What is in the water, besides fish?

Several recent talks, studies and webinars have focused on the various chemicals and compounds that are found in Wisconsin waters and their varying effects on fish. Researchers have looked at various chemicals and compounds in an attempt to unravel mysteries under the water such as why certain fish and plant communities might be changing and what effects actions on land and around the water may be having.

2-4,D

One particular study looked at the impact of the once often-used herbicide 2,4-D. This herbicide has been used to combat Eurasian Water milfoil (EWM) in many lakes across the Northwoods. In recent years, it has been found to not be as selective as once thought, meaning it has had impacts on not only EWM, but also native plant communities. 

A recent paper, published in Science Direct by Brain J. Anton, Gavin K. Denhert and William H. Karasov, looked at sub-chronic impacts of 2,4-D (Weedestror(R)AM40) on associative learning in juvenile yellow perch. The active ingredient in 2,4-D mimics the plant growth hormone auxin. At low concentrations it induces uncontrollable plant cell growth that eventually leads to plant death. According to the study, approximately 950 million kg of herbicides are used each year worldwide, and one quarter of those are used in the United States.

“Due to the stability of 2,4-D in aquatic environments, many non-target aquatic species experience prolonged exposure throughout critical developmental life stages that can affect essential behaviors,” the abstract said. It was found that the presence of 2,4-D at common concentrations used in chemical treatments in lakes could cause a change in feeding behavior in juvenile yellow perch. It was found juvenile perch exposed to the chemical showed their ability to perform feeding functions was slowed significantly and their ability to perform associated learned behaviors was inhibited. 

The data suggested it took longer for yellow perch to complete a feed associated learning behavior when exposed to 2,4-D, or the behavior could be obstructed altogether. Further experiments showed no significant decreases in locomotion, hunger motivation or a visually guided startle response in all treatment groups as compared with the control group. According to the abstract of the paper, the results did indicate “that the use of 2,4-D herbicide for weed control in aquatic ecosystems could present risks to cognitive function that control essential behaviors of yellow perch.” 

This study, and others like it, point to the idea that effects of herbicides may not only stretch to native plant species, but may impact aquatic species as well.

Mercury

Another recent study looked at mercury contamination and fish. Because fish in mercury-laden waters are exposed to that compound 24/7/365, mercury can bioaccumulate in fish. Bioaccumulation occurs over the lifetime of a fish, which is why older, larger fish are more prone to have higher mercury levels. 

Mercury brings about consumption advisories for humans.

For instance, a 50-inch musky is well over a decade old. In waters where mercury is present, it is not recommended for children and women under the age of 50 to eat musky at all. For women over 50 years of age and men, the limit should be one fish per month.

Biomagnification is another way by which contaminants such as mercury can get into fish. Biomagnification increases the higher a fish or animal is on the food chain. If fish eat contaminated invertebrates, for instance, then a seal comes along and eats the fish, and a polar bear comes and eats the seal, the polar bear will have higher levels of contamination due to the amount of its food that is contaminated. Because humans find their place at the top of the food chain as well, biomagnification can be an issue when humans consume fish out of waters with high levels of mercury.  

The advisory from the Department of Natural Resources (DNR) states that children under 15 and women of child-bearing age should restrict their walleye intake to one serving per month.

This moves to one serving per week for women over 50 and men. 

While men and women over 50 have an unrestricted advisory for yellow perch, bluegill and crappie, children under 15 and women under 50 should limit their consumption to 1 serving per week. 

Full guidelines can be found on the DNR website at dnr.wi.gov in the publication, “Choose Wisely: A health Guide for Eating Fish in Wisconsin.”

PFAS

Another study looked at PFAS and fish. Patrick Gorski, the Wisconsin Department of Natural Resources (DNR) emerging contaminants research scientist, spoke about PFAS in Wisconsin’s surface water in a recent talk. 

His study found that biomagnification was not highly correlated where PFAS was concerned. Fish higher on the food chain did not necessarily have higher concentrations of PFAS. However, concentrations found in water and in fish were highly correlated. This shows bioaccumulation is at play where these chemicals were concerned. 

Gorski’s study looked specifically at the Wisconsin River. Both PFAOA and PFOS were found to be non-detectable in the headwaters of the river. That changed, however, in testing starting below Hat Rapids Dam south of Rhinelander. Here PFOA spiked to over 25 ng/L, which he said, was still below the 95 ng/L mark, which is the surface water standard. 

For surface water used as drinking water by a municipality, that standard is 20 ng/L. However, there is no municipality that uses Wisconsin River surface water as drinking water, he said. After the increase at Hat Rapids, levels dropped, but still remained elevated. As for PFOS, it did not exceed standards at any of the sites. 

There have been fish advisories created in some of the areas that were sampled, however. PFAS compounds have been found to have a number of human health risks, making this testing important.

Triclosan

Pharmaceuticals and personal care items such as antibacterial soaps, deodorants, cosmetics and even fabrics, toys and other household personal care products have been found to contain a substance called Triclosan. 

Triclosan is fat soluble, so it can be found and accumulates in fatty tissues, breast milk and blood. A 2010 Centers for Disease Control (CDC) report found Triclosan in the urine of 75% of the U.S. population. The study stated the levels of Triclosan found had increased 42% from 2004 to 2006. The chemical has also been found in treated waste water, natural streams, sewage sludge and fish as well as humans. This has led to concerns over potential long-term effects on environmentally sensitive species and also human health.

“Studies have increasingly linked Triclosan and its chemical cousin Triclocarbon to a rant of adverse health and environmental effects from allergy susceptibility, bacterial resistance, endocrine disruption and impaired fetal development to water and food contamination,” according to a fact sheet created by BeyondPesticides.com. A 2010 study from the University of Florida found Triclosan interfered with estrogen metabolism in women and could disrupt a vital enzyme during pregnancy. A 2012 study entitled, “Triclosan impairs excitation-contraction coupling and Ca2+ dynamics in striated muscle,” found that both cardiac and skeletal muscle function was decreased in fish species in their test. This was the case both in vitro and in vivo. They reported even low concentrations of Triclosan in water impaired swimming performance of larval fathead minnows. Not only did they report impaired mobility in fish, but in mice that were tested, they also found impairment of cardiac and skeletal muscles, resulting in impaired grip strength and hemodynamics (blood flow within the organs and tissues of the body).

The USDA found that Triclosan only slowly degrades in biosolids and “can persist in low levels in the environment for a long time.” 

Some of the unknown questions relate to what that persistence of the chemical can do to fish and other aquatic life when they are exposed 24/7. Long-term exposure is a concern, of course, and may lead to more marked results. 

Other studies looking at Triclosan have found changes in the endocrine system as well as reproduction. This compound has been found to have adverse effects on these systems in various fish and animals.

Beckie Gaskill may be reached via email at [email protected].