ANTELOPE ISLAND — Researchers from Weber State University are monitoring the amount of mercury cycling through the Great Salt Lake’s food web by catching and analyzing some of the island’s most multitudinous residents.

Rebecka Brasso, a professor in WSU’s Department of Zoology, was trained as an ornithologist and has studied birds for much of her career. However, her efforts to understand the lake’s mercury levels find her and her team working instead with western spotted orbweaver spiders.

“It was a very weird transition, especially for the undergraduate students who had signed on for a bird research project for the summer,” Brasso told the Standard-Examiner.

Brasso said her original objective was to study the birds that consume the lake’s brine flies — which spend their larval and juvenile stages in its waters, absorbing/ingesting its mercury — and measure how much of the metal was ending up in their bodies.

“From a large perspective, that is a puzzle piece that fits into the larger narrative regarding understanding the health of the Great Salt Lake,” she said.

When it became clear, though, that the birds she was hoping to study weren’t breeding in the region, she made the pivot to spiders.

“I noticed that there were thousands and thousands, probably millions, of [spiders] on the island at this time and that their webs were full of brine flies,” Brasso said.

So, just like that, she and her students were in the spider business, and business has been good.

Brasso and her team are in their sixth year of data collection on Antelope Island, during which they’ve spent the summer months gathering up spiders and brine flies.

Her website notes that more than 900 spiders and 4,500 brine flies have been analyzed for mercury at her WSU lab.

So far, her research suggests that as the lake level decreases, the mercury concentrations in brine flies and, in turn, orbweaver spiders, also decrease. And while there are some hypotheses on why that may be, no determination has been made.

“One thing that I will be looking at is trying to understand if the diet of the spiders is changing in years when the lake changes levels,” Brasso said. “Did their food come from the water itself, or were they starting to eat more things from the land?”

Brasso also wonders whether elevated salinity at the lake caused by decreased water levels might be preventing certain bacteria from converting inorganic mercury into bioaccumulative methylmercury.

In any case, mercury contamination can be harmful for humans and wildlife alike.

“In general, mercury is a potent neurotoxin. So, it impacts brain development and cognition …. Concentrations of mercury have also been shown to affect reproduction in a wide variety of animals,” Brasso said.

“Part of this research is understanding, first of all, how much mercury is there? Is it at a concentration that could have potentially negative effects?”

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