The Hawaiian Islands have an invasive algae problem. The eight major Hawaiian Islands harbor more than 60 percent of the coral reefs found in the waters surrounding the United States. Non-native algae species infect these reefs. They spread aggressively. This deters local marine life from building their habitats in the coral. Hawaii needs to address the issue at a broader public level. Then, more needs to be done to remedy the problem.
Corals are ancient animals that evolved into modern reef-building forms over the last 25 million years. Hawaii’s geographical position presents an advantage to species crossing the Pacific as well as a disadvantage to Hawaii’s native species. University of Hawaii professor Celia Smith notes that 25 percent of Hawaii’s coral and at least that much of its algae are endemic. They’re found nowhere else on the planet. Naturally, when an ecosystem has such a high rate of endemism, it becomes an unintentional target for marine-based invaders. When the algae overgrow the coral reef, they smother and kill the corals by blocking the sunlight the organisms need to live.
Biologists commonly assume that many of these foreign organisms were transported to Hawaii’s ecosystem via ballast water from cargo ships. These invasive species are difficult to contain because of their structure and ability to infect their hosts. They don’t just block sunlight. In some instances, they distort sunlight. This hinders proper UV absorption and siphons nitrogen from otherwise rich sources. Environment Hawaii writer Teresa Dawson argues a different cause for invasive algae. Specifically, alien organisms growing on the outside of vessels’ hulls vitiate the ecosystem more serverly than ballast water.
Either way, when invasive algae arrive, strange things happen. Much like a biological virus that attacks the human body, invasive algae can morph in troubling ways. Most notably, they spread and regenerate rapidly while weakening their host. In fact, these weedy tropical species fragment and regrow whole plants from fragments in nutrient-poor, oxygen-rich conditions.
A Division of Aquatic Resources (DAR) study outlines the major economic and environmental damage invasive species inflict on the islands. Economically, the the state will experience “decreased property values, loss of tourism revenue, near-shore fishery impacts.” Add to this increased clean-up costs. Environmental impacts include native biodiversity depletion, functional changes to all major marine ecosystems, altered nutrient cycles, and decreased water supply. Tourism accounts for 20% of Hawaii’s gross domestic product. The state must implement major changes for the protection and conservation of the coral reefs. Otherwise, it stands to lose millions in tourism and local revenue.
As previously mentioned, invasive algae overgrow coral reefs, smothering and killing corals by blocking the sunlight they need to survive. These algae are difficult to control because of their ability to fragment readily and grow rapidly. This makes even their detection and classification difficult. The five major algae currently affecting the Hawaiian coral reefs are Smothering Seaweed, Gorilla Ogo, Leather Mudweed, Hook Weed, and Prickly Seaweed.
Smothering Seaweed is a Philippine native. Entrepreneurs introduced it during the 1970s hoping to produce a food thickener used in processed and milk-based foods. Smothering Seaweed grows in tumbleweed-like bundles. The Department of Land and National Resources (DLNR) notes that it causes a shift in the ecosystem. A low-diversity algae now infests a once coral-dominated environment. This habitual loss damages recreational and commercial fisheries.
Unfortunately, this agricultural undertaking never took root. Moreover, the entrepreneurs gave little thought to securing this seaweed to prevent introduction into the local ecosystem. In the span of roughly 50 years, the seaweed has taken over various coral reefs located in Oahu’s Kane‵ohe Bay. Now, invasive algae, not coral, dominate some areas of Kane‵ohe Bay.
This invasive seaweed damages more than just coral. It affects Green turtles as well. Teresa Dawson notes, “As the algae crowd out the turtles’ sleep holes and affect their feeding habitat and mating and cleaning stations. Green turtles will stand on coral outcroppings and allow reef fish to nibble away, they by getting their shells cleaned.” Worse still, many other species rely on these coral outcroppings for shelter and nutrients. Thus, they suffer, too.
Gorilla Ogo is another aquaculture release threatening Hawaii’s reefs and marine life. Its small, cylindrical, segmented branches typically intertwine themselves with nearby native plants, forming a thick mat. Because of its mat-like structure, Gorilla Ogo also grows under the coral formation, causing total suffocation and complete UV blocking of the formation. Gorilla Ogo tends to spread rapidly given its brittle nature and propensity to fragment. This invasive algae tends to be more successful in brackish waters or fish pools. This means it poses an obvious threat to any intertidal species that rely on these calm waters for their foraging needs.
Leather Mudweed’s origin is unknown, but Kittinger notes that it “was first observed in the Paikō area of Maunalua Bay following a large storm in 1987 that deposited a layer of terrestrial sediment on the reef flat.” Its structure is made up of paddle-shaped leaves that are connected to a stem-like root. By design, these algae trap marine debris that other aquatic creatures rely on for nutrients.
Generally found growing along sandy bottoms, this algae rivals and pushes out native sea grasses which are a vital nutrient source to some turtle varieties. By 2010, the Hawaiian DAR recorded up to 90% of the Paikō reef. Currently they estimate its spread to over 270 acres of reef in Maunalua Bay. Removal of Leather Mudweed can prove to be a strenuous task requiring ‘all hands on deck’ since it must be manually pulled from the smooth sediment and then placed in bags and removed from the site.
Hook Weed has long, slender, intertwining branches. The algae grows in knots and tangles due to its hook-like fingers. Florida aquaculture introduced it to the Hawaiian Islands. Like its counterparts, Hook Weed spreads by fragmentation but can also be free-floating while in bloom. When Hook Weed blooms, it washes ashore and can be found decaying in large, thick mats. These unsightly eyesores rapidly decrease property value.
In addition to its high growth rate, Hook Weed produces foul-smelling Hypnea blooms that have plagued Kihei in multiple ways. The state has had to remove 20,000 pounds a week. They’ve also spent $100,000 a year cleaning the beach. In addition, the state and county lose millions of dollars a year in lost rental income and decreased property values because of the Kaihei algae.
The Prickly Seaweed consists of thin spindly spines that branch out in a radial symmetry. It probably arrived on the island via ballast water or fouled ship hulls. Prickly Seaweed grows rapidly. It causes problems both above and below water given its ability to grow and germinate on hard surfaces. This includes growing on rock ledges and dead coral. Reducing its exposure to seawater will not hinder its growth. It has a high survival rate when exposed to air, while also being able to retain water. Since its introduction in 1950, it has become the most prolific invasive algae due to its existence on all the main Hawaiian Islands.
Clearly, the problem of invasive algae requires an immediate solution so that further damage by alien species may be mitigated. As with all solutions to environmental issues, cost is key. What kind of monetary investment will be required? What about manpower? The issue of reef cleanup hits home for many native islanders who have suffered economically and, in some cases, socioculturally.
The government group NOAA and state group DLNR are spearheading current efforts to reduce the spread of invasive algae. Furthermore, this ecological issue has caught the attention of professors and students from universities located on the Islands. Researchers have determined a need for both the removal of the algae and the revival of the native coral. Dawson notes, “Most of Hawaii’s alien algae grows on living coral reefs. Kappaphycus in Kaneˋohe Bay is increasing at a rate of 10 percent a month and as a result, areas of exposed coral are decreasing. And when the algae is removed, the coral beneath is sick or dying.”
Researchers hope that once workers clear the algae and infected corals heal themselves, then new coral will grow. Then, available seafloor real estate will no longer be at risk for invasive algae infection. NOAA’s response and restoration department notes a two-fold benefit from removing the algae from the area’s coral reefs. First, “clearing away the carpets of algae saves the corals that are being smothered beneath them. Second, opening up seafloor areas previously covered by algae alters the environment. Young corals can settle and establish themselves, growing new reef habitat. When native corals can support native marine life, the reef can defend itself against future invaders.”
Local and national lawmakers have proposed a “black list” to better catalog treatments that have been proposed, tried, and failed. Bishop Museum researchers Lucius Eldredge and Donna Turgeon propose a website listing all verified aliens. This pilot warning system could include risk assessments and predictions of those animals. It could aid in the development of federal and state rapid responses. It could also suggest mitigation measures as necessary.
This solution would benefit future researchers establishing treatment methods. However, it fails to enact the physical aspect of removal and revival. The DLNR/ DAR have formulated a plan that takes the black list one step further by introducing a financial plan. Organizers would establish a bank account to collect money from fines incurred by any damages caused by the reef. The funds collected would then be used in restoration efforts.
Under the proposed program, the DOT (Department of Transportation) would pay into the bank any amount agreed to by the DLNR and the Army Corps. Thus, the DOY would cover the cost of a restoration project that offsets coral damage. These would more likely be projects already ongoing, i.e. invasive algae removal at Kaneˋohe Bay. Once again, this solution does not answer the question of who will be doing this cleanup and restoration. Regardless, it would assist in the algae identification process and help determine funding sources for this restorative project.
University of Hawaii researchers have been conducting experiments with water composition. Their data might eventually determine whether a change in salinity or temperature can further help the reduction of alien algae. However, researcher Eric Conklin notes that the salinity and temperature levels needed to harm the algae have turned out to be too extreme. Moreover, temperature and salinity control experiments take place in a vacuum setting. Trying to establish a testable control group in the ocean would prove very difficult.
Currently, the manual removal of these algae receives much attention at state, local, and national levels. Biologists are considering using Tripneustes Gratilla, a native sea urchin that has shown a taste for Kappaphycus. Still, one Tripneastes Gratilla urchin takes a few months to clear a half square meter plot. This process might be too slow.
The use of sea urchins could still be one part of a polymorphous plan. Manual removal requires a properly trained work force. In 2013, local Hawaiians carried out a manual clean-up effort in Maunalua Bay in Oˋahu. Results indicated substantial economic benefits, including the creation of more than 60+ jobs. This improved the lives of more than 250 individuals and 81 households. A cleanup effort benefitting the local economy serves two purposes. First, the cleanup requires manual labor, e.g., employment. Second, locals gain the opportunity to have an active role in the betterment of their land.
NOAA has proposed the use of an underwater vacuum to facilitate the manual removal of the seaweed. A Super Sucker pulls the algae and its remnants through the hose up to a mesh table on the barge. People then pack the algae in mesh bags and take it back to shore. The Super Sucker would clear the way for researchers to embed sea urchins for further removal and reduction of future invasive algae.
After cleanup, what will people do with such large amounts of removed algae? Kittinger suggests some major benefits from the process. For instance, local farmers can use the invasive algae as compost. As a result, the project heightened community awareness and a broader sense of stewardship. This leads to collective community action.
Local Hawaiians will benefit economically and psychologically from being involved and employed in the clean-up effort. Kittinger observes that increased sharing of knowledge between generations will benefit the community. This will lead to the next generation better understanding the history of the bay. In turn, everyone will gain a stronger appreciation for ecosystem health. Providing a link between the community and its preservation gives all generations the opportunity to find commonality in the interest of preserving their native land.
Removing these various forms of invasive algae manually spells a realistic avenue for success. Attempting to save corals in a lab or with a database proves fruitless without manual labor. Hands-on activity gives the community a chance to get involved. It also adds another dimension to the sociocultural practices of the Hawaiian people. The invasive species problem plagues Hawaii. Proper mitigation and implementation could preserve native flora, fauna, and, in this case, organisms.
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Katherine Vandyke is a wife, mother of four, and college student. She enjoys the outdoors, thrifting, and reading.
