Moreton Bay, on the eastern coast of Australia, is always a rich and diverse ecosystem. Beds of sea grass stretch over miles, providing the foundation for fish, marine mammals and some truly ancient mariners(海员).

Protected areas, like Moreton Bay, seem like safe heavens for these ancient reptiles. But increasingly, this sanctuary is under siege from even more ancient life form, ("Ah, look at that.”) one (that) the Dr. Judio Neo knows all too well.

"That, here is a piece that was growing straight out of the settlement. Once it pulls up and it just rolls and rolls around, and then you have this sort of yarning mass."

What looks like a piece of sea grass is an epic scourge(灾难,祸患) in Moreton Bay. A species of blue-green algae, its scientific name is Lyngbya Majuscula and it flourished 2.7 billion years ago. It emerged from the primordial(adj.原始的) ooze(软泥) that began all life. Now, it's making a comeback in Moreton Bay and many other places. And it grows at astonishing rates. At the height of bloom, its edge can cover an area the size of a football field in an hour. Dr. Karen Arthur has observed the invasion of fireweed(杂草) in Moreton Bay.

"We've had extensive blooms of Lyngbya for the past 60 or 70 years. And they have become fairly predictable, because they occur every year in summer time. Um, it is related to water temperature. Um, the warmer waters, allow that, some (of the) bacteria to grow and bloom all across the sea grass beds."

Green turtles have long been thought to be the vegetarians of the turtle world. But, when fireweed infests the local salad bar, what a veggie-loving turtle to do? To find out, Karen and Judy want to learn more about how green turtles in Moreton Bay find food. They join forces with National Geographic's Greg Marshall. Greg has brought Crittercam, the small imaging and data logging system that can be deployed on marine creatures to study what they eat. But before you can deploy crittercam, you have to catch a turtle, and they can be hard to find.

Spending most of their time below the surface, they only come up occasionally for air, and that's the time to strike.

Karen Arthur is a pro of turtle rodeo(竞技表演), and this time she’s got a whopper(特大之物)-- a big healthy female. Turtle is weighed and measured. "One and seven-nine" She looks big and strong. So she doesn't seem to be going hungry. Greg cleans her shell, so Crittercam can be attached with a suction cup. (We're gonna go. Okay.)

At an equipped point, then the turtle is released back into the bay. The team can track crittercam's homing(回家的) beating with a radio receiver at a pre-set time the system releases. Hopefully, it contains information on how green turtles manage to make a living in Moreton Bay.

"Almost safe and sound."

The turtle swims rapidly after released, only surfacing quickly to breathe. She passes by ashovel nose shark(铲鼻鲨), fairly harmless local. Fish went by, but don't seem to strike an interest. Then something catches her attention. It's another turtle. They meet and greet. And after a quick that of socializing, it's time to move on. The team watches as she settles on the ocean floor. In front of her is a patch of sea grass. Not the freshest-looking greens, but free of fireweed. She takes a bite, and settles in for a rest.

Green turtles don't have swallowing muscles. So, the green noose(套索) that's coming from her mouth and nostril is backwash from the salt water she drinks to force the seaweed down her throat. Then as she swims toward the surface, the team is surprised to see her snap up a jellyfish. The grass-eating turtle does seem to occasionally dine on more hardy fare. These are first insights. They supplement Karen's initial findings.

"We found the turtles are trying to avoid the areas where there is a lot of Lyngbya. So as this Lyngbya is growing on their sea grass, they actually avoid the sea grass with the Lyngbya areas, and now swim to areas where perhaps the sea grass isn't as nutritious, and isn't as good for them. And so it means they get substandard diet when there is an extensive bloom, they don't have this much choice at the really not so juicy leaves they might sometimes wanna eat."

The Crittercam shows that the green turtles have some tricks up their sleeves. Their palate(味觉) is more diverse than previously thought. And with the sight of jelly, they may be able to make due when the local salad bars closed. It remains to be seen if fireweed will impact the comeback of the endangered green turtle in Moreton Bay. But the team will be back to do what they can to protect it from the rise of sly.

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