https://cpw.cvlcollections.org/files/original/04bd393a7fb401a095ce697c7189afbd.pdf 07882a9db040b51b12bcd00b5c9fdb4e PDF Text Text C O L O R A D O P A R K S & W I L D L I F E Experiments Show Iron Pollution Limits Fail To Protect Aquatic Species April 2020 Experiments conducted by Colorado Parks and Wildlife (CPW) suggest the current water quality standard for iron (Fe) is two to four times higher than it should be to protect Colorado’s aquatic life. Are Colorado’s iron water quality standards protective of fish? For many decades, state and national water quality standards have considered 1,000 µg/L of iron to be acceptable to allow fish and aquatic life to survive. Unlike most toxicants, Fe does not stay in solution. It precipitates out and settles on the floor of streams and lakes (Figure 1). Over time, even low concentrations of Fe have potential to heavily accumulate and smother habitat of fish, and the aquatic insects and algae that fish eat. Colorado Parks and Wildlife has long noticed that Fe can overburden aquatic ecosystems, even when below the standard of 1,000 µg/L. To address this concern, a series of experiments Figure 2 - Iron oxides smother a Colorado a. stream affected by legacy mines were conducted by CPW’s Aquatic Toxicology Laboratory and by Colorado State University’s (CSU) Ecotoxicology Laboratory. Laboratory studies - We exposed Mountain Whitefish, Boreal Toads, Rainbow Trout, Brown Trout, Mayflies, as well as Planarian and Lumbriculus worms to increasing level levels of iron. We then used the standardized US Environmental Protection Agency methods to derive water quality standards incorporating our results and the results of other published studies. The calculated safe water quality standard was found to be 499 µg/L total Fe. This is less than half the current acceptable level of Fe pollution. Mesocosm studies – CPW and CSU researchers feared the reason the scientific community failed to consider Fe a threat to ecosystems was related to the way experiments were conducted. CSU and CPW incorporated more ecologically relevant methodologies to examine effects of iron pollution on aquatic insects, the primary food source for most of Colorado’s sport fish. Communities of aquatic macroinvertebrates were allowed to colonize substrate in the field (Figure 2a). Assemblages were then transported to experimental streams (Figure 2b). Eighteen streams were assigned various concentrations of Fe. After ten days insect survival was assessed. When these mesocosm results were applied to the derivation, the final proposed chronic b. Figure 1- (a) Aquatic benthic communities colonized substrate for 30 days prior to use in mesocosm experiments. (b) Experimental streams allow for a more ecologically relevant exposure of benthic communities. COLORADO PARKS & WILDLIFE • 317 W Prospect Rd, Fort Collins, CO 80526 • (970) 472-4332 • cpw.state.co.us �criterion for iron was found to be 251 µg/L total Fe. This is 25% of the current state and national limit for Fe. Synergistic interactions with other metals - Water quality standards often assume the stress from one toxicant does not reduce an organism’s resiliance against another toxicant. This is especially true for Fe. Studies from the late 20th century suggested that Fe has a protective effect against other metals. However, when we exposed algae to copper (Cu) and zinc (Zn) in the presence and absence of Fe, we observed tissue concentrations of these toxicants to be higher when Fe was present (Figure 4). Given algae is the base of most aquatic food chains, Fe can indirectly increase dietary exposure to other metals. How did CPW and CSU find effects well below the existing standard? We conducted ecologically sound research rather than simply following standardized methods to the minimal level of compliance. ●We included benthic (bottom dwelling) organisms that were smothered by Fe, not just pelagic (free swimming) organisms. ●By using naturally colonized substrate we included small and rare species, not just laboratory cultures (i.e. Water Fleas). ●Standardized methods allow static renewal, or infrequent replenishment of toxicants. We used continous flow systems that better simulate nature. ●Standardized methods require scientists to record only survival as an appropriate endpoint. The most sensitive endpoints in our laboratory trials were endpoints such as growth and reproductive success. ●Standardized methods are perhaps fitting for direct toxicity of some chemicals through gills. But these methods fail to include dietary exposure as well as the indirect toxicity observed when Fe smothers habitat or retards ecosystem processes. Mesocosm studies incorporate indirect effects. What is next? Figure 3 - Zinc (Zn) and copper (Cu) accumulation in algae in low metal (ML) and high metal (MH) treatments was greater when Fe (red) was present. Different letters represent statistical difference. DW=dry weight Each water quality standard is ostensibly reviewed by federal (USEPA) and state (Colorado Dept. of Public Health and Environment) regulatory agencies every three years. CPW’s calculation followed the guidance of CDPHE and USEPA experts and incorporated all supporting details. Revised iron standards have potential to align closely to our derivation of 251 µg/L. This will improve conditions for aquatic life in Colorado streams affected by Fe pollution. To read more, see these recent publications: Cadmus, P., Guasch, H., Herdrich, A.T., Bonet, B., Urrea, G. and Clements, W.H. (2018) Structural and functional responses of periphyton and macroinvertebrate communities to ferric Fe, Cu, and Zn in stream mesocosms. Environmental Toxicology and Chemistry. 37: 1320-1329. https://doi.org/10.1002/etc.4070 Cadmus, P., Brinkman, S.F. & May, M.K. (2018) Chronic Toxicity of Ferric Iron for North American Aquatic Organisms: Derivation of a Chronic Water Quality Criterion Using Single Species and Mesocosm Data. Archive of Environmental Contamination and Toxicology. 74: 605–615. https://doi.org/10.1007/s00244-018-0505-2 Kotalik, C. J., Cadmus, P. and Clements, W.H. (2019) Indirect Effects of Iron Oxide on Stream Benthic Communities: Capturing Ecological Complexity with Controlled Mesocosm Experiments. Environmental Science & Technology 53:11532-11540. https://doi.org/10.1021/acs.est.9b04236 � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Fact Sheets Type The nature or genre of the resource Fact Sheet Format The file format, physical medium, or dimensions of the resource application/pdf Description An account of the resource CPW Fact Sheets Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Experiments Show Iron Pollution Limits Fail to Protect Aquatic Species Description An account of the resource Experiments conducted by Colorado Parks and Wildlife suggest the current water quality standard for iron (Fe) is two to four times higher than it should be to protect Colorado's aquatic life. Creator An entity primarily responsible for making the resource Colorado Parks and Wildlife Subject The topic of the resource Aquatic animals -- Effect of water pollution on -- Colorado Metals -- Toxicology -- Colorado Extent The size or duration of the resource. 2 pages Date Created Date of creation of the resource. 2020-04 Rights Information about rights held in and over the resource <a href="http://rightsstatements.org/vocab/NoC-NC/1.0/">No Copyright - Non-Commercial Use Only</a> Type The nature or genre of the resource Fact Sheet Format The file format, physical medium, or dimensions of the resource application/pdf Language A language of the resource English