Coping with climate stress in Antarctica
Some polar fish can cope with warming or ocean acidification, but not both together
Some Antarctic fish living in the planet’s coldest waters are able to cope with the stress of rising carbon dioxide levels the ocean. They can even tolerate slightly warmer waters. But they can’t deal with both stressors at the same time, according to a study from the University of California, Davis.
The study, published recently in the journal Global Change Biology, of emerald rockcod is the first to show that Antarctic fishes may make tradeoffs in their physiology and behavior to cope with ocean acidification and warming waters.
(The research is described in a web feature, “The Last Stop,” at the UC Davis Science & Climate website.)
“In dealing with climate stress, these fish are really bad multi-taskers,” said senior author Anne Todgham, an associate professor with the UC Davis Department of Animal Science. “They seem quite capable of coping with increases in CO2, and they can compensate for some warming. But they can’t deal with both stressors at the same time. That’s a problem because those things happen together–you don’t get CO2 dissolving in the ocean independent of warming.”
Antarctic fishes live in water that is typically about -1.9C (28.6F). At their field site in Antarctica, the authors exposed emerald rockcod to two temperatures: -1 degree Celsius (30F) and 2 degrees Celsius (36F). The latter is the threshold for global warming that the Paris Agreement targets to prevent the most catastrophic impacts of climate change. They also exposed the fish to treatments of three different levels of CO2 ranging from ambient to elevated projected levels.
Increased CO2 levels by themselves had little impact on the fish. After a couple of weeks, heart, ventilation and metabolic rates increased with warming. Their behavior also changed with warming. The fish swam less and preferred dark zones, which suggests they were attempting to conserve energy. Then after 28 days, juvenile rockcod were able to compensate for the warming temperatures. However, this temperature compensation only happened in the absence of rising CO2.
NO COLDER PLACES TO GO
While some species are beginning to shift to cooler places to escape warming habitats, polar fish have no colder places to go. They have to cope by using their existing physiology, which the study shows is limited.
Emerald rockcod help form the basis of the Antarctic food web, supporting an ecosystem of species such as Emperor penguins and seals.
“The Antarctic has contributed very little to the production of greenhouse gases, and yet it’s one of the places on the planet receiving the most impact,” Todgham said. “I feel we have responsibility to care about the spaces that are so fragile. If we can provide reservoirs of areas that are less stressful to plants and animals through protecting natural places, we can buy ourselves some time to deal with things like climate change that will take a long time to get in line.”
The study’s authors include lead author and Ph.D student Brittany Davis, Erin Flynn and Nann Fangue of UC Davis, Frederick Nelson of UC Davis and Howard University; and Nathan Miller from San Francisco State University.
The study was funded through grants from the Division of Polar Programs, National Science Foundation, and University of California Agricultural Experiment Station.
Added: Here is the paper: http://onlinelibrary.wiley.com/doi/10.1111/gcb.13987/full
Back at the research station, Todgham and her team place the eggs and juveniles in plastic buckets with water that is 2 degrees Celsius, a temperature scientists predict will be the norm in 80 years. Researchers pump in various levels of CO2 via colorful tubes that snake in and out of each bucket.
For several weeks, Todgham measures how the fish cope. She looks at gene expression, the cellular stress response, metabolic changes and physiological factors like activity level and growth rates.
“We’re trying to predict how each species will cope with warmer water and higher CO2 emissions,” Todgham said.
The short answer: not well.
As anyone who has ever owned a saltwater aquarium and tried to keep it alive without crashing can tell you, a tank, let alone a plastic bucket, is a far cry from the actual ocean.
Of course these sci-fi kids don’t seem to understand that switching the environment from the sea to a plastic bucket is a stressor in and of itself. Further, the speed at which the water temperature change is induced on these hapless creatures removes any possibility of a long term natural adaptations. Let’s reduce 80+ years of predicted climate change induced ocean temperature and posited pH change to a few days in a bucket, without accounting for that change of environment, yeah, that’s the ticket.
I mean seriously, this is peer-reviewed science? This isn’t even at the junior science fair level.
Then there’s this:
Polar fish have nowhere colder to go, but so far, it looks like other species have not migrated in to their ecosystem. Antarctica is ringed by a circumpolar current that acts like a barrier, so it would not be easy for aquatic creatures to migrate in.
“Except for the crabs,” Todgham says. “It looks like they can enter by marching along the bottom.”
Gosh, a current is a “barrier” to fish? They can’t swim in water with a current? According to Woods Hole Oceanographic Institute, the speed of the Antarctic Circumpolar Current is pretty low:
It is a very cold current with temperatures ranging from –1 to 5°C depending on the time of the year, and with speeds up to 2 knots (2.3 miles per hour or 3.7 km per hour). This is the same speed as a brisk walk. Antarctica is also the birthplace of deep ocean waters that make up part of the global Ocean Conveyor.
It’s more likely that fish at warmer southern hemisphere latitudes don’t like the subfreezing water near Antarctica and aren’t equipped with the cellular antifreeze to deal with it. So, they don’t go there.
The stupid, it burns.
You think that’s bad, watch the video they produced which due to the number of smiling headshots and irrelevant imagery of seals and penguins looks more like “my grant sponsored summer vacation in Antarctica“.
UPDATE: This is a curious development, within 30 minutes of publication of this critique, it seems the press release has disappeared. (h/t to David Middleton)
This was the original link: https://www.eurekalert.org/pub_releases/2018-01/uoc%E2%80%93cwc011618.php
That link now gives:
Page not found.
The page you are looking for has moved. Please go to the main EurekAlert! homepage to locate the section you are interested in and reset your bookmarks.
For further assistance, please contact firstname.lastname@example.org.
I still had my browser window open showing it in the daily feed, you can see it right at the top in this screencap:
That’s gone missing from Eurekalert too:
The feature at UCDavis still exists though:
And you can still see the press release in Google cache:
UPDATE2: I received this reply from the UC davis Press office (email redacted to prevent spamming):
Andy Fell <email@example.com>
For logistical reasons we are issuing the news release tomorrow. I think it may have inadvertently appeared briefly on Eurekalert, but it should be up there tomorrow.
The original paper can be found here: http://onlinelibrary.wiley.com/doi/10.1111/gcb.13987/full
Biological sciences, physical sciences, engineering & police
UC Davis News & Media Relations
UPDATE3: I missed this the first time around, but this is really the fatal flaw in the study. As water temperature increases, CO2 solubility becomes less. See the reference curve for CO2 solubility in distilled and seawater comparing temperature and Chloride concentration:
This is long established in chemistry and is indisputable, so the elevated levels of CO2 they are testing with would not naturally occur. I also believe that water under the sea ice would have far less interaction with the atmosphere, and would not be prone to dissolving as much CO2 compared to open water.