Michael B. Mahon | Lightnews

Michael Mahon, PhD

@mmahon.bsky.social

310 followers 360 following 18 posts

Postdoc. Dad. Quantitative ecologist. Food webs, PFAS, and other contaminants in the Great Lakes; large scale freshwater biodiversity trends. Opinions are my own. He/him.

Duluth, MN.

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Environmental science 64%

Geography 16%

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Michael Mahon, PhD @mmahon.bsky.social · Sep 24

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...

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.

www.nature.com

Reposted by Monica G. Turner, Silvia Secchi, Michael B. Mahon

Anna Clark @annaleighclark.bsky.social · 21d

"The Great Lakes Science Center in Michigan would lose 108 of 137 positions."

via @eenews.bsky.social

E&E News: USGS science centers face Trump’s chopping block

Interior has indicated that it plans to lay off employees in science centers across the country, including deep cuts at some offices.

subscriber.politicopro.com

Reposted by Michael B. Mahon

Steve Ormerod @steveormerod.bsky.social · Sep 29

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...

Climate change is reshaping fish communities in the United States

Rising temperatures and the introduction of non-native fishes have been linked to rapid changes in fish communities across the United States.

www.nature.com

Reposted by Jonathan Lenoir, Julie L. Lockwood, Michael B. Mahon

Nature Portfolio @natureportfolio.nature.com · Sep 24

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 🧪

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

Michael Mahon, PhD @mmahon.bsky.social · Sep 24

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

Michael Mahon, PhD @mmahon.bsky.social · Sep 24

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

Michael Mahon, PhD @mmahon.bsky.social · Sep 24

“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.

Michael Mahon, PhD @mmahon.bsky.social · Sep 24

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.

Michael Mahon, PhD @mmahon.bsky.social · Sep 24

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.

Reposted by Daniel Hering, Michael B. Mahon

Ecotoxicology lab RC One Health Ruhr @ecotox.bsky.social · Sep 24

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...

Diverging fish biodiversity trends in cold and warm rivers and streams - Nature

www.nature.com

Reposted by Ken Caldeira, Stephen D. Murphy, Michael B. Mahon

Mike Dettinger @mdettinger.bsky.social · Sep 20

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...

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.

www.washingtonpost.com

Michael Mahon, PhD @mmahon.bsky.social · Jul 14

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

Reposted by Carlos Carroll, Michael B. Mahon

Dave Levitan @davelevitan.bsky.social · Jul 3

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.

Reposted by Thessa Jensen, Michael B. Mahon

Nathan Kalman-Lamb @nkalamb.bsky.social · Jun 19

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

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.

Reposted by Michael B. Mahon

MPR News @mprnews.org · Jun 16

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.

Vance Boelter, suspect in shooting of Minnesota lawmakers, taken into custody in Sibley County

www.mprnews.org

Reposted by Michael B. Mahon

Lawrence Hurley @lawrencehurley.bsky.social · May 16

There are now emergency applications pending at SCOTUS on SIX different Trump policies. That must be an unprecedented number.

-birthright citizenship
-agency firings
-Alien Enemies Act
-TPS for Venezuelans
-DOGE access to SSA data
-Ending parole for 500k immigrants

Reposted by Michael B. Mahon

Josh Gerstein @joshgerstein.bsky.social · May 10

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...

storage.courtlistener.com

Michael Mahon, PhD @mmahon.bsky.social · May 3

Not to mention the coming dissolution of ORD.

Reposted by Michael B. Mahon

Jeff Dukes @dukesjeff.bsky.social · Apr 21

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.

Screen capture of again-functional MRCC web site.

Reposted by Emanuela Galasso, Michael B. Mahon

Alexander Berger @albrgr.bsky.social · Apr 17

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

Reposted by Michael B. Mahon

Duluth News Tribune @duluthnewstribune.com · Apr 15

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."

Our View: Threats to Duluth water lab not well-thought-out

www.duluthnewstribune.com

Michael Mahon, PhD @mmahon.bsky.social · Apr 4

But I do have baseball opinions!

Michael Mahon, PhD @mmahon.bsky.social · Apr 4

I don’t remember going on a baseball podcast…

Michael Mahon, PhD @mmahon.bsky.social · Mar 24

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

Reposted by Michael B. Mahon

The Athletic @theathletic.com · Mar 21

ANOTHER UPSET.

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

Michael Mahon, PhD @mmahon.bsky.social · Mar 18

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

The New York Times @nytimes.com · Mar 18

Breaking News: The EPA plans to eliminate its scientific research arm, firing as many as 1,155 chemists, biologists, toxicologists and other scientists.

Trump Administration Aims to Eliminate E.P.A.’s Scientific Research Arm

More than 1,000 chemists, biologists and other scientists could be laid off under a plan to dismantle the Office of Research and Development.

www.nytimes.com

Reposted by Larry W. Horowitz, Christoph Scherber, Timo Seppälä , and 3 more Larry W. Horowitz, Christoph Scherber, Timo Seppälä, Sara D. Adar, Kathleen M. Comerford, Michael B. Mahon

The New York Times @nytimes.com · Mar 18

Breaking News: The EPA plans to eliminate its scientific research arm, firing as many as 1,155 chemists, biologists, toxicologists and other scientists.

Trump Administration Aims to Eliminate E.P.A.’s Scientific Research Arm

More than 1,000 chemists, biologists and other scientists could be laid off under a plan to dismantle the Office of Research and Development.

www.nytimes.com

Reposted by Michael B. Mahon

Sarah Posner @sarahposner.bsky.social · Mar 13

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

Biggest Federal Employee Unions Says Shutdown is Preferable to Elon/Trump CR

Federal workers obviously don’t like government shutdowns. Most of them are furloughed....

talkingpointsmemo.com

Reposted by Michael B. Mahon

David Shiffman, Ph.D. 🦈 @whysharksmatter.bsky.social · Feb 27

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...

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.

www.nytimes.com

Michael Mahon, PhD @mmahon.bsky.social · Feb 21

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).

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