Sunday, March 29, 2015

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

Sunday, March 22, 2015

Pesticide drift: just how controllable is it?

Those of us who can remember cropdusters and the pesticide fog trucks driving through neighborhoods have reason to be concerned about pesticide drift.

Drift is one of the key arguments associated with efforts to prevent pesticide exposure to Island residents. 

But it turns out modern drift management is a mature science, and safety measures are well established. There’s an impressive array of equipment, chemical formulations and best management practices to prevent unwanted pesticide movement.

(Image: A Hawai`i farm’s spray hoods, yellow boxy units which are affixed over spray nozzles during use to prevent drift.)

On a recent windy day, I drove by a subdivision neighbor who was using a spray rig to kill weeds in the cracks in her driveway. She was directing a fine spray from hip height, and it was apparent that most of the herbicide was blowing down the road in a big cloud.

To learn how it’s done in agricultural industry, I toured a West Kauai seed company, attended a class on proper pesticide use, and conducted some online research.

Among the things I learned was that my neighbor was doing just about everything wrong that day. Spraying during high winds. Using too fine a spray droplet size. Spraying from too high. Using too wide a spray pattern for the need. And not mechanically controlling the spray.

For the farmer, the drift discussion starts with this point: The farming industry has no interest in letting their pesticides drift. Pesticides are expensive—they are one of the big costs of farming, whether you’re using organic or non-organic compounds. (Yeah, the big seed companies use a fair amount of organic pest control products.)

And farmers clearly get the political climate as well—nobody wants drift—not their bosses, not their neighbors, not the larger community and not the regulators.

So, how do you control drift? There is a LOT of literature in this area. Here and here and here are a few resources.

Some of the key messages regarding drift control are these, all of which are employed by modern farms. 

Don’t spray on windy days. That’s an absolute rule. One of the reasons farmers sometimes spray at night is that wind speeds may be lower then. A standard for a lot of products is that if it’s blowing more than 10 miles an hour, the spray rigs stay in the barn.

Pesticide labels establish permissible wind speeds, can require buffer zones, set air temperatures allowable on spray days, identify additives that may be required, and so forth.

Control droplet size. Tinier droplets are more likely to get caught on the breeze and travel. So spray rigs are outfitted with nozzles that set droplet size to reduce drift potential. There are nozzles used by Hawai`i seed companies that surround the finer spray with a cone of bigger droplets to prevent their drifting.

Droplet size is also controlled through the pressure applied. You might get a finer spray at high pressure of 20 pounds per square inch, but a satisfactory droplet size at lower pressure of 15. 

Droplet size can also be controlled by how fast the spray rig is moving, and whether the spray nozzle is facing with the direction of travel, or straight down, or backwards. Going slow and aiming backwards results in bigger droplet size.

Control spray height. The higher the spray nozzle, the less control you have in where the product goes. Thus the industry’s fertilizer, herbicide and pesticide applicators keep the spray nozzles as low as they can be to best accomplish the task.

Sticking, bouncing, shattering. Droplet size and velocity can also impact the effectiveness of the spray. “Droplets that strike the target’s surface will do one or more of three things: shatter, bounce back, or stick to the surface,” says a University of Hawai`i pesticide application study paper.

You don’t want them to shatter into smaller and more driftable droplets, and don’t want them to bounce back. But it’s a fine dance: “Generally, small droplets make drift riskier but they have the potential for more thoroughly covering the target’s surface. On the other hand, large droplets may not cover the target’s surface so thoroughly but they do lessen the risk from drift.”

Control the characteristics of the liquid spray. Spray professionals may add products, called adjuvants, to change the characteristics of the spray, including their tendency to “stick” to the target plant.

“An adjuvant is any substance added to a spray tank to modify a pesticide’s performance, the physical properties of the spray mixture, or both,” says this University of Hawai`i publication.

Sometimes an adjuvant will be added to a mixture before spraying, to accomplish one or more of several tasks. A key task of an adjuvant might be to make the product stick better to its target crop, perhaps by reducing the surface tension and increasing the product’s “wettability”. But others might make them less likely to foam up, make the formulation thicker, or increase its ability to get into the plant.

From an effectiveness standpoint, sticking means it’s getting where it’s meant to be. But that’s also important from a drift perspective. If it’s sticking, it’s clearly not drifting.

Some pesticide labels require an adjuvant be added.

Mechanically control drift. Farming companies in the Islands use a range of hood designs to control drift. The hood fits over the spray nozzle, ensuring that no (or very little) spray can escape. There are cone-shaped hoods, box shaped hoods and others, designed for the crop and conditions. The one shown with this article is boxy, but I also saw cone-shaped hoods that follow the pattern of spray developed by the particular nozzle being used.

Pick the right product. Modern agricultural chemicals are formulated to reduce both drift and volatilization. Volatilization is the term for another part of the drift discussion: when instead of drifting particles of spray, the chemical converts into a gas.

It is all complicated stuff, and while it makes you worry about the neighbor who hasn’t read any instructions or taken any training, it gives a lot more confidence about the professional farming community and its approaches.
And if you’re the neighbor planning to begin spraying stuff, here’s a resource to help do it more safely—protecting both yourself and your neighborhood. 

© Jan TenBruggencate 2015

Saturday, March 14, 2015

Leatherback turtle navigation mystery deepens

Leatherback turtles leave their hatching beaches as feisty
infants little bigger than a silver dollar.

As long as 10 years later and vastly larger, they are able to return to those very same beaches with pinpoint accuracy to reproduce, despite changing ocean currents, changing weather, changing climate cycle, changing food resources.

(Image: Capt. Mark Leach with satellite tag-outfitted leatherback off Cape Cod, immediately before its release. Credit: LPRC.)

It remains one of the great mysteries of the animal world. What kind of memory and genetics make that kind of navigation possible? 

In a new paper on leatherback navigation, authors Kara Dodge, Benjamin Galuardi and Molly Lutcavage, if anything, expand on the mystery. The three are with the Large Pelagics Research Centre at Gloucester, Mass.  The paper is entitled “Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre.”

Lutcavage is also conducting yellowfin tuna research in Hawai`i, and is a member of the scientific advisory panel of the Western Pacific Regional Fishery Management Council.

“Leatherback sea turtles (Dermochelys coriacea) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation,” the authors write.

They followed 15 turtles with satellite tags over a two-year period in the Atlantic. The Pacific hosts the same species of turtle. They found the warm-blooded animals were able to maintain consistent direction, day or night, in changing conditions of all kinds.

Leatherbacks are ancient, remarkable creatures. They are the last surviving species of warm-blooded turtle. (Once there were many) They grow from 1.3 ounces to as much as 2,000 pounds over a lifetime. They eat only gelatinous marine life--like jellyfish and salps. And while they are able to relocate their home nesting beaches, for unknown reasons, they are also known to select alternative beaches in some nesting years, Lutcavage said.

The turtles clearly use a range of wayfinding techniques throughout their lives. As hatchlings, light direction and beach slope help them find their ways from the beaches to the ocean, the authors write.

“In deep water beyond the reach of shoreward-propagating waves, hatchlings switch to other cues that may include the Earth’s magnetic field,” they write.

There is evidence of a magnetic compass component to their navigation, but a compass alone won’t get you across a complex, diverse landscape—or seascape. In the case of leatherbacks, visual cues won’t work that well, and checking the stars won’t, because they have poor eyesight.

“Adult female loggerhead turtles appear to use geomagnetic cues to find their natal beaches along continental coastlines through a combination of geomagnetic imprinting and magnetic navigation,” the authors write.

 But other possibilities also present themselves.

“We also cannot rule out the possibility of alternative perceptual cues that have yet to be discovered,” the authors write.

The New York Times covered the research here. 

The Boston Globe here

And lead author Dodge writes a lay version at The Conversation.

© Jan TenBruggencate 2015

Citation: Dodge KL, Galuardi B, Lutcavage ME. 2015 Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre. Proc. R. Soc. B 282: 20143129.

Tuesday, March 3, 2015

The Milky Way has suburbs?

New research conducted at the Chilean sister of the Big Island’s Gemini Observatory has identified a small star cluster that lives, well, out of town.

"This cluster is faint, very faint, and truly in the suburbs of our Milky Way," said Dongwon Kim, a student at the Australian National University, who worked with a team on the Stromlo Milky Way Satellite Survey.

The initial identification of the new stellar formation was made on during a survey of the southern sky by the Dark Energy Camera on the 4-meter Blanco Telescope at Cerro Tololo Inter-American Observatory. 

It was confirmed using the immense light-gathering power of the southern Gemini: the Gemini South telescope on Cerro Pachon in Chile.

More on the Gemini Observatories here.

The new cluster, dubbed Kim 2, is vanishingly faint and far, far away. The authors called it a “a new, low luminosity star cluster in the outer halo of the Milky Way.”

But its presence is based on such challenging calculations that they’re not real sure about the identification. “Spectroscopic observations for radial-velocity membership and chemical abundance measurements are needed to further understand the nature of the object,” they write.

Here’s the Science Daily report on the find. 

Here’s where you canfind the report.

© Jan W. TenBruggencate 2015