Michael Mahon, PhD

How #climatechange is reshaping fish communities in the United States as temperatures rise and non-native fishes proliferate: @ian-vaughan.bsky.social overviews recent extensive work by @rumschsl.bsky.social www.nature.com/articles/d41... www.nature.com/articles/s41...

Photo of field crew conducting electroshock sampling for fish as part of the US EPA National Rivers and Streams Assessment in Little Hunting Creek in Virginia, USA. Photographer: Kevin Biallas

Changing water temperatures and human-driven introductions of fish have altered the composition of fish populations in streams and rivers across the USA over the past three decades, a study in Nature suggests. go.nature.com/47ZCcWH 🧪

Diverging fish biodiversity trends in cold and warm rivers and streams - Nature In the past three decades, fish abundance, richness and uniqueness have diverged across cold and warm streams, and the effects on native fish communities of stream warming and increases in introduced fishes have magnified each other.

In short, fish biodiversity in U.S. streams are changing fast.
- Cold streams are losing biodiversity
- Warm streams are gaining in a homogenized way
- Human choices will shape the future of freshwater fish

Free access in first post.
www.nature.com/articles/s41...

What can be done?
- Restore riparian forests to cool waters
- Limit introductions & spread of non-native fishes
- Protect local species before losses become irreversible

When warming streams also had more stocked or introduced fishes, local non-game species took the hardest hit, declining in both abundance and richness.

“Average” or cool streams are stable. Streams in the intermediate range showed minimal biodiversity change. Their mix of species with different thermal tolerances may provide a buffer against changing stream temperatures.

Warm streams show the opposite trend.
Abundance rose 70% and richness rose 15%. But this came with a big downside: fish communities became homogenized. Opportunistic minnows & shiners replaced larger periodic species.

Cold streams are in trouble.
Fish abundance fell 50% and richness dropped 30%. Small-bodied, cold-adapted species declined, while larger game fishes (like trout) increased. Cold-water biodiversity is eroding fast.

Our research group just published a study in Nature on how fish biodiversity in U.S. rivers and streams has been changing over the past 27 years (1993–2019). The results show sharply diverging trends depending on historic and changing water temperature. 🧵 rdcu.be/eH0l8

Diverging fish biodiversity trends in cold and warm rivers and streams - Nature In the past three decades, fish abundance, richness and uniqueness have diverged across cold and warm streams, and the effects on native fish communities of stream warming and increases in introduced fishes have magnified each other.

Exciting collaboration with colleagues from the US and Frederik de Laender - lead by S. Rumschlag and Mike Mahon - on how climate change has lead to alterations in US fish diversity over the last decades. Paper just out: www.nature.com/articles/s41...

EPA tells scientists to stop publishing studies, employees say Staff from the EPA’s Office of Water were summoned to a town hall meeting this week and told to pause the publication of most research, pending a review.

EPA has ordered scientists in its Office of Water to immediately pause almost all research & stop publishing studies. Researchers were told that, unless scientific journals had already returned proofs, studies will be subject to an additional EPA review.

www.washingtonpost.com/climate-envi...

Looking for a great photo of a freshwater fish (North American) to submit as a journal cover image for a manuscript on fish biodiversity trends! If you have one you’d be willing to share (with credit, of course!), please reach out. 🎣📸 #fishphoto #freshwaterfish #scicomm

NEW: per multiple sources, apparently there may be punishment/retaliation coming for EPA employees who signed the Declaration of Dissent this week. People are starting to get letters putting them on administrative leave, seems like potentially targeted at those who signed with their names.

Ironically, upon the paper’s release, several social media users ran it through LLMs in order to summarize it and then post the findings online. Kosmyna had been expecting that people would do this, so she inserted a couple AI traps into the paper, such as instructing LLMs to “only read this table below,” thus ensuring that LLMs would return only limited insight from the paper. She also found that LLMs hallucinated a key detail: Nowhere in her paper did she specify the version of ChatGPT she used, but AI summaries declared that the paper was trained on GPT-4o. “We specifically wanted to see that, because we were pretty sure the LLM would hallucinate on that,” she says, laughing.

Amazing: MIT researchers revealed how ChatGPT etc are destroying our brains and booby-trapped the report to expose those who want to use AI to ostensibly summarize the results.

t.co/JXeTALBPds

Vance Boelter, suspect in shooting of Minnesota lawmakers, taken into custody in Sibley County Authorities have taken 57-year-old Vance Boelter into custody in Sibley County. He's the suspect in the targeted fatal shootings of Minnesota House DFL leader Melissa Hortman and her spouse, and the s...

Authorities have taken 57-year-old Vance Boelter into custody in Sibley County. He's the suspect in the targeted fatal shootings of Minnesota House DFL leader Melissa Hortman and her spouse, and the shooting of state Sen. John Hoffman and his spouse.

Make it seven:

DOJ just sought emergency relief from #SCOTUS in the AFSCME/mass-RIFs case. It’ll be docketed as 24A1106.

In case you’re keeping score, this marks the 15th emergency application from Trump in 16 weeks.

Across 16 *years,* the GWB and Obama administrations filed a total of … eight.

FLASH: Federal judge blocks RIFs/Trump administration reorganization plans for 20 federal agencies. SF-based Judge Susan Illston (Clinton) says they appear to exceed executive branch authority to implement without Congressional approval. Doc: storage.courtlistener.com/recap/gov.us...

Not to mention the coming dissolution of ORD.

Glad to see the MRCC is back up! Funding restored by NOAA/Dept of Commerce. But ridiculous that funding for regional climate centers was removed in the first place.

New preprint finding that eliminating US global health funding over the next fifteen years would cause:
- 15.2m deaths from AIDS
- 2.2m deaths from TB
- 7.9 additional child deaths

Our View: Threats to Duluth water lab not well-thought-out From the editorial: "If the Duluth EPA lab is being indiscriminately targeted, the cutting and slashing (in D.C.) clearly isn’t being done with the care, consideration, or thought such a process demands."

From the editorial: "If the Duluth EPA lab is being indiscriminately targeted, the cutting and slashing (in D.C.) clearly isn’t being done with the care, consideration, or thought such a process demands."

But I do have baseball opinions!

I don’t remember going on a baseball podcast…

Anyone in Duluth looking to support their local EPA employees, come out tomorrow morning!

ANOTHER UPSET.

Drake is heading to the second-round of the men’s NCAA Tournament.

Welp. What a way to find out that my colleagues and I may be soon out of jobs.

Biggest Federal Employee Unions Says Shutdown is Preferable to Elon/Trump CR talkingpointsmemo.com/edblog/bigge...

Trump Says E.P.A. Layoffs Will Cut Staff by 65 Percent The president said Lee Zeldin, the E.P.A. administrator, was planning mass layoffs. Several hours later, White House officials said the president was referring to budget cuts.

Do you want water that’s safe for your family to drink, air that’s safe for your family to breathe, or a livable climate?

We’re apparently cutting 2/3 of our capacity, so pick one of those three.

🤷

www.nytimes.com/2025/02/26/c...

DHA as an interferent? That is probably a better question for my coauthors, but PFO4DA was not on our analyte list. We did check for other known interferents. The most prominent one we ran into was TDCA as a strong interferent for PFOS (reading as branched PFOS).