Researchers Link Oceanic Land Crab Extinction to Colonization of Hawaii

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University of Florida researchers have described a new species of land crab that documents the first crab extinction during the human era.

Geograpsus grayi

Geograpsus Grayi

The loss of the crab likely greatly impacted the ecology of the Hawaiian Islands, as land crabs are major predators, control litter decomposition and help in nutrient cycling and seed dispersal. Their disappearance was caused by the arrival of humans to the islands and resulted in large-scale changes in the state’s ecosystem. Researchers said the full impact of the extinction on Hawaii is unknown, but they are certain it led to changes in the diversity of the food web, a continuing concern to conservationists studying species loss in other habitats. The study will be published online May 16 in PLoS ONE.

“If these land crabs were alive today, Hawaii would be a very different place,” said lead author Gustav Paulay, marine malacology curator at the Florida Museum of Natural History on the UF campus. “They certainly were major ecological players, as they were very abundant, large, carnivorous omnivores.”

Numerous fossils of the new species, Geograpsus severnsi, have been found on the major Hawaiian Islands for many years, but its identity was not clear. Researchers identified the crab by comparing physical characteristics with specimens from various collections. The species is unique to the Hawaiian Islands and the most land-adapted crab in the Pacific, expanding further inland and to higher elevations than any other. Like other island land crabs, G. severnsi appears to have retained ties to the sea, where its larvae developed.

Analysis of the radiocarbon-dated specimens show they vanished soon after Polynesians colonized the Hawaiian Islands about 1,000 years ago. Colonists brought novel predators to the islands, including lizards, rats, pigs, dogs and jungle fowls, profoundly altering coastal and low-elevation habitats, Paulay said.

“When people arrive on an island, initially it’s like the Garden of Eden – few people and lots of resources,” Paulay said. “I can imagine a period when humans and the introduced rats, dogs and pigs would have preyed heavily on the crabs, especially during their mass migrations to release larvae in the ocean.”

The sister species to G. severnsi, Geograpsus grayi, still lives on many Pacific Islands, so researchers can only speculate the exact cause of the extinction of G. severnsi, whose fossils are common on Hawaii, Maui, Oahu and Kauai. Oceanic land crabs occupy nearly all tropical islands, but many in the Pacific appear to be in decline from different causes.

“Islands have a limited habitat area, so that makes organisms on them inherently vulnerable,” Paulay said. “Because islands are isolated, major groups of species, like mammals or ants can be absent. Thus, island species evolve in their absence and often can’t cope when such continental predators are introduced.”

As important predators of invertebrates, plants and even nesting sea birds, land crabs probably affected the establishment and shaped the evolution of many species on the islands, Paulay said. Geograpsus severnsi was the largest species of this carnivorous genus.

“A study like this can reveal what the structure of the natural ecosystem was before these human-caused ecological changes, and that’s very important for moving forward with conservation,” said Helen James, curator of birds at the Smithsonian Institution’s National Museum of Natural History. “It highlights the complexity of the ecological changes that took place on the Hawaiian Islands and their severity in causing the extinction of a land crab.”

One example of how crabs affect the ecology of islands can be seen on Christmas Island in the Indian Ocean, where the invasive yellow crazy ant is destroying crab populations of a different species of land crab.

“The loss of this crab from areas has led to change in the structure of the forest because the crabs controlled litter and ate the seedlings of weeds,” Paulay said. “We don’t know the full ecological impact of all these land crabs, but we know that on islands, it’s usually substantial.”

Because oceanic islands have never been connected to a landmass, species establishment is based entirely on dispersal, a process that likely allowed land crabs to spread more easily because they have a marine larval stage in their development. For terrestrial organisms, arrival is usually less likely so there are missing organisms and altered ecological conditions

Patterns of Ancient Croplands Give Insight Into Early Hawaiian Society, Research Shows

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A pattern of earthen berms, spread across a northern peninsula of the Big Island of Hawaii, is providing archeologists with clues to exactly how residents farmed in paradise long before Europeans arrived at the islands.

The findings suggest that simple, practical decisions made by individual households were eventually adopted by the ruling class as a means to improve agricultural productivity.

The research was reported in the latest issue of the journal Proceedings of the National Academy of Sciences.

“Archeologically, this kind of research is really hard to do in most places since there is rarely a ‘signature’ for the agricultural activity, or a strong connection between the remains of a house and a plot of farmland,” explained, Julie Field, an assistant professor of anthropology at Ohio State University.

Julie Field

Julie Field

Field, along with colleagues from California and New Zealand, has spent three field seasons unearthing the remnants of an agricultural gridwork that dates back nearly 600 years.  The pattern was formed by a series of earthen walls, or berms, which served as windbreaks, protecting the crops.

“In this part of Hawaii, the trade winds blow all the time, so the berms are there to protect the crops from the winds,” she said. “The main crop was sweet potato which likes dry loose soil.  The berms protect the soil from being blown away.”

The researchers are familiar with the challenges the winds posed.  Field said that while they were excavating sites, the wind would “blow so hard, the skin would come off our ears if they weren’t covered.  It just sandblasts your ears and you have to wear goggles to see.”
“It is an intense place to work,” she said.

Previous work by other researchers has radiocarbon dated organic material found in the berms, establishing a timeline for when the agricultural system was first built.  Over time, more walls were built, subdividing the original agricultural plots into smaller and smaller parcels.

At the same time, other researchers were able to date materials from household sites of the early Hawaiians, and link those dates to the building of specific agricultural plots.

This showed that individual households that farmed the land expanded over time and then separated into new households as the population grew.

“Within a 300-year period, 1,400 AD to 1,700 AD, the data suggests that the population at least quadrupled, as did the number of houses,” Field said.

The researchers believe the data also provides insight into the structure of Hawaiian society at the time.  “We know that there was a single chief for each district and a series of lesser chiefs below that,” she said.

Similar to the feudal system of Europe, a portion of the crop surplus was always designated for the chiefs.

“This suggests to us that the field system was originally put in place probably by individual households that produced crops for their own consumption.

“It was then appropriated by the chiefs and turned into more of a surplus production system, where they demanded that the land be put into production and more people would produce more surplus food,” she said.

“Our study is unique in that we can trace the activities of very, very small groups of people and, from that, try to glean the larger processes of society,” Field said.

“We want to look at parts of Hawaii and treat them as a model for the evolution of Hawaiian society.”

The researchers said that the next question is whether the field system was used seasonally, whether they modified it over the year and used different parts of it depending on the season.

“That’s what it looks like happened, but we need more dating of different features at the sites to be able to figure that out,” Field said.

The National Science Foundation provided support for the project.  Along with Field, Patrick Kirch of the University of California, Berkeley, Thegn Ladefoged of the University of Auckland, New Zealand, Shripad Tuljapurkar and Peter Vitousek of Stanford University, and Oliver Chadwick of the University of California, Santa Barbara, worked on the project.

Hawai’i Police Department is Searching for a 17-Year Old Boy Reported as Missing From Hilo Since March 14

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The Hawai’i Police Department is searching for a 17-year old boy reported as missing from Hilo since March 14.

Jeremy Perreira-Kanakanui ...missing from Hilo since March 14

Jeremy Perreira-Kanakanui ...missing from Hilo since March 14

Jeremy Perreira-Kanakanui is described as Hawai’ian, 5 feet-5 inches tall, about 150 pounds with black hair and brown eyes.

Police ask that anyone with information on his whereabouts call the Police Department’s non-emergency line at 935-3311. Tipsters who prefer to remain anonymous may call Crime Stoppers at 961-8300 in Hilo or 329-8181 in Kona and may be eligible for a reward of up to $1,000. Crime Stoppers is a volunteer program run by ordinary citizens who want to keep their community safe. Crime Stoppers doesn’t record calls or subscribe to caller ID. All Crime Stoppers information is kept confidential.

Native Hawaiian Law Certificates More than Doubled this Year

The number of Native Hawaiian Law Certificates awarded to graduating Hawaiʻi law students increased to 15 this year compared to 7 in 2010, at the William S. Richardson School of Law.

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The 15 awardees are diverse and composed of both Native Hawaiian and non-Native Hawaiian students: Natasha Baldauf, Amy Brinker, Elena Bryant, Maria Carmichael, Amanda Donlin, Mark Jensen, Ha‘aheo Kaho‘ohalahala, Ryan Kanaka‘ole, Sarah Kaopuiki, Kekoa Keiley, Christopher Leong, Ann Otteman, Jeannin-Melissa Russo, Sherilyn Tavares, and Alexa ZenThe certificate’s coursework requirements include Native Hawaiian Rights, Administrative Law, Federal Courts, legal clinics, Federal Indian Law, International Law, Pacific Islands Legal Systems, as well as a research and writing requirement.

In addition to fulfilling the required courses, several law students played meaningful roles in the community and experienced important successes.  Baldauf and Kahoohalahala participated in outreach efforts to 11th grade students at Kula Kaiapuni O Ānuenue, a Hawaiian-language immersion school, this spring, and Hakipu‘u Learning Center, a public charter school, in the fall.  Brinker spearheaded a successful legislative effort to “legalize pa‘i‘ai” through Senate Bill 101, which passed both the state House and Senate and now awaits Governor Abercrcombie’s signature. Carmichael, Jensen, Kaopuiki, Russo and Tavares represented Hawaiʻi at Columbia Law School in New York for a national native moot court competition where team members brought home First and Third Place awards.  Donlin was an intern at KAHEA: the Hawaiian-Environmental Alliance and the Native Hawaiian Legal Corporation, two public-interest law firms.  Zen volunteered with attorneys Carl Varady and Tom Grande as they proceed with the Kalima case involving trust claims against the Department of Hawaiian Home Lands.

Hilo-born Sherilyn Tavares described her Environmental Law Clinic as memorable because, “for the first time, a class actually put me back on the land, where I was able to reconnect and make that important connection between what we do in law school classrooms, and what the real world needs are.  It was such a valuable class on so many levels.  It made us accountable to actual people doing work on the ground to preserve our culture and way of life.  It was real and the work was important and gratifying.”

When asked how he’ll apply what he’s learned through the certificate program to his legal practice, Mark Jensen replied, “Without sounding too idealistic, I’d like to think that I will have plenty of opportunities in the public interest field to help advance the interests of Native Hawaiians.”

Jeannin Russo commented that the certificate “is a great accomplishment and it has given me more knowledge of the issues I need to protect and address in my career.”

“Native Hawaiian law is challenging!  I find this subject to be very dimensional, given that it spans both state and federal law, and within that encompasses property law, Indian law, historic preservation, legislative and political work,” is how Alexa Zen described the program.

Amanda Donlin described the writing requirement as memorable and explained, “I wrote my paper on the legal certification of traditional Hawaiian healers.  It was the first time I wrote a paper of that magnitude and I enjoyed the journey.  I even had my paper published in a law journal, something I never dreamed I would ever accomplish.”

The annual spring commencement of the William S. Richardson School of Law awarded 15 students with Native Hawaiian Law Certificates on Sunday, May 15, 2011.

Established with federal funding in 2005 at the William S. Richardson School of Law, Ka Huli Ao Center for Excellence in Native Hawaiian is an academic center that promotes education, scholarship, community outreach and collaboration on issues of law, culture and justice for Native Hawaiians and other Pacific and Indigenous peoples.  Law Professor Melody Kapilialoha MacKenzie serves as the Director of Ka Huli Ao, and is also among the Law School’s first graduates.