Wednesday, August 8, 2018

Kane`ohe corals more resilient to bleaching after 50 years of hot


Montipora capitata coral. 
Credit: Keisha Bahr
Corals in Kane`ohe Bay seem more resilient to bleaching in warming waters today than they were 50 years ago—the first evidence that coral may be gaining tolerance to rising global temperatures.

It may not be enough to keep up with the pace of climate change, but it's a hopeful sign.

“Although these results are encouraging in their indication that acclimatization/adaptation of corals and their symbionts can occur at an unexpectedly rapid rate, increased bleaching tolerance may not be enough for widespread coral survival,” said researcher Ku‘ulei Rodgers

A complex study by University of Hawai`i and Bishop Museum researchers looked at how corals responded to hot spells in 1970, and then in 2017 when the research team repeated the earlier studies. They found that corals today take longer to respond to superheated water, that they recover more readily and start growing again more quickly.

There are caveats here, but the indications are hopeful for the future of our reefs.

The new study in the journal PeerJ: The Journal of Life and Environmental Sciences, is entitled "Evidence of acclimatization or adaptation in Hawaiian corals to higher ocean temperatures." The authors are UH Institute for Marine Biology scientists Steve L Coles, Keisha D. Bahr, Ku'ulei S. Rodgers, Stacie L. May, Ashley E. McGowan, Anita Tsang, Josh Bumgarner and Ji Hoon Han. Coles, a veteran coral scientist who also works with Bishop Museum, was part of the original 1970s study.

Science Daily reported on the study. 

Reef corals are two-part organisms. The coral polyp provides a home to single-celled algae called zooxanthellae. It's a mutual relationship, and corals get both their color and some of their food from the algae. When corals are stressed, as when water temperatures rise, they eject their zooxanthellae and begin to starve. They also look white, bleached.

The 1970s experiments studied how corals responded to periods of abnormally warm water. The 2017 experiments recreated those studies.

"Re-running a 50-year old experiment using the same coral species, same experimental setup, and same observer allows us to directly test changes in coral temperature tolerance,” said co-author Keisha Bahr.

After nearly five decades of increasingly warm oceans, those corals seem to behave differently now, the team said. They keep their zooxanthellae longer, and recover quicker after waters return to normal temperatures. The warming trend has been carefully tracked, and offshore sea temperature rise amounts to 1.13 degrees Centigrade from 1958 to 2014, the report says.

Why are the corals more resistant to warming?

It isn’t clear whether that's because corals are adopting more resilient zoozanthellae or whether the corals themselves are more temperature resilient. And Coles warns that it might also have something to do with cleaner waters in Kane`ohe Bay, where in the 1970s, nutrient-rich secondary treatment sewage effluent was being dumped in the bay.

"Elevated levels of dissolved nitrogen have been implicated in stimulating coral bleaching," Coles said.

"Available evidence indicates that the lower concentrations of nutrient pollutants, particularly dissolve organic nitrogen, have played an important role in the increased temperature tolerance of corals after nearly 50 years as was determined by these experiments," the paper said.

In other words, corals can respond better to change when the water is cleaner.

This evidence from a single location is important in a special way, the authors said.

"Our experiments are the first to demonstrate thermal acclimatization/adaptation to elevated ocean  temperature for corals of the same species and from the same location over the past half-century."

The three species of corals they studied are Lobactis scutaria, mushroom or plate coral, Montipora capitata, called rice or pore coral, and Pocillopora damicornis, the cauliflower or lace coral.


© Jan TenBruggencate 2018

Tuesday, August 7, 2018

Random climate science: Hot seas, marine debris, changing forests and, of course, goats


They've been taking temperature measurements at San Diego's Scripps Pier for 102 years.

And on Aug. 1, 2018, they measured the highest temperature in all that time: 78.6 degrees. And summer's not even over yet. 
The same day, a half-mile offshore they measured 79.7 degrees, second highest at that location after a 2015 El Nino year measurement. 

Yeah, that's just one location, and you can get isolated peak temperatures, but large scale temperature data continue to move in one direction. The image at upper right represents global land and sea temperatures from 1880 to 2015. It comes from the National Climate Data Center.

There are still plenty of skeptics out there, but the science seems clear.

We all know about rising sea levels, California wildfires, increasing droughts, acidification of the oceans and so on. But what are some of the likely impacts that we don't hear much about?

For the Hawaiian and Pacific Islands, a warming climate has other kinds of implications. Marine debris, for example, can not only be a nuisance, an entanglement threat to turtles, an ingestion threat to seabirds, but a bunch of other things.

Climate change can alter storm frequency, change current patterns, and move plastic debris into new parts of the sea and the coast, according to a study in the journal Aquatic Invasions.  

"Climate change may also increase the frequency and magnitude of storm activity capable of washing the immense amounts of plastic material now poised on the edges of the world’s coastlines into the sea," the authors write.

Have a child interested in medical school? Suggest a career in treating parasitic worms. There's evidence that a warming climate will increase the populations and virulence in a range of nasty bugs that like to bore into human tissue.

In the PLOS journal Neglected Tropical Diseases, there's this paper: " Global 'worming': Climate change and its projected general impact on human helminth infections." 

Not every nasty parasite will increase but many will, and some of those will be able to move into areas where they now don’t exist. And here's a word to get familiar with: ancylostomiasis. It is caused by a hookworm and can cause anemia in humans. Here's another: ascariasis, a disease caused by a roundworm. Both are expected to thrive in a warming climate.

There are a lot of folks in the Midwest who have felt secure that climate change will impact them minimally, since, after all, they aren't going to be impacted by rising seas or tropical storm systems. But there's increasing evidence that they can expect disruptions, too.

The Indiana Climate Change Impacts Assessment suggests that the growing season will be longer, but that with more spring floods and summer drought, the state might not be able to take advantage of it. 

And not just Indiana. 
Northern European forests will see big species changes, with declines in species like silver fir, beech, common ash and common oak, and a better habitat for alien species like the Douglas fir, red oak and black locust. With the change in species will come a dramatic change in the natural species that rely on those forests, said a paper in the journal Global Change Biology called "How much does climate change threaten European forest tree species distributions?" 

Should you get used to goat-milk ice cream? One research paper suggests that in a more extreme environment, goats present the best option for milk and meat. 

"Goats have numerous advantages that enable them to maintain their production under extreme climate conditions. Principally, goats have higher capacity than other farm raised ruminants to effectively convert some feed sources into milk and meat," write authors Nazan Koluman Darcana and Nissim Silanikoveb in the journal Small Ruminant Research.

Additionally, they produce less methane than cattle, they write.
©Jan TenBruggencate 2018

Sunday, July 29, 2018

Big Island fish evolving without geographic barriers: this is strange stuff


Arc-eyed Hawkfish, this one from Fiji in 2008. 
Credit: NOAA photo by Julie Bedford
If you isolate populations of animals and plants long enough, they can evolve into different forms, even different species.

That's been known for a long time.

In the Hawaiian Islands, we also have lots of evidence that the isolation doesn’t require long distances. A plant or insect in one steep-sided valley can have evolved into a unique species from its relatives in the next valley.

The valley itself may be sufficient to isolate the genetic flow, and allow each group to evolve independently.

But can species isolate themselves without geographic barriers? Apparently so, and you can find examples on Hawaiian reefs.

Researchers Jonathan Whitney, Brian Bowen and Stephen Karl, all of the Hawai`i Institute of Marine Biology studied arc-eye hawkfish (Paracirrhites arcatus) off the Big Island, where they found dark-colored fish on basalt bottoms and light-colored fish in coral habitats—all within a few feet of each other.

And it turned out that the dark colored hawkfish were more closely genetically related to dark hawkfish far away than they were to their light-colored cousins nearby. The fish apparently were isolating themselves voluntarily by their preferred habitat.

Whitney, Bowen and Karl published their research in the journal Molecular Ecology, under the title, "Flickers of speciation: Sympatric colour morphs of the arc-eye hawkfish, Paracirrhites arcatus, reveal key elements of divergence with gene flow." 

They wrote: "We observed greater genetic divergence between colour morphs on the same reefs than that between the same morphs in different geographic locations. We hypothesize that adaptation to the contrasting microhabitats is overriding gene flow and is responsible for the partial reproductive isolation observed between sympatric colour morphs."

Apparently, the light-colored fish on coral select their mates from among the other light-colored fish on coral, rather than from among the dark-colored fish on the basalt a short distance away. And vice versa.

"The combination of ecological, behavioural and now genetic  studies of the arc-eye hawkfish provides compelling evidence for partial reproductive isolation resulting from ecological barriers in the absence of geographic isolation."

The hawkfish have not been sufficiently isolated to have developed into separate species, but they seem to be on their way in that direction. And that's both interesting and strange, but may be a piece to a puzzle, the authors write:

"Whether complete reproductive isolation will develop between arc-eye colour morphs remains speculation. Regardless of the outcome, P. arcatus provides a rare case confirming that partial reproductive isolation can evolve in the face of continuous gene flow, bringing us one step closer to understanding the role ecological barriers play in initiating the early stages of speciation."

©Jan TenBruggencate 2018

Thursday, July 12, 2018

New study finds rat eradication improves fisheries around islands

Rat on palm. Credit Island Conservation, USFWS
If the rat eradication of Lehua Island ends up being successful, it could result in a more productive nearshore fishery.

Which is ironic, in that many of those fighting the eradication program were fishermen.

A new study in the journal Nature says that when rats kill off seabirds on islands, it means those birds are no longer pooping in the nearshore waters, fertilizing reefs. And that means fewer fish on those reefs.

This study was done in the Chagos Archipelago, where some islands have rats and others are rat-free. Researchers looked at both the fertility of the land on those islands and the productivity of their reefs, where erosion from the land would carry nutrients like bird-poop-sourced nitrogen.

The Chagos are atolls and reefs just south of the Equator in the Indian Ocean. Their ownership is disputed between Great Britain and Mauritius. One is Diego Garcia, which houses a U.S military base.

The results of the research were clear, said the authors, who are from Australian, British, Danish and Canadian research institutions.

On islands without rats, seabird density as well as nitrogen deposits were hundreds of times higher. Yes, hundreds: 250 to more than 700 times higher.

Those rat-free islands had reefs that had 48 percent more biomass of "macroalgae, filter-feeding sponges, turf algae and fish."

The researchers looked specifically at damselfish, and found that they both grew faster and had higher total biomass on the rat-free islands.

The theory, then, is that seabirds feed in the open ocean, deliver bird poop to the islands, and that the islands then feed the nearshore waters, which makes the waters more productive and capable of producing more fish.



"Rat eradication on oceanic islands should be a high conservation priority as it is likely to benefit terrestrial ecosystems and enhance coral reef productivity and functioning by restoring seabird-derived nutrient subsidies from large areas of ocean," the authors wrote.
Vampire mouse victim. Credit USFWS

Rats are not the only problems on islands. On Midway Atoll, near the western end of the Hawaiian archipelago, mice began eating seabirds after rats were removed from the islands there. The case of the vampire mice, which chewed into the necks of Laysan albatross, is reviewed here.

On other islands, the mice even seemed to be getting bigger on their diets of eggs and bird flesh. The Washington Post was among the many international publications that picked up the vampire mouse story.

All that said, rodents mainly go after eggs and chicks of nesting seabirds. That was the case at Lehua Island. Here is a description of the situation on the little island north of Ni`ihau before an application of a rodenticide to try to wipe out the rats.

"We found Wedge-tailed Shearwater and Red-tailed Tropicbird eggs broken open, the edges gnawed, the insides consumed. Tiny seabird chick bodies were commonplace–pulled out of burrows and half eaten. This was particularly true for the diminutive Bulwer’s Petrel–the vast majority of Bulwer’s Petrel burrows we found had bits and pieces of chick inside," wrote Andre Raine, Project Manager for the Kauai Endangered Seabird Recovery Project.



A couple of months after the 2017 rat eradication effort at Lehua, Raine said he could clearly see the difference:

"Fat, healthy Wedge-tailed Shearwater chicks shuffled about in their burrows looking like animated fuzzballs. One of our burrow cameras showed a Bulwer’s Petrel chick exercising outside its burrow and actually fledging – a great omen, as this is something we have never recorded on our cameras in previous years," he wrote.

Most, but not all the rats were killed off at Lehua, and wildlife crews were back this year with rat-hunting dogs to try to kill off the survivors and protect the island's nesting seabird population.

And the island's coastal reefs and fisheries.
The removal of rats from islands is a major conservation effort. It has been done successfully at islands in Hawai`i like Mokoli`i off O`ahu and Mokapu off Molokai. When it was accomplished at Palmyra Atoll south of the Hawaiian Islands, it had the unintended effect of killing off the disease-causing Asian tiger mosquito, which had depended on rats for blood meals. 

© Jan TenBruggencate 2018

Sunday, July 8, 2018

Drink coffee, live longer. It seems strange, but the science is compelling.


So what's with the health benefits of coffee?

New studies suggest you will live longer drinking coffee than from taking vitamins, eating good fruits and engaging in the latest "miracle diet" craze.

It's not entirely clear why. Its not the caffeine, because even decaf coffee has the impact of reducing mortality by statistically significant amounts.

One British study released this month followed half a million people over 10 years, and found not only that coffee drinkers live longer, but that the more coffee you drink, the better your chances of a longer life than those who drink less.

The study is entitled "Association of Coffee Drinking with Mortality by Genetic Variation in Caffeine Metabolism." It was published in the journal JAMA Internal Medicine, a publication of the American Medical Association, by authors are Erikka Loftfield, Marilyn Cornelis, Neil Caporaso, Kai Yu, Rashmi Sinha and Neal Freedman.

The study was designed to look into whether drinking a lot of coffee is a problem for people with genetic issues with caffeine metabolism, but it found that everyone—including those whose caffeine metabolism was faster or slower—had reduced mortality if they drank coffee.

This isn’t entirely new. There have been previous studies linking coffee to better longevity and to reduced rates of various diseases. That helped lead to the recommendation that up to 40 ounces of coffee (five 8-ounce cups) can be part of a healthy diet, from the 2015 report of the U.S. Dietary Guidelines Advisory Committee.

This new study is a massive study using the more than 9 million members of the UK Biobank. This study targeted 503,000 volunteers—excluding those who were pregnant, or whose coffee or nicotine intake information was incomplete. It looked at those who drink ground coffee, instant coffee and decaffeinated coffee. The average age going into the study was 57, and there were slightly more women than men. The researchers followed them for 10 years, during which time more than 14,000 of them died

People lived longer, even if they drank decaf—so it's something in the coffee or the coffee drinking, and not just the caffeine. "These findings suggest the importance of noncaffeine constituents in the coffee-mortality association and provide further reassurance that coffee drinking can be a part of a healthy diet," the study's authors write.

The authors looked at details of participants' smoking, as well as sex, weight, exercise, race, education and how much they also drank tea (it is a British survey, after all). A fifth were non-coffee-drinkers.

Ground coffee was a little healthier than instant and decaf, but they were all better than none. The study found that sex, age, weight and previous health issues did not make much difference in the outcome.

The study 's conclusion ends with this key message: "Our results provide further evidence that coffee drinking can be part of a healthy diet and may provide reassurance to those who rink coffee and enjoy it."

An earlier study of 400,000 people was published in 2012, in an edition of the New England Journal of Medicine. It had similar results. The study was entitled "Association of Coffee Drinking with Total and Cause-Specific Mortality," and was by Neal D. Freedman, Yikyung Park, Christian C. Abnet, Albert R. Hollenbeck, and Rashmi Sinha. Freedman and Sinha were authors of both papers that we discuss here.

They followed 230,000 men and 170,000 women aged 50 to 71 over 13 years, during which period about 50,000 of them died. The study found that people who drink several cups of coffee daily have lower mortality—they don't die as early as ones who don't drink coffee or who drink less coffee.

This is particularly noteworthy—and strange—because coffee drinkers tend to make bad lifestyle choices:

"As compared with persons who did not drink coffee, coffee drinkers were more likely to smoke cigarettes and consume more than three alcoholic drinks per day, and they consumed more red meat. Coffee drinkers also tended to have a lower level of education; were less likely to engage in vigorous physical activity; and reported lower levels of consumption of fruits, vegetables, and white meat. However, coffee drinkers, especially women who drank coffee, were less likely to report having diabetes. About two thirds of coffee drinkers reported drinking predominantly caffeinated coffee.

Still, according to both studies, if you drink three to five cups of coffee a day, even decaffeinated coffee, you're roughly 10 percent less likely to die in a given period.

What the heck is going on? Everybody knows about the caffeine, but if the decaf drinkers get the same protective effect (which may mean that caffeinated soft drinks don't do the same thing, incidentally) what's causing the reduce mortality?

Well, it turns out there are about 1,000 other compounds in coffee. So it might be one or more of those things.

The authors point out that they can't prove the coffee causes the health effect. It might be that something else about coffee drinkers is making them less likely to die as soon.

If it is not caffeine having an effect, maybe it's antioxidants, the authors of the 2012 paper suggest.

"Coffee contains more than 1000 compounds that might affect the risk of death. The most well-studied compound is caffeine, although similar associations for caffeinated and decaffeinated coffee in the current study and a previous study suggest that, if the relationship between coffee consumption and mortality were causal, other compounds in coffee (e.g., antioxidants, including polyphenols) might be important.

There's also a 2017 study in the Annals of Internal Medicine of coffee drinkers in 10 European countries. It had similar results: " Coffee drinking was associated with reduced risk for death from various causes. This relationship did not vary by country." 

Still, this research isn't entirely straightforward. This article from the Mayo Clinic suggests that while there may be health benefits from coffee, there are also risks for some folks. 
Oh, and taking vitamins and supplements? One study says "the results from controlled trials are dismal."
Another, on antioxidant vitamins in heart health says: "After an initial enthusiasm for antioxidants in the secondary prevention of cardiovascular disease, recent reports from of several large randomized trials have failed to show any beneficial effects." 
The takeaway seems to be that it's healthier to eat a good diet with lots of fruits and vegetables than to take supplements to make up for a bad diet. But also, that there might be some benefit to having a couple of cups of coffee with those leafy meals.
© Jan TenBruggencate 2018