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late season collecting query

Started by Guest_exasperatus2002_* , Dec 05 2011 01:52 PM

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#21 Guest_farmertodd_*

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Posted 06 December 2011 - 03:03 PM

Submitting the paper that will give me a baseline to work on that stuff this week. We'll see what the reviewers do with it.

Todd

#22 Guest_FirstChAoS_*

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Posted 07 December 2011 - 12:59 AM

Correct. NO Johnny's in the Susky. Now if you're still interested in the interaction between native and non-native darters, bandeds have had documented effects on tessellateds in the Susquehanna and I would hypothesize greensides have also had some influence on benthic fish resource use. I don't think you'd get your direct competition though among closely related species. I can't remember what directions the current winds suggest for the status (native v. non) of greenside and rainbow in the Potomac. I think it's pretty well evident that roanoke darters and their rapid expansion have likely had effects on native darters in the respective VA basins they were introducted.

Wait, Banded Darters, a highly riffle specific species, impact tesselated a more slack water species found occasionally in riffles? Odd, how does this work as the habitat overlap is minimal from my experience.

#23 Guest_mneilson_*

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Posted 07 December 2011 - 09:22 AM

Correct. NO Johnny's in the Susky. Now if you're still interested in the interaction between native and non-native darters, bandeds have had documented effects on tessellateds in the Susquehanna and I would hypothesize greensides have also had some influence on benthic fish resource use. I don't think you'd get your direct competition though among closely related species. I can't remember what directions the current winds suggest for the status (native v. non) of greenside and rainbow in the Potomac. I think it's pretty well evident that roanoke darters and their rapid expansion have likely had effects on native darters in the respective VA basins they were introducted.

In the USGS NAS database, we currently list greenside as introduced and rainbow and native to the Potomac drainage. I do plan on revisiting rainbow darters at some point in the future, however, after I've given the remaining ~400 species on my list a once-over.

Wait, Banded Darters, a highly riffle specific species, impact tesselated a more slack water species found occasionally in riffles? Odd, how does this work as the habitat overlap is minimal from my experience.

There is some evidence of hybridization between tessellated and banded darters in the Susquehanna, as well as some evidence of competition between the two species (and subsequent changes in morphology in tessellated darters due to a shift to more marginal habitat). Our page on banded darter has some references.

#24 Guest_farmertodd_*

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Posted 07 December 2011 - 11:28 AM

In competitive release and moderate productivity levels, banded darter will occupy very broad habitat characteristics. In my data from across the Ohio River watershed, I've found the sole habitat character they require is water.

Todd

#25 Guest_fundulus_*

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Posted 07 December 2011 - 01:00 PM

In competitive release and moderate productivity levels, banded darter will occupy very broad habitat characteristics. In my data from across the Ohio River watershed, I've found the sole habitat character they require is water.

Todd

Huh. I believe it, and that's what Van Snik et al. (2005) found and remarked on with introduced populations in the Susquehanna system. But, in two north Alabama streams (Flint and upper Paint Rock), we've found bandeds to be largely restricted to the crazy-fast parts of riffles where they can be dominant. But along the stream edges they're replaced especially by the local snubnoses, but also rainbows, redlines, stripetails and fantails. This could be an edge of range effect, since we're at the far southern edge of their range. We're working on niche breadth and overlap numbers now, which should be part of a master's defense by early March.

#26 Michael Wolfe

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North Georgia, Oconee River Drainage

Posted 07 December 2011 - 01:15 PM

...the sole habitat character they require is water.

I know y'all are being serious and scientific here and I appreciate that... but this has got to be ranked in the top ten all time best things that have ever been said here... this fish needs water... who'd a thunk it.

But to the part that Bruce pointed out, it is interesting that they can out-compete everybody in some systems... since they can apparently be such a generalist... but in another situation they do not out-compete... if this was a sports situation I would say that it makes you wonder about the strengths of the competition. Its like saying you were the top of teh league in one situation... but in another you could not dominate. So what makes the snub-noses tougher competion? And interesting that the snubs can do better in edges and slower water... begins to make me think about stream modification and such.

Either write something worth reading or do something worth writing. - Benjamin Franklin

#27 Guest_fundulus_*

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Posted 07 December 2011 - 01:37 PM

I'm not exactly certain why at least Tennessee and Black snubnoses are such good competitors, and are often the dominant darter species in local streams. One interesting thing we've found in another study is that both of those snubs have very low rates of gill parasites, and the bandeds are almost as low; redlines are intermediate with these parasites, rainbows next higher, and the stripetails and fantails have the most of species we've examined over a year. That's probably not the whole story, but it might be indicative of other factors.

#28 Guest_Newt_*

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Posted 07 December 2011 - 01:41 PM

Sort of looking at it from the other end, but...in species-rich faunas like the ones Todd and Bruce work in, every fish has got to be either a tough competitor or find a specialization. The Ohio-Tennessee-Mobile wedge has got gobs of sympatric darter species with overlapping habitat requirements, as well as darter analogues such as Erimystax and Phenacobius minnows. Competition must be intense. The Atlantic Slope fauna is less speciose, so it benefits the darters there to concentrate their evolutionary "energy" on vertical effects (exploiting prey and avoiding predators) and being good generalists, able to use varied habitats. Which is great for them until a hyper-competitive trans-Allegheny species is introduced.

#29 Guest_farmertodd_*

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Posted 07 December 2011 - 02:21 PM

So... Where have banded darter managed competitive exclusion? I'd also been more satisfied with the Van Snik conclusion is if they thought about where tesselated ended up partitioning TO. Kinda reminds me of another conspecific, known as the johnny darter, when they appear in species rich assemblages, no?

There's another way to view this... Banded aren't competitors, they're adapted to anywhere someone else isn't. They are the most sensitive species in my pool to everything else. Even still, they cause shifts for other species because they can occupy some space.

Now if you wanna to see a competitor, get out my boy ol' maculatum. They're a-holes, they move everyone's distribution around when they show up. Why? Because they're habitat specialists and specialists have to be able to claim the habitat they need.

Even still, you can find spotted darter dominated riffles, but never where they competitively exclude all other species. Everyone is still there, just in lower abundance. Why? Now that's an interesting question!

Sorry for the derail

Todd

Edited by farmertodd, 07 December 2011 - 02:38 PM.

#30 Guest_gerald_*

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Posted 07 December 2011 - 02:41 PM

We supposedly have both Johnny and Tesselated darters in the upper Tar and Neuse Rivers near Raleigh. I cannot distinguish them by sight, except maybe breeding males. See Jenkins & Burkhead's VA fishes book for ID features: they are slight and not easy to observe on a live fish (head pores, dorsal rays). If anybody has tips on visually separating Johnny vs Tesselated in the field (other than breeding male colors), I'd love to hear about it.

Also I suspect many fish collection records used whichever name (Johnny or Tess) they thought the fish were "supposed" to be based on location, without really checking the meristic features.

#31 Guest_gerald_*

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Posted 07 December 2011 - 02:57 PM

Whoa -- A plant-spawner hybridizing with a cave-nest-guarder? So either a banded darter would have to "learn" how to spawn upside-down under a rock with a tess mate, or a tess would have to "learn" how to spawn in plants with a banded mate, right? Would love to see video of THAT happening!

There is some evidence of hybridization between tessellated and banded darters in the Susquehanna, ...

#32 Guest_fundulus_*

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Posted 07 December 2011 - 03:36 PM

"So... Where have banded darter managed competitive exclusion? I'd also been more satisfied with the Van Snik conclusion is if they thought about where tesselated ended up partitioning TO. Kinda reminds me of another conspecific, known as the johnny darter, when they appear in species rich assemblages, no?" True, but to some degree it's trying to prove a negative. Johnnys are in the upper Paint Rock but we've never seen them in the Flint, and in the Paint Rock we find them in shallower, slower channels or pools, which is consistent with the Van Snik observation. This stretch of the Paint Rock, Estill Fork, has 15 darter species present, so various competitions and exclusions are in play. Interestingly, where we've worked in the Flint has a very large population of blotched chubs, Erimystax insignis, which really are a darter-like minnow. They're reported as present in the Paint Rock, but we never encounter them.

#33 Guest_mneilson_*

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Posted 07 December 2011 - 04:27 PM

Whoa -- A plant-spawner hybridizing with a cave-nest-guarder? So either a banded darter would have to "learn" how to spawn upside-down under a rock with a tess mate, or a tess would have to "learn" how to spawn in plants with a banded mate, right? Would love to see video of THAT happening!

Raesly et al. (1990) mention this difference in reproductive behavior and suggest a few ways that this could have occurred, and came to the conclusion that "Because hybrids were collected from localities where E. zonale was rare, active participation of banded darters (in the absence of conspecifics) with mating E. olmstedi...".

Evidently, it gets pretty lonely out there when you're the new species in the stream, and introduced fishes have needs too...

Edited by mneilson, 07 December 2011 - 04:27 PM.

#34 Guest_farmertodd_*

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Posted 07 December 2011 - 04:34 PM

Right. So the niche is conserved among sister taxon... Both species move to a similar habitat in the presence of competitor(s), which is plum right out of the riffle. So then why is it a big deal that the "exotic" has "shift" the "native"? If natives shift natives, then why are we so proud of ourselves when we show that exotics shift natives?

I guess that's what I'm after. I'm interested in what it can tell us about all these ongoing invasions, and how we can best mitigate, and even better, stop them. Otherwise, we're going to continue doing this Han-Solo-Running-Out-of-the-Bunker-Hands-Flailing "The snakeheads are coming!" dance over and over and over. Which results in management policies where they dip out entire ditches so we can better apply rotenone from helicopters. And... removes ALL ecological resilience against the invasion.

Now if you want to get into why they're not in the Flint, that might tell you some of why they're in the Paint Rock. It's not proving a negative, it's using an absence to declare what's specific to the presence. I'm going to take a guess that the Flint is sand starved for some reason, maybe by a series of dams?

Todd

#35 Guest_fundulus_*

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Posted 07 December 2011 - 05:03 PM

By "they", do you mean johnnys? The Flint is essentially undamned, there has been maybe one lowhead way up one of the branches. Where we've mostly observed is a very dynamic riffle system largely over exposed sandstone bedrock and fragments thereof. And by dynamic I mean the water level can rise quickly, as happened this past weekend, so I think much but not all of the local sand gets scoured out in pulse events. All of this discussion is directly relevant to what we've been poking along at, because these two rivers are close to each but in well-defined basins, and both rise on the southern edge of the uplift of the Cumberland plateau not too far north in Tennessee. They're similar but different, and both the similarities and differences can be examined from a variety of explanatory angles. And back to your original question, Estill Fork of the Paint Rock has a lot more sand in it, and is also a smaller stream; it averages about 12 m wide where we've worked, while the Flint is 35-40 m wide. So there is some element of comparing apples to oranges. For us logistically it's hard to gain easy, legal access to much of the upper Flint because it's closer to Huntsville, and more thickly settled, while the Paint Rock is more remote to the east, and certainly as you go north access is easier with a thin human population.

#36 Guest_farmertodd_*

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Posted 07 December 2011 - 05:19 PM

Yes, nigrum. So, for whatever reason, the Paint Rock is more sand-rich? Have you tried visualizing your environmental variables in PCA and overlaying the samples from each individual riffle to see where they fall in that PCA space? I've seen plenty of riffles that are similar, but there are riffles that are seriously different. It wasn't until we got down to the PCA and got the community noise out of the way that we could really see what it was they were responding to.

Maybe we should start a new topic and I can post some figures if this is of interest to more than just Bruce and me

I can do that later tonight. Again, sorry for the derail.

Todd

#37 Guest_frogwhacker_*

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Posted 07 December 2011 - 05:42 PM

Maybe we should start a new topic and I can post some figures if this is of interest to more than just Bruce and me I can do that later tonight. Again, sorry for the derail.

Todd

Yes, Please do. This is some really good stuff. I think we all want more of it for sure. =D>

#38 Guest_fundulus_*

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Posted 07 December 2011 - 05:51 PM

Yeah, we're due for a new topic so can really get weird with the data analysis. I'll close out here by saying that we've done multiple transects across multiple riffle points in both rivers for over a year, identifying depth, bottom flow, and substrate; we're gearing up for CCA rather than PCA (statistics, hooray!). I checked in with the Boschung & Mayden Alabama book, and in the Tennessee Valley of 'bama johnnys are known only from the Paint Rock, Shoal Creek and Bear Creek (the latter always a strange one...). So what historic forces are at work here, present in the Paint Rock but not the Flint, present in Shoal Creek but not Cypress Creek? Sand budget and extent of slow flowing side channels might be part of the answer.

#39 Guest_exasperatus2002_*

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Posted 08 December 2011 - 12:03 AM

Whoa -- A plant-spawner hybridizing with a cave-nest-guarder? So either a banded darter would have to "learn" how to spawn upside-down under a rock with a tess mate, or a tess would have to "learn" how to spawn in plants with a banded mate, right? Would love to see video of THAT happening!

I think I know how that looked like. But it'd involve a high school flash back & my prom date. LOL

Edited by exasperatus2002, 08 December 2011 - 12:05 AM.

#40 Guest_FirstChAoS_*

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Posted 08 December 2011 - 10:58 AM

Now if you wanna to see a competitor, get out my boy ol' maculatum. They're a-holes, they move everyone's distribution around when they show up. Why? Because they're habitat specialists and specialists have to be able to claim the habitat they need.

Interesting. Usually when I hear of generalists vs specialists it usually mentions specialists as fragile. They have one trick and they do it well, but when a habitat disturbance happens the specialists lost their spot and the generalists rush in to take the spot and don't let them recolonize.