Voyaging: Nailing down when the first canoe pulled up on a Hawaiian beach.

 

Your grandfather might tell you otherwise, but it is increasingly clear that the first humans set foot in Hawai’i in the year AD 1000, give or take a few decades.

Archaeologists and other researchers have been honing on that period for a couple of decades as their tools have improved for determining the age of human-related activities and artifacts. Early, widely varying carbon-14 dates have been adjusted and refined, and several new technologies have been added to the tool kit.

This isn’t brand new information, but I still hear older Hawai’i people advocating for dates they remember being taught as little as 30 or 40 years ago.

Until and into the 1980s, the common assumption was that the Hawaiian Islands were first inhabited early in the first millennium after Christ, and a few folks still still argue for AD 500, 300 or occasionally even earlier.

In his seminal 1985 book Feathered Gods and Fishhooks, leading Pacific archaeologist Patrick Kirch reflected the wisdom of the period: “It is clear that colonization parties from the Marquesas were responsible for the settlement of Easter Island by about A.D. 400 and of Hawai’i by possibly by A.D. 300.”

But the science has improved much since then, and the errors of the early dating have been corrected. By the 2023 revision of Feathered Gods and Fishhooks, Kirch and Mark McCoy had moved the number to closer to 1000.

Why? Wrote the authors: “No one could have foreseen…the major technological advances that would come…the use of GPS and GIS in settlement archaeology, AMS radiocarbon dating and Bayesian modeling…high-precision dating of corals, stable isotope analysis of faunal remains or XRF geochemical analysis of stone artifacts.”

Professional archaeology now assumes there weren’t any humans in the eastern Pacific as early as CE 300 or 400. (Maybe a lost fisherman or an intrepid sailor who left no evidence.) It is more likely that Polynesian voyaging canoes around AD 900 began pushing—probably from the Samoa islands—into eastern Polynesia.

Why did those Polynesians voyage? There have been many theories, but one recent one is that they were driven out of their home islands by drought. David Sear and co-authors Melinda Allen, Jonathan Hassall and Emma Pearson said that drought may have lasted 200-400 years, certainly from before AD 900 to after 1100. 

Whether or not drought alone was enough to coerce people to abandon their homes, there’s an associated stressor. Population pressure would have been a big factor as expanding island families began outgrowing their small islands’ ability to feed them.

Science now generally presumes that on departure from the central Pacific islands, some of the eastern Pacific islands south of the Equator were populated first. Perhaps the Cook Islands, which are just to the southeast and downwind of Samoa. Then the nearby islands and finally then canoes came north to Hawai’i, east to Rapa Nui (Easter Island) and then west to Aotearoa (New Zealand.) The chronology could change with additional findings and new technologies.

But all of that voyaging may have occurred in a pulse of only a few generations. The voyaging canoes left Samoa around 900 and would have populated all those other islands within just a couple of hundred years.

“The archaeological and paleoenvironmental estimates of the colonization date show a striking convergence, indicating that initial settlement (of Hawai’i) occurred at A.D. 940–1130…and most probably between A.D. 1000 to 1100,” wrote pollen expert Stephen Athens and Timothy M. Rieth and Thomas S. Dye, in a 2017 article in the journal American Antiquity, entitled, “A Paleoenvironmental and Archaeological Model-Based Age Estimate for the Colonization of Hawai’i.” 

They cited updated radiocarbon dating and pollen from archaeological coring data.

One of the best resources for dating first human activity on Kaua’i was developed by David Burney and William “Pila” Kikuchi at Makauwahi Cave on the swampy south coast of the island. Their 2006 paper, based on flooded sediments in the cave floor, estimated first Polynesian activity at between AD 1039-1241. 

A lot of the earliest archaeological dates in Hawai'i are now settling in on that time period.

What is amazing, given the compressed period of Hawaiian occupation, is the extent of the great public works that were completed: the many hundreds of fishponds, the massive stone temples, the remarkable waterworks for flooded kalo fields and the vast dryland field agricultural systems.

© Jan TenBruggencate

Global temperature estimates are way low; newest data shows the pace of change is accelerating

 

Global temperature will rise far faster than current UN estimates, even if we don’t keep dumping carbon dioxide into the atmosphere. A lot of the projected heating is already baked in.

That will lead to temperatures higher than the human race has experienced in its few hundred thousand years of existence, according to new research published in June 2024.

For coastal areas like the Hawaiian Islands, that also means dramatic changes in sea level estimates. Changes in terms of several feet rather than inches. In some areas, even rock walls won’t protect from that. Retreat to higher ground may be the only option. The cost, for low-lying facilities like airports, harbors, resorts and high-end beach communities may be unsupportable.

Here’s the threat, in jargon:

“We calculate average Earth system sensitivity and equilibrium climate sensitivity, resulting in 13.9 °C and 7.2 °C per doubling of pCO2, respectively. These values are significantly higher than IPCC global warming estimations, consistent or higher than some recent state-of-the-art climate models, and consistent with other proxy-based estimates.” (Those numbers in Fahrenheit are 25 and 13 degrees.)

That quote is from a paper by a team of Dutch and British researchers who tracked global temperatures against atmospheric carbon dioxide over 15 million years, using proxy sources including deep ocean core samples.

You can read what the journal Phys.Org wrote about the paper, in plainer language, here.  

The authors are Caitlyn R. Witkowski, of the Department of Marine Microbiology and Biogeochemistry at the Royal Netherlands Institute for Sea Research, and Anna S. von der Heydt, Paul J. Valdes, Marcel T. J. van der Meer, Stefan Schouten and Jaap S. Sinninghe Damsté.

Another team last year had more modest estimates, but they were still higher than those of the Intergovernmental Panel on Climate Change. They argued that doubling CO2 could result in 5-8 degrees Centigrade in warming, or 9-14 degrees Fahrenheit. 

Carbon dioxide in the atmosphere has gone up 30 percent in just the last 60 years or so, according to Keeling Curve records at Mauna Loa on Hawai`i. Before the Industrial Age, there were 280 parts per million CO2 in the atmosphere. That number now is 419. That’s a 50 percent increase. And it continues to rise faster.

The CO2 numbers are the catalyst for catastrophic change.

There is an estimated 50-year lag between when the CO2 enters the atmosphere and when the temperature responds.

So it’s going to keep getting hotter for generations, based on what we’ve already done to the atmosphere.

And there is an additional lag between temperature increase and sea level rise, because of the thermal inertia in melting glaciers and thermal inertia in the oceans.

What does that mean for my favorite beach, surf break, coastal restaurant or shoreline hotel?

In the most recent estimates, the best case, according to an article in MIT’s Climate Portal, is 8 to 20 inches of additional sea level rise by 2100. That’s still catastrophic for low-lying areas. But the worst case is six feet.

The National Ocean Service estimates by 2100 we will have between 1 and 8 feet of sea level rise, a little higher at the top end. 

CO2 is not only rising, but the rise is accelerating. New data from this month. 

Temperature is not only rising, but accelerating.

The melting of Antarctic glaciers is accelerating, too. And another source on that.

Ocean temperature increases are accelerating.  

Sea level is not only rising, but the that rise is accelerating. 

It’s a bad trajectory, and as a species, we’re not taking it seriously.

© Jan TenBruggencate 2024

Stone adzes traveled widely, perhaps as a lubricant for Polynesian trade networks

 

How valuable was high-quality stone in a stone-age culture?

So important that the valuable stone found its way long distances from home.

This isn’t news to the archaeological community. It has found a Kaho`olawe-sourced basalt adz in the Tuamotu Islands. Mauna Kea adz quarry stone tools in the Marquesas. Marquesan Eiao Island adzes throughout what is now French Polynesia. The longest adz in the Bishop Museum’s collection was found in the ocean off O’ahu, but came from the Pu‘u Pāpa‘i quarry on Molokai.

Quality stone tools traveled. Maybe as trade items. Maybe a gifts between chiefs. Maybe because a stone tool from afar had a special prestige, or a mana, a perceived spiritual power.

They were part of what archaeologists call “interaction networks” between the spread-out islands across the Pacific.

The Museum of Stone Tools has some adz images here. 

Most volcanic islands had at least some good quality stone, although the quality varied. New Zealand and Australian researchers Christopher Jennings, Marshall Weisler and Richard Walter last year in the journal Archaeology in Oceania published a comprehensive report on stone quarries across the Pacific. It is entitled, “An archaeological review of Polynesian adze quarries and sources.”

They argue that stone tools were more than just useful implements, but a significant part of cultural activity in Polynesia. They hold that “the adze industry played a much more significant and complex role in Polynesian cultural history than is currently realized.”

Early Pacific residents could make tools from readily available sources near home, but if they found exemplary qualities in remote sites, they would go to great lengths to get that material—such as quarrying in the frigid heights of Mauna Kea, or an isolated island like Eiao.

Adzes, they say, were “the most distantly exchanged items in the Neolithic world.”

But why? “We can establish a relationship between large scale quarry production, fine grained stone, highly skilled flaking technology and long-distance exchange, but we still do not know what drove these associations,” they wrote.

A good quarry would be used continuously over long periods of time. The Pu‘u Pāpa‘i quarry on Molokai is one of the oldest in Hawai’i, perhaps because it had high quality stone and was near an early settlement site at Kawela.

Researchers Marshall I. Weisler, John Sinton, Quan Hua, and Jane Skippington reviewed that quarry in the Journal of Pacific Archaeology, a 2024 paper with the ponderous title, “Indirectly Dating one of the Oldest Adze Quarries in the Hawaiian Islands Provides Insights into the Colonisation Process and Community Network.”

Adzes made from stone at this specific Molokai quarry are readily identified because it the unique chemical characteristics, high in strontium and phosphate. The unique chemical makeup of quarry stones is how adzes are sometimes linked to their home islands.

One suggestion from a lot of recent work is that adzes were a key component of exchange networks. It is not clear whether adzes were a lubricant that facilitated trade between distant islands, or whether voyaging canoes were simply early Snap-On tool trucks, hauling quality tools to customers.

One thing that seems clear is that hauling valuables between island was a long-standing practice in the Pacific. It dates back at least to the Lapita culture of thousands of years ago, according to paper from May 2024 by Nicholas W. S. Hogg, Scarlett Chiu, Patrick V. Kirch and Glenn R. Summerhayes. 

That paper, in Archeology in Oceania, reviews early exchange networks involving adzes and pottery in the Lapita era of far western Polynesia.

© Jan TenBruggencate 2024

Are we seeing more flight turbulence, and is it linked to climate change? Yes and yes.

 We have seen numerous reports of airliners suddenly plunging hundreds or thousands of feet midflight.

And a fair amount of suggestion that atmospheric turbulence is the cause, along with some guesswork that turbulence is increasing due to climate change.

Could that be true? The answer seems to be, yes.

There does seem to be a fair amount of turbulence-related airline drama this year. Here is a review of one kind, clear-air turbulence. 

There is also thunderstorm-related turbulence, and other kinds.

In February 10, 2024, a United flight experienced “moderate turbulence” between Newark and Los Angeles. Several passengers were injured.  

On May 20, a Singapore Airlines flight experienced severe turbulence over Myanmar, which caused significant injury.

Also in May, a Qatar Airways flight between Dohar and Dublin was knocked around, apparently by turbulence May 26. 

To be clear, a review of many recent incidents of bumpy plane rides suggests that a lot of them have little or nothing to do with climate or turbulence.

An April 11, 2024, Southwest flight had a sudden drop while approaching Lihue Airport, leveling off at about 400 feet above the ocean. That, investigators said, was due to mistake at the controls by a pilot.

In a Latam Airlines incident in March 2024, a plane apparently went into a dive when the cockpit crew briefly lost control of the aircraft. The pilots brought the plane back into control. Latam called it a “a technical event during the flight which caused a strong movement.”

A 2022 United flight event involving a sudden drop was determined to be pilot error, according to the National Transportation Safety Board. 

In 2019, Psychology Today published an article about a Delta flight, on the fear generated by these kinds of events. 

In that case, the incident was a controlled descent apparently associated with a cabin pressurization event. The article decries media sensationalizing and mischaracterization.

But there are plenty of occasions when actual turbulence, rather than equipment or human error, are involved.

Hawaiian Airlines had such an incident in December 2022, 65 miles north of Maui. The National Transportation Safety Board report said, “A cloud shot up vertically (like a smoke plume) in front of the airplane in a matter of seconds, and there was not enough time to deviate.”  

No previous flights in the area that day had reported turbulence, but the NTSB report said: “Postaccident examination of the weather in the area revealed that there was an occluded frontal system with an associated upper-level trough moving towards the Hawaiian Islands. Satellite and weather radar imagery, and lightning data depicted strong cells in the vicinity of the flight.”

An article in Smithsonian Magazine argues that climate change may be causing increases in turbulence, and therefore in aircraft-involved incidents. 

U.S. Secretary of Transportation Pete Buttigieg in May said turbulence is increasing, and that climate change is a big factor. The Smithsonian article said that technology is also improving, and will help moderate risk, but that bumpier flights may be in our future.

Many of the injuries in such incidents involve people being thrown around the aircraft. It’s a reminder to keep those seat belts fastened.

© Jan TenBruggencate 2024

Finally, a thorough tally of Hawaiian canoe plants, including pa'ihi and kamole.

 Which Hawaiian plants are canoe plants, the plants that Polynesian voyagers carried on their voyaging canoes to support new lives in new islands?

Some folks will say there were as few as 23. Others say as many as 32, Most are in between. Where’s the truth? Come on along for this investigation.

In most parts of the world, plants are conveniently divided into native and introduced. And among the natives, there are the endemics that are found nowhere else and the indigenous, which somehow got here without human assistance, but are also found in other parts of the world.

Canoe plant kukui (left), alongside hala, which might be but was already here. 
Jan TenBruggencate photo.

In Hawai’i, we had another classification: canoe plants or Polynesian introductions—the plants the Polynesian canoe voyagers carried with them to support their lives on newly found islands.

The late Lynton Dove White, in her book Canoe Plants of Ancient Hawai’i, lists 24 canoe plants. 

Art Whistler has more.

“The farther into the Pacific from the center of dispersal (Western Polynesia), the fewer successfully introduced canoe plants there were (e.g., ca. 60 in Tonga, c. 27 in Hawai‘i). Only about six canoe plant species were successfully introduced to New Zealand by the Maoris, mainly because canoe plants are tropical, and did not survive or thrive in temperate New Zealand,” wrote ethnobotanist Art Whistler. He is the author of “Plants of the Canoe People.” 

They are probably both low in their counts.

There were certainly somewhere between two and three dozen of them. 

At a minimum, these: `ape elephant ear, `awa kava, ‘auhuhu wild indigo or fish poison plant,`awapuhi shampoo ginger, ipu Lagenaria gourd vine, kalo taro, kamani Alexandrian laurel, ki ti leaf, ko sugar cane, kukui candlenut, mai`a banana, niu coconut, noni Indian mulberry, `ohe bamboo, `ohi`a `ai mountain apple, `olena turmeric, pia arrowroot, `uala sweet potato, uhi yam, `ulu breadfruit, and wauke paper mulberry.

That’s 21.

Many think hau or sea hibiscus and milo or portia tree were likely canoe plants, but could also have already been on the Islands.

That’s 23

Hala or pandanus used to be on the canoe plant list, but then fossils of hala were found in rocks erupted 100,000 to 500,000 years ago, and later ancient pollen was found in sediments that predate human arrival in the island.

The orange-flowered Kou (Cordia subcordata) also used to be placed on the list, but again, ancient pollen showed there were forests of it already there to greet the first canoes.

That said, the quartet of hala, hau, milo and kou were such valuable plants in Hawaiian and the larger Polynesian culture that they might have been on the first arriving canoes as part of the Polynesian survival kit, even if they turned out to be already in the Islands.

They would make 25.

There are problems with the list we’ve made so far. It is as far as most tallies go, but it is incomplete. For example, it lists banana as mai’a, but there were at least two quite different species of mai’a, and it lists one but there were three species of yam. And there are other plants that are not on the most common lists at all.

The yams: not only the uhi or winged yam, but also the hoi or bitter yam and pi’a Hawai’i, or five-leaf yam, Dioscorea pentaphylla, which is different from the Polynesian arrowroot that is also known as pi’a, Tacca leontopetaloides.

There appear to have been not one but two bananas, the more common mai’a , but also the fe’i banana, he’i, Musa troglodytarum.

The Bishop Museum’s Plants of Hawai'i program lists 32 canoe plants, some of which are so obscure they most people won’t know them. This Bishop Museum botany site seems to be the most thorough list out there, although (as I write this) it is missing the Hawaiian names of a couple of the less common species.

Plants of Hawai’i includes the popolo, or American nightshade, which clearly was an early arrival in the Islands, and is not commonly included in canoe plant lists.

Another canoe plant on its list is the Oxalis corniculata, yellow wood sorrel, has several Hawaiian names, ‘ihi ‘ai, ‘ihi ‘awa, ‘ihi maka ‘ula, ‘ihi mākole. It is edible, used medicinally for several ailments and made a dye.

Plants of Hawai’i cites two canoe plant species without Hawaiian names, although other sources do identify the Hawaiian names of those plants.

One is the Mexican primrose willow, Ludwigia octovalis, which other sources call water primrose, and in Hawaiian kamole or alohalua. It is said to be edible, but seems primarily to have been used medicinally, often in the form of a tea.

Another is pa’ihi, Polynesian cress, Rorippia sarmentosa. It is both edible and medicinal. Plants of Hawai’i lists this cress, as well as the primrose willow and wood sorrel, as possible accidental introductions—which suggests that perhaps seeds were on the canoes, but that they were not intended canoe plants.

The upshot is that while some folks will tell you there were precisely 23 or “more than 24” or 27 or exactly 30, or 32 canoe plants, nobody can be entirely sure. Here’s our comprehensive list—including the ones that might have been canoe plants but were also here already, and the ones that might have hitchhiked on canoes.

‘Ape, ‘auhuhu, ‘awa, ‘awapuhi, hala, hau, hoi, ‘ihi’ai, ipu, kalo, kamani, kamole, ki, ko, kou, kukui, mai’a, mai’a he’i, milo, niu, noni, ‘ohe, ‘ohi’a ‘ai, ‘olena, pa’ihi, pi’a Hawai’i, pi’a, popolo, ‘uala, uhi, ‘ulu, wauke.

And that’s 32 canoe plants.

© Jan TenBruggencate 2024

Unique Hawaiiian farming system being revived: kalo growing in kukui mulch

 

While early Hawaiian agriculture clearly grew out of Polynesian farming systems, these islands developed a unique food-production structure quite different from those elsewhere in the Pacific.

Ethnobotanist and forest ecologist Noa Kekuewa Lincoln reviewed that uniqueness in a book chapter, “Pakukui: The productive fallow of ancient Hawaii,” printed in the book Farmer Innovations and Best Practices by Shifting Cultivators in Asia-Pacific.

Kukui (left) and Hala trees. 
Jan TenBruggencate photo.

“The Hawaiian Islands, one of the endpoints of Polynesian settlement of the Pacific, saw the development of unique agricultural advances that have not been seen anywhere else,” he wrote.

While flooded taro paddies (kalo,) hilled sweet potato fields (‘uala) and garden plots with sugar cane (ko) and fiber plants like wauke and mamaki are well understood, the importance of tree crops—agroforestry—has perhaps been overlooked, he argues.

“Although a robust literature and investigation of Hawaiian agriculture exists, arboriculture is severely underrepresented. This had led to a simplified understanding of Hawaiian arboriculture with an emphasis on permanent, breadfruit-dominated arboricultural systems.”

It may be that Western viewers look at agroforestry through shaded lenses, missing key features. For example, focusing only on foods, oils, medicines and fiber may miss key contributions of some tree crops, he suggested.

“In some regions, it may be that Hawaiians planted trees specifically to accumulate fertility. In these systems, very fast-growing woody plants that decomposed quickly, such as candlenut and hau, were cultivated,” he wrote.

Candlenut or kukui (Aleurites moluccanus) is and was an immensely useful tree, providing food for humans and livestock, oil for many purposes, dyes, medicine and much more. 

Less well understood is its value as a mulch. In a culture without Western fertilizers, mulches were of inestimable value. Mulches of kukui and other plants were stamped into the muds of kalo fields, where they rotted and improved fertility.

“In a recent experiment we grew taro in pure mulches of candlenut, sugar cane, and hau (Hibiscus tiliaceus), and the growth in candlenut mulch was by far the largest (by ~150%), despite it having the lowest nitrogen content of the three treatments,” Lincoln wrote.

Kukui leaves, branches and logs could also be used to create soils on solid lava. A mulch pit filled with kukui was called a pakukui.

“In these situations, litterfall was gathered into relatively impermeable pits in the lava and composted in order to create a growing medium. Local organic waste and small amounts of soil that could be excavated nearby was added to these enclosures, or pa, to aid in the rotting of composts.”

The system is similar to but larger than the manavai planting technique in Rapa Nui, where circular walls of stone protected small planting areas in rugged windswept environments. Manavai were also used for taro, as well as banana and sugar cane. 

The use of the pakukui led, Lincoln said, to a shifting agricultural pattern, in which farmers would be growing crops in some fields while other were composting. That contrasted with areas with breadfruit forests, which would be harvested year after year.

Kukui helped to make poorer soils much more viable for agriculture, though only for intermittent use. With the decline in Hawaiian population, the practice appeared to have died out.

“Following European contact in Hawaii, several forms of traditional agriculture rapidly declined, primarily due to the population crash that accompanied the introduction of foreign diseases. Among the practices that declined rapidly was the pakukui,” he wrote.

But the agricultural system still has value, and should be revived, he said. He is working with partners in Hamakua to convert “a long-established pasture back into a candlenut forest to reinitiate the practice of nutrient accumulation and natural fertilization to realize significant taro productivity.”

Lincoln works with Indigenous Crops and Cropping Systems in the Tropical Plant and Soil Sciences Department, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. His pakukui chapter was published in December 2023.

© Jan TenBruggencate 2024

Fire-prone invasive grasslands need intense work to restore native species

 Invasive grasslands, like those linked to the destruction of Lahaina, are remarkably stable systems, and will be difficult to change.

That’s a conclusion of a new report by federal foresters.

They determined that active and intensive wildland management will be required to restore native-dominated landscapes. The alternative is a continued dominance of fire-prone grasslands.

The study, in the journal Ecology and Evolution, is entitled “Invasive-dominated grasslands in Hawaiʻi are resilient to disturbance.” The authors are Stephanie Yelenik and Eli Rose of the U.S. Geological Survey’s Pacific Island Ecosystem Research Station and  Susan Cordell of the U.S. Forest Service’s Institute of Pacific Islands Forestry.

The conclude that once a native Hawaiian ecosystem is converted to an alien grassland, it becomes difficult to change to another system, such as one dominated by native species that might be less fire-prone.

They did the research by disturbing six 100-square-meter plots with different vegetation mixes.

“We implemented a disturbance experiment to assess how plant communities would reassemble,” they wrote. They included in each plot plantings of two native species, ‘a’ali’i (Dodonea viscosa) and a native bunchgrass known as Hawaiian lovegrass (Eragrostis atropioides.)

The plantings were done on Hawai'i Island, in the Keʻāmuku Maneuver Area of the Army’s Pōhakuloa Training Area.

They found that competitive invasive grasses tended to become dominant after disturbance. They generally do better than native species in disturbed habitats. And once they have taken over, they tend to stay in charge.

“Our results highlight that the altered post-agricultural, invaded grassland landscapes in Hawaiʻi are stable states,” they wrote.

Some of those invasive non-native species they found include buffel grass (Cenchrus ciliaris,) Kikuyu grass (Cenchrus clandestinus,) fountain grass (Cenchrus setaceus,) Natal red top (Melinis repens,) and a toxic daisy called fireweed or Madagascar ragwort (Senecio madagascariensis.)

This study involved bulldozing the land, but the reaction to this disturbance seems similar to that found after fires, they said.

“While the disturbances that we imposed differ significantly from fire, wildfire resulting from invasive grasses are increasing in Hawaiʻi,” they wrote. “Past research in Hawaiʻi shows that fire in invaded grasslands generally results in the return of the same grass species across various ecosystems including those dominated by invasive grasses…”

They conclude that active management is needed if the goal is to return alien-dominated grasslands to native-dominated ecosystems.

“If the desired management goal is native-dominated ecosystems, such stable states will likely take large inputs of time and resources to alter,” they wrote.

© Jan TenBruggencate 2024

Gray-backed terns produce a second keiki at Palmyra since rat removal at the atoll

 A second gray-backed tern chick has been spotted at Palmyra Atoll, several hundred miles south of Hawai`i.

Gray-backed tern chick at Palmyra.
TNC photo.

The first was raised last year.

The birds were killed off on the atoll by rats, but have begun to return since The Nature Conservancy, which manages Palmyra with the U.S. Fish and Wildlife Service, eradicated the invasive rat population.

Many seabirds nest at Palmyra and many of the other remote atolls and islands of the central Pacific. But eight species known to the region were absent from Palmyra, and rats, which take both eggs and chicks, were believed to be the reason.

Rats were wiped out in 2011, and the island’s managers quickly began to see changes in vegetation and wildlife. In 2020, they began experiments to try to attract seabirds that might be flying by, using both recorded calls and decoy birds.

Last year, the first gray-backed terns nested at the atoll, and this year, more did.

 “Our science volunteers Oliver (Dunn) and Cass (Crittenden) saw 5 adults in the last month and three adults in the area near the chick. They also saw an adult feeding a chick. Thanks to their efforts, we have more data to show that our seabird attraction efforts are working,” said Katie Franklin, Island Conservation Strategy Lead for The Nature Conservancy, Hawaiʻi and Palmyra.

Alex Wegmann, lead scientist for The Nature Conservancy’s Island Resilience Strategy, said it is a milestone for TNC’s efforts.

 “It also emphasizes the value of decades of conservation and management by TNC, the US Fish and Wildlife Service and our many partners, as well as the efficacy of seabird social attraction methods,” Wegmann said.

Adult gray-backed terns at Palmyra.
TNC photo.

Gray-backs are one of eight species of seabird now missing but which may once have nested there. The grays are the first to return after the rat eradication. They are known in Hawaiian as pākalakala and their scientific name is Onychoprion lunata.

© Jan TenBruggencate 2024

Oxygen deprivation will accompany warming for Hawai'i oceans

 

The ocean waters around the Hawaiian Islands are likely to become less productive as climate warming reduces their ability to hold oxygen.

Some ocean species may be unable to survive the depleted oxygen levels. And yes, that could translate to less sashimi on Island platters.

It is a silent crisis, driven by two linked inevitabilities: Climate change is driving warmer temperature that is being absorbed by the seas; and warmer water loses its ability to hold oxygen.

We have already seen fish kills in areas with high temperature waters with low dissolved oxygen. 

And various other places are already seeing reduced oxygen levels in warming deep waters, like this example in the Sea of Japan. 

A wide range of changes is occurring in the oceans as a result of both warming and the increased uptake of carbon-dioxide from the atmosphere, which results in acidification of the seas. That’s another thing that’s not good for much marine life.

This paper reviews some of the changes that are already occurring or soon will. It is ponderously entitled “An Overview of Ocean Climate Change Indicators: Sea Surface Temperature, Ocean Heat Content, Ocean pH, Dissolved Oxygen Concentration, Arctic Sea Ice Extent, Thickness and Volume, Sea Level and Strength of the AMOC (Atlantic Meridional Overturning Circulation).” 

The upshot of this for us is that things in Hawai’i’s oceans are going to be different. The consequences of lower oxygen levels are far-reaching.

Big game fish like tuna and marlin, which require high levels of oxygen, are particularly vulnerable. They may be forced to move to waters away from the Hawaiian Islands where temperatures are cooler, or to shallower waters where oxygen levels are higher, making them more susceptible to overfishing. Neither is good for Hawai’i anglers and seafood eaters.

Creatures like jellyfish, which do better in low-oxygen conditions, may become more common.

This article reviews many of the ways climate change is impacting key habitats for marine life. 

“Driven by climate change, marine biodiversity is undergoing a phase of rapid change that has proven to be even faster than changes observed in terrestrial ecosystems,” the authors say.

Some species may be able to respond by moving toward the poles where water is cooler and has more oxygen. Some may be able to abandon oxygen-deprived deep waters and move to shallower waters. But some may completely lose core habitat, the paper says.

And as long as climate change keeps going, the problem keeps getting worse. “Our study highlights that the degree of range contraction and loss of suitable habitat will critically depend on the realized greenhouse gas emission pathway.”

© Jan TenBruggencate 2024