More than 100 dolphins dead in Amazon as water hits 102 degrees Fahrenheit | Hacker News Reader

More than 100 dolphins dead in Amazon as water hits 102 degrees Fahrenheit

cnn.com

128 pointshnuser000087 comments

There was a similar report earlier this summer from the Florida coast. Wouldn't it be deadly to swim in waters that warm? (I mean clearly it was for the dolphins, wondering about human ability to cool when perspiration is not possible)

Anything above 104F/40C will rapidly lead to heatstroke in humans, that’s why hot tubs are kept at 100-102F. Depending on human, you’ll last 10-20 minutes, but the flesh eating bacteria or brain eating amoeba might still get you.

Edit: hah

> flesh eating bacteria or brain eating amoeba might still get you.

Wanna add some context here?

> brain eating amoeba

That one is naegleria fowleri, which just loves warm, even hot water [1]. It's incredibly rare, but incredibly deadly.

> flesh eating bacteria

That is vibrio vulnificus [2] or a bunch of other bacteria which love brackish water [3].

[1] https://www.cdc.gov/parasites/naegleria/general.html

[2] https://www.cdc.gov/vibrio/wounds.html

[3] https://www.cdc.gov/groupastrep/diseases-public/necrotizing-...

Flessh eating bacteria is Necrotizing Fasciitis a bacterial infection that will quickly spread, resulting in amputation and even death.

And I have to imagine that 10-20 minutes would drop significantly if you were exerting yourself instead of relaxing.

According to NHS ophthalmologists at Moorfields eye hospital, I had acanthamoeba keratitis - a rare eye infection which… well… just Google pictures for what happens if left untreated. Theory is, I picked it up after staying in a hot tub too long and then leaving contact lenses in over night.

It’s so rare that the trainees never see any patients with it. The consultant asked me if I was OK for all the doctors there that night to have a look. They were fascinated but I was in a fair amount of pain!

I had to apply drops of what was effectively bleach to my eye for six months to ensure it went. Very painful. The diagnostic process was incredibly painful too. I can’t wear lenses anymore as I think my cornea is permanently damaged. Luckily my vision is back to normal but took nearly a year to recover.

Don’t sleep in your lenses. Don’t wear lenses in the hot tub!

> Don’t sleep in your lenses. Don’t wear lenses in the hot tub!

I know this isn't a solution for everyone, but if a candidate for corrective surgery (PRK, LASEK, LASIK, etc), I highly recommend it. PRK was the best $3k I've ever spent. 20/15 vision for over a decade since surgery, no need to worry about glasses or contacts. Might be able to get away with LASIK or LASEK for faster recovery, I went with PRK and a bit longer recovery time because I live a life where head trauma is more likely than not (which can cause corneal flap complications).

102 is a good temp for a hot tub. Definitely not deadly, but would not be helpful to cool down on a sweltering day neither (actually I never had the experience of sitting in a hot tub that was cooler than the air, maybe when its 130 out, 100 is refreshingly cool)

anyway my bigger concern would be brain eating amoeba

edit: jinx

I tried this once (in a swimming pool, not a hot tub) -- outdoor temps were around 110F and the pool was over 90F. It was quite unpleasant and definitely not refreshing.

Your body can evaporatively cool in hot weather as long as it's dry out and the humidity (and hence wet bulb temperature) is low enough. In a pool, there's no evaporative cooling, and your skin surface will be the same temperature as the water. If it's too hot, it's too hot.

Does it work with lower temps? I’ve always found it odd that human body temp is close to 100F but getting into 90 degree water feels hot. I wonder if it’s the evaporative effect like you said and if it reverses when it’s hot enough. Like if it’s 110 and I get in a 90 degree tub, does it feel good? That’s below the temperature my body naturally wants to be at, why doesn’t it feel “cool”?

The human body is producing about 80 watts of heat just from basic metabolism (unless you're dead) which you need to dissipate to keep your body temperature from going up. The rate of heat transfer out of your body is proportional to the temperature difference, so the environment needs to be cooler than your body.

If your environment was exactly the standard body temperature, your body would actually get hotter until the temperature delta was enough to dissipate 80 watts, which would likely be too hot to survive.

Huh! Does this account for the difference between what we perceive as "room temperature" and our body temperature? I suppose that delta in temperature depends on medium the body is surrounded by and effectiveness of heat transfer (e.g. similar issue as evaporation, but maybe not the same direction?)

Yes, indeed! The actual rate of heat transfer is equal to the temperature delta divided by the thermal resistivity of the body-environment interface. So, to keep your body temperature constant, the temperature delta needs to be your metabolic rate multiplied by the thermal resistivity.

The thermal resistivity depends on, among other things, the material you're surrounded by. That's why if you wear insulating clothes, you're comfortable at a lower environmental temperature (i.e. higher temperature delta).

To this you can add the effect of convection: if the air is moving then you don't accumulate a layer of warmer air around you, so the effective temperature delta is higher. And unless you're in a hot tub or air at 100% relative humidity, then some of the heat you produce goes into evaporating sweat. It takes energy to vaporize water, and this energy is locked into the water vapor until it condenses somewhere else.

That was in a somewhat enclosed bay (Manatee Bay), and the ocean temperature was an anomaly compared to the surrounding buoys.

Not that the rest of the ocean wasn't boiling hot at that time!

Was out on a boat this summer, on a hot day with moist air.

Normally (in summer) it's cooler out on the water. But on that day I had a kind of 'choking' feeling even on the middle of a lake. Like being in an elevator or bus packed with people & not enough ventilation.

It was easy enough to take a swim to cool down. But for these dolphins? The water not cooling them down. Swimming at all would raise their body temperature.

Out in the ocean they could have dived to deeper (cooler) waters. Or swim to cooler areas. But in the lake/river they were in? No escape from the hot water.

One can only imagine how desperate they must have felt right before they died.

Why would perspiration not be possible? Humans can perspire when swimming [1]. Though it's effectiveness may be diminished.

https://www.a3performance.com/blogs/a3-performance/do-you-sw...

Without evaporation sweat cannot cool

Perspiration is only useful via evaporative cooling. It is of no use underwater.

When we sweat pores on the skin open (increasing the surface area of the skin). Vasodilaton results in increased blood flow to the skin. The skin is in contact with water. Water ia a better conductor of heat than air.

When the water is warmer than human body temperature - 102F in the article - guess which way that heat conducts.

Good point, however still means that. Perspiration in water can lead to increased cooling over non perspiring (if the water is colderthan there swimmers body tenperature).

People don't swim in the Amazon river, there's lots of other things in there that will kill you!

Edit: to clarify, in the areas of the Amazon that I've been to (maybe the more remote areas), nobody swam. Most of the locals didn't even know how to swim despite living on the river. It may be different in other areas.

Of course people swim in the Amazon. I did it myself and you can find plenty of videos of people swimming in it and enjoying the river.

They must've forgot a comma sign there.

I wonder what you think all those lethal things are.

Swimming in the river (with the dolphins!) is a very popular tourist attraction in the Amazon, actually. Just don't pee in the water![1]

[1] https://en.wikipedia.org/wiki/Candiru_(fish)#Modern_cases

Or if not kill you, certainly spoil your day. Candiru.

this sounds quite sad.

I'm also experiencing the hottest 1st October I had in my life, around 27° C. Everybody is outside in t-shirt when the usual thing is to wear a jacket in 15-18° C...

It is quite scary :/

How old are you? It helps knowing due to your phrasing of _in my life_. Also geographic region is a helpful indicator.

They may be German, it's the literal translation of how one would say it in Germany, and we're still having a heatwave - the Oktoberfest vendors are happy AF, but it's far from normal.

For everyone on earth, it's the hottest October of their lives ...

I mean, I live in Seattle, and it is 57F today, supposed to hit max 63F. Just in my 8 years living there, i’ve experienced more than one October hotter than this. The historical average for the 1st of October is 67F during the day[0], which seems to affirm my observation.

So no, your statement is just trying to dismiss a perfectly valid question in the parent comment.

0. https://weatherspark.com/m/913/10/Average-Weather-in-October...

I mean, when answering an impossible to answer question (there is only one person on earth who can answer it), you can only choose satire and sarcasm.

This was a play on a fairly popular meme: https://ourplnt.com/wp-content/uploads/2021/07/The-Simpsons-...

So it wasn’t meant to be taken seriously.

That’s fair, the reference definitely whooshed over my head entirely.

To those downvoting my previous comment: no, I am not a climate change denialist, and my comment wasn’t meant to argue against climate change by pointing out that today in Seattle is colder than it typically is on Oct 1st. I am well aware that it would be a really silly argument to make.

Dunno where he is from, but it's the same here in Poland. In 90s when I was a kid September was usually around 10-15 C, you wear autumn clothing and it rains a lot. October was often when the first snow happened. This year it's been around 25 C for the whole month, it barely rained, it's like summer never ended.

And for like 10 years we had very little or no snow in October-December. For the last few years first snow happens for 1-2 weeks in March/April or even May (!) and it's also the last snow. In 90s snow usually lasted for a few months between December-February.

It's not only that the weather gets hotter but the seasons are also delayed by around 1-2 months relative to where they should be...

Reminds me of this Simpsons meme: https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fd...

I can confirm. I’m in the same boat, as the parent commenter. It’s especially visible because Poland experiences all four seasons that used to be dramatically different. Winter temperatures were often reaching -30 Celsius with heavy snowfall. You’re lucky to see any snow in some winters nowadays in parts I’m from.

Its not even summer in Brazil yet! They're just coming out of winter, right?

Are there any Brazilians on HN?

Yes, but there is no winter on that region, it’s always 30+

https://weatherspark.com/y/28814/Average-Weather-in-Manaus-B...

> Its not even summer in Brazil yet! They're just coming out of winter, right?

> Are there any Brazilians on HN?

Of course!

As the sibling comment indicated, the region in question is near the equator, where the "winter" versus "summer" distinction is less relevant (though AFAIK it does have "wet" versus "dry" seasons).

I live much further south (this country is huge), where seasons are more relevant, and around here we're leaving an abnormal winter; last week we had summer-like temperatures, to the point that we broke the previous record in both country-wide and region-wide electricity consumption (due to all the cooling loads, hot days always consume more electricity compared to cold days).

I have friends living in French Guyana (both work for the space program), they told me the two seasons were rather 'wet' and 'very wet' there.

This doesn't matter much on the Amazon.

I live a few thousands of kilometers south from it, it is still doesn't matter a lot here. Brazil is passing through an abnormally hot season, but those come from chaotic reasons that can happen on any time at all.

Around here the summer tends to be hotter than the winter, but it's a slightly biased coin-toss. At the Amazon, it's much more random (slightly biased into being the hottest at the fall).

Winter ended on October 23 here in Brazil. Two days later, Belo Horizonte, the capital of the state of Minas Gerais, recorded the hottest day in history. 38.6oC, 101oF. The hottest day since 1910. It wasn't the hottest day of September or spring. It was the hottest day in recorded history. Hotter than the summer record.

I'm in the far south of Brazil. Known for its cold. Brazilians come here to feel the cold, to do cold weather tourism. This entire winter has been absolutely bonkers. Heat wave after heat wave.

https://www.vox.com/climate/23864998/heat-wave-south-america...

https://edition.cnn.com/2023/09/25/americas/extreme-heat-sou...

And it's not just the heat. It's the crazy swings.

There are people here who are hearing the word "cyclone" for the very first time. And dying in the process. While it was still winter. The town of Muçum is no more. Cyclones were thought to be impossible in the South Atlantic until recently.

https://www.todayonline.com/world/least-39-dead-cyclone-hits...

https://en.wikipedia.org/wiki/South_Atlantic_tropical_cyclon...

I know very little about the climate of the Amazon. I know that it's such a vast system that it has its own climate rules. We are only just beginning to understand how it works. But we have already discovered in recent years that the Amazon rainforest has a direct and gigantic impact on the climate and rainfall of the rest of Brazil.

And the lake where the dolphins died is deep in the heart of the Amazon. The entire state has declared a state of emergency because of the drought.

https://www.google.com/maps/place/3%C2%B019%2719.9%22S+64%C2...

https://www.lemonde.fr/en/international/article/2023/09/29/b...

I'm worried about what kind of hell it's going to be like here in the summer.

https://www.theguardian.com/world/2023/sep/26/brazil-tempera...

=38.88°C

It's probably suffice to say 39°C. It's unlikely the temperature was exactly 102°F; these measures are almost always rounded to the whole unit.

According to a recent article in Portuguese (https://g1.globo.com/am/amazonas/noticia/2023/10/01/icmbio-v...) "[...] em alguns pontos do lago a temperatura está ultrapassando a marca dos 39°" so the correct value is "above 39°C".

Aye. Anything above 39.16 °C would get translated whole-units to 103° F.

Some smartphone, I think it was Apple, had an issue like this where they got weather information in whole units of celsius and translated to Fahrenheit for display at the user's option. Since Celsius is not as fine-grained of a unit, it caused skips of the nature like 68°F to 70°F. Using finer-grained measurements, it would be possible to convert to every whole-unit °F, but it wasn't being done.

This is the problem with the trawls

CNN reporting is the absolute worst, crap reporting out there.

"It’s still early to determine the cause of this extreme event but according to our experts, it is certainly connected to the drought period and high temperatures in Lake Tefé, in which some points are exceeding 39 degrees Celsius (102 degrees Fahrenheit),” the institute said in comments carried by CNN affiliate CNN Brasil."

It's the drought and that is causing the temperature of the water to increase, too, not just the "global warming" bearing down on a roaring Amazon, slaying dolphins left and right.

Yellow journalism at its finest.

What is causing the drought?

Perturbations in regional weather cycles, made statistically more common by climate change.

The devastation of the rainforests. No rainforest= no rain

Literally the first paragraph seems to spell out everything quite clearly, so your entire comment is a straw man.

I would be very careful with your outlook on consuming news, with the amount of bias displayed in your comment, is very obvious your filter will remove a significant amount of factual information from your understanding, drastically reducing the quality and quantity of information available to you.

The article doesn't blame global warming directly and does mention the drought.

What is your problem?

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