, so between the two of them something should come out soon. One relatively easy study is the size of fish brains relatively to body size. Many of the scarlet shiners that Christian has used in her parasite study can be used for this, since they're tagged with ID information in a gallon pickle jar of formaldehyde with only the right gill arch removed. I'm not sure I've ever seen such an allometric study of shiner brains, hopefully we'll produce some interesting data (how could we not?).

Today I showed a video to my Vertebrate Reproduction class from the Nature series, The Nature of Sex. It involved all sorts of animal sex, including a few fish scenes such as amorous jaw fish avoiding ambushes by scorpion fish. It's not Alabama, but it was fun. I warned this class we'd talk about sex, sex and sex; the good news is that they all seem to like it.