Wednesday, September 30, 2009

It Feels Like All Scarlet Shiners, All The Time

I talked to Alexandra yesterday morning about how we can best organize and present the data she's generated about silverstripe shiners about sex-based differences in brain size. My assumption was that we also had telescope and scarlet shiner data that's equivalent, with measurements of brain volume and the volume of individual parts of the brain such as the optic tectum. And we do indeed have this data for telescope shiners, generated by Alexandra and Brittany last year. But when I tried to find the data I "knew" we had for scarlet shiners, I couldn't find it. Because, of course, we never had it... Enrique did brain measurements but he seems to have disappeared with that data. We have data on brain mass, but nothing on volume. After several minutes of feeling like a total maroon, I realized that we have to generate our own for this paper. So, I've asked Alexandra to do this with a group of formaldehyde-fixed scarlet shiners we captured last June, at peak breeding season. So far we've only used these fish for gill parasite work, so they're in good condition with the brains ready to go. That's irritating but nothing else we can do about it.

And we made our September collection of scarlet shiners today at Limestone Creek in Limestone County. Andrew and Taito went out with me on a somewhat cool but sunny day. The water was about 35 cm higher than any time this year, and flowing very fast, and was cool but not too cool for wading. We were able to collect 40 scarlets by concentrating on areas sheltered from the strongest current. Taito brought his camera so we have some photos, which I hope to post once he emails them to me. One of them might be of me standing in an area of high flow looking stunned, we'll see.

Sunday, September 27, 2009

Male Silverstripe Shiners Have Bigger Brains, Too

Alexandra has been analyzing her examination and measurements of silverstripe shiner (Notropis stilbius) brains a bunch of different ways. In short, the results are similar to those for the related telescope and scarlet shiners: the males have bigger brains by relative volume than females. We're still working on the exact presentation of this data, but it's the missing piece for our NeuroReport article. Now we have western blot data on NMDAR for all three species, and brain size measurements to go with that. What we can say is that adult male breeding condition shiners have larger brains than females, and also have higher average NMDAR levels in their brain. But sexually dimorphic male scarlet shiners have higher NMDAR levels that are statistically significant. This implies that developing strong sexual dimorphism involves some subtle but fundamental brain reorganization.

I'll admit that for the moment I'm not entirely certain what it might mean that male shiners have larger brains than females. This relationship is also true for individual parts of the brain such as the optic tectum, cerebellum and telencephalon. It's not for being "smarter", but it could have something to do with processing environmental and/or social information. That's still a very large subject, with a very large handwave!

Tuesday, September 22, 2009

Estill Fork Between Rain

We went out Sunday morning to our site on Estill Fork to run the drift net and collect shiners. It's been raining daily for 5 or 6 days now, and Estill Fork was a lot higher than our last trip in August. I'd guess that it overflowed Saturday night, judging from the wrack lines around the low bridge, but luckily for us the level had dropped by Sunday morning. A lot of the plant growth in the stream channel was carried away by high water. We calculated the flow rate at a foot/second at the drift net site, compared to 0.8 feet/second last month. Needless to say there was a lot of material trapped in the net over about 80 minutes. With higher water it was also easier to catch telescope shiners, in particular, since they like to hang out in scour holes which are actually scour holes again. We also caught a single blotchside logperch in one of those scour holes. We left after about 2 hours, and soon drove into a cloudburst, so we were lucky to go out in a lull.

I still haven't figured out how to get pictures off of my phone, but I have some good ones(!).

Friday, September 18, 2009

Bifax Project Back In Gear

I had a good meeting yesterday with Stever Rider, Alabama's nongame aquatic biologist. He and co-workers had done a survey in 2004-05 in the Tallapoosa River system looking for Fundulus bifax, the stippled studfish, and had visited many but not all of the same sites my group did last year. Between us we have a comprehensive data set showing the decline of this species from its historic range. A difference between our results is that he apparently found bifax at a site in Cleburne County, north of where we found any and an area that in our two days of site surveys the streams were largely degraded. Any population there would be a connection between other known populations to the south (especially Tallapoosa and Randolph counties) and any remaining population(s) to the east in Georgia. No one has found the species in Georgia since the 1980s, so it's increasingly likely that the species is extirpated in Georgia. I spent much of the afternoon yesterday summarizing our visits and findings in an Excel spreadsheet, from which Steve and I can blend our findings. The one thing we may still do is a boat-based survey of the Tallapoosa itself, from the Wedowee reservoir downstream to the Harris reservoir. My guess is that the Tallapoosa no longer has the right microhabitat needed for bifax, especially clean sand bars the species needs for successful spawning. But the river may function as a population sink for existing creek populations, with individuals entering the river but never able to reproduce.

The Athens, GA, office of the Fish and Wildlife Service appears to be preparing to make bifax a candidate species for protection under the Endangered Species Act. I think our data will help in this process, documenting the rapid disappearance of this fish from much of its original range as its habitat is degraded. This species needs the protection even more than the flame chub, which itself is well down the road to extinction without some help.

Tuesday, September 15, 2009

Check Out The Interactive Flame Chub Map

It's currently a work in progress, thanks to Kris. It's hosted on his website and he put it together from a spreadsheet I gave him. As of this writing only 12 of the 53 records work, and I'll have to edit some of it. The red flags are sites where I found flame chubs over the last three years, and the blue flags are historic collection sites where I didn't find flame chubs. The ID number on the flags if you click them is from the University of Alabama Ichthyology Collection, which sites made up 51 of the 53 sites I visited. The link is: (I'll try to make this a live link later). The only trouble with Google maps is that it may not be possible to show county lines. Other than that I'm impressed, I'll admit...

Saturday, September 12, 2009

A Day At A Tennessee Creek, And Gill Flukes!

I've been distracted the past week by the beginning of school and general running around. But now I'm focused enough for a post. I spent last Saturday at 48 Creek outside of Waynesboro, TN. Some other NANFA people were supposed to meet there as part of a fish weekend, but they stayed at their base camp and we missed each other because I foolishly didn't have their cell numbers, and they had written mine down wrong. It wasn't a total loss though, I used the 12 foot seine as a 4 foot seine by rolling it up and pushed it around this beautiful riffle system. I caught lots of striped shiners, scarlet shiners, and telescope shiners of which I kept a good number for our various purposes. After this upper body workout I hurt for two days, though. It ain't easy pulling a big net out of fast flowing water, trust me.

Our big discovery this week in the lab was made by Andrew. He started a project to examine the scarlet shiners Jennifer used in her masters' project for gill flukes. We know what the 11-KT concentration was in the blood of most of these scarlets, so in principle we should find some relationship between elevated 11-KT levels (breeding condition) and fluke number. Andrew was floored yesterday, because in the first group of fish he's examined there's a pretty tight correlation between gill fluke infection and 11-KT value (if known). The rap on testosterone is that it's usually an immunosuppressant, and I think we have some good evidence of that with these scarlet shiners, collected in May or June three years ago. I'll keep you posted.

Friday, September 04, 2009

Recycling Old Silverstripe Shiners, Kinda

I keep poking at this NeuroReport manuscript we have. The big revelation this week is that we need brain size data from telescope and silverstripe shiners to go along with our western blot data as we've done with scarlet shiners. We already have telescope data from last fall, thanks to Brittany and Alexandra. So I've put Alexandra on to dissecting the brains from a monthly collection of silverstripe shiners we collected at Borden Creek in the Sipsey Wilderness in May 2004. They've been in formaldehyde, but weren't in really top condition; five of the twenty were dried out, five of the ten males at that. So I changed over the fluids of the remaining fifteen, and Alexandra has so far done the basic moves on ten of them a five/five sex ratio. With the last several females done, we'll have a believable sample size to make some kind of statement about brain size. We collected 17 silverstripes in June, but we removed the brains from all of them and suspended them in lysis buffer for western blots. Phew!

I've also made some serious progress on my flame chub manuscript, which has been lingering for eight months. NatureServe has some articles written by their staff about assessing element occurrences, basically a scale for rating the near-term viability of a local population. It runs from A at the top, to D for poor, and F for failed to find, X for extirpated. So I rated the 18 historic collection sites where we found flame chubs in our survey. The element occurrence distribution broke down as follows: for the sites where we found no flame chubs, 31 F, 4 X (basically the creek was gone); for the sites with flame chubs, 1 A, 4 AB, 5 B, 1 BC, 5 C and 2 CD. This means that in my opinion eleven out of the eighteen current occurrences have a good chance of surviving over the next 20-30 years, and this from a total of 53 sites we visited. That's pretty poor. So I argue that the state status for flame chubs should be lowered to S2, Imperiled, from the current status of S3, Vulnerable, and the global status should be changed to G2, Imperiled. Hopefully various editors, etc., will agree with me.

I'm going up to Tennessee tomorrow to spend the day with Casper and some other NANFA people in the Buffalo River system. The weather should be perfect.

Tuesday, September 01, 2009

Significant Relationship Between Telescope Shiner Length & Parasite Load

I finally had a chance to sit down, set up the data, and run a regression on the relationship between standard length and number of Dactylogyrus spatulus parasites for telescope shiners from Hurricane Creek in 2007. We knew that the r-squared was 0.08 from doing the calculation within the graphing function of Excel, but I had a suspicion that there could still be significance in that number because we have 280 fish in the sample set. And sure enough, we got an F value of over 25, with P<0.01. So there's not a sharp rise in parasite load with increasing fish size, but it is a statistically robust relationship. I still want to do separate regressions for males and females which will take a little more wrangling to set up the data sets.

Yesterday I had another realization, that we should examine the brain size of silverstripe shiners collected from Borden Creek in 2004. We have the GSI information for them too, so it would be an interesting data set for comparison to both scarlet and telescope shiners. The relationship should be pretty similar to telescopes, since they're closely related as well as minimally sexually dimorphic. Maybe Alexandra would like to do this?