Rusty Spinner
Active member
We've largely been led to believe that with increasing temperatures here in the East, we would see a 1:1 correlation in water temps and, hence, a significant loss of brook trout (up to 75% loss of current habitat). I just sat through a USGS webinar presentation that largely refutes that and has great empirical data to back up their findings. If air temps raise a full 5 decrees Celsius over time which is 3 degrees C more than is predicted, we would retain 75% of current brook trout habitat.
What their research is pointing to factors in groundwater and the effects of the hyporheic (sounds like hi-po-ree-ick) zone under a given stream. While air temperature increases are important factors in warming our waters, groundwater now has been proven to have a stronger influence throughout the study ranges. Other factors are slope, geology and elevation. The studies we view today were from Delaware Water Gap National Recreation Area (DWGNRA) where I didn't get the # of watersheds and from the Great Smoky Mountain National Park (9 watersheds within the Park). Climatologists predict higher than average winter precipitation here in the Northeast which bodes well for groundwater supplies. That is all good news regardless of where you stand on climate change as in if man is to blame totally, somewhat or not at all. We know the climate changes because we have had dinosaurs living here in hot temps and have had glaciers here in cold temps. I'll leave that argument for others to have.
The downside to increasing air temps and corresponding water temperature increases is habitat fragmentation which is interesting. We initially thought we'd simply see brook trout finding thermal refugia in the headwater streams. But it turns out that some headwater streams are just as strongly impacted by thermal issues as the lower rivers they flow into in certain cases. One study in the DWGNRA showed that many headwater streams are thermally impaired because of dams and many small impoundments like we see with the Big Flat Brook throughout its upper reaches. This river sees better temps in its middle reaches for that reason. All in all, I found this topic highly interesting and look forward to it being formally published and peer reviewed. Some good news for our natives for a change!
:fish:
What their research is pointing to factors in groundwater and the effects of the hyporheic (sounds like hi-po-ree-ick) zone under a given stream. While air temperature increases are important factors in warming our waters, groundwater now has been proven to have a stronger influence throughout the study ranges. Other factors are slope, geology and elevation. The studies we view today were from Delaware Water Gap National Recreation Area (DWGNRA) where I didn't get the # of watersheds and from the Great Smoky Mountain National Park (9 watersheds within the Park). Climatologists predict higher than average winter precipitation here in the Northeast which bodes well for groundwater supplies. That is all good news regardless of where you stand on climate change as in if man is to blame totally, somewhat or not at all. We know the climate changes because we have had dinosaurs living here in hot temps and have had glaciers here in cold temps. I'll leave that argument for others to have.
The downside to increasing air temps and corresponding water temperature increases is habitat fragmentation which is interesting. We initially thought we'd simply see brook trout finding thermal refugia in the headwater streams. But it turns out that some headwater streams are just as strongly impacted by thermal issues as the lower rivers they flow into in certain cases. One study in the DWGNRA showed that many headwater streams are thermally impaired because of dams and many small impoundments like we see with the Big Flat Brook throughout its upper reaches. This river sees better temps in its middle reaches for that reason. All in all, I found this topic highly interesting and look forward to it being formally published and peer reviewed. Some good news for our natives for a change!
:fish:
