Is a healthy ecosystem one that is rich in parasites?

I stole this entry's title from a still-unpublished paper by Hudson, Dobson and Lafferty that will soon appear in one of my fave journals, Trends in Ecology and Evolution (TREE). The three authors have worked on a variety of ecological questions with parasites, such as how do they affect their host populations, affect their host's predators, affect their host's food items and environment, and thus how might parasites shape community structure and energy flow within ecosystems. Their single most interesting observation is that if one counts parasite species in biodiversity analyses, the number of species ("biodiversity") doubles. But this is rarely the case because parasites are still fairly obscure taxonomically.

For my own work this is an astounding thought. Like I've mentioned before, I'll be participating in a Bio Blitz this coming weekend at the Walls of Jericho tract in Jackson County, Alabama. My part will be working to identify how many fish species are on the property, especially in Hurricane Creek. That's fairly cut and dried, identifying the various cyprinids, suckers, darters, etc. I predict that we'll find about 30 species of fish in that creek if we're able to electroshock and ID some of the more athletic species like redhorse. But I know from my ongoing research that it's a reasonable assumption that every local freshwater fish species has at least one species of Dactylogyrus monogenean gill parasite endemic to the host, and that doesn't count various nematodes and acanthocephalans that are probably endemic to the guts of each fish species. So right there we're talking 120 species, starting with the original 30 fish species. I may have to keep voucher samples of all fish species found and attempt at least Dactylogyrus ID's in the lab, to give a more accurate species total. (I hope you don't think that I'm a totally lost obsessive compulsive....)

So the lesson here is that a biodiverse, healthy, dynamic ecosystem is one rich in parasite diversity, which is a powerful regulator of community diversity. That's contrary to typical thought.

We Found A Flame Chub Today In Mud Creek In Tanner, Alabama

This is the one and only flame chub we found today in my first summer school "Stream Survey" class meeting. I had three historic locations to visit, all in the southern edge of Limestone County, Alabama, near the Tennessee. The first site we visited, Spring Creek, was pretty swampy but the creek had a gravel bottom in waist deep water in the middle. In 8 seinings we found bluegills, green sunfish and redbreast sunfish but no shiners or minnows. The creek showed evidence of degradation from poor soil management in the upstream farmland.

The second site, Mud Creek at Lindsay Road in the town of Tanner, was a pleasant surprise. The creek had trees as a riparian buffer, and a substrate of coarse gravel and crumbling limestone bedrock. Intact barbed wire fences kept dairy cows away from the creek, in their lush pastures. We worked about 300 meters upstream from the small bridge, catching large numbers of scarlet shiners, striped shiners and blackspotted topminnows along with some black darters. In the fourth pool system, making our last darter-dancing seining, I found a female flame chub in the middle of a pile of colored-up scarlet shiners. So now I've found flame chubs in 8 of 27 (30%) of the historic sites that we've visited, and at 5 of those sites we've only found one flame chub. In Mud Creek I estimate that we caught 300 scarlet and striped shiners, to one flame chub. So these are small populations, at best.

The third site on our visit list was Pickens Spring, which has hazy location information on my list from the UA Ichthyology Collection: "south of Old Highway 20", halfway between Greenbriar Road and County Line Road. Using GPS coordinates we found where it should be, which is behind a hay field and small band of woodland on a small farm. We started to drive down a dirt road near the farm house, but the road just ran into their back yard, so we backed out. I'm terrible about knocking on people's doors and asking, "Can we go look for minnows in your spring pool?" I shouldn't be but I am... So this site doesn't count as visited in my tally.

Next Friday there's the beginning of a 72 hour Bio Blitz at the Walls of Jericho state land in northern Jackson County to the east of here. I've been invited to go and sample the upper reaches of Hurricane Creek, a Paint Rock River tributary, on the property. My 4 students have all agreed to go for the day on Friday, which involves driving there, hiking in 2 miles, doing the stream work, and hiking out, uphill, before dark. It should be great!

Shiner Photography Technique Development

I worked with Jennifer yesterday for the first time on photographing scarlet shiners for her project. Our goal is to be able to quantify coverage and intensity of body and fin color in breeding condition males. I read of one study with male guppies in which a guppy was anesthetized with MS-222 and photographed with ASA-100 slide film under tungsten light. The resulting slide would be projected on to paper taped to a wall, the fish's body would be outlined, and color spots of interest would be drawn in, allowing coverage to be calculated. We're working with Jennifer's digital camera, trying to do a similar analysis with a software package. So, yesterday we euthanized a beautiful male scarlet with MS-222, and set him up on an old photo light table with a camera attachment that I have. We figured out the best presentation was to put the male out on brown corrugated cardboard, with fins held in display with insect pins. Light was provided in a dark room from wall bouncing of light from the four floodlights on the arms of the photo table. This allowed images to be made at 1/6 of a second, at F 3.2, with a minimum of glare on the fish. My wife Ruth is an artist, and her critique of this approach is that the cardboard will add a yellow tinge to the image; she says we should use a neutral gray background for minimum alteration of color. We'll try that in the near future. But with the brown cardboard we got some really nice photos with which we can at least begin analysis. If you do a Google search, few good images of scarlet shiners come up; I think we'll post one soon for everyone's perusal.

The bad news yesterday was that when I approached my aquarium room door in the morning I could smell very dead fish. Sure enough, all of the fish that we collected in Limestone Creek on Monday were dead, apparently from a crashed aquarium (sudden bad water quality). They were so dead that I had to throw away all 12 of them rather than try to save them for gill examination. I think the fact that the fish were collected in very turbid conditions, and some of that water was put in the tank, contributed to the crash. Luckily all the fish from Swan Creek were alive, including some primo alpha male scarlet shiners and some lunker striped shiners. I'm replacing the 10 gallon tank that crashed with a slate-bottom 20 gallon I just acquired from another lab, so a bigger tank size should help prevent future crashes. It's mildly embarassing to have this crash, I haven't had a tank do that in years.

Also, I submitted the paper on burrhead and silverstripe shiners to Ecology of Freshwater Fish yesterday. They have an elaborate system for online submission, as is typical of journals published by Blackwell Scientific. It took me less than an hour, including registering for an account before the actual submission. Our manuscript is number 96 for the year, an interesting thought. I'm hoping for both a fast and affirmative decision from the editors; I assume that David Heins from Tulane will be the editor handling our manuscript since he's done work similar to ours.

Nothing But Shiners Yesterday

I went out collecting with Jennifer and Christian to Limestone and Swan Creeks. This was Jennifer's first trip, looking for male scarlet shiners for her project assaying breeding color intensity. Christian was out for both scarlets and striped shiners as part of looking for gill parasites.

It has rained off and on over the last several days, and Limestone Creek looked awful when we arrived. The water looked like coffee & cream, loaded with clay silt like we haven't seen. But the water wasn't high or fast, and we were able to collect lots of striped shiners with a few scarlets, just the opposite of our May 1 visit. We found no darters, since we were working deeper runs rather than the shallow riffles. The pH was depressed at 7.2, and total dissolved solids was at 52 ppm.

Swan Creek in Athens, AL, was clear and lower than our last visit on May 1, with similar water chemistry to Limestone Creek. After tossing out the empty 4 liter jug of Cossack vodka we netted lots of both scarlet and striped shiners. We also found black darters, one of whom was still in relatively bright breeding coloration. The scarlets were in full coloration, with tuberculated males feeling like sandpaper.

It's not quite an hour back to my lab aquaria, so I was hoping that all of the fish we caught at both creeks would make it back alive. Unfortunately we kept more fish at Swan Creek than I realized, and we got back with about 25 live fish and 17 dead. I've got to finally get a battery powered air pump, and at least one more bucket. It's not a total loss, since Christian can use the dead ones for parasite examination.

The good news is that several alpha male scarlets survived in good shape so Jennifer can start working with them this week. Her task for the summer is to figure out the best way to photograph the colored-up parts of the males so that we can quantify how colored up they are using a software package that can analyze images. This might involve focusing on the caudal and dorsal fins and the operculum which has a vivid orange streak in most males. The capstone will be analyzing males for circulating levels of testosterone, which we might do next spring in conjunction with image analysis.

By coincidence, yesterday morning there was an interview on NPR with the Swedish biologist who came up with ELISA, the anitbody assay method for testing for various molecules. We'll use an ELISA test for testosterone in male (and female, too) scarlet shiners. I'd forgotten that pregnancy test kits use a simple form of ELISA, obviously a yes or no response. So next time you hear the Aerosmith song "Sweet Emotion", when Stevie Tyler sings "You can't catch me, the rabbit done died" it's about a negative ELISA assay (lucky for him, the girl wasn't pregnant).

More Gill Parasites in Scarlet Shiners? And the Limestone Creek Aquarium.

Christian has been steadily examining shiners over the past two weeks, and we're going out to collect more on Monday, weather allowing. Interestingly, of late she's been finding a relatively high occurence of Dactylogyrus gill parasites on scarlet shiners, certainly relative to striped shiners. I'm not sure what it means yet, but once we have 100-200 fish examined I hope to see a pattern.

I realize that my new 20-gal. aquarium is best described as a Limestone Creek tank, with fish from both our upstream and downstream collection sites. At the moment the population includes about 14 scarlet shiners, 3 striped shiners, 2 blackspotted topminnows (Fundulus olivaceus), 4 telescope shiners (Notropis telescopus) and one stoneroller (Campostoma oligolepis). All are young adults, maybe a year old. The topminnows really do stay at the surface for the most part, and the stoneroller is usually near the bottom. One thing I have to examine further is the presence of telescope shiners in this creek, even at the downstream site. That's something of a range extension, since they're usually more common in highland settings. They're pretty fish in an understated way.

Skewed Sex Ratio In Burrhead Shiners?

I asked on the NANFA mailing list yesterday if anyone knew anything about skewed sex ratios in North American minnows. Only Jeremy Tiemann had anything, sending me a .pdf of an article from a 1929 issue The American Naturalist about bluntnose minnows (Pimephales notatus). The article actually showed sexual size dimorphism, but it was interesting on its own. I spent some time today wrangling through Google and found some interesting references on the question. As far as most researchers say anything about it, it's that they've found essentially 1:1 M:F ratios in various species of interest. But some skew surfaced in some research, although no one seems to have thought much about it. For example, Brooks Burr and Richard Mayden found a male skew in three populations of Notropis chihuahua, only one of which was statistically significant (Copeia 1981(2) 255-265), but they ascribed no significance to their observation. Shawn Dahle found in his study of N. topeka in Minnesota that females made up 59% and 62% of the Age-1 and Age-2 populations he sampled, but again ascribed no significance to the observation (M.S. Thesis, 2001, University of Minnesota). And Glazier & Taber found more females in their study of the Ozark Minnow, Dionda nubila. But they ascribed this to an artefact of sampling, since they felt that smaller males were more likely to swim through the seines they used for collection (Copeia 1980(3) 547-550).

So there might be something to my observed sex skew in burrhead shiners, N. asperifrons. I found 29 males to 42 females, which is not quite statistically signifcant as a deviation from 1:1. This touches on a lot of evolutionary and sexual selection theory. Being a female may be advantageous for reproduction in this case; female burrheads are significantly larger than males. One data set of 71 fish is not enough to make a definitive statement in this case, but it raises interesting questions. Hmmmmm.....

I Started My Scarlet Shiner Display Tank

I've had a group of about 15 scarlet shiners plus a few striped shiners that are left over from my parasite study. They're all yearlings, 20-30 mm long, and stay together in a nice school. The tank they've been in is needed to house future fish collections for parasite work, so I've moved them all to an empty 20 gallon tank in my main teaching lab. There's about 5 cm of medium coarse sand on the bottom, and an oversize hanging filter to generate steady current flow. I've been congratulating myself all day for how good it looks, with a tight school of fish moving away from motion but towards food. I'll try to get a decent photo to post soon.

Next week we'll go out to collect more shiners for various projects. Until then, I'll just clean up what we've been working with. I have to get some paper and string price tags to ID sacrificed shiners that have had their gills removed. Right now I have a growing mess of jars of formalin with small numbers of fish from the same stream and date. Once I get the right tags we can mark individual fish and put them in big gallon pickle jars for long term storage, in such a fashion that they're out of the way.

Dauphin Island Trip

I know that everyone has seen too many images of damage from Hurricane Katrina. But I had to share the above photo I took yesterday on the western end of Dauphin Island, AL, at the mouth of Mobile Bay. Dauphin Island is the easternmost edge of really severe damage from Katrina, in particular the above area that used to be packed with expensive beachfront homes. Now the main road barely exists; you can see what's left of it in the lower left of the photo, just packed sand. In this field of view you see two ruins in the midrange. There were probably 20 houses in this view before the hurricane came in from the Gulf, on the right of the picture. Most of the debris has been cleared, so what's left is just barely an island anymore at this point, maybe closer to a low-tide bar. The most insane thing is that many property owners are rebuilding along this strip, which is a typically exposed barrier island. Human goofiness knows few limits.

Luckily the Sea Lab itself survived with minor damage at the eastern tip of the island. The research facilities are being expanded as I write. A new Marine Science research center will be finished by October, with seven new labs of different types. One of the labs is explicitly designed for visiting researchers so they can sort and pack collected specimens or physical samples. Another new building is also being planned, a new lab building across the street from the Marine Science center that will be built and partially staffed by the National Marine Fisheries Service. The Sea Lab hopes that this will allow collaboration between NMFS scientists who are mostly fisheries biologists, and the Sea Lab faculty who are community ecology oriented. This new lab building would also allow expanded collaboration both with graduate students and visiting researchers. So things look good for the Sea Lab I'm happy to say.

It's Raining, No Limestone Creek Trip Today

Since we're in the middle of a monsoon of sorts, I had to cancel a trip to Limestone Creek today to collect scarlet shiners with a new graduate student. Jennifer has just finished her undergraduate degree, and is willing immediately to start work towards her Master's thesis. Her immediate task is to figure out how best to photograph male scarlet shiners in breeding colors, and with those photos, how best to analyze them for intensity and coverage of color. But today the creek is undoubtedly running dangerously high and fast, and as always I have qualms about being in water during a thunderstorm; hanging out with copperheads streamside would be more relaxing.

Tomorrow Ruth and I are driving to Dauphin Island at the mouth of Mobile Bay for a three-day visit. Technically it's a business trip, since I represent UAH on the Dauphin Island Sea Lab Consortium, the overseeing board for the summer school program hosted by the state-operated Sea Lab on the eastern tip of the island. Five of our undergraduates are taking at least one course at the Sea Lab this summer. These courses include Marine Turtles, Marsh Ecology and Marine Invertebrate Zoology. All are high intensity, hands-on field oriented classes that the students always rave about. So I try to stay on top of what's happening at the Sea Lab so that I can convince our biology majors that they should take a class at the Sea Lab if at all possible. I always tell students that this is real biology, and after they try it, they agree.

A Flame Chub Sketch (I Had To Share It)

My wife Ruth was hanging out in my office yesterday while I was talking to a student. She sat down next to several jars of recently preserved fish I've collected this spring, and by chance did a quick sketch in her journal of the most recent flame chub I found. This flame chub came from the uppermost reaches of Little Piney Creek in Thach, Limestone county, AL.

I like this sketch because it's an accurate, if loose, view of this fish in a jar with my pencilled label inside the jar with the binomial and location information visible. Any flame chubs I find and keep as vouchers I put in ethanol so that DNA could be easily extracted from them if someone is up for such a study; anyone?

Flame Chub Update

I've been visiting sites around north Alabama for the last year now, going to streams where flame chubs (Hemitremia flammea) have been found and a record made of it at the University of Alabama Ichthyological Collection in Tuscaloosa. So far I've visited 25 of those sites with students helping me, from a total of 151 on the list. We found at least a single flame chub at 7 of those sites, but only a single flame chub at 4 of them. That's pretty bad. In the professional literature, it's considered bad if a species has had a 30% range reduction, and so far I've observed a 72% range reduction.

We've visited all or most of the listed sites in Jackson, Madison and Limestone counties along the northern tier of Alabama. At the end of the month I start another Friday collecting schedule, with three students who have signed up for credit to cruise around with me on county roads all day. We'll focus on what's left to visit in Limestone county and move to Lauderdale county in the northwest corner of the state, around Muscle Shoals. This area includes the Shoal Creek system, which is a relatively undisturbed, diverse drainage system. I would expect to find flame chubs at some of these historic sites, but we'll see.

The good news is that I've found flame chubs at three sites that are not in my UAIC list. The one healthy population is in Little Paint Rock Creek in Marshall County, halfway between Huntsville and Guntersville up the Tennessee. I've found singletons in Limestone Creek at Highway 53 in Madison County, and in French Mill Creek at Cambridge Lane southeast of Athens in Limestone county. So there are undoubtedly small pockets of flame chubs around. But when you seine a creek with several people for several hours and only find one individual of a minnow species, that's a pretty good sign that there aren't bunches of them present.

Burrhead and Silverstripe Shiner Reproductive Biology

I'm finally starting to wrap up a paper on a research project that I started over two years ago. Many common fish species in the southeastern United States are still poorly known in terms of their reproductive ecology. I became interested in two such common species, the burrhead shiner, Notropis asperifrons, and the silverstripe shiner, N. stilbius. Both species are found throughout the Mobile basin in Alabama, especially above the fall line.

My question was the timing and relative effort of their reproduction. Shiners are typically reproductively active in Alabama from April through July, more or less. Individuals of these two species had been observed either tuberculated or gravid in this time frame, and that's been the extent of knowledge. Both species are found in the Sipsey Fork system in and near the Bankhead National Forest in north Alabama, so I arranged for permission to collect these fish in Borden Creek in the Sipsey Wilderness of the Bankhead. We (me and two students) made monthly collections of both species from late March until September. Our primary interest was examination of the ovaries of females of the two species, involving the histological preparation of stained tissue samples to quantify oocyte development. I made four random microscopic photos from individual females so prepared, to count and measure these developing eggs at different stages. Two such images are below:

This image is of ovarian tissue from a burrhead shiner collected in early July, using standard histological stains, embedding in parafin, and sliced 4 micrometers thick. The large red cells are in a late stage of maturation called late exogenous vitellogenesis, and are about half a millimeter across. The smaller purple cells are in earlier stages of development. This is evidence that burrheads in Borden Creek are still reproductively competent in early July.
The above image is from a silverstripe shiner in May. The edges of the ovary are clearly visible looking like a relaxed bag, probably evidence that this individual has recently spawned and the ovary isn't jammed with mature ova. But the red cells are maturing oocytes, not quite as mature as the big red oocytes in the burrhead image. And there are a lot of smaller oocytes in earlier stages of development, evidence of on-going ova production for the near future.

What we found was that burrheads are more reproductively active in April, and continue into late July, while the silverstripes don't really kick in until May and drop off more quickly than the burrheads but are still active in late July. Silverstripes are also bigger than burrheads, with females averaging about 56 mm long compared to burrhead females at about 46 mm. In a given time period burrhead oocytes are also usually larger than silverstripe oocytes, often statistically significantly so. Freshly spawned burrhead eggs are 2 mm in diameter, while mature silverstripe eggs found in sacrificed females were found to be 1.4 mm. It seems that relatively small burrheads produce fewer, larger eggs while larger silverstripes produce more small eggs.

Another interesting difference between the two species is that burrheads show sexual size dimorphism, with females being statistically significantly bigger than males (46 mm vs 42 mm) while female silverstripes are only slightly larger than males (56 mm vs. 55 mm). Neither species is territorial or nest-building, which usually results in larger males. But it seems that larger bodied female burrheads may be an adaptation for the production of larger eggs over a longer spawning season, compared to silverstripes.

This is a synopsis of our research, which also includes aquarium work done by Bob Muller. I'll be presenting this at the July meeting of the American Society of Ichthyologists and Herpetologists (ASIH) in New Orleans. If you're there, I'll be moderating the Fish Reproduction session at 8 a.m. on Saturday, July 15, as well as presenting the 15 minute version of this work. And I hope the editors at Ecology of Freshwater Fish like the full article for publication(!).

Two Fish From Monday's Trip

This lunker (at least for a minnow) is a striped shiner (Luxilus chrysocephalus) we collected on Monday at Swan Creek at Elkton Road just north of Athens in Limestone County, Alabama. I was wrong before; he's only 12 cm long, snout tip to the base of the tail, not 14 cm. This picture was taken just after he was euthanized through an overdose of MS-222, a fish anesthetic (same with the photo below). MS-222 tends to release all of a fish's colors just after death.

Here is the colored-up male scarlet shiner (Lythrurus fasciolaris) I mentioned the other day. He was collected in Limestone Creek at Highway 53 in Madison County, Alabama. This fish is about 7 cm long, snout tip to the base of the tail. If you look closely you can see tubercles on top of his head and the front part of his back, typical of all male cyprinid minnows in breeding condition. This guy is part of our gill parasite study. But we'll be collecting more scarlet shiners soon so that we can quantify the coverage and intensity of the various reds and oranges on the fins, which should be indicative of attractiveness to females (we think...).

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High Water Today But We Found The Fish... Alive!

I went out today with Rachel and Christian to collect fish for their respective projects. We had substantial rain in the area Saturday and Sunday, but today was beautiful and clear.

When we arrived at our first site, Limestone Creek at Highway 53 south of Ardmore, Alabama, the water was running fast and high like I haven't seen since early February. Water chemistry reflected the recent rain, with TDS at 38 ppm and pH at 7.1, rather than the more typical 60 ppm and 8.0. Our goal was to catch black darters for Rachel and striped shiners and scarlet shiners for Christian. We've caught as many as 30 black darters at this site for Rachel's research on the reproductive ecology of the species. But today, we were lucky to find three. I'm convinced, but without evidence, that a lot of the adults die this time of year after spawning. And this site has produced surprisingly small adults compared to other sites we've collected. For Christian we found about a dozen scarlet shiners just going into breeding coloration. One male in particular, the largest, has vivid red fins and a patchily turquoise body. And we found about 6 striped shiners, medium sized, roughtly 7 cm long. Almost all of these shiners made it back to the lab alive, where we're holding them in an aquarium until they're executed so their right gill arch can be removed and examined for parasites.

The second site of the day was Swan Creek at Elkton Road, just north of Athens, Alabama. This site was also fast and high compared to our last visit, with similar water chemistry to Limestone Creek. All we wanted at this site were scarlet and striped shiners for Christian's work. We only found two scarlet shiners, but we netted some of the biggest striped shiners I've seen out of local creeks, the biggest one maybe 14 cm long. The funniest thing was that Rachel saw her 80 year old grandmother drive by us without noticing.

Our last stop was Town Creek in downtown Athens, AL, looking for more black darters for Rachel. We didn't see her grandmother at the site, but we could've used her help, as we found 4 black darters after about an hour's effort (along with a few stripetail and greenside darters which we released). One male was still in bright colors, but not as bright as the ones we found a month ago at the site. These four were visibly longer and more robust than the three from Limestone Creek. This site is more eutrophic than the others, with TDS of 75 ppm today; maybe there's more available food? That's a whole research topic in its own right.

So Rachel will do her histological work on the black darters once she finishes her final exams, and Christian will start preparing shiners' gills for parasite examination on Wednesday after her finals are done. I hope to get a decent picture of that large colorful alpha male scarlet shiner on Wednesday and post it for your perusal.