stoneflies yet another group of aquatic life disappearing from rivers john woodling colorado mesa u...
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StonefliesYet another group of aquatic life disappearing from rivers
John Woodling
Colorado Mesa U
Environmental Sciences Department
Plecoptera (stoneflies) are the most primitive insect order that can flex or fold wings in some manner.
Early Triassic period stoneflies (250 million years ago) are much like the species found today throughout the world.
Stoneflies survived the event that killed off Dinosaurs 65 million years ago.
Stoneflies do not appear to be able to survive human society. 43% of all United States stonefly species are at
risk
Stoneflies in United States
In Illinois 25%(1) of all stonefly taxa have become extirpated since the 1950s.
In Indiana 11.5%(1) of all stonefly taxa have become extirpated since the 1950s.
Other studies are reporting the same pattern in other states for other aquatic insect orders.
Stoneflies in Colorado
Not a lot of studies where one stream reach sampled through time for aquatic insects.
The Colorado Division of Wildlife* did a long term sampling of Eagle River (on going from 1989), aquatic insect samples from 1993 until 2011 (no samples 2006 – 2010).
Site at Arrowhead Golf Course chosen as Reference Location
Site downstream of Minturn and above Gore was impacted by Eagle Mine. Arrowhead bugs better.
* =And a lot of others, HAZMAT, CBS, ERWC, EML LLC, local volunteers and schools
Stoneflies in Colorado
Aquatic insects sampled from 1993 to 2005 and again in 2011 by DOW*.
All sampling used the same techniques. All samples identified by Aquatics and Associates from
1993 through 2005 and by David Rees in 2011 Data collation and photography by Colorado Mesa U.
Aquatic Entomology classes of 2009 and 2011.
* = And a lot of others, HAZMAT, CBS, ERWC, EML LLC, local volunteers and schools
Stonefly families
The order Plecoptera is divided into families including Perlidae – the golden or summer stones Nemouridae – spring stones or tiny winter
black stoneflies Pteronarcidae – Salmon flies, giant stones Perlodidae – Springflies, yellow sallies
Stoneflies – functional feeding groups
Stoneflies can also be separated into groups based on what species consume.
Pteronarcella badia is a shredder and eats plant material. Shredders turn leaf litter or algae into insect body mass. That
insect mass is an important trout food.
Isoperla fulva and Isogenoides sp. are predators. Aquatic insect predators are also an important component of
trout food.
Number of Pteronarcella badia collected each year at Eagle River at Arrowhead (Site 6)
0
20
40
60
80
100
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
Number collected
None were collected in 2004, 2005 and 2011.
No official samples from 2006-2010*.
* = 0
* = I did look for P. badia in 07-2010
Number of two predatory stoneflies collected each year at Eagle River at Arrowhead (Site 6)
05
1015202530354045
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
number Isoperla fulvanumber Isogenoides sp.
No samples from 2006-2010.
Isogenoides, photo credit“Discover Life”
Number of 3 dominant stoneflies each year at Eagle River at Arrowhead (Site 6).
Dominant taxa from 1993 to about 2000 gone in 2005 and 2011.
0
20
40
60
80
100
120
140
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
Number of Pteronarcella Number of Isoperla fulva
Number of Isogenoides sp. Number of all other stoneflies
Number of Nemouridae (shredders) collected each year at Eagle River at Arrowhead (Site 6)
0
1
2
3
4
5
6
7
8
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
Number collected
None were collected in 2004, 2005 and 2011.
No samples from 2006-2010.
Stoneflies – in the Eagle River at Arrowhead
Stoneflies are only an incidental component of aquatic community at the Arrowhead Golf Course as of the spring of 2011.
A large component of the aquatic biota in the Eagle River is gone.
Shredders seem to be the most severely impacted group. The same observation made in Illinois and Indiana.
Stoneflies – in the Eagle River and Colorado River
Study by Timberline Aquatics demonstrated that aquatic macroinvertebrates in the Eagle River from Vail to Edwards reduced in numbers and types of mayflies, stoneflies and caddisflies.
DPW has noted decrease in Pteronarcidae in mainstem Colorado River upstream of Eagle River.
Few stoneflies captured in mainstem Colorado River from Glenwood Springs downstream to Grand Junction, Colorado by CMU entomology class.
Number of Nemouridae collected yearly, Eagle River above Gore compared to Arrowhead
0
10
20
30
40
50
60
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
Arrowhead Above Gore
None were collected in 2004, 2005 and 2011.
No samples from 2006-2010.
Number of Pteronarcella badia collected each year at Eagle River above Gore Creek
0
10
20
30
40
50
60
70
80
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
Number collected
No samples from 2006-2010.
Same pattern as Arrowhead?
* = 0
Stoneflies – Limiting environmental factors Eagle River
Eagle River substrate at Arrowhead not a typical mountain stream.
Lots of nitrogen and phosphorus in water column Substrate cobble covered by fine sediments in April of
each year. Sediments appear as fine brown material along with algal and
fungal mats covering stream cobble. Sediments are periodically black and anaerobic with a smell of
sewage to a depth of several inches in eddies.
Stoneflies – The Contaminant sources in the Eagle River
Interstate 70 – from the top of Vail Pass to Vail. Traction sand and magnesium chloride
Urbanization of valley floor Domestic wastewater effluents Loss of dilution water – transmountain diversions. Tree spraying – has resulted in shredder loss in many
other parts of U.S. Vail encouraged tree spraying starting in 2004?
The impact on stoneflies is probably due to a combination of factors.
Number of Ephemerella infrequens collected yearly, Eagle River at Arrowhead
0
20
40
60
80
100
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
Arrowhead
No samples from 2006-2010.
E. infrequens one of few mayfly species that colonizes sand and gravel (2).
Number of Drunella mayflies collected yearly, Eagle River at Arrowhead
0
50
100
150
200
250
300
19
93
19
95
19
97
19
99
20
01
20
03
20
05
20
07
20
09
20
11
D. grandis D. doddsi
No samples from 2006-2010.
One D. grandis collected in 2011.
D. grandis is more of a habitat generalist than D. doddsi and is found in areas with gravels and fines. D. doddsi is not found in areas with small gravels and fines (3).
Stoneflies – Influence of tree spraying on numbers of Eagle River stoneflies.
Town of Vail actively encouraged landowners to spray trees for two different pests.
Shredders have decreased in many U.S. rivers due to spraying programs.
Spraying is part of the problem with stoneflies in the Vail area.
Stoneflies – Influence of sediments on numbers of Eagle River stoneflies.
Increased sedimentation has filled the interstitial spaces on stream substrate in mainstem Eagle River downstream of Gore Creek
Shredders have decreased in the Eagle River at Arrowhead since the late 1990’s.
Increased sediments could be part of cause in declinde of stonefly species and other taxa due to habitat loss.
Stoneflies – Influence of nutrients on numbers of Eagle River stonefly shredders.
Multiple studies have shown that addition of nutrients to leaf litter increased the numbers of shredders present.
These studies lasted for one year. Recent multi-year studies seem to indicate the reverse,
increased nutrients lead o increase fungal growth and eventual reduction in the numbers of aquatic insects.
Stoneflies – How to protect Colorado species.
Stop spraying trees on the side of the river Reduce sediments, Highway and urban Tertiary treatment of domestic wastewater
Stoneflies – Future in large rivers in the State of Colorado.
Stonefly perspective in mainstem Colorado Rivers = “The Sky IS falling,” C. Little finally got it right.
The large river stonefly perspective from human eyes = “We have met the enemy and he are us,” Pogo.
Lit cites.
1. DeWalt, R.E., C. Favret, & D.W. Webb. 2005. Just how imperiled are aquatic insects? A case study of stoneflies (Plecoptera) in Illinois. Annals of the Entomological Society of America, 98:941–950.
2. Hawkins, C.P. 1984. Substrate associations and longitudinal distributions in species of Ephemerellidae (Ephemeroptera:Insecta) from western Oregon. Freshwater Invertebrate Biology. 3:181-188.
3. Winget, R.N. 1993. Habitat partitioning among three species of Ephemerelloidea. Journal of freshwater ecology. 8. 227-233.