Stoneflies - Colorado Mesa University

Stoneflies Yet another group of aquatic life disappearing from rivers

John Woodling Colorado Mesa U Environmental Sciences Department

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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

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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

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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

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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

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The order Plecoptera is divided into families including  

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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

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Stoneflies can also be separated into groups based on what species consume. Pteronarcella badia is a shredder and eats plant material. 

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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) 100

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80

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60

None were collected in 2004, 2005 and 2011. No official samples from 2006-2010*.

40

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0

1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

20

Number collected

* = I did look for P. badia in 07-2010

Number of two predatory stoneflies collected each year at Eagle River at Arrowhead (Site 6) 

1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

45 40 35 30 25 20 15 10 5 0

number Isoperla fulva number Isogenoides sp.

No samples from 20062010.

Isogenoides, photo credit “Discover Life”

Number of 3 dominant stoneflies each year at Eagle River at Arrowhead (Site 6).

 140 120 100 80 60 40 20

Number of Pteronarcella

Number of Isoperla fulva

Number of Isogenoides sp.

Number of all other stoneflies

2011

2009

2007

2005

2003

2001

1999

1997

1995

1993

0

Dominant taxa from 1993 to about 2000 gone in 2005 and 2011.

Number of Nemouridae (shredders) collected each year at Eagle River at Arrowhead (Site 6) 

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1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

8 7 6 5 4 3 2 1 0

Number collected

None were collected in 2004, 2005 and 2011. No samples from 20062010.

Stoneflies – in the Eagle River at Arrowhead

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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

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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 60

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50 

40 30 20

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1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

10

Arrowhead

Above Gore

None were collected in 2004, 2005 and 2011. No samples from 20062010.

Number of Pteronarcella badia collected each year at Eagle River above Gore Creek 

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1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

80 70 60 50 40 30 20 10 0

Number collected

No samples from 20062010. Same pattern as Arrowhead?

Stoneflies – Limiting environmental factors Eagle River 

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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. 

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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     

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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 

100

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80 60 40

0

1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

20

Arrowhead

No samples from 20062010. E. infrequens one of few mayfly species that colonizes sand and gravel (2).

Number of Drunella mayflies collected yearly, Eagle River at Arrowhead 

300 250

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200 

150 100

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1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

50

D. grandis

D. doddsi

No samples from 20062010. 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. 

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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. 

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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. 

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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.

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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. 

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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.

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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.