Didymo (rock snot) is an invasive microscopic alga that grows in long stalks which are resistant to decay.It forms thick mats that have negative impacts on streams and can make fishing impossible. Didymo is expanding its range and tolerance throughout the world. Currently, Didymo exists in 19 states and occurs as close as northern Arkansas.
What anglers need to do:Check -Remove all visible clumps of algae and plant material from fishing gear, waders, water shoes and sandals, canoes and kayaks and anything else that has been in the water.
Clean your gear in a 2 percent household bleach solution (1/3 cup per gallon of water), 5 percent saltwater solution (1 cup per gallon of water) or dishwashing detergent. Scrub boats and other “hard” items thoroughly. Completely soak equipment, felt-sole waders, personal flotation devices and other “soft” material for at least 20 minutes.Use the Boot wash stations at Missouri’s Trout Parks before entering the stream 3 Minutes in the salt solution will destroy Didymo cells on nonporous wader soles and equipment
Dry -Allow any item that has been in contact with the water to completely dry; the item should be exposed to sunlight and left to dry for at least 48 hours before entering a different trout stream.Do your part–don’t spread Didymo.Please remember to Check and Clean or Dry your fishing gear and waders when moving between waters.
On March 1, 2012 all porous soled waders, boots and shoes are prohibited in the four state trout parks: Bennett Spring, Montauk, Maramec Spring and Roaring River as well as all managed trout streams in Missouri
The Missouri Department of Conservation and Didymosphenia geminata aka – Didymo or “rock snot” Presenter: Mark Van Patten Fisheries Management Biologist Missouri Department of Conservation
Didymosphenia geminata aka – Didymo or “rock snot”• Didymo (rock snot) is an invasive microscopic alga that grows in long stalks which are resistant to decay.• It forms thick mats that have negative impacts on streams and can make fishing impossible.• Didymo is expanding its range and tolerance throughout the world.• Currently, Didymo exists in 19 22 states and occurs as close as northern Arkansas.
Didymo in Arkansas The brown color is due to fucoxanthin, a pigment contained in each cell, (although each cell also contains chlorophyll) and the white or translucent color is due to the stalks.
Didymosphenia geminata• Colonial diatom• Cells divide• Attachment as gelatinous stalks• Massive plant• Cells (200-300 microns)• A cell cleaned in sulphuric acid and showing the ornamentaion critical for identification
Below are both a cell and stalk of Didymo found in the gut content ofGammarus (Scud) which was living in the stalk portion of Didymo atthe time of collection. Also present are cells of epiphytic diatomsthat were attached to the Didymo stalks.A Gammarus found in acolony of living Didymo
Microscopic colony of Didymo scraped from a rock in the Beaver tailrace, March 2006 The ability of Didymo to remain attached to the substrate by the basalportion of the stalks probably contributes to its continued presence andredevelopment after a flood type event and/or seasonal changes. (1)
Gomphonema with stalks and divisionsimilar to Didymo. The major difference isthat the stalk material of Gomphonema isslippery and that of Didymo is cottony.
Conditions most favorable to Didymo colonization• High N/P ratio, low phosphorus (< 2 ug/L) in the water.• Bright sunlight• Low TSS (total suspended solids)• pH (7-9)• Generally cold waters from 4 to 27 C (2)• Stable water flow: “mean flow regime is associated with bloom development, based on a significant negative relationship detected between D. geminata biomass and mean discharge” (3)
What are its negative effects?• The damage caused by Didymo is largely from the stalks produced by each cell of the diatom colony which form large mats on streambeds, decreasing clarity and oxygen availability (especially at night). In some areas mats 20cm (6 inches) thick have been reported. (6)• When Didymo is absent or in low numbers, diversity of invertebrates is increased .(6)• Significant changes in the kinds of invertebrates were found in an excellent study by EcoAnalysts Inc. (12) in examining the effects of Didymo in the Kootenai River, Montana/Idaho – EPT’s declined (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)), – “mats were a haven for midges and worms” (12)
More negative effects• Another study on the negative effects of Didymo was undertaken by Erica Shelby of the Arkansas Department of Environmental Quality (26). She found decreases in the biodiversity of invertebrates associated with populations of Didymo.• “In New Zealand D. geminata has been correlated to increases of invertebrates that are indicators of poor stream health” (7).• Canals used for irrigation and aquifers in California are scraped of Didymo. It also clogs grates in the water supply canal (2).• The stalks create a very unsightly looking benthos on the stream and on the shore where they dry resembling toilet paper.
Effect on trout Trout have been adversely affected by the presence of Didymo.John Bell - Fisheries Biologist AG&F 2007The relative weight of brown trout belowBull Shoals dam in November 2006 wasthe lowest that has ever been recorded. It is believed that blooms of didymo inRelative weight for both brown and upper Bull Shoals tailwater have had therainbow trout have been falling in Bull predicted detrimental effect on trout forageShoals tailwater since 2004, which and trout foraging. Didymo carpets thecoincides with the appearance of the bottom of the river and makes it impossibleinvasive algae, didymo. This decrease in for native macro invertebrates to colonize orrelative weight has been documented in survive. Further, trout cannot forageother trout waters around the world efficiently in didymo and get no nutritionalwhere didymo has occurred. value from ingesting it.
What is being done to control Didymo in the streams that are infected?• Models: One approach is to develop models that may predict the distribution of Didymo based on a sorting of habitats by air temperature, base water flow, precipitation seasonality, and other parameters. The former two seem to be able to account for much of the variance (10).• Addition of phosphorus (8)• Copper: In New Zealand, a copper compound Gemex@ is being used to control the growth of Didymo. Final field trial results show the potential of reducing growth of Didymo in applications in New Zealand (13). Some juvenile trout mortality occurred. Further testing is needed.
What else is being done!!• DNA testing (19)• Scouring (5)• Cleaning Equipment after fishing• Public awareness: Many states have developed awareness programs through website, posters, and talks such as this to create a public awareness tuned to the prevention of spreading Didymo from one habitat to another. One of the main “culprits” in the spread of Didymo from one stream to another is felt sole waders.
In Missouri we need to:• Survey likely locations of Didymo• Spread the word of the potential impact of a Didymo “bloom” on the fisheries• Utilize posters and other forms of information regarding the hazards of not cleaning fishing equipment
Help Stop Didymo Check and Clean or Dry• Check -Remove all visible clumps of algae and plant material from fishing gear, waders, water shoes and sandals, canoes and kayaks and anything else that has been in the water.
Help Stop Didymo Check and Clean or Dry• Clean your gear in a 2 percent household bleach solution (1/3 cup per gallon of water), 5 percent saltwater solution (1 cup per gallon of water) or dishwashing detergent. Scrub boats and other “hard” items thoroughly.• Completely soak equipment, personal flotation devices and other “soft” material for at least 20 minutes.• Use the Boot wash stations in the four state trout parks
Help Stop Didymo Check and Clean or Dry• Dry -Allow any item that has been in contact with the water to completely dry; the item should be exposed to sunlight and left to dry for • Please remember to Check at least 48 hours. and Clean or Dry your• Do your part–don’t fishing gear and waders spread Didymo. when moving between waters.
3 CSR 10-6.415 Restricted Zones PURPOSE: This amendment prohibits the use of porous-soled waders orfootwear incorporating or having attached a sole of felted, matted or woven fibrous material when fishing in the following managed trout waters.(A) Barren Fork Creek - Shannon (L) North Fork of White River - OzarkCounty County(B) Blue Springs Creek - Crawford (M) Roubidoux Creek - Pulaski CountyCounty (N) Spring Creek - Phelps County(C) Crane Creek - Stone and Lawrence (O) Capps Creek - Barry and Newtoncounties counties(D) Current River - Dent, Texas andShannon counties (P) Niangua River - Dallas and Laclede(E) Dry Fork Creek - Crawford and countiesPhelps counties (Q) Roaring River - Barry County(F) Eleven Point River - Oregon County (R) Maramec Spring Park - Phelps County(G) Hickory Creek - Newton County (S) Montauk State Park - Dent County(H) Lake Taneycomo - Taney County (T) Roaring River State Park - BarryLittle Piney Creek - Phelps County County(J) Meramec River - Crawford and (U) Bennett Spring State Park - Dallas andPhelps counties Laclede counties(K) Mill Creek - Phelps County (V) Stone Mill Spring Branch - Pulaski County
References1. Whitton B, Ellwood N, Kawecka B. Biology of the freshwater diatom Didymosphenia: a review. Hydrobiologia [serial online]. September 2009;630(1)2. http://epa.gov/Region8/water/didymosphenia/White%20Paper%20Jan%202007.pdf Spaulding, S and L. Elwell (2007)3. Kirkwood, A. E., S. Troina, L. J. Jackson, and E. McCcauley. 2007. Didymosphenia geminata in two Alberta headwater rivers: an emerging invasive species that challenges conventional views on algal bloom development. Canadian J. Fisheries and Aquatic Sciences 64:1703-1709.4. Floeder S, Kilroy C. Didymosphenia geminata (Protista, Bacillariophyceae) invasion, resistance of native periphyton communities, and implications for dispersal and management. Biodiversity and Conservation [serial online]. December 2009;18(14)5. Miller M, McKnight D, Cullis J, Greene A, Vietti K, Liptzin D. Factors controlling streambed coverage of Didymosphenia geminata in two regulated streams in the Colorado Front Range. Hydrobiologia [serial online]. September 2009;630(1)6. http://ecosystem-preservation.suite101.com/article.cfm/didymo_freshwater_diatom7. http://wildlife.utah.gov/pdf/AIS_plans_2010/AIS_12bDidymo-Dan-final.pdf8. http://www.ncd-afs.org/Pages/59/RSTC%20State%20Rpt%202007.pdf9. http://www.niwa.co.nz/news-and-publications/publications/all/abb/2006-19/copper10. Sunil Kumar, Sarah A Spaulding, Thomas J Stohlgren, Karl A Hermann, Travis S Schmidt, Loren L Bahls (2009) Potential habitat distribution for the freshwater diatom Didymosphenia geminata in the continental US. Frontiers in Ecology and the Environment: Vol. 7, No. 8, pp. 415-420.11. Pitte, D. P, K. A. Lane, A. K. Hermann, S. A. Spaulding, B. P. Finney. 2009. Historical abundance and morphology of Didymosphenia species in Naknek Lake, Alaska. Acta Bot Croat 68:183-197.
References (continued)12. www.amaab.org/images/1510_Lester_Effects_of_the_Nuisance_Diatom_Didymosphenia_Gemi ata.pdf13. www.niwa.co.nz/news-and-publications/publications/all/abb/2007-25/didymo14. www.hoaff.org/newsletters/NL2007-04.htm15. www.asee-nc.org/Conferences/Spring08Meeting/Srping08Proceedings/pdf/set2/71.pdf16. www.flyfishnewengland.com/didymos-study.htm17.www.mucinex.com/18. www.articles.baltimoresun.com/2009-12-17/sports/0912170014_1_didymo-trout-waters-fishing-gear19. www.waikato.ac.nz/news/archive.shtml?article=62721. www.coyotegulch.wordpress.com/2009/05/11/large-instream-flows-help-control-didymo21. http://www.westdenvertu.org/snails.htm#cleaning22. http://www.chrisdore.com/whattobring.htm23. http://www.unclejacks.co.nz/1.htm24. http://www.fs.fed.us/r4/resources/aquatic/literature/matthews_quat_disinfectants_didymo.pdf25. http://www.unclejacks.co.nz/4.htm26. Shelby, E. L. 2006. An Assessment and Analysis of BenthicMacroinvertebrate Commumities Assocoated with the Appearance of Didymosphenia geminata in the Whitw River Below Bull Shoals Dam. ADEQ Final Draft. 42 pages.