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Tuesdays with Turtles – Climate change and nesting patterns

Byoliveridley

Turns out that in Guyana, nesting patterns are changing. Different types of sea turtles are showing up, and earlier than they used to. The earlier part can be explained by climate change, but the species distribution? I am sure there are other factors involved including habitat loss, poaching, etc. Anyway, interesting story.

Stabroek News

The changing nesting patterns of endangered sea turtles in Guyana, is alerting environmentalists to the impact of climate change on these marine animals.

The shell beaches in Region One have hosted thousands of nesting turtles over the years, and conservationists have been endeavouring to protect the turtles from heavy domestic use and from being traded.

Project Coordinator of the Guyana Marine Turtle Conservation Society (GMTCS) Michelle Kalamandeen told Stabroek News recently that climate change is affecting the sea turtle population.

According to Kalamandeen, in the 1960s the Hawksbill (critically endangered) and the Olive-Ridley (endangered) were our main nesting turtles, now the green turtles (endangered) and the leatherbacks (critically endangered) are mostly coming to nest on Guyana’s shores. The Pacific Leatherback is said to be now extinct and the Atlantic Leatherback is facing extinction.

The change in the time period for nesting in Guyana, she said, may also be a significant sign.

Usually sea turtles nest in Guyana from March to August every year. However, for the last three to four years, says Kalamandeen, the nesting pattern has shifted from mid-January to mid-July. This may have a significant impact on the hatchlings as food availability may be an issue for them.

Tuesdays with Turtles – Must See TV Edition

Byoliveridley

PBS is showing a nature film following a loggerhead turtle on a looooooong journey.

Nature . TV Schedule | PBS

Voyage of the Lonely Turtle
Sunday, April 15, 8:00pm
CHANNEL 4 (UNC-TV)

F. Murray Abraham narrates this account of a 30-year-old female loggerhead turtle’s journey from Mexico to Japan (its birthplace) to lay eggs. During the yearlong trip (travel speed: 1mph), she passes an array of marine creatures, including blue whales.

Here’s a press release on the show, sounds great, don’t forget to watch (or record!): April 15th at 8:00 PM.

The Olive Ridley Arrives in BC

The Olive Ridley Arrives in BC

Byoliveridley

No, not me, the sea turtle! When this blog migrated to BC in 2008, it surely didn’t expect the sea turtle it was named after to follow suit, but here we are…

A species of sea turtle never before seen in B.C. waters arrived on Wickaninnish Beach this week.

Parks Canada, the Department of Fisheries and Oceans, and the Vancouver Aquarium worked together to confirm the event as the first-ever sighting of an olive ridley sea turtle in B.C. waters.

“B.C. residents can be proud to learn that we now officially have three sea turtle species in our waters,” stated a media release from the three organizations involved.

via Sea turtle found in Pacific Rim park.

I would quibble with “never before seen”, this is highly unlikely in the many years Canada’s indigenous have made their home on the ocean, and given that turtles tend to stray. It appears this female arrived nearly dead, and died of possible blunt force trauma, which can be caused by many things including propeller hits, boat collisions, etc. Also found, large bits of plastic inside her stomach, which is all too common.

So, farewell, dear friend, you strayed a bit too far north for your tastes, not as far as Alaska, but far enough.

Tuesdays with Turtles – Navigation

Byoliveridley

If you did not know already, sea turtles tend to nest on (or close to) the beaches they were born at. It is known that they use the Earth’s magnetic fields to navigate. Here’s an article on the navigational natations (I strain to alliterate at times, but natation means swimming!) of the Green Turtle.

ScienceDaily: How Do Marine Turtles Return To The Same Beach To Lay Their Eggs?

I flagged this article not because it tells us much new, but just adds some nuances to sea turtle navigation.

The study has shown that the marine turtles’ navigation system allows them to maintain their course towards the egg-laying site wherever they find themselves. It is almost as if they were equipped with a compass pointing towards the beach in question. So they can correct any deflection they are subject to: transport by boat, ocean currents… But, unlike human navigators, they are not able to correct for ocean drift in plotting their course. So the movements recorded by the satellite are a combination of deliberate action by the turtles and the effect of currents. So it appears that the turtles’ navigation system is relatively simple and may cause them to be wander at sea for long periods during adverse ocean conditions. One turtle released 250 km from its egg-laying site on Europa traveled more than 3 500 km in two months before returning there!

Well, that’s interesting, if not surprising. It’s one thing to have a magnetic bookmark of a destination in your head (pretty wonderful thing, I wish I had it!) and swim continually towards this destination. It’s quite another thing to keep track of complex parameters like ocean drift and keep correcting continuously.

In essence, what they’re saying is that turtles home in on their destinations, but don’t always take the shortest way in because they tend to drift and not correct for this drift dynamically. It is not evolutionarily necessary because turtles probably do not get thrown way of course often enough that evolving even more sophisticated navigational systems (Garmin?) would provide a significant enough survival advantage.

In the Mozambique Channel, between the east coast of Africa and Madagascar, on the beaches of the French Islands of Europa and Mayotte, they caught turtles at the beginning of their egg-laying cycle, so that the animals were strongly impelled to return to this area to complete their cycle. After having Argos transmitters fitted to their shells in order to satellite track their return journey to the beach, the animals were released in open sea, several hundred kilometers from the egg-laying site.

Now that’s just mean! Imagine being kidnapped, tagged and released many miles away from home, and having to find your way back. Apparently, these turtles did it. Man, that would be such a cool navigational aid to have, quite a party trick!

Tuesdays with Turtles – Triumphant Return

Byoliveridley

So, blogging has been light this summer as Olive Ridley’s partner made her way to Canada and is settling in. Also, it is summer in BC and beautiful as hell, so the prospect of sitting down and typing on a computer with brains that are only half working, well, ain’t so hot! Also, Canada is just a much calmer place than the U.S. As I looked back at my many posts, most of them are bitter fulminations against American politics or the various shenanigans of the Emperor. Anyway, I am not under his rule any more, and while he’s gutting the Endangered Species Act as we speak, he will be history soon.

While Canadian policy debates are equally interesting, they are generally civil in comparison, except the occasional kerfluffle where old white men want their female opponents to go back to making tea, charming…

Anyway, I felt the blogging itch again and as always, it’s nice to get back with a story about turtles.

Researchers say they have figured out why sea turtles that normally feed and breed in shallow water or on land will, very rarely, go deep sea diving: the reptiles are on reconnaissance.

Sea Turtles Dive to Depths for Reconnaissance : Discovery News

Leatherbacks have amazing diving capabilities and can get up to a kilometre below the surface. Why? for food, of course! More precisely, the promise of future food. Turns out that jellyfish (or jellyfish like animals) hang out in the deep during day time and surface at night. Leatherbacks go looking for them during the daytime down in the deeps so they can get them on the surface for dinner. It’s akin to you taking a leisurely walk around downtown looking for the perfect dinner spot.

Interesting. As always, very fascinating and sexy creatures, and critically endangered.

Expect more regularly scheduled blogging just in time for the late summer sweeps!

Tuesdays with Turtles – Green Turtles Deluged?

Byoliveridley

I mentioned recently that elevated temperatures from climate could skew sea turtle sex ratios towards females. The featured news article highlights research which speculates that storm surges caused by increased hurricane (they call them cyclones in Austraila and India) intensity from climate change might lead to the flooding of green turtle nests in Florida, hastening their extinction. Why only the greens? Because they nest later than the other turtles and tend to be around during the height of the Atlantic hurricane season.

We know from previous research that loggerhead turtles have been nesting earlier because of elevated temperatures. Will the greens catch up. More pertinently, will there be enough survival of the early nesters of this generation to keep a viable population going while the whole population adapts? As with all climate change suspense thrillers, only time will tell… Depressing, at any rate.

News in Science – Cyclones may blast turtles to extinction – 15/05/2007

More severe tropical cyclones expected as a result of climate change may lead to the extinction of the green sea turtle in some areas within 100 years, researchers say.

The cyclones are expected to threaten how well the turtles nest and hatch eggs, placing pressure on already endangered populations, some of which are also threatened by fish trawling.

Researchers including PhD candidate David Pike, from the School of Biological Sciences at the University of Sydney, report their findings online in the journal Oecologia.

The researchers studied more than 40,000 sea turtles nests on an uninhabited, 38 kilometre stretch of beach along the Atlantic coast of Florida from 1995 to the end of 2005.

Each night during this period researchers surveyed the beach for turtles emerging to lay eggs, or for tracks of turtles that had already deposited eggs.

The stretch of beach is home to the loggerhead, green, and leatherback sea turtles, which start nesting at the beginning in April and end in late September.

This nesting season largely coincides with region’s tropical storm season, which runs from June to November.

Leatherback turtles (Dermochelys coriacea) and, to a lesser degree, loggerhead turtles (Caretta caretta) get around this by nesting and hatching earlier.

Only nests laid late in the season are inundated with seawater during storm surges.

But green turtles (Chelonia mydas) nest last.

Their entire nesting season occurs during Florida’s tropical cyclone season, which means their nests and developing eggs are extremely vulnerable to being washed away and killed.

Researchers are concerned that increases in the severity of tropical cyclones in the future may cause green turtle nesting success to worsen.

One Comment

  1. “Dont Hyde” !! Ha, ha, thats so funny.. “Dont Hyde!” ROTFL

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