Hawai`i causes vast ocean eddies, and whales take advantage of them

As winds and currents sweep across the central Pacific, the Islands cause disruptions in their flow—creating vast eddies.

Those eddies can bring nutrient-rich waters up from the deep, and create an extensive food chain.

(Image: Three melon-headed whales. Credit: © Robin W. Baird.)

New research indicates that melon-headed whales take advantage of this food resource. Satellite tagging indicates they regularly feed around the fringes of some eddies, and near the centers of others.

Researchers placed satellite tags on 10 adult melon-headed whales that are part of a population that stays around the main Hawaiian Islands.

In analyzing the tracks of the whales, they found that several of them spent significant amounts of time around several of the major eddies around the Hawaiian Islands, and were presumably feeding there, since it is known that these eddies concentrate fishery resources.

The whales tended to use the edges of counter-clockwise (cyclonic) eddies that have cold centers, and to go to the hearts of clockwise-turning (anticyclonic) eddies that have warm centers.

What’s going on at these locations? The authors write of the fringes of one such eddy: “This edge region is characterized by convergence of nutrients and phytoplankton upwelled in the eddy’s divergent center. Several studies identify this convergence zone as a fruitful foraging ground for species such as sea turtles, marlin and tuna, seabirds, and cetaceans.”

The paper, “Eddies as offshore foraging grounds for melon-headed whales (Peponocephala electra),” was written by: Phoebe Woodworth of NOAA’s Pacific Islands Fisheries Science Center in Honolulu; Gregory Schorr, Robin Baird and Daniel Webster off the Cascadia Research Cooperative; Daniel McSweeney of Wild Whale Research Foundation; Bradley Hanson of NOIAA’s Northwest Fisheries Science Center in Seattle; Russel Andrews of the University of Alaska Fairbanks’ School of Fisheries and Ocean Sciences; and Jeffrey Polovina, of the Pacific Islands Fisheries Science Center in Honolulu. It was published in the journal Marine Mammal Science.

“Both warm and cold core eddies are continually recurring features in the lee of the Hawaiian Islands. Wind stress from easterly trade winds is intensified by the islands’ topography, leading to the formation of eddies,” the paper says.

These kinds of research often turn up other mysteries that need solving. In this case, some of the whales went to feed in an area west of Ni`ihau, where no eddies are known to occur. What’s happening there? That’s a new subject for inquiry.

“The melon-headed whale tracks … indicate a potentially favorable habitat southwest of the Hawaiian island of Ni‘ihau, although the factors contributing to this area’s desirability are unclear,” the authors wrote.

© Jan TenBruggencate 2011

New `opihi science: lots to know about limpets

An 'opihi came to the Hawaiian archipelago, and evolved into three distinct species, each with specific characteristics built for their specific habitats.

You may not have thought much about 'opihi, but there's a lot to know about these limpets--besides that they are growing so rare due to overharvesting that they're priced like gold. That's because `opihi is a prized item at any Hawai`i gathering--a salty, crunchy condiment served raw, and delicious grilled with a little butter and garlic.

But we digress. Back to the science.

One thing: There's nothing to prevent their seagoing larvae from invading other shores, but Hawai`i's three edible `opihi are only found in Hawai`i.

Another: Since the original migrants could readily cross with others of their species, how and why did they evolve into three distinct species.

“Speciation seems highly improbable under these circumstances,” writes author Christopher E. Bird, of the Hawai`i Institute of Marine Biology at the University of Hawai`i. His paper is “Morphological and Behavioral Evidence for Adaptive Diversification of Sympatric Hawaiian Limpets (Cellana spp.)” The paper is in the journal Integrative and Comparative Biology: Integrative and Comparative Biology, pp. 1–8 doi:10.1093/icb/icr050

But they did evolve, and probably they did it, he argues, due to natural selection—the individuals found environments to which they could adapt, and they and their offspring stayed there.

Still, it seems odd that you can find three different species of 'opihi on the same slab of rock—the exarata or makaiauli baking in the sun above the tide; the sandwicensis, `alinalina or yellowfoot taking the brunt of the wave force at the interface between air and sea; and the talcosa or ko`ele fighting off marine predators below the surface.

Bird argues that those locations below to above the water define their ecological niches: “Overall, C. talcosa is regularly exposed to pelagic predatory fish, C. sandwicensis is subject to the greatest amount of wave energy and mechanical stress, and C. exarata is subject to the most extreme temperatures and desiccating conditions.”

The ko`ele is sometimes called the kneecap `opihi. It's much bigger than the others, and its shell can be very thick—perhaps a trait developed to protect it from marine snails and predatory fish.

In another just-published article, this one in Molecular Ecology, Bird teamed up with Brenden Holland, Brian Bowen and Robert Toonen, all of the University of Hawai'i. This paper is “Diversification of sympatric broadcast-spawning limpets (Cellana spp.) within the Hawaiian archipelago,” Molecular Ecology (2011) 20, 2128–2141 doi: 10.1111/j.1365-294X.2011.05081.x

They say genetic studies suggest that the limpets first arrived in the Hawaiian archipelago between 3.4 and 7.2 million years ago—back in a time when Kaua`i, Ni`ihau and Nihoa were young islands

They probably arrived from the vicinity of Japan as free-floating larvae, and the original migrant was probably an inhabitant of the high shoreline, like Cellana exarata. Their nearest relative outside Hawai`i are probably the Japanese limpets, Cellana nigrolineata, C. mazatlandica and C. grata.

As little as six years ago, when this article was written, those things weren't known. http://the.honoluluadvertiser.com/article/2005/Jun/01/ln/ln08p.html

The researchers found that the Hawaiian 'opihi technically can hybridize but rarely do. They also found that they have different ranges throughout the island chain. All three are found in the main Hawaiian Islands, but talcosa doesn't go beyond Kaua`i and Ni`ihau. Sandwicensis stops at the basalt bastion, La Perouse Pinnacle. And exarata extends to the northewestern most Hawaiian land that still has volcanic rock above the surface, Gardner Pinnacles.

To confuse things, there are a couple of other `opihi reported from Hawaii. One is the small false `opihi, `opihi `awa, or Siphonaria normalis, which isn't eaten and isn't closely related to the others. The other is sometimes called Cellana melanostoma, which characteristically has steep sided shells, but genetic tests suggest it's a form of exarata.

© Jan TenBruggencate 2011

Midway's golden gooney fledges

Midway Atoll's golden gooney chick, the first of its species hatched outside Japan, has fledged—flown out to sea, most likely to the rich waters to the northwest.

(Image: The golden gooney chick is still mostly black, but eventually will develop white plumage and a striking yellow-gold head, like its papa, shown here. The chick is seen here sitting under its dad. For more recent shots of the chick, check our previous posts (see links at the end of this story.) Credit: U.S. Fish and Wildlife Service.)

“It happened just as most followers of the bird’s short life drama expected, the bird slipping away from the Atoll’s Eastern Island sometime during the day, with no one there to watch,” said a press release from John Klavitter of the Midway Atoll National Wildlife Refuge.

Midway and the other Northwestern Hawaiian Islands, all part of the Papahanaumokuakea Marine National Monument, are home to hundreds of thousands of Laysan albatross and black-footed albatross, but only within recent years have these cousins been joined by a handful of short-tailed albatross—also known as golden goonies for their yellow heads.

In January this year, a courtship between an 8-year-old male and 24-year-old female produced an egg that hatched into a healthy young bird. The chick has been knocked around some during its brief life, and was washed from its nest by the recent Japan tsunami.

In May it began stretching and flapping its wings, and in early June began paddling out to sea.

“The chick’s first swim in the ocean lasted 15 minutes. It walked into the lapping waters, paddled out 50 meters, submerged its head for a quick look, sipped some sea water, and then practiced flapping before paddling back to the shore. The chick was last seen the evening of June 15. By June 17 it was gone, most likely headed in a northwesterly direction to the rich and productive waters near Hokkaido, Japan, perhaps to join others of its kind,” a Fish and Wildlife Service release said.

Although its parents are both from Japanese-controlled islands, the birds normally return to their home islands to nest, and wildlife officials hope the chick will eventually settle on Midway for its own family.

“This event is a milestone in our international efforts to expand the range and population of this species,” said Fish and Wildlife Service Superintendent Tom Edgerton, one of seven co-stewards of the marine national monument.

“Once one of the world’s rarest birds, the endangered short-tailed albatross continues to recover,” said Refuge Manager Sue Schulmeister. “Sightings of the species have been relatively rare over the years, even on Midway Atoll National Wildlife Refuge. In the years to come, following this event, perhaps that will start to change.”

See earlier stories on the young golden gooney at RaisingIslands here, here, here and here.

© Jan TenBruggencate 2011

Rare plants rebound in newly fenced Ka`u preserve

If you fence it, will things come back?

The Nature Conservancy is reporting resounding—one might say rebounding—success at its Kaiholena Preserve at Ka`u on Hawai'i.

“It’s amazing to see the abundance of new plant life. Plants that haven’t been seen in years are popping up all over the preserve,” said Shalan Crysdale, the Conservancy’s natural resources manager at the preserve.

A six-mile, six-foot-high fence protecting 1,200 acres was completed in 2007. The last of the pigs inside the lowland forest area were removed two years ago. The fence also keeps out Mouflon sheep. And the results are heartening.

The most impressive of the returning wild plants is a native vine, the nuku `i'iwi, whose name reflects the similarity in shape and color between its blossoms and the orange beak of the native red `i`iwi bird. An image of the blossom is shown here, courtesy of The Nature Conservancy.

It's a gorgeous blossoming display, and rare, except in fairly pristine native forest.

The evidence indicates that if you don't wait too long to protect native ecosystems, they can heal.

“The resurgence in plant life is a standard response of our native forest to protection from browsing animals. If there isn’t a major weed problem, the natives often come roaring back,” said Sam Gon, the Conservancy's cultural adviser and senior scientist.

Crews walk the fence perimeter weekly to ensure pigs haven't burrowed under it, and falling trees haven't compromised it. John Repogle, a senior member of the Conservancy's Ka`u field crew, said the fence-walkers can see the improvement in environment inside the enclosure.

“Over time, as we do our fence checks, we have seen dramatic changes in the number of rare native seedlings popping up. I would not have thought pigs had such a destructive effect on these particular plants until I saw how many are now germinating and growing to maturity.

“There is moss on the ground now where it was just soil before. When you look along the fence, the ground level on the outside is three to four inches lower than inside the fence. This is erosion caused by the presence of pigs.”

Among the returning wildlife are lobelias: two species of koli‘i (Trematolobelia wimmeri and Trematolobelia grandifolia) and three species of ‘ōhā wai, including one named for Mauna Loa (Clermontia montis-loa).

© Jan TenBruggencate 2010

First Hawaiian "golden gooney" chick to fly soon

There are few good-news stories on the environmental beat, but the tale of Midway's golden goonies is one.

These charismatic and endangered seabirds are known to professionals as short-tailed albatross, but their regal golden heads give them their popular name.

(Images: Papa golden gooney sits on young chick. Later, big chick nears fledging age. Credit: U.S. Fish and Wildlife Service photos.)

They are rare birds anywhere, and nesting colonies only occur on a couple of small islands controlled by Japan. A few years ago one, then two, then three of them appeared among the massive colonies of Laysan albatross and black-footed albatross in the Northwestern Hawaiian Islands.

This year, a pair produced a live chick at Midway Atoll—the first known short-tailed albatross hatched outside Japan. And since albatross tend to return to their islands of hatching, it's hoped the chick will decide to stay in Hawai`i and establish a small colony here. (They don't always go back to their birthplace. Both parents were banded and are believed to have been hatched at Japan's Torishima Island.)

“We are very excited that the chick, raised by first-time parents, has made it to where we believe it will fledge, perhaps by mid-June,” said Deputy Refuge Manager John Klavitter, deputy refuge manager of the Midway Atoll National Wildlife Refuge.

“This chick is a survivor,” Klavitter said. “Hatched in the middle of a raging storm in January, it was swept 30 meters from its nest during a second storm in February, then survived the March tsunami that caused tens of millions of dollars in damage and the loss of some 100,000 Laysan and black-footed albatross chicks.”

See additional photos of of the golden goonies here.

See previous RaisingIslands.com stories here, here and here.

© Jan TenBruggencate 2011