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Seaweed, macroalgae, kelp there are many different names for the plants of the ocean but in Hawaii, it’s limu.
Before Western contact, the Hawaiian culture and lifestyle had limu. It was used in many dishes, but also in medicine and cultural practices like dyeing clothes or making lei. One variety limu kalaAs a way to forgive the participants who ate or held the plant, he was often a part of hooponopono reconciliation ceremonies.
Limu is the base of the marine food chains and provides shelter and food for smaller invertebrates as well as herbivores.
Over the past two decades, however, native limu has faced many challenges in Hawaii’s waters. The deadly combination of groundwater contamination and land development has made it difficult for limu to survive.
Veronica Gibson, a doctoral student in the University of Hawaii Manoa has been studying limu since 2000. She says we are only just beginning to understand it. It is clear, however, that people play a significant role in shaping its future.
She said that humans are the ecosystem engineers, and they decide what becomes invasive and how to control these impacts.
Gibson believes that if people are more aware of how native ecosystems look, they will be better equipped to report abnormalities.
She said that we want to manage it for future generations so they can enjoy these things, and not lose the biodiversity and productivity associated with them.
It is difficult to solve the problem. But it starts with understanding what’s invasive and why.
The Department of Land and Natural Resources offers a comprehensive list of resources. List of invasive speciesIn Hawaii. It is well-known for taking over native species like hook weed, muckweed, and even smothering.
Invasive macroalgae are usually defined as an alien species that can overtake reefs or inhibit the growth and development of other plant, invertebrate or fish populations. Even native limu may overtake coral, and introduced limu might adapt to their environment.
Ryan Okano, DLNR Ecosystem Protection Program Director, said that he views introduced or alien as a state. I consider invading a characteristic that can only be expressed by introduced species in unnatural circumstances.
Gracilaria salicorniaThe gorilla ogo (or gorilla ogo) was originally brought to Hawaii to be eaten. Although some people use it for poke or pork, the small and stocky species was introduced to Hawaii from Hilo.
Gibson has watched the spread in Oahu waters of gorilla ogo over the past 12 years, even taking part in cleanups in Waikiki.
Be careful of what you introduce because it’s really hard to predict what will happen, Gibson said.
Fragmentation, which is the asexual reproduction of a single fragment, enabled gorilla ogo to quickly take over the east and north shores from its native counterpart, limu Manauea.
Gibson stated that it can change the ecosystem by increasing its abundance, but it is not desirable.
Wally Ito is a local limu expert who retired recently as a coordinator Kuaina Ulu AuamoOver the past 50 years, he has seen how invasive limu overtaken native species.
The Kahe and Ewa shorelinesOnce prized for their many limu varieties, they were once highly valued. Ito recollects that the beaches were covered in a variety of shades of green and that locals would take them home.
Increased urbanization and agriculture inland led to a decrease in the groundwater needed for Limu to thrive in coastal waters. Native limu didn’t have a chance. Invasive species were introduced to Hawaii waters in the 1970s and ’80s for aquaculture.
Ito spends his time sharing his knowledge about limu with communities that want to restore it on their shorelines. He is known as Uncle Wally and often takes students and other community members on limu walks to survey the growth and types at Oahu beaches.
There are many shades to limu, both literally as well as figuratively. It’s not just good limu versus bad limu. Scientists must consider how invasive algae is affecting entire ecosystems both negatively and positively.
Limu is an important food source for fish, urchins, and limpets. It also acts as a sanctuary for small marine life. Some limu can even help create sand or build up reefs.
Okano stated that it is not about controlling bad limu. We must also think about what we have done to these ecosystems.
Limu requires nutrient-rich groundwater for its survival. However, if it is polluted by humans, even native limu may develop invasive traits. There are many ways to make a difference: wastewater, conventional agriculture, land development, and cesspools.
Gibson stated that native species will grow very fast to absorb all the nutrients. Too much algae can cause the fish to become sick and reduce their oxygen levels, which will eventually force them to leave.
The climate change, especially the effects on rising sea levels and warmer oceans, further complicates matters.
Kanoe Morishige, a Coordinator Na Maka Onaona, who has studied opihi, limu, and haukeuke populations. She predicts that limu will die back if there is little or no wave movement and prolonged temperatures. This, in turn can change the food and habitat of fish while making it possible for invasive species like limu to thrive.
She said that if these types of environmental factors change in the right timing, it can actually offset the growth of the population.
Keeping the needed balance of an ecosystem is hard, she said, and it’s only worsened by invasive species and out-of-season changes happening in the waters.
Nicole Yamase is aware that there are more than 500 species of limu in Hawaii. We are only just beginning to understand limu’s growth and ecology. Because of its importance in Hawaiian culture, the Micronesian doctoral candidate loves studying limu in Hawaii.
She said that she wanted to make this connection and bridge the knowledge gaps.
In Hawaii, there are so many cultural practices associated with limu due to its abundance and accessibility. What happens if there is less native limu
No limu, no culture, Yamase said.
As Hawaii deemed 2022 The Year Of The LimuThere is still much to learn. Yamase says it is a sign that people care about sharing native limu knowledge with the community. She is currently studying limu Kala, a species Ito hopes will become the state’s limu.
Morishige said its more than just learning about limu as food; it’s a way to bring people together and champion traditional knowledge.
She explained that Limu traditions are tied with an intimate understanding of place as well as a kuleana that our fishermen have to their wider communities.
And limu will be the proverbial canary in the coal mine when it comes to the health of our nearshore ecosystems, she said, so it’s important to pay attention to it. She knows that if the limu environment changes, it will have an impact on the haukeuke, opihi, and fish populations. Because all these systems are interconnected and depend on each others, they can’t be separated.
Limu will be our first indicator on the shoreline as far as what’s happening in the ocean and on land, Morishige said.
Civil Beats coverage of climate changes is supported by the Environmental Funders Group at the Hawaii Community Foundation, Marisla Fund at the Hawaii Community Foundation, and the Frost Family Foundation.
“Hawaii Grown” is funded in part by grants from the Ulupono Fund at the Hawaii Community Foundation and the Frost Family Foundation.
