The Hawai`i Conservation Alliance held its annual conference in July, providing an embarrassment of riches to our two reporters in attendance. Here’s the second, and final, installment taken from our reporters’ notebooks.
Avoiding Beach Loss: A century from now, people wanting to attend the 114th annual Hawai`i Conservation Conference may find the Hawai`i Convention Center defended by a moat. According to Zoe Norcross-Nu`u of the University of Hawai`i’s Sea Grant Program, if sea level rises a meter over the next hundred years, as it well might, the ocean would reach the center’s doorstep.
“It’s getting harder to be optimistic,” Norcross-Nu`u told her audience as the screen behind her displayed a map showing the gradual inundation of Waikiki that can be expected if nothing is done to impede rising waters. Recent data on the melting of the Greenland and Antarctic ice sheets suggest that a rise of one meter in mean sea level over the next century is not out of the question, she said.
This inundation is particularly worrisome for those who enjoy Hawai`i’s famous beaches. When the ocean advances in areas that have been artificially defended with seawalls or other human constructions, margins of sandy beach are constricted and natural beach movement is impeded. The result is beach loss.
If Hawai`i does not become more aggressive in protecting its beaches, Norcross-Nu`u said, it can expect to see current trends toward beach loss exacerbated in the future. To preserve beaches for future Hawai`i residents, she said, the state needs to consider a range of policy approaches, including: purchase of coastal properties from willing sellers; replenishment of eroding beaches; bans on seawalls and revetments fronting public lands; an increase in setbacks on which development is banned or limited; and development of strategic management plans for given stretches of the coast.
Hawai`i’s beaches have already experienced substantial loss, Norcross-Nu`u said. She recounted how an intern with the Maui County Planning Commission walked Maui’s 56 miles of sandy shore, where tourists and kama`aina alike have access to the water, and found seawalls present along 26 percent of the shoreline. Seawalls interfere with the processes of sand deposition and removal by tides, and may lead to permanent beach loss seaward of the wall.
Once the beaches begin to erode, property owners become worried about further losses and view seawalls as their best defense. Recently, Norcross-Nu’u said, some resort areas on Maui where beaches have eroded have applied for permits to build seawalls. Still, she said, it is not likely they’ll get the required permits, since “they must show that a hardship will result if there is no seawall, and economic hardship does not count.”
In connection with Maui County’s efforts to address beach erosion, Chip Fletcher of the University of Hawai`i conducted a review of beach profiles from 1949 to 1989. On average, beaches eroded a foot a year, he found. Options for ensuring that beaches stay put, such as the importation of sand and the purchase of coastal areas for preservation, are costly, and, in the case of replenishment, not always permanent, Norcross-Nu`u said, adding that more sensible approaches involve planning decades into the future and giving up beach-hugging development.
Since 2003, almost all new proposals for near-shore developments on Maui have to be set back fifty times the annual erosion rate plus 20 feet, as a margin of safety. The idea behind the deeper setbacks is that they will eliminate the need for seawalls by allowing the natural beach processes of erosion and accretion to occur without interruption during the building’s lifespan. Maui is the first county in Hawai`i to have adopted such a setback law, although other states – including Florida, North and South Carolina, and New Jersey – have passed similar measures. Thorne Abbott, a coastal resource planner for Maui County, said Maui had helped Kaua`i planners draft a similar proposal, which will probably come before the Kaua`i County Council later this year. The Kaua`i draft ordinance calls for an even greater distance between dwellings and the sea – 70 times the annual erosion rate, plus a 40-foot buffer.
Apart from increasing the setbacks, another option to protect beaches is banning seawalls on public beaches, even if it means losing existing structures. Norcross-Nu`u noted that relocating structures further from the shore is less expensive than building walls to defend them and has the added benefit of preserving the beach. As an example of short-sighted efforts to protect parks from eroding beaches, she to Norcross-Nu’u pointed to the mammoth stone works installed at Maui’s Kalama Beach Park in the 1970s. By 1988, the beach had completely disappeared.
Willing-seller purchases as an option for preserving beaches “is not a tool that we should be prioritizing,” due to the present high cost of coastal real estate, Norcross-Nu`u said.
Sand replenishment may make the most sense for small-scale projects or areas heavily visited by tourists, she said. The results of a sand renourishment project undertaken by the condominium association at Sugar Cove on Maui have been “excellent,” she said. Still, the many obstacles to sand replenishment, like the task of finding sand compatible with the targeted beach, the question of water quality impacts, and the need to reapply sand every three to five years, preclude this option from being used in many cases.
“Developing strategic management plans is the most important of the five strategies,” she said. Taking into account factors such as recreational and cultural uses, beach width, shoreline access, water quality, and the extent of development, these plans split the shoreline into management segments which would dictate what type of development would be allowed. Maui’s Beach Management Plan was released in December 1997, and O`ahu is considering a plan. An essential component of Maui’s plan is the recommendation for proactive coastal development, which calls for the Planning Department to work closely with developers to encourage appropriate setbacks from the shoreline, post-and-pier construction rather than slab-and-grade, layouts with less frontage paralleling the shore, and more portable minor structures. – Malie Larish
Ladies in Red: Why do some females of one species of endemic damselfly, Megalagrion calliphya, dress themselves up as males?
That question puzzled Idelle Cooper of Indiana University. All the males of the species are bright red, but females can be either green or, like the males, brilliant scarlet.
At the 2006 Hawai`i Conservation Conference, Cooper reported that she found a clue to the puzzle on the Ka`u coast of the Big Island. There, the androchromes, as females with male coloring are called, increase in abundance with rising elevation. At the 1,500-foot elevation, females were exclusively green. At 4,000 feet, the female population was half green and half red, and at 6,500 feet, 97 percent of the females were androchromes.
One hypothesis that occurred to Cooper was that the color change might be due to increased solar intensity at higher elevations. In the lab, Cooper confirmed that the red-dressed females could withstand increased light, whereas the green females were less thermally tolerant.
As further confirmation of her suspicion, Cooper said, a survey for M. calliphya on the low-lying island of Moloka`i yielded no bright-red females. Such female-specific dimorphism has been recorded in butterflies, copepods, and other damselflies and dragonflies of the order Odonata. Earlier hypotheses about the color variation had centered on the possibility that male-mimicking female damselflies evolved in order to avoid male aggression. — M.L.
Damsels in Distress: Studies such as Cooper’s are important for understanding Hawaiian damselflies, but what’s the point if they all go extinct? Entomologist Dan Polhemus warned that despite the solid foundation of scientific knowledge about these animals, “it’s been a long time, nothing has happened, and we are still losing populations.”
“Damselflies are among the best-studied of all Hawaiian insect lineages,” said Polhemus, director of the state Department of Land and Natural Resources’ Division of Aquatic Resources, and their threats have been well-documented. The insects are found in a variety of habitats – from leaf litter under uluhe ferns, to seepages on the sides of gorges to rushing streams and still pools. Development has degraded, altered, and at times completely removed these habitats, Polhemus said, starting with the massive harnessing of water for agricultural and residential purposes in the early 1900s. More recently, damselflies have suffered as wetlands have been filled and anchialine pools destroyed. Some of the alterations give rise to acceptable habitats, such as ditches and flumes, but often these are rendered unusable by the presence of invasive fish species, which prey on damselfly nymphs, or invasive plants, such as California grass, which choke away water habitat.
As a result, Polhemus said, “Rome really has been burning.” A population at Ahuimanu, O`ahu, that existed ten years ago is now gone; the terrestrial species Megalagrion jugorum and M. molokaiense have not been seen for 75 years; and M. nesiotes has been reduced to a single population on Maui. The lowland species M. xanthomelas, described by British entomologist R.C.L. Perkins in 1913 as frequenting gardens of Honolulu, is now confined to a small population on O`ahu, and is extinct on Kaua`i and Maui.
Despite the dwindling populations, none of the Hawaiian damselfly species has been listed as endangered by the U.S. Fish and Wildlife Service, although at least six species have been proposed as candidates for listing. In Polhemus’ view, the failure to list is basically political: damselflies have not been designated because of the conflicts that could arise with water users should aquatic areas be deemed critical habitat for the species.
With federal support lacking, the brightest opportunities for the endemic damselflies occur at the local conservation level, he said. “If you are going to save them, you have to have a constituency,” Polhemus said, noting that the publication of Hawaiian Damselflies: A Field Identification Guide, which he authored with Adam Asquith, has been the best public outreach for the species.
Damselflies “have become part of Hawai`i’s charismatic megafauna,” he said, a trend confirmed by damselfly mugs and T-shirts, and their presence on the 2006 conference logo. The establishment of safe habitat for existing populations has progressed as well, he says, noting that sites such as Kalaeloa and Makiki, on O`ahu, may eventually be new homes for threatened damselflies, such as the population of M. xanthomelas at Tripler Medical Center. A custom-built damselfly habitat free of foreign fish is in the works at O`ahu’s Waimea Valley, under management by the National Audubon Society. On a positive note, M. xanthomelas has “modestly good populations” on the Big Island and Maui. As a last resort, molecular analysis of species has confirmed that some Moloka`i damselflies are similar enough to O`ahu’s to replace them in the event of an extinction. — M.L.
No Water, No Rainforest: “Is Water a Limiting Resource in a Hawaiian Rainforest?” The question, which was the title of a poster displayed at the Hawai`i Conservation Conference, appears to be a little silly on its face. Of course, if you have no water, you have no rainforest.
On second glance, however, the work of Colleen Cole and Susan Cordell, of the U.S. Forest Service’s Institute of Pacific Islands Forestry, and Rebecca Ostertag and Jene Michaud, of the University of Hawai`i at Hilo, is a serious study of the ways in which the presence of alien species in lowland wet forests near Hilo can limit the availability of water for native plants. The four researchers compared soil water potential in four experimental plots, where all non-native vegetation was removed, to four control plots, which were heavily invaded. In rainy periods, there was no difference in moisture availability, they found, but in droughts, the availability of water in plots where alien species had been removed was up to 50 percent greater. “This result suggests that even in lowland wet forests, water may be a limiting resource,” they concluded. “As conservation and restoration become a priority for Hawai`i’s endangered lowland wet forests, it is important to recognize how alien species alter ecosystems and limit even seemingly abundant resources.” — Patricia Tummons
Snowflake Coral Invasions: The presence in Hawaiian waters of the invasive soft coral Carijoa riisei, nicknamed snowflake coral because of its delicate white branches, was first noted in 1972, at Pearl Harbor. Until recently, most of the populations found since then, including the colonies that threaten commercially valuable stands of black coral in the `Au`au channel, were thought to descend from that initial invasion.
But at the conference, Greg Concepcion of the University of Hawai`i’s Hawai`i Institute of Marine Biology set the record straight. He presented the work of himself, Sam Kahng, and Rob Toonen, all of HIMB, who studied the various populations of C. riisei and, through genetic analysis, determined that there have been multiple recent introductions of snowflake coral to Hawai`i, brought in almost certainly by “maritime vectors” (that is, as hitchhikers on ships).
Also, the three researchers put to rest the theory that the first introduction of snowflake coral came on the hull of a ship arriving in Hawai`i from the Caribbean. To the contrary, the Hawai`i populations of snowflake coral came from the Indo-Pacific.
Finally, they question whether C. riisei is in fact an alien invader at all. “We can’t rule out that it has always been present at low levels in Hawai`i and has simply gone undetected by current sampling methods,” Concepcion said. –P.T.
Snowflake Coral Control: Native or not, C. riisei has recently shown up in places where it is unwelcome. As Dan Wagner, a lab technician at HIMB, told the conference, this coral is “a superior competitor” that can alter habitat and has the potential to destroy the black coral beds in the `Au`au channel.
As a means of controlling the soft coral, Wagner proposes using a nudibranch predator, Phyllodesmium poindimiei, which preys exclusively on Carijoa species in the Pacific. According to Wagner, P. poindimiei was first reported in Hawai`i in 1995 and is established here – an important consideration in evaluating the suitability of a biocontrol agent.
In the laboratory, the nudibranch devastates colonies of snowflake coral, Wagner said, but no similar impact has been observed in the field, possibly because of high death rates for youngsters. If the predatory nudibranch can be cultivated in captivity, he suggested, “inundative biocontrol” of snowflake coral might be possible. Before that can happen, though, more work needs to be done to assess the potential effect on other hard corals of releasing large numbers of captive-raised nudibranchs.
— Patricia Tummons
Volume 17, Number 4 October 2006
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