Sunday, April 29, 2007

Telescope Shiner Ooctyes, March vs April

We've started to examine the ovaries of telescope shiners we've collected from March 3 and April 7. What we're doing is to photograph the intact ovaries, and then tease them apart and separate the developing eggs out on to glass slides for microscopic photography at 10X. Below are two such shots, the first from March and the second from April. My working theory was that the fish would be reproductively competent by early April. I think that's basically true, although with the cold snap and drop in water temperature that weekend they probably weren't until temperatures rebounded a week later. Three differences emerge comparing these oocytes: the March ones are smaller, in the range of .5 - .7 mm in diameter compared to .8 - 1 mm for the April fish; the March ovaries contain fewer maturing ooctyes, by a margin of roughly 500 to 250; and the whitish March ooctyes are whitish with little evidence of yolking compared to the April oocytes which are distinctly yellow. We still have to examine the oocytes at higher magnification to better characterize the development of internal membranes. Interestingly, the nucleus can be seen in many of the March oocytes but not the April ones which are loaded with yolk and lipoproteins. The separated oocytes are stored in small glass vials for easy (I hope) later examination.

We go back to Hurricane Creek next Saturday for our next collection.

Tuesday, April 24, 2007

Enrique Will Be Going To The Neuroscience Meeting In San Diego

We officially decided this morning that Enrique will go to the Society for Neuroscience's meeting in San Diego in November to present a talk on our scarlet shiner brain research. It's kind of a goof for me because I never would have thought I'd be co-author of a submission to that meeting, which is huge with thousands of attendees. But it's also good for Enrique as a Masters student to have that kind of presentation on his CV. I'll be third of four authors, with Enrique first and my colleague Amy Bishop last as supervising author. I guess it would be an even bigger goof to go to the meeting, but I don't think I have the money to pull it off.

But I will be going to the Joint Meeting of Ichthyologists and Herpetologists in St. Louis in July. I heard last week that both of my submissions have been accepted. I'll be doing a talk on what I've found with flame chub distribution in north 'bama, and Christian will be the lead presenter of a poster on seasonal gill parasite load in scarlet and striped shiners in two local creeks. Ruth will be going too. The site of the meeting is the Hyatt Regency Hotel in St. Louis, built up from the old railroad station downtown. It's supposed to be an amazing view inside of the original station with the modern hotel rising from it. It's just the kind of upscale tourist thing that we need.

Three of the students on the telescope shiner project are continuing with it this summer for credit. Our "final exam" for the spring will be a trip to the Walls of Jericho on Saturday, May 5, for the monthly collection of fish. For once I hope it will be a warm day there, we've picked strangely cold days for the first trips. I look forward to wading in the creek with only wading shoes and shorts rather than waders!

Sunday, April 15, 2007

Telescope Shiner Length-Weight Chart, Feb. - April

As mentioned in yesterday's post, our first three months' data for the length-weight relationship of telescope shiners shows a clear trend of increasing body mass with no change in length. See for yourself below:

Saturday, April 14, 2007

Telescope Shiners Get Fatter As The Spring Goes On...

We've done much of the first round of processing the telescope shiners we collected last Saturday at the Walls of Jericho. This gives us three months of length and weight data, back to February. I took the opportunity to run ANOVAs with the length and weight data (males and females combined) to determine if there are significant differences between months. These tests show no significant difference between the length of fish from the three months, with the mean bouncing around 45 mm for each month. But the weight showed an interesting pattern. Average mass has increased from month to month, especially from February to March. The February cohort is significantly different from March at the .05 level, and February is different from April at the .01 level. But March and February are not significantly different. My working hypothesis is that average mass will peak in July, but I'm not sure what level of statistical significance will appear when warm-season months are compared.

We eviscerated all 39 fish in the April collection yesterday. I don't have GSI values yet but many of the ovaries are large and nearly mature; oocytes are yellow with yolk, and something like 1 mm+ in diameter. This Friday we'll sit down and characterize the maturation status of ovaries, and begin to count eggs per fish. I came across one interesting way to characterize a fish's fecundity today on the NANFA Forum: once eggs are counted, calculate the ratio of eggs per gram of fish's body mass. Of course, since the biggest shiner we've collected weighs just over 4 grams, maybe we should transform that ratio to eggs per mg of mass. But I'll keep you posted.

Monday, April 09, 2007

April Visit To The Walls Of Jericho

Last Friday night was a hard freeze around the Tennessee Valley, so of course we went out early Saturday morning to Hurricane Creek in the Walls of Jericho property to collect telescope shiners. We were able to find telescopes without too much trouble. Water temperature was 10.5 C, down from 13 C two weeks ago. Luckily only two of my assisting students fell in the water, and only one had to call it quits and warm up in the truck after changing clothes...

Besides the telescopes we found three interesting species of fish: a fair number of flame chubs in a side pool fed by springs (didn't keep any), a pair of large greenside darters in breeding coloration (didn't keep them) and a single male blotchside logperch in breeding colors, also released. We'd seen blotchside logperch while snorkeling but had never netted one. This is a rare, widely-scattered species that's probably deserving of Federal protection under the Endangered Species Act. In Alabama it's listed by NatureServe as S1, Critically Imperiled, found only in the upper Paint Rock River system (like Hurricane Creek) and parts of the Cypress Creek system in Lauderdale County. So it was a thrill to net one and be able to photograph it. Below are two photos of this fish still in the seine net; I didn't want to handle him anymore than necessary. In the first photo the characteristic side blotches of this species are visible, and in the second photo the bright red line at the top of the dorsal fin is visible. The pig-like snout is also clearly visible. The snout is used to flip over small stones so that any small invertebrates under the stones can be eaten.

The next photo is of three of the students, Emily, Loren and Andrew on and around my truck. My 12-foot seine used to capture the blotchside logperch is leaning against the tailgate.

Friday, April 06, 2007

100th Entry, And I Can Tell You About Enrique's Western Blots

Yeah, this is my 100th entry, pretty good considering that I haven't updated for a week. The big news is that Enrique seems to be rolling with running Western blots of proteins isolated from scarlet shiner brains. We're trying to identify concentrations of the NMDA receptors in male vs. female brains, and trying to pinpoint where in the brain they're found. The blot Enrique ran yesterday clearly showed that the forebrain (telencephalon) of a male fish had significantly more of these protein complexes than the forebrain of a female fish. This is kinda what we expected, since research on a very distantly fish species showed that male brains have a steady, high concentration of these proteins and female brains are variable with more of this complex present when the fish is ready to spawn. These complexes are also related to learning processes, at least in other vertebrates.

We went out on Wednesday and collected about 20 scarlets from Limestone Creek upcounty, so we have a new stock to work with. We'll probably sacrifice several of them tomorrow so that Enrique can work with very fresh brains, and we can relate NMDA receptor number to size and reproductive status as well as to sex.

Tomorrow my main business is going to Hurricane Creek with the telescope shiner research group for our monthly allotment of telescopes. We're in the middle of a cold snap, so it'll be freezing tomorrow as we rendezvous and head out to the Walls of Jericho. At least the creek level should be normal and easier to work with for our seining. I still have the prejudice of thinking that temperatures around freezing aren't so bad for field work; it's much worse if there's rain. I'll tell you what we find.....