Blame it on the rat:--the original Pacific invasive species

When humans populated the Pacific Islands, they brought immense ecological change—perhaps approached only by the change caused by their traveling companions—rats.

(Image: A Pacific rat, Rattus exulans, in a New Zealand government photo.)

The body of scientific evidence has grown dramatically to indicate that the impact of the secretive rodents has been significantly underestimated. But that's changing.

Polynesians carried four animals with them to most of the island they occupied: dogs, pigs, chickens and rats. Not every island had all four, but most did. (Australian researcher Atholl Anderson discusses it here.)

“Ecological, paleoecological and archaeological studies have documented the direct and indirect impacts of rodents on native plants and animals, and implicated them in transforming many island environments,” wrote Donald Drake and Terry Hunt, both of the University of Hawai'i, in a 2008 article, “Invasive rodents on islands: integrating historical and contemporary ecology.”

The thing about rats, of course, is that they'll eat most anything. Among plants, they'll munch on seeds, seedlings and fruit. They'll eat ground and tree snails. And native birds and their eggs. And all kinds of other things.

They reproduce quickly and compete aggressively.

In a 2008 paper, Hawai'i researcher Steve Athens gave an overview in his article, “Rattus exulans and the catastrophic disappearance of Hawai'i's native lowland forest.”

The rats expanded far faster than humans did, and research now shows they were changing the character of the Islands well ahead of human movements in many areas.

“Rats radiated ahead of human colonizers on O'ahu, eating their way through the vegetation, perhaps before the colonizers had encountered much of the pristine lowand forest into which the rats had radiated,” Athens wrote.

In many areas, by the time humans began moving into new areas, the rats had already significantly altered the ecosystems—including the killing off of some species of native birds.

Scientists have come to this conclusion slowly and deliberately. A quarter of a century ago, the changed landscape was blamed largely on human-caused fire and agricultural clearing of the Polynesian era, and then the multiple land use impacts that followed European arrivals.

But increasingly, these conclusions didn't answer several questions. Notably, why were there such dramatic changes, even in places neither the early Hawaiians nor the later Europeans used much—like upland forested areas.

Research at 'Ewa on O'ahu showed that the native forest disappeared before humans showed in any numbers, and notably, before the charcoal evidence of widespread fire.

Two of the most common plants of early Hawai'i, based on pollen found in old sediment, were the loulu or Pritchardia palm, and the kanaloa, a legume of which now only one individual survives in the wild—on a sea stack off Kaho'olawe.

With the Kanaloa nearly extinct and the Pritchardia now rare, what happened?

And isn't it intriguing that two places with dense stands of Pritchardia—Nihoa Island west of Kaua'i and Huelo Island off Moloka'i—are both rat-free?

For Athens, the answer to the mystery is almost certainly rats—in this case the Polynesian or Pacific rat, Rattus exulans.

And of course, what rats did in Hawai'i, they've also done elsewhere. Hunt found that in archaeological digs on Rapa Nui or Easter Island, every seed of the extinct Rapa Nui palm is rat-eaten.

New Zealand researcher George Gibbs blames rats for “the end of an 80-million year experiment," in this paper.

He refers to the long isolation of New Zealand, and the development of its unique environment free of terrestrial mammals.

“The arrival of Polyesians in the 13^th (century) heralded the end of this era, with the introduction of kiore (Rattus exulans, or Pacific rat), which had far-reaching effects on plant regeneration, survival of small ground vertebrates, larger invertebrates, and seabird breeding colonies,” Gibbs wrote.

“One could argue that rats are the original invasive species,” wrote Drake and Hunt.

© Jan TenBruggencate 2009

Whale Fall: energizing life on the seafloor

When big creatures like whales die, they create diverse and dense congregations of seafloor life.

To figure out just how dense and diverse, a team of researchers sank a dead 30-ton grey whale and followed the progress of its decomposition over several years.

(Image: A live gray whale, sounding. Credit: NOAA.)

The whale was dropped to water a mile deep. The researchers visited the whale remains repeatedly over 6 to 7 years, using a remotely operated undersea vehicle.

They reported the results under the title “Biogeochemistry of a deep-sea whale fall: sulfate
reduction, sulfide efflux and methanogenesis,” in the Marine Ecology Progress Journal (Vol. 382: 1–21, 2009; doi: 10.3354/meps07972). http://www.int-res.com/articles/feature/m382p001.pdf

The authors include University of Hawai'i Department of Oceanography scientists Craig R. Smith, Angelo Bernardino and Angelos Hannides, along with Tina Treude, Frank Wenzhofer, Erin Carney, Martin Kruger and Antje Boetius of Germany's Max Planck Institute for Marine Microbiology.

The term “whale fall” is used for whales that die and rain down on the ocean floor. The team identified four stages of decomposition.

The first is one where swimming scavengers feed on soft tissue. The creatures include sharks, hagfishes and amphipods, which are shrimp-like crustaceans.

The second phase is called the enrichment-opportunistic phase, in which a comparatively few species feed on what's left of the scattered remains after the flesh-eaters have taken their portion.

Third, microbes attack the organic compounds in bones, producing hydrogen sulfide, which in turn feeds another group of deep sea life forms. This is the stage that the paper studies most closely.

Finally, in what the paper calls the reef stage, the cluster of bones becomes habitat, a place for a range of deep sea animals to hide.

The appearance of a whale carcass creates a center of fertility on the ocean floor. It prompts the arrival of a range of species, creates habitat for things like mats of bacteria, and increases the nutrient levels in the seafloor sediment immediately around the carcass.

Some of the life forms are the same ones that are found at sulfur-rich hot water vents on the ocean floor.

© Jan TenBruggencate 2009

From Blue Planet: A TV show on cutting your own home energy use

Just how difficult is it to cut your home energy bills?

Not that hard, unless you don't know where to start.

The Blue Planet Foundation hopes to bring folks a little understanding with the sponsorship of a new television show, to be aired this fall on KGMB9.

The show is Hawaii Home Energy Makeover. Blue Planet is seeking applicants to fill two spots on the show. Interested? Click here for information.

The program is looking for two different kinds of homes.

The first will be one with high energy costs in which little has been done toward energy efficiency. The goal is to cut that home's power bill in half, using insulation, more efficient lighting, a solar water heater and Energy Star appliances.

The second home, selected to show more advanced techniques, will be one that has already done the basics. The goal here, to include a photovoltaic system, will be to make it a zero net energy home. Through efficiency and solar generation, it will produce as much energy as it uses.

“Simple home upgrades and lifestyle changes can translate into significant energy savings. Blue Planet would like to show you just how easy it is to save money while doing your part for Hawaii’s clean energy future,” said Blue Planet executive director Jeff Mikulina.

Hawai‘i Home Energy Makeover will feature local contractors, local vendors and local products, and aims to provide a roadmap for how to cut energy costs.

“Cutting your power bill in half or even eliminating it entirely isn’t as far-fetched as it seems. We want to take you inside some local homes and walk you through the process,” Mikulina said.

If you apply and are not selected for the show, you can participate in a contest. Those not selected will be provided with home energy monitors that will help track their electrical use. They can then apply energy efficiency techniques themselves. The home that cuts its power bill the most, percentage-wise, wins.

© Jan TenBruggencate 2009

Hawai'i's other whales, the beaked variety

Most folks who think of whales and Hawai'i imagine that the seasonal humpbacks are the whole story.

But although the humpbacks are the most visible, with their dramatic flipper and tail flaps, and athletic leaps, they are hardly alone out there in the cetacean crowd.

(Image: An adult Cuvier's beaked whale. Credit: Robin Baird, Cascadia Research Collective.)

And while humpbacks are seasonal, other whales are full-time residents.

The beaked whales, for example, are smaller, but faithful residents, cruising the Islands' waters year-round.

Robin Baird's Cascadia Research Collective has been conducting research for a number of years on the beaked whales, notably Cuvier's and Blainville's beaked whales. The three whales they've seen the most are Cuvier's beaked whale (Ziphius cavirostris), Blainville's beaked whale (Mesoplodon densirostris) and Longman's beaked whale (Indopacetus pacificus).

Twenty-one of the 86 recognized species of cetaceans are beaked whales.

For those interested in being able to recognize these whales, and to learn about their behavior, and their responses to Navy sonar deployment, Baird has established a website with photographs and links to many of the group's research papers.

For more information, including crittercam video, see another Cascadia page .

© Jan TenBruggencate 2009

The towering risk of making this place like every other place

Bringing new things to an old place is a two-edged sword.

We have a paradoxical love for places that are different, yet we desperately work to make them like someplace else.

It was ever so.

(Image: 'Ohi'a rust on rose apple, Syzygium jambos. Credit: Forest and Kim Starr.)

Among the newest threats to the differentness of Hawai'i is the 'ohi'a rust , eucalyptus rust or guava rust, Puccinia psidii. The fungal disease, first noticed in an O'ahu plant nursery in 2005, hits many members of the myrtle family, which includes eucalyptus, guava, ohia, mountain apple, rose apples and many more. There are more than 200 species of myrtle in Hawai'i, some native, some introduced.

The host plants of this particular rust variety are fairly limited, but scientists fear its relatives could attack other myrtles.

One fear is that Hawai'i's rainforests could be destroyed if we import a form that targets the myrtle 'ohi'a, which is arguably the mother of the Hawaiian forest. With the rainforest goes the watershed.

Those concerned with Hawai'i's plant life are urging the state Department of Agriculture to quickly adopt a permanent rule banning the importing of myrtle family members, for fear they will bring in new and even more aggressive forms of the rust. (A temporary ban was allowed to expire last year.)

While some argue such a strict quarantine is uncalled for, noted Hawaiian botanist Lloyd Loope said that a stringent quarantine may be the only protection Hawai'i has.

“If we lose 'ohi'a, we lose our forest,” he said. For more, see the Hawai'i Ecosystems at Risk (HEAR) website on the rust.

Today, we import large amounts of plant material from Mainland nurseries. With the living plants come other living things, including plant diseases and various pests. Many other pests simply ride along in container shipments of other products--from household goods to supermarket vegetables.

Let's list a few:

The coqui frog, which now interrupts the once-peaceful nights in many Island communities.

The two-spotted leafhopper, a sucking insect with 400 or so host plant species, including ornamentals, native rare plants and food plants.

The erythrina gall wasp, which has destroyed much of the streetscape of wiliwili trees.

I've just read Ursula Meier's book, “Dr. William Hillebrand: His Life & Letters,” a fascinating, if poorly edited, Bishop Museum Press book about Hawai'i's first great Western botanist.

Hillebrand, the physician to Hawaiian royalty in the mid to late 1800s, had two great avocations: One was collecting and documenting Hawai'i's amazing native flora; the other was bringing in new species.

He brought in poincianas and monkeypods, cinnamon and its cousin camphor, mandarin oranges and Java plums, plumerias and ironwoods. And lots more.

His goal, to shade the public areas, provide taste treats, and spruce up the bare dusty streets of Honolulu.

But Hillebrand was hardly the first plant importer. Other westerners, notably Don Francisco de Paula Marin, brought many species. Marin's grape orchard gave Vineyard Street in Honolulu its name.

And the first humans to inhabit these islands, the Polynesians, also brought more than two dozen species, among them the kukui, sugar cane, banana and taro.

But the worm comes with the apple. Being able to import species we like comes with the likelihood that we bring in species we hate. Centipedes, mosquitoes, ants, stinging wasps and all kinds unwelcome imports have also joined the Hawaiian biota.

So far, only one variety of the 'ohi'a rust is here. To put this in the calmest terms possible, it seems reasonable to take action to prevent the importing of varieties that will cause more severe problems.

© Jan TenBruggencate 2009