Baby sea turtle mystery partly solved: they're independent swimmers not drifters

A great mystery of the marine world—what green sea turtles do as keiki—has partly been solved.

Researchers caught yearling turtles and attached tags that would slough off after a couple of months. 

They found the young turtles aren’t just drifting around—they’re actively swimming. Which is interesting, because nobody's been able to prove this before, and it contradicts conventional wisdom.

(Image: When buoys and tagged turtles were placed in the water together, they went different ways. Here, two blue lines track the buoys, and the green is the track of one of the turtles followed in this study. Credit: NOAA Fisheries.)

Nathan Putman and Katherine Mansfield published their results in the journal Current Biology. Their tagging included the green sea turtle, Chelonia mydas, which is the dominant nearshore turtle found in the Hawaiian Islands, as well as Kemp's ridley turtles.

The first couple of years of most turtle species' lives are sometimes called the “lost years.” The keiki hatch on beaches, scramble into the sea, and then disappear until they come back to they show up again as much larger animals.

“It has been widely assumed that turtles simply drift with ocean current,” says a NOAA press release on the study.

Putman, a sea turtle biologist with NOAA's Southeast Fisheries Science Center, and Mansfield, director of the University of Central Florida's Marine Turtle Research Group, set out to find out for sure.

Mansfield put solar-powered satellite tags on 44 wild-caught young turtles, and at the same time deployed drifting satellite buoys that would follow the currents. If the turtles and the buoys went the same places, then it would suggest the turtles simply followed the currents.

But they didn’t.

Within the first few days, some of the turtles were already 125 miles from the buoys. The young turtles were actively swimming and navigating independent of current flow.

Anyone who has seen freshly hatched green sea turtles flap and clamber up out of the sand and then down the beach can appreciate how animated they are. Their single-mindedness and independence seems to continue in the ocean.

“The results of our study have huge implications for better understanding early sea turtle survival and behavior, which may ultimately lead to new and innovative ways to further protect these imperiled animals," Mansfield said.

In the past, young turtles have sometimes been found downstream from nesting sites, suggesting they might move passively with currents. They’ve also been found collected in association with drifting organisms, like Sargassum seaweed, also suggesting they’re mainly drifters.

“Our data show that one hypothesis doesn't, and shouldn't, fit all, and that even a small degree of swimming or active orientation can make a huge difference in the dispersal of these young animals,” Mansfield said.

“We conclusively demonstrate that these turtles do not behave as passive drifters. In nearly all cases, drifter trajectories were uncharacteristic of turtle trajectories,” the paper said.

© Jan TenBruggencate 2015

There's good science and bad--how do you tell them apart?

The legitimate science community is increasingly concerned over the proliferation of bad science--biased, not peer-reviewed, unrepeatable. 

It's a problem, because there are true believers who insist public policy be made, but they point to pseudo-scientific papers that don’t pass the smell test.

How can you tell a scientific paper ought to red-line your BS meter? There are many clues, and any paper with more than one of these problems should worry you. Here are some things to look for.

The authors: Are they real researchers? Are they associated with a legitimate institution? If the authors are clearly associated with an advocacy organization, for example, you have some cause to at least be cautious. Is their scientific training in the subject area of the paper? (Nothing like a “policy advisor” from an institute you never heard of, writing “authoritatively” about genetic engineering or vaccination. Or a political science major professing expertise on climate change or fishery regulation.) 

The publisher: There are reliable peer-reviewed journals. Peer reviewed science means that before publishing your work, the publisher shows it to other experts in the field, and the author needs to respond to their criticisms to the satisfaction of the journal’s editors. 

But now there are journals that require no peer review and some that will print anything for an advance payment.  Medical ethicist Arthur Caplan calls them “predatory publishers.” 

Peer review or refereeing is a powerful tool to ensure the science is good and relevant. Sometimes journals will even do “blind reviews,” sending out papers for review without telling the reviewer who wrote them—a technique to avoid favoritism. 

The short version: Read the title, the abstract, and near the end, the conclusion and occasionally the discussion. Do they make sense? Are they consistent? Do they betray an obvious bias? 

Be aware that conclusions may reflect the authors’ interpretation of the science in addition to what they actually found in their research. If the abstract is all you’re reading, you’re not getting the whole story.

The meat. Few lay readers get this far, but here’s where the science makes its bones. There’s often an introduction, a review of methods used, and the results.  Be wary of too-small sample sizes. Be aware of so finely focused a research area that you can’t realistically draw broad conclusions (although some people will.) Be alert for which data is statistically significant and that which isn’t. Look for red flags.

As an example, the seminal document among folks who believe that low-level electromagnetic fields cause injury is the Bioinitiative Report, a selective review of studies on electromagnetics. It fails the real-science test on several levels. 

The lead author is an activist without scientific training. It was initially published online without peer review.  It was long, and complicated, and few in the media took the time to test it. But when independent national and international scientific organizations studied it, they tore it apart for cherry-picking the data it cited (in many cases peer-reviewed data) and then basing conclusions on that selective data. 

The Health Council of the Netherlands was one of its many critics, saying the project was so badly done that it had the opposite of the desired result: “...the BioInitiative report is not an objective and balanced reflection of the current state of scientific knowledge. Therefore, the report does not provide any grounds for revising the current views as to the risks of exposure to electromagnetic fields.”

The Bioinitiative Report was eventually extensively revised and shortened to resolve some but not all of its issues, and was published in the peer-reviewed journal Pathophysiology. 

In another example, a group of Australian researchers set out to determine how hogs respond differently to being fed genetically modified corn as opposed to organic corn. If you read the conclusion of the authors, you would be led to the conclusion that pigs fed GM corn got more stomach inflammation than the others.

This one is trickier than the Bioinitiative report. The conclusions partly reflect the research, but leave some interesting parts out. 

The first hurdle is the lead researcher, a biochemist and university professor, also operates an anti-GMO website that is funded by anti-GMO organizations. Critics of the biotech industry regularly decry research by scientists who work for or whose work is partly funded by industry. But yep, it works both ways.

 The paper was published in a journal that specializes in organic farming issues.

And while the author's conclusions make a big point about the severe inflammation numbers, there is little reference to another fact: While it was true that more GM-fed pigs than organic-fed pigs had severe inflammation, it was also true that twice as many GM-fed pigs as organic-fed pigs had no inflammation at all.

The takeaway is that the conclusions didn’t tell the whole story. 

Rarely does a scientific paper stand alone. To be taken seriously, its experiments need to be repeated, and the repetitions need to get the same results

You may recall the kerfuffles over cold fusion. A couple of times now, researchers have announced they’ve succeeded in conducting nuclear fusion on a tabletop, at near room temperature. The problem is that other researchers have never been able to repeat the results, leaving much of mainstream science deeply skeptical.

Clearly, few scientific papers are perfect, but if you’re going to rely on them, it makes sense to understand what they don’t say, what they do, and now much of it is believable.

© Jan TenBruggencate 2015

Hāpu`upu`u and `ōpakapaka are way older than anyone knew

Groupers are among the grandfathers of the Hawaiian reef. And in the deep waters, pink snappers are right up there with them.

Some of them live for as many as five decades.

(Image: The Hawaiian grouper hāpu`upu`u or Hyporthodus quernus. Credit: NOAA.)

And you can thank the nuclear bomb testing of the 1950s and 60s for knowing that. The nuclear testing put a pulse of radiation into the environment that scientists are using to date biological material.

It has extended dramatically the previously believed maximum age of both the  hāpu`upu`u and the `ōpakapaka.

A group of researchers led by Allen Andrews from the Pacific Fisheries Science Center (PIFSC) used radioactive carbon signatures in the bony parts of fish—like the ear bones or otoliths—to determine their age.

Previously, fish ages have been estimated by counting the growth zones in the otoliths. But earlier tests indicated that otolith age testing was of questionable value for determining grouper ages when it came to the bigger, older fish. The age of young fish worked out well, but as the animals reached maturity, the otolith growth zone technique delivered more challenging results.

“Age estimates were dubious for the largest fish,” said a NOAA report on the subject in 2012.

But the nuclear testing inserted known data point into the mix. Researchers know when the ocean radioactivity increased as a result of the bomb testing, and in older fish, they could see that radioactivity signature in the bones.

“As they grow, otoliths reflect the ocean chemistry during the time they are formed. Thus by comparing measurements of radiocarbon in the otolith to a marine radiocarbon reference, the fish's age can be determined,” the PIFSC paper says.

(Image: an otolith or fish earbone, which can be used to determine the fish’s age. Credit: NOAA.)

So by adding the valid growth zone data from before the radioactivity spike to the time since the spike, they were able to accurately age groupers. It is a type of study that had previously been performed on the bottomfish `ōpakapapa, also known as pink snapper or Pristipomoides filamentosus. 

With respect to the hāpu`upu`u, the oldest fish found using growth zone counting was 34. But the bomb counting technique brought an oldest age of 43. And since there are bigger fish than the 43-year-old, the researchers assume there are still older groupers.

In the `ōpakapaka paper, researchers Andrews, Robert L. Humphreys, Edward E. DeMartini, Ryan S. Nichols and Jon Brodziak found that previous estimates of a maximum 18-year longevity for the pink snapper was wrong. There was a similar problem as with the hāpu`upu`u with difficulty of aging older fish.

“Bomb radiocarbon dating requires birth year otolith material to have formed between

approximately 1955 and 1970 for age determination, and recently collected fish would need to be between 40 to 55 years old for the method to be applicable,” they wrote in their 2011 paper. 

They came up with a mean age of 45.6 years for the largest Hawaiian `ōpakapaka—more than twice as old as previously assumed. And some of them, too, may be way older than that.

© Jan TenBruggencate 2015

Fisheries science challenged: Little fixes won't do.

We assume that a high human population like O`ahu’s is why that island’s fisheries are depleted—more fishing, more activities destructive of reefs,  more development and the associated toxic runoff.

But the science is more sobering. 

(Image: The Hawaiian parrotfish uhu-uliuli, or Chlorurus perspicillatus. Parrotfish are among the first species to be fished heavily and to suffer significant population declines on human-impacted reefs. Credit: Dr. Dwayne Meadows, NOAA/NMFS/OPR.)

It doesn’t take near that many people to have deeply destructive impacts on coastal marine life. And the first impacts of human activity significantly change mix of reef inhabitants.

A new study from researchers at the University of Hawai`i’s School of Ocean and Earth Science and Technology (SOEST) looked at nearly 2,000 sites on 40 islands and atolls around the Pacific. Among its conclusions is that a pattern of fishing regulation might not be as valuable in protecting reef resources as complete bans in some areas--what the authors refer to as "full protection over large areas."

They found that deep declines in fish abundance occur at pretty low human population densities. Sure, O`ahu and Guam are marginally worse, but human impact on reef populations is severe right from the start, and then declines at lower levels as human populations rise dramatically.

But the team also found that just because there’s no human impact, it doesn’t mean a particular reef will be amazingly productive. There are significant natural differences in reef productivity.

“Our results emphasize that coral reef areas do not all have equal ability to sustain large reef fish stocks, and that what is natural varies significantly amongst locations,” the authors wrote'

"It is...important to recognize that among islands and regions there are substantial differences in reef habitats and structure that are likely independent of human impacts, as well as in potentially influential oceanic factors such as wave energy, water temperature, and oceanic productivity that confound our ability to understand what might be considered ‘natural’ for a particular region or reef," they wrote.

The paper was published in the journal PLOS One by a team led by SOEST researcher Ivor Williams, along with Julia Baum, Adel Heenan, Katharine Hanson, Marc Nadon and Russell Brainard, under the title “Human, Oceanographic and Habitat Drivers of Central and Western Pacific Coral Reef Fish Assemblages.”

If you have swum some of the really impressive waters of productive tropical coral reef ecosystems, it’s not safe to assume, for example, that subtropical Hawai`i ever had that kind of assemblage of marine life.

“Perhaps the most important component of this study is the demonstration of the extent to which coral reefs’ capacity to support large fish populations varies among what we assume are relatively unimpacted reef areas,” they wrote.

“In our study, oceanic productivity appeared to be a key driver of those differences, but clearly there are also other factors driving differences among and within island reef ecosystems. We caution against any assumption that the spectacular high biomass fish assemblages seen at some remote reefs represent a natural level that all reefs would attain in the absence of humans.”

To assess impacts of human activities, the researchers looked at uninhabited islands like Jarvis and Kingman Reef, lower population islands like Ni`ihau and Samoa’s Ofu and Olosenga, and higher population islands like O`ahu, Tutuila in Samoa and Guam. A lot of the data was collected from 2010 to 2013 as part of the Pacific Reef Assessment and Monitoring Program (Pacific RAMP).

“Sharp declines in fish biomass at the low end of that human population scale are consistent with earlier smaller-scale studies on human impacts to coral reef fishes along fishing-intensity and population gradients in Fiji and the Seychelles,” they wrote.

Sharks and parrotfish are the first to go, along with total reef biomass. And this kind of removal has an impact. Groupers

“There is strong evidence that key aspects of reef fish assemblages including total biomass, top-predator density, and grazing potential, are highly susceptible to even low levels of human impacts, and therefore that full protection over large areas is probably necessary for a natural coral reef ecosystem to persis,” they wrote.

© Jan TenBruggencate 2015

Citation: Ivor D. Williams, Julia K. Baum, Adel Heenan, Katharine M. Hanson, Marc O. Nadon, Russell E. Brainard (2015) Human, Oceanographic and Habitat Drivers of Central and Western Pacific Coral Reef Fish Assemblages. PLOS ONE, DOI: 10.1371/journal.pone.0120516.

Milk, health and Hawai`i

Lost in the battles over whether a dairy ought to be established on south Kauai pastures is the value of cow’s milk in human nutrition.

Milk has picked up a couple of gold stars in recent months, confirming once again that mom was right when she told you to drink it. But what perhaps hasn’t been clear is the importance of milk consumption in older adults.

Milk is important for supporting levels of anti-oxidants in the body, according to University of Kansas Medical Center researchers In-Young Choi, and Debra Sullivan. Their research was published in February 2015 The American Journal of Clinical Nutrition.

 Choi said recent milk consumption was correlated with high levels of the brain anti-oxidant glutathione, which he said may help reduce oxidative stress that can cause diseases like Alzheimer’s and Parkinsons.

The editors of the American Journal of Clinical Nutrition  cited the study as revealing "a provocative new benefit of the consumption of milk in older individuals." 

An October 2014 study found that replacement milks like those from soy, nuts and even goats do not provide the vitamin D levels of cow’s milk. Kids who drink the alternative milks are twice as likely to have low Vitamin D levels, said researchers from the Canadian St. Michael’s Hospital. The work was published in the Canadian Medical Association Journal.

"Children drinking only non-cow's milk were more than twice as likely to be vitamin D deficient as children drinking only cow's milk," said St. Michael’s pediatrician Jonathon Maguire. "Among children who drank non-cow's milk, every additional cup of non-cow's milk was associated with a five per cent drop in vitamin D levels per month."

Vitamin D deficiency is associated with a variety of bone weakness diseases.  Vitamin D supplements are an alternate means of getting the nutrient, as are certain fish. Although sun exposure can help with Vitamin D levels, there have been cases of Vitamin D deficiency even in sunny Hawai`i.

© Jan TenBruggencate 2015