For the better part of the last three decades, every summer on the Big Island, Stanford University professor Peter Vitousek has hosted a meeting of researchers, resource managers, students, and others who have an interest in understanding ecosystem elements and processes in Hawai`i. This year, the gathering took place on June 27 and 28 at the University of Hawai`i-Hilo.
Unlike other meetings where these same people might present their findings, there are no breakout sessions. Those in the audience can take it or leave it, as far as the presentations go, but there are no hard decisions to make regarding what workshop or seminar to attend, which has the intended effect of exposing experts in one field to those with expertise in another – and discovering just where their interests might converge.
Presenters are given five or ten minutes to summarize their work and are held to that by Vitousek himself. With nearly 80 talks over two days in late June, taking it all in is, as some have commented, like drinking from a fire hose.
Here, in no particular order, are some of the highlights from this year’s gathering.
* * *
Band-Rumped Petrel Nest
Confirmed at Army’s PTA
The band-rumped storm petrel (Oceanodroma castro), Hawai`i’s smallest seabird, used to be present in large numbers on all islands, but with the arrival of humans, its population declined drastically. By the time the U.S. Fish and Wildlife Service listed the Hawai`i population of these birds as endangered last fall, nesting sites had been confirmed only on Kaua`i and Lehua island, although vocalizations led researchers to suspect nesting burrows could also be found on Lana`i and the Big Island.
After years of effort, Nicole Galase, the seabird project leader with the Natural Resources Office at the Army’s Pohakuloa Training Area, and colleagues were finally able to confirm the presence of nesting burrows at around the 6,000-foot elevation of Mauna Loa, at PTA.
“Even though there have been sightings throughout the islands, and we had heard their calling, there was no discovery of a colony until this study,” Galase said. “They’re very elusive seabirds to study.”
Prior to the bird’s being listed as endangered, Galase said, “the Army collected data for consultation with the U.S. Fish and Wildlife Service. We did acoustic monitoring, night vision surveys, dog searches, personnel searches, and visual monitoring.”
There are four criteria for determining the presence of a colony, she noted: circling flight patterns, ground calling, visual observation of a seabird landing, and activity observed in a burrow. In 2015, “all were confirmed,” she said.
Confirmation came after seven years of searching that began in 2008 as the Army was looking for the presence of the Hawaiian petrel, `ua`u (Pterodroma sandwichensis). “There was not much evidence for the Hawaiian petrel,” Galase said, “but we did discover calls from the band-rumped petrel.”
“Then we started to use night-vision surveys. There were 449 visual observations. We saw birds circling and saw a bird land. We saw a carcass where it landed next to a collaped lava tube. The next day we heard ground-calling in the area and suspected it was from chicks. We couldn’t pinpoint it because the terrain is vast and lava tubes are intricate. So we needed to employ dog searches.”
The searchers employed Makalani, a Springer spaniel, to help out. “Makalani found feathers and would point when he thought an area might have a petrel in it. We found seven potential areas of burrows and put up cameras.”
On September 19, one burrow was confirmed. Two days later, another hit.
Makalani was brought back to explore the same area on September 29, but by then, there were no more birds in the burrow.
This year, she was expecting birds to arrive in May and June. Sure enough, “we caught them arriving.” And, she told Environment Hawai`i, “we have continued to capture activity into July.”
In light of the evidence of predation, Galase was asked whether any predator control had been undertaken in the area of the burrows.
“While the area is remote and rugged, we do some predator control for rats and mice – snap traps and Good Nature repeater traps,” she replied in an email. “This is just around the areas where we have known or suspected burrows. The area is not fenced, so a full-scale trapping is not really ideal yet.”
For the present, she continued, “we’ll do small grids of trapping to keep the numbers of predators down around the burrows, and after consultation with the [U.S. Fish and Wildlife Service], we will determine what further steps should be taken.”
While the area where the burrows were found is within the boundary of PTA, band-rumped petrels have been seen flying south past the PTA border, into the adjoining state Mauna Loa Forest Reserve. “Currently, the state is starting to explore what activity is happening there,” she said.
“We don’t have an estimate of how many O. castro are using the area,” she noted, “and because they are so cryptic, it will be interesting to try to figure that out.”
* * *
Progress in Search
For Biocontrol of Albizia
Albizia (Falcataria moluccana) is the scourge of Hawai`i’s forests and a threat to power lines and roofs across the islands. With no natural enemies here, it is larger and more robust here than in anywhere else on Earth, including its native range.
That may be about to change. Kenneth Puliafico and Tracy Johnson, researchers with the U.S. Department of Agriculture’s Institute of Pacific Islands Forestry, have been searching for biocontrol agents. As Puliafico reported, they identified the source of the albizia introduced in Hawai`i in 1917, tracing it back to Java and Northern Borneo.
As it turns out, those islands are way outside the species’ native range.
“What happened is, Joseph Rock must’ve gone to Borneo and Java in 1917 and brought back seeds and plant samples from there,” Puliafico said in a phone interview. (Rock, a self-taught botanist, was charged by the territorial government of Hawai`i with locating species of trees that could reforest denuded slopes and restore watershed functions.)
Albizia has been grown in plantations on the Indonesian islands for the last 150 years or so, with the wood being used for light construction – “disposable boxes, pallets, everything from matches, chopsticks, and shoes,” Puliafico said. At present, he added, it’s “used for plywood and a little bit of paper pulp.”
“The native range of our albizia is much further to the east, the other side of the famous Wallace Line. It’s more associated with New Guinea island and some of the smaller islands off there,” he said.
Although it’s still a major commercial tree in the western Indonesian islands, “in its native range, it’s nearly impossible to grow commercially because of natural predators. They can put in plantations, but after 10 years, the trees are just hammered by everything.”
In 2015 and 2016, Puliafico traveled to Indonesia and Papua New Guinea on the hunt for organisms that could halt albizia in its tracks. He was able to identify several candidate species, including a rust fungus that, Puliafico said, “turns albizia into pretzels.”
“This is a disease, in the genus Uromycladium, that has been used by biocontrol practitioners in South Africa,” he said. “They used a related species to control invasive acacia plants from Australia. Extensive testing has gone into that previously. We’re looking at a related species that’s supposed to be specific to our albizia.”
“Once it got into plantation areas, it destroyed the crop of albizia,” he said. His colleagues in Indonesia have begun testing the fungus for host specificity to see if the rust could affect the two Hawai`i species most closely related to albizia – koa and koaia.
Other biocontrol candidates include a shoot-tip mining moth, which attacks young trees and slows their growth; a stem-mining weevil that feeds on the woody stems of older trees; leaf-feeding beetles; and a gall-forming mite that causes leaflets to curl up and no longer be able to photosynthesize.
Future steps include identifying the potential biocontrol agents and ranking them by the degree of specialization, exploring their life history in their native range, and, finally, testing them for host specificity — how likely, or unlikely, are they to attack non-target species in Hawai`i.
How soon might an albizia biocontrol agent be released in Hawai`i? Puliafico was asked.
“If everything continues to go as well as it has now, we’re looking at a three-year window” for the first biocontrol agent to be completely tested, he replied, with additional time before obtaining all official permissions needed to release it into the environment. “Of course, if the five species we choose turn out not to have host specificity or we lose funding, that could postpone things.”
* * *
Fishing Gear Continues
To Harm False Killer Whales
Robin Baird of Cascadia Research Collective, who literally wrote the book on whales and dolphins in the central Pacific region, summarized his ongoing research into interactions between false killer whales and fishing gear.
False killer whales (Pseudorca crassidens) in the region belong to one of three populations: open ocean (pelagic); Main Hawaiian Island (insular); and Northwestern Hawaiian Island. Of the three, the MHI is the only one that has been listed as endangered (in 2012), with a population estimated at about 175; Baird’s earlier surveys of the MHI population were instrumental in the decision to list.
Baird has continued to document harm to the animals in the insular population caused by interaction with fishing lines. Three of the individuals documented in 2016 showed new injuries, when compared with photos of the same individuals taken earlier. “So injuries are still occurring today,” Baird said, despite the regulations on longline fishing vessels that were intended to end or minimize such harm.
All the observed injuries to individuals whose population affiliation was known were seen among the insular population. The proportion of individuals with dorsal fin injuries in that group was 9.1 percent (16 of 175 individuals). In addition, two false killer whales whose population affiliation was not known were seen with dorsal fin injuries from interactions with fishing lines.
Of the 11 individuals with line injuries where sex was known, ten were females. Baird speculated on reasons for this: “Females may depredate more due to their energy needs,” he said, while “males may be more likely to break gear due to their larger size.”
One of the potential consequences of this disproportional harm to females, he said, is “the female bias in general will reduce the population’s potential for recovery.”
Injuries are generally manifested in two areas: mouths and dorsal fins. When a false killer whale pulls against a line, the line can cut into its dorsal fin, leaving it disfigured. The lines also cut their mouths.
Dorsal fin scarring has in the past been used to estimate the extent of fishing gear interaction among the MHI false killer whales. However, Baird said, “Mouthline injuries should be a much better indication of interaction rates than dorsal fin injuries.”
A hooked animal will almost always have mouthline injuries, but, Baird continued, “only those that struggle a lot might end up with a secondary dorsal fin injury.”
In reviewing photographs of 73 animals where at least 50 percent of the mouthline was visible, Baird and his colleagues found 17 of them, or 23.3 percent, had injuries consistent with fisheries interactions. And the more visible the mouth, the greater the chance that the animal would show signs of an injury.
“Of animals with mouthline injuries, we could see an average (median) of 75 percent of the mouthline,” Baird told Environment Hawai`i. Photos of animals not showing mouthline injuries revealed on average just 53 percent of the mouthline.
“So the 23.3 percent with mouthline injuries should be an underestimate of the proportion of the population that have survived hookings in the mouth,” he said.
The false killer whale surveys Baird has undertaken suggest the rate of interactions between the whales and fishing vessels is probably higher than what is indicated by reports from observers on longline vessels targeting tunas. Baird was asked what might account for this.
“The (significantly) higher rate of dorsal fin injury in the Main Hawaiian Islands population of false killer whales, compared to that among the pelagic population, suggest that fishery interactions are occurring more often for MHI FKWs (from whatever fisheries) than for pelagic FKWs (interacting only with the longline fishery),” he replied. “It is also possible that longline interactions are more likely to be fatal (and thus no injured animals to document) than are the interactions with lighter-weight gear used in many of the nearshore fisheries.”
Baird mentioned that the observed rate of interaction between fishing vessels and the pelagic false killer whales is higher than what the population is able to sustain (a level called potential biological removal), which suggests this is also the case with the Main Hawaiian Islands population. With observers assigned to only about 20 percent of the longline vessels at any given time, he continued, “it wouldn’t surprise me if captains of vessels with observers on board are changing their behavior in a way to minimize interactions with MHI FKWs (for example, fishing outside of the area where the pelagic and MHI populations overlap) or with false killer whales in general inside the exclusive economic zone.” By fishing outside the EEZ, incidental takes of false killer whales don’t count towards the trigger that would result in curbing longline fishing in a large swath of the ocean south of the Main Hawaiian Islands.
Asked whether the non-regulated fisheries might be harming the false killer whales, Baird said that that is likely the case. “Given what we know about the movements of the Main Hawaiian Islands false killer whales from our tagging work (i.e., that they rarely go offshore far enough to interact with the longline fishery), I think the vast majority of fisheries-related injuries are from local fisheries, which could include short-line as well as trolling, ika shibi, and other fisheries. From our analysis of overlap between MHI FKWs and fisheries catch data, I think the majority of those interactions are happening with a small subset of fishermen who fish in the high-density areas (e.g., off Kohala, north of Maui, north of Moloka`i).”
In an email to Environment Hawai`i, Baird outlined steps that could be taken to reduce the harm to false killer whales: “Any long-term solution is going to require working with fishermen to figure out ways to reduce interactions, and when interactions do occur, to minimize the chances of injury. Switching to circle hooks, when possible, would be one potential way of minimizing injury. But we are at a stage right now where we need more information.”
Ultimately, he said, “electronic video monitoring is needed in the longline fishery to really get at the issue of bycatch (and handling techniques for bycaught animals) when no observers are on board.”
* * *
Progress in Research
Into Rapid `Ohi`a Death
Across Hawai`i island, the fungi that are killing `ohi`a trees continue their spread. And as if to underscore the significance of this phenomenon, the first six presenters at the meeting reported on their recent research into the disease.
First was Lisa Keith, the plant pathologist with the USDA’s Pacific Basin Agricultural Research Agricultural Center in Hilo. Until a few years ago, the focus of Keith’s work was on diseases of crops. As one of the few plant pathologists on the island, however, she was drafted into service when it became clear that a new disease was sweeping through `ohi`a stands in Puna.
Keith and colleagues identified the fungus in late 2014 as Ceratocystis fimbriata, a species that has a wide variety of strains, none of which had been known before now to affect trees in Hawai`i.
Since then, she has determined that there are actually two different Ceratocystis species at work, neither of which has been identified before. “The idea two years ago was to define the symptoms, how the tree responds to the fungus,” she said. But then she and her co-workers found, “it’s not one pathogen. We’re actually dealing with two, both Ceratocystis,” called for the time being Species A and Species B.
The discovery came about as they were examining seedlings that had been infected in the lab with the fungus and trying to determine how fast it moved in the tree. “We started seeing significant differences with the degree of discoloration and the amount of spores produced,” she said.
“From there, we tried to see it in the field. In trees that died because of Ceratocystis fimbriata, you come upon a dead canopy in either case, but discolorations differ. There’s more diffuse coloration with type B, a type more typical of infestations elsewhere.”
Ceratocystis fimbriata has existed in Hawai`i for close to 100 years, she noted. “It’s broadly distributed around the world, and it does affect a lot of crops, including sycamore and eucalyptus.
“We wanted to determine if this is something that’s been here and is now attacking `ohi`a. But now we know these are actually two new species of Ceratocystis. We were hoping to say right away where they’re from, how they’re getting here, but that’s still a big question mark,” she said. “Nothing that was here earlier caused ROD,” or rapid `ohi`a death.
Examining the phylogeny of the two fungi revealed that Species A “is a Latin American clade,” she said, with origins thought to be near the Caribbean, while Species B has origins in Asia.
Although the outward effect of both species is the same – causing the death of the infected tree – internally, Keith said, they are markedly different. A new “lab in a suitcase” – developed by Carter Atkinson of the U.S. Geological Survey in Volcano – has allowed crews with the Big Island Invasive Species Committee to determine exactly which species has infected a dead tree by removing a spoonful of sawdust from a drill hole instead of having to fell the tree to see whether patterns of discoloration match those caused by Species A or B. That, said Keith, “was a major advance.”
Blaine Luiz, who works with Keith at the USDA, has been looking closely into how Species A affects `ohi`a. This species, he said, is thought to be more virulent than Species B. To understand it better, he took three different samples of Species A and infected four different varieties of `ohi`a. Two of the varieties had high mortality, while the other two were not as severely affected.
“With further testing, we can get a better understanding if resistance and tolerance exists in nature,” he said.
Marc Hughes, also at the USDA center in Hilo, has been trying to figure out how the fungus spreads. Unlike several other Ceratocystis species, it doesn’t spread through root-to-root contact. Instead suspicion is turning to insects as the means of transmission. The fungus gives off a “very fruity smell,” he said, that is attractive to insects. But it will still take a lot of work “to determine if vectors spread it tree to tree,” he added.
There’s also a chance that the disease is spread by frass, the dust and excrement of boring insects. In the lab, he said, “frass is able to kill seedlings” if there is a wound in the tree.
Human activity may also be responsible for spreading the fungus, through cutting of firewood, which releases sawdust that can be carried in the wind to another tree, or by using sawdust from infected trees as mulch.
“Sawdust can serve as an inoculum,” Hughes said. “However, wounds are necessary for colonization.”
As the research continues in the lab, work in the field is ongoing as well to document the reach of the disease. Flint Hughes has been engaged in this study since before the pathogen was identified.
In recent years, Hughes and his team have developed a network of 43 plots in the districts of South Hilo, Puna, and Ka`u, where the presence of the disease has been confirmed. In each 0.1-hectare plot, they measure every `ohi`a tree and track the progress of the disease in each plot over time.
To date, the average annual loss to ROD is about 9 percent in each plot. “We’re seeing much lower mortality rates where younger trees predominate,” he said. “There’s about 300 percent greater mortality in plots where trees are older and larger.
“That seems to be saying there are big differences in how susceptible stands are when the disease is present. Maybe it’s because smaller trees are less likely to be wounded, or maybe they have smaller mass and are less attractive to beetles. There’s lots to be figured out down the line.”
The disease also affects regeneration of `ohi`a. Hughes: “In the majority of plots, we see no seedlings. We’re not likely to see `ohi`a recruitment at this time. In 17 of the plots, we see some seedlings, …[but] they are not abundant across any of the plots.”
In some stands, mortality of `ohi`a has exceeded 90 percent, he continued. “If we were to lose all `ohi`a in all plots measured, on average, what we would see is a decrease in about 80 percent of biomass.” The size of forests would be reduced, and the proportion of alien to native species would increase to 50/50, he added.
— Patricia Tummons