Home > Sustainability > When Evaluating the Impact of Copper on Salmon, Water Chemistry Matters

When Evaluating the Impact of Copper on Salmon, Water Chemistry Matters

December 13th, 2012

By Joe Gorsuch, CDA, Manager,  Health,  Environment and Sustainable Development

Joe Gorsuch works with environmental regulations and the collection of ecological toxicity data.  For 30 years prior to joining the CDA in March, 2009, he worked with Kodak, conducting environmental effects and stability studies on chemicals in the laboratory and outdoors to register chemicals for the photographic industry.  From 2005 to 2009 he was President and Owner of Gorsuch Environmental Managements Services, Inc. [GEMS, Inc.] coordinating environmental studies.  He holds an undergraduate degree in Wildlife Biology and a master’s degree in Environmental Sciences, focusing on Aquatic Toxicology, both from Purdue University. 

Recently, concerns have been raised that salmon populations in the Pacific Northwest are declining in part because concentrations of copper allowed in freshwater streams by current regulations may be too high and therefore harmful to the salmon who live in those waters.  In our work examining the presence of copper in the environment, to ensure that the science we rely on is accurate and unbiased,  the Copper Alliance frequently relies on highly respected scientists from outside our ranks to provide scientific expertise. For example, we frequently work with Dr. Joe Meyer on issues related to the field of aquatic toxicology. In this instance, Joe is lending his expertise to objectively evaluate studies about the effects of copper on salmon.

Joe is a Technical Expert for ARCADIS, an international organization that provides consultancy, design, engineering and management services in the fields of infrastructure, water, environment and building. Prior to his work with ARCADIS, he was a professor in the Department of Zoology and Physiology at the University of Wyoming. While at UW, Joe was involved with U.S. EPA Science Advisory Board activities in both aquatic toxicity and water quality programs, studying what toxic effects resulted from different types of exposures.  He is also one of the scientists who helped to develop the Biotic Ligand Model (BLM), a computer model that uses 10 water chemistry parameters to calculate freshwater copper criterion. The National Oceanic and Atmospheric Administration (NOAA) and the Copper Alliance are collaborating on a saltwater olfactory study being conducted at NOAA, and Joe is serving as the liaison between the two organizations.

I wanted to introduce you to Joe and present his credentials here, because his point of view on the subject of copper and the safety of salmon is very important to clearing up any potential misunderstandings on the subject. Here is Joe’s perspective in his own words:

The sense of smell is critically important to the life of salmon. They need it to find food, to avoid predators and to find spawning streams. In the Pacific Northwest, some people are concerned that copper might impair the sense of smell in salmon. However, the question is not whether excessive amounts of copper in water are harmful to fish, because we already know they can be. Instead, the important question is: Will copper impair the sense of smell in salmon and thereby detrimentally alter their behavior at concentrations allowed by current regulations?

The concerns about potential impairment of olfaction by copper are legitimate and should not be minimized. However, it is important to be sure that accurate conclusions are being drawn from the research being conducted. This is where I come in. My role for the Copper Alliance is to evaluate recent and ongoing studies in various research laboratories about the effects of copper on the sense of smell and behavior of salmon.

The crux of this discussion can be summed up in three words: “water chemistry matters.” The water often used in the laboratory tests is ultra-pure water with copper added as a soluble salt, and those tests show that the relatively low concentrations of copper can be harmful. But that ultra-pure water used in lab studies is not the same composition of water that is found in the natural environment. A chemical model called the Biotic Ligand Model (BLM) – currently used by the U.S. EPA, but not yet adopted by all state regulatory agencies – is a more accurate measure of the impact of copper on salmon, because it uses real-world water chemistry in the calculations. In nature, some substances like dissolved organic carbon bind to copper whereas other substances like calcium and magnesium compete with copper, and both processes make the copper less bioavailable to the fish, which means they cannot take in potentially harmful amounts of copper as readily in real-world waters. Therefore, the fish can continue to survive, grow, reproduce, and detect important odors in real-world waters at concentrations of copper that would be detrimental in ultra-clean laboratory waters. That’s the important difference some people ignore when interpreting results of laboratory toxicity studies.

When the BLM is used to evaluate test results, the answer to the question of whether copper concentrations in streams and rivers within current regulatory limits cause damage to the salmon is – No. The current U.S. EPA’s regulatory guidelines for copper successfully protect salmon. It’s easy to oversimplify a story if you don’t interpret the data appropriately. It would be unnecessary and even counter-productive to impose stricter limits on allowable copper concentrations, based solely on the conclusion that copper in ultra-clean water harmed fish in a laboratory study.

As I’ve said before, the Copper Alliance is committed to pursuing and relying on accurate, objective science to be sure that the use of copper is appropriate and safe for people, wildlife and the environment. To that end, we seek independent reviews from experts known worldwide for their capabilities and expertise in metals. I am very appreciative of the expertise of Dr. Joe Meyer and for his contributions, which have been invaluable in this important work.

Categories: Sustainability Tags:
Comments are closed.