Leatherbacks

Last weekend, I visited lovely Monterey, California to check out Whalefest Monterey, an annual celebration of marine science hosted by the town's Fisherman's Wharf Association

In the course of reporting a story about leatherback sea turtles that I wrote for the San Jose Mercury News, I learned that leatherback hatchlings, which start life small enough to fit in your palm, grow up into adult turtles that can weigh as much as a ton. Turns out leatherbacks are seasonal visitors to California's coast, which was news to me, though their numbers are dwindling rapidly and they're considered critically endangered

To learn why paying attention to the source of the swordfish you eat could help leatherbacks make a comeback, check out my newspaper story here

A leatherback hatchling makes its way to the ocean. 

(Image by Ken Clifton via Flickr; creative commons license)

Sea tomatoes

In the southwest corner of Greenland, where the tundra is dotted with small lakes, scientists spied something unusual beneath the surface of the ponds: Piles of giant colonies of toxin-producing Nostoc bacteria, each colony a jelly-like, spherical blob, some as big as softballs.

Greenlanders call them sea tomatoes.

“These are really slow growing,” biologist Jessica Trout-Haney of Dartmouth College told me. “Some of the big ones are 25 years old.”

Not much else can survive the harsh conditions of the lakes, Trout-Haney said, where organisms must contend with the annual cycle of freezing and thawing and periods of intense sunlight in summer and equally profound under-ice darkness in winter.

That lack of ecological competitors might explain why sea tomatoes can survive for so long in Greenland’s Arctic lakes, Trout-Haney said.

To read more about Trout-Haney’s research on sea tomatoes and Arctic lakes, check out the article I wrote for Eos.org last week.

 Lakes and ponds are scattered across the Arctic landscape near Kangerlussuaq, Greenland, where Trout-Haney and her colleagues spotted sea tomatoes growing on lake bottoms.   (Image by Miss Copenhagen via  Flickr ; creative commons license)

Lakes and ponds are scattered across the Arctic landscape near Kangerlussuaq, Greenland, where Trout-Haney and her colleagues spotted sea tomatoes growing on lake bottoms. 

(Image by Miss Copenhagen via Flickr; creative commons license)

Water on Mars

Usually posts on The Watershed focus on Earth-bound water. But water, it turns out, can be extraterrestrial, too. 

Last week I wrote a story for the Santa Cruz Sentinel on local elementary schoolers learning about NASA research on Mars. The students were excited to learn that liquid water exists on the Red Planet – according to NASA, a recent research paper offers "the strongest evidence yet" for water on Mars. 

Martian water is too salty to drink in its current form, the students learned. Still, it could be purified, and perhaps even used to support human exploration in the far-off future. As the authors of the paper wrote, "Water is essential to life as we know it."

Water also exists in the form of white clouds above the surface of Mars. (Image by NASA/JPL-Caltech/MSSS)

Scoops of seawater

The Great Barrier Reef World Heritage Area, off the northeast coast of Australia, is “one of the richest and most diverse natural ecosystems on Earth.” Thousands of species of mollusks, more than 1,500 species of fish, and 400 species of coral live within its waters.

There’s something else there, too – herbicides, washed into the ocean via rivers draining agricultural areas.

Herbicides can breakdown in nature (UV rays can degrade the molecules, or microbes can consume them), but it’s unclear how long that process might take under the conditions that occur around the Great Barrier Reef – many of the studies conducted in the past included unrealistic conditions, like unusually low temperatures or levels of herbicides 500 times higher than what researchers typically find there. A group of scientists working in Queensland, Australia, sought to detail the timing of herbicide persistence in seawater from the Great Barrier Reef lagoon kept under more natural conditions; they recently published the results of their study in the journal PLoS ONE.

Working with samples of water scooped up from off the coast of Queensland, the researchers added several different herbicides, then stored the flasks under different combinations of conditions: some in the dark, some under partially lit conditions, some at 77 degrees Fahrenheit (the average temperature of seawater around the Great Barrier Reef over the course of a year), and some at 88 degrees Fahrenheit (the summertime high temperature of seawater near the shore in part of the Great Barrier Reef lagoon). They took samples from the flasks every few weeks for a year to measure the herbicide concentrations, allowing them to estimate how quickly the herbicides broke down.

The estimated half-life of each herbicide – the time it takes for half of the initial amount of the chemical to degrade – ranged from about 150 days to more than 5,000 days. The light and temperature conditions the flasks were stored under didn’t lead to consistent patterns in how the herbicides broke down.

The scientists also added a chemical that stops microbial activity to some of the flasks, and no herbicide degradation occurred under those conditions, suggesting that it was the microbial community present in the seawater collected from the Great Barrier Reef lagoon that broke down the herbicides.

“Chronic exposure of [the Great Barrier Reef] and catchment biota to . . . herbicides (from microbial communities to macrophytes) remains largely unstudied,” the researchers note, “and should be a future focus for research and risk assessment.”

Australia's Great Barrier Reef World Heritage Area stretches over 1,000 miles along the coast of Queensland. 

(Image by Tchami via Flickr: Creative Commons license)