Nymph Survey Through the Seasons

[Dave_W]

I enjoy seining for aquatic insects. This year, I think I'll try to make this a bit more systematic and allow for comparison through different seasons.

Here's my plan (subject to change):
Survey three characteristic, local wild trout streams at least four times per year. Streams will be Falling Springs, Big Hunting Creek, and Yellow Breeches.

These streams include a "pure" limestoner (FS), a medium sized "semi" limestoner (YB) and a medium sized but fairly fertile freestoner (BHC). These streams all have good populations of wild trout, some stocked fish (a lot in YB), and are popular with fly fishermen.

Will pick out a good riffle with various habitat, conduct a seine sample in the exact spot with the exact kick method, and do this in January, April, July, and October. Macros will be identified and counted (not sure controlling for size, but this would be interesting, esp for mayfly ad stonefly nymphs). Conventional wisdom is that nymphs are larger in springtime before hatching, but how does species and size vary over the year? Are the nymphs fewer and smaller in October? Are caddis more prevalent in the autumn?

I'll re-fresh this thread as the season progresses. . . and we'll see what turns up.

 

[troutfanatic]

I like where you are going with this.

I need to do a senior research project to finish my degree change. I am looking at selection pressures on S. trutta by microhabitat on a tailwater I fish. It's a very diverse from one half mile stretch to the next. Some areas have very high reproductive success but growth is poor. Other areas have extremely high growth but poor reproduction. Food and water conditions are the keys. Some areas have very high insect hatches and an abundance of nymphs year round. in other areas, crayfish and various forage fish make up the diet. Meanwhile I need to figure out how to quantify what is a good insect population versus a poor one. Everything else gets shock sampled.

 

[dc410]

Neat idea, Dave. I'm looking forward to seeing what kinds of trends show up with your survey. Good stuff.

 

[OldLefty]

Dave, some of your discoveries will prove very interesting/enlightening. Trust me on this.

Dave R.

 

[nomad_archer]

I cant wait to see what you learn. I think it will be pretty interesting.

 

[1manwolfpack]

Keep in mind that by only sampling riffles you are only surveying insects that live in the riffles and not the stream as a whole. Many insects such as burrowing mayflies, damselflies and dragonflies prefer slow water with a silty bottom. Just something to keep in mind. Interesting project though, good luck with it. Great to see people take more of an interest in their local water besides how many fish they can pull out of it. +100

 

[PocketWater]

Cool idea. Looking forward to seeing your study as it progresses.

 

[steveo27]

Agreed. Looking forward to seeing what ya find.

 

[Camp]

Bookmarked.

 

[sandfly]

most insects in January will be buried deep in substrate (hibernating). just like trout their metabolism slows way down.

 

[pcray1231]

Maybe, but I bet the limestone is more consistent.

Agree on the riffle vs. pool and substrate thing. I'd pick variable locations and keep track by location. The results you get in heavy current, boulder bottom is different from moderate current gravel which is different than slow water silt. And the presence of aquatic vegetation further complicates it.

 

[dsmith1427]

Dave, thanks for doing this and sharing it with the community. It sounds like a great project. I'm looking forward to seeing your results.

No offense to the OPs that discussed sampling other environments but in project management we call that scope creep which can kill a project. If you choose two more environments in the three difference creeks that means nine sets of data instead of three meaning more time to sample, analyze (and hopefully publish) data.

No matter when and where I fish, I always turn over rocks, logs, etc. to sample the aquatic life. I did this for my spin fishing brothers and nephews one time and they couldn't believe what they saw. I told them that's why I out fish them! LOL.

Anyway, it's times/things like this when I wished I still lived in PA. If we could use a standard format, I would extend the study and pick a different stream to share. After the findings, I would consider extending the study to different environments.

Don

 

[troutbert]

It sounds like an interesting study.

Is there a particular question or questions that you're hoping to answer? What is it that you are trying to find out?

 

[Dave_W]

Thanks folks - nice to get so much encouragment. I'm looking forward to it.

I'll post the first sample data set in a week or two. At that point, I'll try to consider some more questions, but I'm mainly interested in seeing if there are differences in macroinvertebrate populations in a specific riffle during different seasons. Agree that a broader survey would be better, but as others have pointed out, this study needs some limitations.

The conventional wisdom, of course, is that pure limestone streams have greater biomass, but less species diversity. Will be fun to compare this to the semi-limestoner and freestoner.

I'm not sure if I'll try to control for other prey items that turn up in the net - sculpins, crayfish, aquatic worms, dace, etc. We'll see.

I'll also move this thread over to the Entomology forum eventually as well.

 

[djs12354]

Thanks for taking this on, Dave.

It will be educational for me, certainly, and for others, as well.

Looking forward to seeing results.

 

[gulfgreyhound]

There will be a lot learned from this project. There will be a wealth of valuable information gleaned from your study. I'm looking forward to your reports. GG

 

[cjc71]

My wife did what the OP described for years as part of her job in the SEPA counties. I ask her what flies I should take for what streams, nice little resource.

 

[salmonoid]

troutbert wrote:
It sounds like an interesting study.

Is there a particular question or questions that you're hoping to answer? What is it that you are trying to find out?

"I enjoy seining for aquatic insects. This year, I think I'll try to make this a bit more systematic and allow for comparison through different seasons."

He likes seining.

And is hoping to compare insects across seasons. Phrased in the form of a question - how does the aquatic nymph life vary over seasons in a given stream?

 

[Dave_W]

Okay, I have completed my sampling for January. Due to some issues, I have switched out Falling Springs and replaced it with Letort and switched out Big Hunting Creek and replaced it with Conococheague. Of course, this still covers the intent of sampling the three different categories: limestoner, semi-limestoner, and freestoner ( I am sampling some other creeks as well, but this thread will have to be limited to these three waterways).

The results were somewhat predictable but interesting nevertheless. In particular, the number of nymphs turned up was higher than I anticipated for this time of year.

Anyway, when I get the photos and numbers together, I'll post the results shortly.

 

[Dave_W]

A few general observations about what I have seen this January: Again, these surveys are done by kick seining in roughly equivalent riffles with mixed gravel and cobble rock. The counts reflect basic species. I did not try to identify specific species but careful observation reveals March Browns, Slate Drakes, Hendricksons, Sulphers, and Perlid stones. I made no attempt to document size, but the photos of the bugs do provide some basic information on size which will allow for comparison later in the year. For all the streams, note the small size of many of the nymphs (except stoneflies) and also of note is the more prevalent amount of green caddis vs brown ones. I was surprised at the relative lack of midge larva at all locations.

The surveyed section of Breeches is mid river and the large number of macros reflects the limestone influence but also rich, somewhat warmer, downstream section. Yellow Breeches was very impressive and the only stream that produced more mayfly nymphs than caddis larva. Breeches reputation as a bug factory is clearly well deserved! Water temp on the day of the survey was 43 degrees F.

For Letort, not surprisingly, the overwhelming biomass was cress bugs. Scuds were much fewer but seemed to me to be somewhat larger on average. Note also the light color and relatively small size of the Letort cress bugs. Only two mayflies turned up in Letort and no caddis or stoneflies. Water temp was 50 degrees.

Conococheague is a freestone stream that, like many that originate up on South Mountain, leans toward the acidic side and holds wild brook trout in the headwaters. The section surveyed is off the mountain, but upstream from Chambersburg and is mainly a stocked fishery. Compared to Breeches, it seems a lot less fertile and the rocks were polished and lacking the typical vegetation that holds so many macros on the mixed limestoners. Nevertheless, it produced a good number of bugs, including a giant Pteronarcys salmonfly, a species I don’t see often in my bug surveys. Water temp was 39 degrees.

Here are the bug counts for January:
CONOCOCHEAGUE:
Mayflies: 7
Caddis: 11
Stoneflies: 2
Scuds and Cress Bugs: 0
Aquatic Worms: 2

YELLOW BREECHES:
Mayflies: 48
Caddis: 6
Stoneflies: 1
Scuds: 6
Cress Bugs: 0
Several midge larva

LETORT:
Mayflies: 2
Caddis: 0
Stoneflies: 0
Scuds: 19
Cress Bugs: 134
Midge Larva: 2

I'll return to the same riffles in April, we'll repeat the process, and see how things look.