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Changing climate threatens local water quality

by Andrew Maciejewski - amaciejewski@h-ponline.com

Purdue University researchers say projected increases in winter and spring rainfall coupled with an expected increase in temperature by mid-century will add significant challenges to Indiana’s aquatic ecosystems.

The latest report from Purdue University’s Indiana Climate Change Impacts Assessment contends that Indiana’s lakes, rivers, streams, wetlands and surface water will experience changes in water quantity, temperature, ice cover, water clarity and oxygen content as the state’s temperature and rainfall patters shift.

The report projects temperatures to rise as much as 6 degrees Fahrenheit and rainfall to increase by 6 to 8 percent across Indiana, by 2050. Researches say these changes could threaten native species, including a few endangered species of mussels in Huntington County.

“Changes in Indiana’s climate are going to affect the timing of water flows, the quality of water and water temperatures. All of these things have major implications for the wide variety of animals and plants that live in aquatic ecosystems,” Jeff Dukes, director of the Purdue Climate Change Research Center, said in a statement. “Climate change is an additional stressor to Indiana’s native fish population. We already have invasive fish in many of our water bodies, and we have added a wide variety of pollutants and nutrients to our streams. How well some of our native populations will be able to deal with this accumulation of stresses piling up on them is still unclear.”

More than half of Indiana’s 80 species of freshwater mussels have disappeared from the state, according to the report, and researches say shifts in climate might disrupt native species’ ability to feed, regulate body temperature and reproduce.

Researches say a fish species that was once native to more than 50 of the state’s lakes, cisco, is already suffering from increasing temperatures. Cisco are now only found in six lakes in Indiana, according to the report, and researches say increases in rain may make things even harder for Cisco to adapt.

Over the last century, annual rainfall has increased by more than 5.5 inches, the magnitude of flooding events in Indiana has been increasing by 6 to 9 percent each decade, the amount of rain falling in heavy rain events increased by 42 percent and the number of heavy rain events increased by 53 percent, according to the Purdue report.

Researchers say the added rainfall and increasing temperatures are expected to contribute to the proliferation of algal blooms, which are masses of photosynthetic bacteria that release toxins.

“Because many of our lakes are very nutrient-rich, they experience large algal blooms in late spring and summer, which may grow larger with warmer temperatures and more spring runoff.” Tomas Höök, Purdue professor of fisheries and aquatic sciences and lead author of the report, said in a statement.

Höök said once the algae die, they are decomposed by bacteria, which depletes the water’s oxygen, making it difficult for fish to survive.

Huntington County is not a stranger to algal blooms

This year, algal levels at Salamonie Lake reached nearly five times the World Health Organization’s “high risk health alert,” when test results peaked in August with nearly 470,000 cells per milliliter, according to Indiana Department of Environmental Management reports.

Contact or ingestion of water with high algal levels can cause rashes, eye irritation, skin irritation, nausea, aches and tingling fingers and toes, according to the Indiana State Department of Health.

The neurotoxins released by algae can poison livestock, pets and wild animals, causing diarrhea, decreased appetite, weakness, seizures and sudden death, according to IDEM reports.

Researches suggest Indiana regulatory departments pay attention to their findings, even though making climate predictions is challenging.

“Trying to make precise predictions of how species will respond to climate change is tricky,” Höök said in a press release. “Climate change is one of many factors impacting aquatic organisms, along with pollution, invasive species, fisheries harvest and habitat destruction. But maintaining a diversity of species, habitats and genetic variation within these ecosystems should help buffer against these different stressors.”

 A full version of the report is available at ag.purdue.edu/indianaclimate/.