UMass Boston researchers: Pesticides negatively impacting crustaceans, fish food source
Hyalella azteca is a shrimp-like crustacean and one of the most abundant small animals in freshwater lakes, streams, and ponds in the U.S. It’s also a primary source of food for fish. New studies coauthored by UMass Boston researchers, however, find that pesticide use, particularly for home and garden care, are negatively impacting their communities and causing harm to our freshwater resources.
“Hyalella azteca do a lot to break up the leaves in streams, so when a bunch of organic matter falls in, it’s really important to cycle that through the ecosystem. They kind of shred it up,” said Kaley Major, a PhD candidate in environmental studies in UMass Boston’s School for the Environment, and one of the authors of three related papers concerning pesticide resistance in crustaceans.
Major and Associate Professor of Molecular Ecotoxicology Helen Poynton found that the Hyalella azteca species is increasingly being exposed to and developing a resistance to pesticides, even though these crustaceans are not the target of the pesticides. They live in water bodies downstream of where pesticides are applied, including in cities and suburban areas where people use insecticides for lawn care.
After finding resistant Hyalella in 2013, Poynton, Major, and Don Weston of UC Berkeley sampled 16 freshwater sites in California in 2015 and found resistant Hyalella in agricultural areas, suburbs, and cities like San Diego, Los Angeles, and Sacramento. The resistance was widespread and found in almost every developed location they looked at. Poynton says this suggests that resistance is common, and likely exists all over the United States. “If our regulations were working properly, then the pesticides would never make it into the water at high-enough concentrations to drive this resistance,” Poynton said.
The pesticide exposure leads to the death of most of the individual crustaceans, but those few animals that happen to have a genetic mutation that provides resistance to the pesticide come to dominate the community.
“Some might say this is nature taking care of itself, but that’s a pretty naïve view, because we think they’re acting more as canaries in the coal mine,” Poynton added.
The Hyalella can evolve resistance quickly because they grow and reproduce fast. Other species in our environment that cannot evolve as quickly are likely dying out, they said. This makes the Hyalella indicators of how we are damaging their environment and causing harm to our freshwater resources.
One of the companion studies, co-led by Weston of UC Berkeley, developed a tool to find what pollutant may be responsible for harm to aquatic life, when it is seen. The third companion study, co-led by Mike Lydy of Southern Illinois University, looked at how resistant Hyalella handle stress.
“What they found is that resistant Hyalella are not as strong as their non-resistant cousins. They are not able to tolerate other stressors like heat stress that are important in terms of climate change,” Poynton said. “They are becoming specialists. Yes, they can handle pesticides, but they are weaklings when it comes to anything else that’s out there. And that’s not good when you live in a changing environment.”
Poynton and her fellow researchers would like to see better education for homeowners on organic methods of gardening and lawn care. Major recommended homeowners avoid lawn care products with ingredients that end in “–thrin,” a sure sign that the active insecticide in the product is a member of the group causing the effects the investigators have seen in Hyalella.
“I think we also do need some tighter regulations especially on home-use products,” Poynton said. “Also, more federal funding into innovative organic methods for food production will help to reduce our dependence on insecticides.”