New hatch appearance

[PAgeologist]

I understand how changes in water quality, stream bed, etc... can drive certain non-tolerant insects from a stream. But how does a new hatch appear? Last year I saw a Yellow drake on a stream that my family and I fish several times a week. This year we saw a good many more. Prior to last year I have never seen a Yellow drake on this stream. I was just curious as to how they may have found there way to this stream.

 

[sandfly]

flight, ducks, geese, eggs will stick to stuff. nature has her way with things. I have seen caddis here fly a mile away from the pine creek, doesn't take much for them to travel distance

 

[PAgeologist]

Thank you. I didnt realize that eggs would last that long out of water. I dont know of any streams nearby that would have a yellow drake hatch. I hope they permanently establish themselves and become as good as the other hatches.

 

[redietz]

There's an evalutionary reason that mayflies have winged adult stages. X-percent of the hatch is going to lost finding their way back to the stream. Some of those will end up colonizing new streams.

 

[JackM]

Since mayflies fly upstream after emergence, why aren't they found only in the headwaters? Hmmmm.

 

[dryflyguy]

Fishing the little juniata for 30 years has been a real saga.
It had great hatches that kept getting heavier each year - until the big spill of whatever, wiped everything out in 1995.
Then the hatches started to slowly return.
Many of the things that it had before did come back - sulphers, gray fox, slate drake.
Some didn't - green drake, rhyocophila caddis, white fly
And one hatch that it didn't have before - the grannom - came on to be one of it's best hatches

I can barely keep track of what does and doesn't hatch there now - let alone try to figure out where they came from.

 

[Maurice]

JackM wrote:
Since mayflies fly upstream after emergence, why aren't they found only in the headwaters? Hmmmm.

Jack,

Mayflys fly upstream in the adult stage (imago/spinner) to counteract the behavioral drift that occurs during their nymphal stage. Each morning and evening during the dawn and dusk for a period of about two hours the nymphs (some of them) release from the rocks and drift downstream making the food supply more readily available to fish in addition to redistributing the species farther through the watershed.

Converse to your question is the one asking; "if they didn't fly upstream, wouldn't they all eventually end up in the ocean?"

Its the cycle of the mayfly.

 

[JackM]

And so the original question is answered....

 

[pcray1231]

I think the "how does a new hatch appear" is rather self evident. A better question is "why does a new hatch appear".

And at first thought, there's 2 reasons.

1. It's not new. It was native to the waterway, but changes in water quality/habitat drove it away. Now as things improve it comes back. It's not colonization, it's RE-colonization.

2. Changes in water quality/habitat were to it's benefit to colonize the stream. Some bugs like silt, for instance, so as a stream silts in, it becomes better for that bug. Water temperature changes. Perhaps changes in the populations of competing species as well.

 

[mikesl]

A little tangentially OT but i had been wondering how mayfly populations don't inevitably end up "washing" downstream, unless they fly a considerable distance upstream... But I had never really heard the upstream flying mentioned. Interesting how they can know what upstream is..
Thanks for confirming that happens. Withiut flying or swimming upstream the population just doesn't work

 

[Chaz]

JackM wrote:
Since mayflies fly upstream after emergence, why aren't they found only in the headwaters? Hmmmm.

Because they can drop their eggs anywhere from the time they molt the last time, until they die. Most streams that have certain bugs will have them through the suitable habitat areas of the stream from the headwaters to the mouth, or until the water quality changes and they won't survive.
It is also how new populations appear, where they haven't been seen before.

 

[Chaz]

mikesl wrote:
But I had never really heard the upstream flying mentioned. Interesting how they can know what upstream is..

They don't 'know' what upstream is, it's genetically encoded into there behavior.

 

[jdaddy]

JackM wrote:
And so the original question is answered....

Circle of life, bro.

 

[jdaddy]

Chaz wrote:

mikesl wrote:
But I had never really heard the upstream flying mentioned. Interesting how they can know what upstream is..

They don't 'know' what upstream is, it's genetically encoded into there behavior.

Do you think that is due to the natural need to "gain ground" from generally being in an environment that is constantly moving them down stream? What is the correlation with broken water in the reproduction cycle?