Monday, March 14, 2011

'Ghost crabs cleaning up the dead" in Northwestern Hawaiian Islands

Thousands, and maybe tens of thousands of seabirds were killed or injured in last week's tsunami in the Hawaiian Islands.

“Thousands of ghost crabs are cleaning up the dead,” wrote researcher Cynthia Vanderlip, from Kure Atoll.

The humans in the Northwestern Hawaiian Islands, as far as we know, had plenty of notice and are all safe. Some were being evacuated today.

(Image: Short-tailed albatross chick survived the tsunami, but was washed far from its nest. Tens of thousands of birds were killed. Credit: Pete Leary, Midway Atoll National Wildlife Refuge biologist.)

Millions of seabirds nest each year on the sand spits and low sandy islands of the Northwestern Hawaiian Islands.

The tsunami completely washed over some of those islands, washing away or burying every bird. In many cases both the flightless nestlings and a roosting parent were swept off nests or buried in their burrows. Other islands had only partial wash-overs.

Many of the uninhabited islands have still not been surveyed, but if the experience at Midway Atoll is a guide, the loss is near incalculable. There were reports of severe bird fatality counts at Kure and Laysan as well.

Here is the initial report, via Twitter, from the Midway Atoll National Wildlife Refuge: “People are OK. No damage to infrastructure. The Short-tailed albatross nest was washed over again and the chick was found unharmed about 35 m away and carried back to its nest cup. Minimum of 1000 adult/subadult and tens of thousands of Laysan Albatross chicks lost. Spit Island completely washed over. Eastern and Sand Island 60% and 20% washed over, respectively.”

The reference to the short-tailed albatross chick is notable. It is the first chick of its critically endangered species known to have been hatched outside a couple of remote Japanese islands. More on that here.

The chick was washed about 100 feet from its nest, but apparently was unhurt. It was moved back to its original nesting location in hopes the parents would continue to feed it. We have no word on whether or how much the main short-tailed albatross colonies off Japan suffered from the tsunami.

Midway Atoll National Wildlife Refuge biologist Pete Leary posted that crews were conducting a salvage operation, going through debris piles in hopes of finding trapped live birds. Firm numbers are not yet available, but he estimated tens of thousands of dead albatrosses.

“There's no way to know how many Bonin petrels were trapped in their burrows,” Leary wrote.

He wrote of boating between islands and finding waterlogged birds, drifting, exhausted and half-sunken.

Beyond Midway is Kure Atoll, where the impact was also severe. Veteran researcher Cynthia Vanderlip, the field camp manager of Kure Atoll Conservancy, sent out this report on the Facebook page for the Kure Atoll Conservancy.

Her team climbed for safety onto to the roof of the old concrete Coast Guard station building, having heard the reports of devastation in Japan on shortwave radio.

“The first wave arrived at around 12:50. We heard cracking branches, but could see nothing, not even with the strong searchlight. Then another one arrived at 1:10, and another at 1:18 and finally, the last one at 1:30 am.”

They stayed on the roof for some time longer, waiting to be sure it was safe. Finally, “everyone climbed down off the roof went straight to bed, except me. I took a quick walk to see the damage at the beach and it is extensive. The wave washed about 400 feet inland. The Black-foot colony at the pier is gone, chicks are everywhere. Thousand of ghost crabs are cleaning up the dead. The wave washed over the top of the pier and tore the window frames out. The ocean is chocolate brown.”

Vanderlip added: “I am thankful that our building is 700′ inland and 20′ above sea level. We were spared, but I fear for all the other folks in the Pacific. The loss of wildlife breaks my heart. Thanks for your thoughts and prayers.”

At Laysan Island, five people—two from the Fish and Wildlife Service and three from the Pacific Islands Fisheries Science Center—were to be evacuated this morning (Monday March 14, 2011) by the research vessel Hi`ialakai. The ship was diverted from a mission to Wake Island.

(Update 12:10 p.m. HST 3-14-2011: Hi`ialakai Facebook site reports that seven people were successfully evacuated from Laysan, having suffered only minor injuries: "only a couple cases of scrapes and bruises."")

The NOAA Coral Reef Ecosystem Division blog had some details. The report indicated that the tsunami had climbed the sand dunes of Laysan Island and inundated both bird habitat and human field researcher camp.

“The field team... reported extensive damage to the island, with the wave line extending well into the vegetation. In places, reef fish were found in the short trees that ring the island. Most of their food buckets and water jugs were washed away, and they were still seeing buckets and jugs being washed back to shore. The kitchen tent was destroyed and they are cooking and eating at the USFWS camp. The USFWS camp has 32 six gallon jugs of water, which should be enough to sustain the Laysan personnel for the remainder of their time on island. Fortunately no injuries have been reported and their office tent was spared and most of their electronics and communication equipment were not damaged.”

Details of the impacts on birdlife at Laysan were not immediately available.

Apparently the waves were comparatively small at Tern Island, the Fish and Wildlife Service headquarters island at French Frigate Shoals, but it was not known at this writing whether waves caused issues with the many small sand spits that create homes for wildlife within the vast reef structure there. Nor have there been reports from Pearl and Hernes Atoll, Lisianski Island, and Nihoa Island.

A tragic loss, but this is a healthy ecosystem, and Vanderlip at Kure notes that the ghost crabs were feeding on the dead birds, and shorebirds were feeding on the dead sea cucumbers and other marine llife washed ashore. Nature was doing what it does.

“This is an ecosystem that is pretty well intact. There were a lot of changes created by the tsunami, but there is abundant life on Kure, ready to pounce on every opportunity that is presented,” she wrote.

© Jan TenBruggencate 2011

1 comment:

Kim said...

Hey, Jan. Nice recap but dreadful news. Very sad. However, Lindsay Young, Laysan albatross biologist, reported that the shortie colony in Japan is safe.