By Ruby Pap
Did you know it is World Wetlands Day on Feb. 2? Let’s celebrate by learning more about the science of wetlands, their importance and issues particular to Kaua‘i.
What exactly is a wetland? Wherever water covers the soil all or part of the time, it is probably a wetland. They are also often characterized by soft-stemmed vegetation adapted to saturated soil conditions.
It is illegal to drain or fill a wetland without proper permission. Contact the Army Corps of Engineers Honolulu District if you suspect you have a wetland on your property. Their website contains helpful information about jurisdictional wetlands: http://www.poh.usace.army.mil/Missions/Regulatory/Wetlands.aspx.
Wetland ecosystems play an integral part in the health of our natural environment, economy and society. Because of their capacity to store and filter water, they improve water quality and control flooding. They also provide important fish and wildlife habitat and help capture and store carbon. Despite these benefits, the value of wetlands is often misunderstood. In the U.S., wetlands were considered wastelands and were drained and filled regularly for agriculture and development until the latter half of the 20th century. Today, while environmental regulation and education has helped to curb this loss, wetlands are still under threat. Since 1900 approximately 64 percent of the world’s wetlands have been lost.
In Hawai‘i, 15 percent of wetlands have been lost since pre-settlement times, according to a 2014 study by Van Rees and Reed. While that number may not seem high, O‘ahu alone has experienced a 65 percent loss (119 square miles). This lends much importance to restoring and maintaining what is left. Kaua‘i has experienced a smaller loss, 8 percent (less than 19 square miles), which means we have an important opportunity to protect them. On Kaua‘i, wetlands today cover about 101 square miles.
Wetlands in Hawai‘i are of the following main types, according to the Hawai‘i Department of Land and Natural Resources: riverine, occurring along the edges of rivers or streams; palustrine, such as marshes or bogs occurring in mountains fed by springs and rainwater; and estuarine, such as brackish water swamps and marshes along the coast where streams enter the ocean. There are also farmed wetlands, such as kalo (taro) lo‘i and anchialine pools on the coastal shorelines of Hawai‘i island.
According to Van Rees et al, Kaua‘i has retained 100 percent of its mid-to-high elevation wetlands, but significant losses occurred in coastal areas, where drainage for sugar cane and other agriculture was common. Of particular note is the Mānā Plain, on Kaua‘i’s Westside, where there was once a large estuarine wetland, first used by Native Hawaiians for wetland taro production and then drained for sugar cultivation by European immigrants. A similar situation occurred in Kapa‘a on Kaua‘i’s Eastside. Additional areas of loss included riverine freshwater wetlands around suburban developments islandwide.
Hawai‘i’s wetlands are home to several rare and endangered plant and animal species, including endemic bird species. In addition to pressure from development, wetlands are threatened by non-native species and pollution. Sea level rise from climate change threatens to drown coastal wetlands, but also form new wetlands inland as the saltwater pushes the freshwater lens to the surface. This points to the need for further research into where these wetlands are likely to occur, and making plans for the future. Upland palustrine wetlands are also affected by rising temperatures and precipitation changes. Diseases affecting native birds, such as Avian botulism, are expected to increase as temperatures rise.
Some of my favorite wetlands to visit on Kaua‘i include the Alaka‘i Swamp in Koke‘e State Park, Kawai‘ele Waterbird Sanctuary on the Mānā Plain, and the Hulē‘ia estuary restoration site. If you are interested in getting involved, keep your ear to the ground for opportunities on Feb. 2 and beyond. Here are a couple of websites to check: Mālama Hulē‘ia at https://malamahuleia.org/ and Hanalei National Wildlife Refuge at https://www.fws.gov/refuge/hanalei/.
Happy World Wetlands Day!
- Ruby Pap is a Coastal Land Use Extension Agent at University of Hawai‘i Sea Grant College Program. She can be reached at firstname.lastname@example.org.