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Two More Things I Just Learned About Fish

When I'm not blogging for mental_floss, I can usually be found wearing bright orange rubber pants and gutting, cutting and selling fish at my local Whole Foods (and winning awards for it). Sometimes, my two worlds collide and I find some scientific research involving my ocean-dwelling friends that begs for a blog post. This is one of those times.

1. There are salmon in Paris

"¦and they're not just on plates, but alive and kicking in the Seine. For the first time in over a century, some 1,000 Atlantic salmon (Salmo salar) used the river to pass through the City of Lights on their migration to their spawning waters.

Before the Industrial Revolution, Atlantic salmon were abundant in the Seine, but as the river became increasingly polluted the fish were killed off. By 1900 the salmon had completely disappeared and most other species of fish followed in the early 20th century. By 1995, only five species of fish "“ carp, bream, roach and eel "“ still swam in the Seine around Paris (and no people "“ summer beaches on the Right Bank had numerous signs warning people to stay out of the water).

Now, 25 years after clean-up efforts began in the river, 32 species of fish—including sea trout, herring, shad, lampreys and the Atlantic Salmon—call Paris home.

Researchers are most excited about the return of the salmon, given the species status as a bioindicator, a species used to determine and monitor the health and integrity of an environment or ecosystem. [Image credit: David Monniaux.]

2. For plankton, global warming isn't such a bad thing

The increasing water temperatures associated with global warming are a problem for all aquatic life, but the creatures that call Arctic waters home have another problem to deal with. A research team from the University of Alaska, Fairbanks has suggested that the Arctic Ocean is especially susceptible to ocean acidification "“ increasing acidity of oceans resulting from seawater absorbing carbon dioxide from the atmosphere "“ and that this will cause problems for Alaska's famous salmon and crab fisheries.

One consequence of the acidification is that increased acidity and decreased pH leaves shellfish like crabs, clams and oysters struggling to pull the minerals they need to build their shells from the water. The team found several areas in the Gulf of Alaska where concentrations of the shell-building minerals were low enough that the shellfish there wouldn't be able to build shells of normal strength. Shellfish aren't going to start disintegrating any time soon, but the change in acidity and shell composition can cause their metabolisms to slow and their stress hormones to fire up, diverting energy from growth and reproduction.

planktonOne organism already feeling the effects of acidification is the sea butterfly, also known as the flapping snail, pteropod or swimming sea snail. Sea butterflies are tiny (about the size of a lentil) mollusks that account for up to 50% of the diet of pink salmon. They're already having trouble building shells at current acidity levels and if they cannot survive, a 10% decrease in their population could mean a 20% decrease in the body weight of adult salmon. By 2050, the sea butterflies may not be able to make shells at all and go extinct, wreaking havoc on the local food web.

BUT"¦researchers at the University of North Carolina, Chapel Hill think that plankton, the base of many other marine food webs, might thrive in warming oceans. The researchers found, after warming 4-liter bottles of seawater over time, that phytoplankton grew slightly faster with every degree that the water temperature rose. Zooplankton, which feed on phytoplankton, grew even faster. This effect could work its way up the food chain, meaning more food for bigger and bigger fish. The number and growth rates of the phytoplankton would have to be sustainable, though, or top-heavy food webs would be unstable and could crash.

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Animals
Why Tiny 'Hedgehog Highways' Are Popping Up Around London
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Hedgehogs as pets have gained popularity in recent years, but in many parts of the world, they're still wild animals. That includes London, where close to a million of the creatures roam streets, parks, and gardens, seeking out wood and vegetation to take refuge in. Now, Atlas Obscura reports that animal activists are transforming the city into a more hospitable environment for hedgehogs.

Barnes Hedgehogs, a group founded by Michel Birkenwald in the London neighborhood of Barnes four years ago, is responsible for drilling tiny "hedgehog highways" through walls around London. The passages are just wide enough for the animals to climb through, making it easier for them to travel from one green space to the next.

London's wild hedgehog population has seen a sharp decline in recent decades. Though it's hard to pin down accurate numbers for the elusive animals, surveys have shown that the British population has dwindled by tens of millions since the 1950s. This is due to factors like human development and habitat destruction by farmers who aren't fond of the unattractive shrubs, hedges, and dead wood that hedgehogs use as their homes.

When such environments are left to grow, they can still be hard for hedgehogs to access. Carving hedgehog highways through the stone partitions and wooden fences bordering parks and gardens is one way Barnes Hedgehogs is making life in the big city a little easier for its most prickly residents.

[h/t Atlas Obscura]

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Big Questions
Where Should You Place the Apostrophe in President's Day?
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Happy Presidents’ Day! Or is it President’s Day? Or Presidents Day? What you call the national holiday depends on where you are, who you’re honoring, and how you think we’re celebrating.

Saying "President’s Day" infers that the day belongs to a singular president, such as George Washington or Abraham Lincoln, whose birthdays are the basis for the holiday. On the other hand, referring to it as "Presidents’ Day" means that the day belongs to all of the presidents—that it’s their day collectively. Finally, calling the day "Presidents Day"—plural with no apostrophe—would indicate that we’re honoring all POTUSes past and present (yes, even Andrew Johnson), but that no one president actually owns the day.

You would think that in the nearly 140 years since "Washington’s Birthday" was declared a holiday in 1879, someone would have officially declared a way to spell the day. But in fact, even the White House itself hasn’t chosen a single variation for its style guide. They spelled it “President’s Day” here and “Presidents’ Day” here.


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Maybe that indecision comes from the fact that Presidents Day isn’t even a federal holiday. The federal holiday is technically still called “Washington’s Birthday,” and states can choose to call it whatever they want. Some states, like Iowa, don’t officially acknowledge the day at all. And the location of the punctuation mark is a moot point when individual states choose to call it something else entirely, like “George Washington’s Birthday and Daisy Gatson Bates Day” in Arkansas, or “Birthdays of George Washington/Thomas Jefferson” in Alabama. (Alabama loves to split birthday celebrations, by the way; the third Monday in January celebrates both Martin Luther King, Jr., and Robert E. Lee.)

You can look to official grammar sources to declare the right way, but even they don’t agree. The AP Stylebook prefers “Presidents Day,” while Chicago Style uses “Presidents’ Day.”

The bottom line: There’s no rhyme or reason to any of it. Go with what feels right. And even then, if you’re in one of those states that has chosen to spell it “President’s Day”—Washington, for example—and you use one of the grammar book stylings instead, you’re still technically wrong.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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