There are many different types of wetlands, they are varied and diverse, and many types are specific to their areas. In Hawaii, we have our own types of wetlands many of which are not found elsewhere. Because of this diversity, it is even difficult for the experts to agree on a single classification system. So in many cases, local definitions and characterizations are used. Hawaiian wetlands are also areas that have been historically utilized and highly valued by Hawaiian society because they contain the most precious and abundant resources such as food and water. The RAMSAR definitions have a broad application because it refers to their geology and place within the watershed. The “Ramsar Convention” has adopted a Ramsar Classification of Wetland Type which includes 42 types, grouped into three categories: Marine and Coastal Wetlands, Inland Wetlands, and Human-made Wetlands.
The RAMSAR definitions have 5 groupings of the major wetland types:
- Marine (coastal wetlands, coastal lagoons, rocky shores, seagrass beds, coral reefs)
- Estuarine (deltas, tidal marshes, mudflats, mangrove swamps)
- Lacustrine (wetlands near lakes)
- Riverine (wetlands near rivers/streams)
- Palustrine (marshes, swamps, bogs)
Wetlands can be natural or manmade: Man-made wetlands can be intentional or unintentional. Intentional wetlands include artificial wetlands or wetland mitigation. Mitigation wetlands (like the ones at Azeka/Pi’ikea in Kihei) are where the original wetlands are relocated. It is widely understood that natural wetlands are far superior to artificial wetlands in many ways. Wetlands are far more than “water features”, they are also repositories of biological diversity and habitat to macro and microflora and fauna. For every species of plant, you can see there are millions of bacteria dependent on those plants that you cannot see. A balanced wetland ecosystem will have millions of species of microorganisms that depend on the life cycles of various plant and animal species. So a long-established natural wetland will have a far greater biological diversity that is not easily replicated by man.
ANTHROPOGENIC FACTORS: The word “Anthropogenic”, refers to “human impacts”. When human activities such as construction alter the natural hydrology of an area, the location and disposition of wetlands change, and new wetlands can be created. Examples of human-influenced wetlands can include, dams, lakes, watercourses, retention ponds, and water features on golf courses. Also retention basins, leech fields, French drains, culverts, irrigation ditches, fish ponds, wetland agriculture, fish-farms, marinas, breakwaters, land reclamation, dikes and levies, sewerage ponds, stormwater retention basins, and wetland mitigation.
DEWATERING: When humans want more land they often repurpose natural waterscapes such as wetlands by “dewatering” them. Many wetlands are deliberately dewatered so that the land can be used for “useful” purposes, such as agriculture or land for development. Drainage ditches are a major factor in wetland health and distribution. Drainage ditches and canals crisscross the landscape, to “dewater” naturally wet areas. On Maui, dewatering wetlands have occurred on a massive scale. And if ever the dewatering infrastructure was to fail, these areas would quickly “re-water” themselves and revert back to their natural wetland hydrology.
WETLAND DISPLACEMENT: When one wetland is displaced another is often created. Areas of man-made surface runoff are regularly diverted onto open ground. Culverts and bridges along roadways have the tendency to concentrate water flows into new areas. Stormwater management infrastructure redistributes the hydrology supporting wetlands and can cause them to migrate, or reappear in totally new areas. Irrigating farmland causes new sources of water, and alters hydrology. Transporting water from sources like rivers to other areas creates a new pathway for water and new hydrology for wetlands.
RECLAIMED WETLANDS: Much of coastal lands used for development are built on “reclaimed wetlands” Often a system of drainage ditches is used to reduce the water levels. However, if this drainage system is not maintained or ever fails the original hydrology is likely to return, and then the original wetlands will reclaim these areas.
UNDERLYING HYDROLOGY: It is very difficult to totally remove the underlying hydrologic geography that creates these wetlands. Wetlands can be temporarily disrupted by man’s activities but the underlying architecture usually remains, waiting for the water to return.
CLIMATE CHANGE: Climate change, increasing rainfall, and rising water tables will hasten the return of wetlands. Wetlands have the ability to revert back to naturally functioning wetlands fairly quickly, and many wetland species are always ready to inhabit any new territory, or re-inhabit an old one.
There are many different types of wetlands found on the island of Maui in Hawaii, including mangroves, salt marshes, bogs, coastal estuaries, tide pools, springs, streams, ephemeral marshes, anchialine pools, inland fishponds, and offshore fishponds. Each of these types of wetlands has its own unique characteristics and ecological features. Here is a table that provides a few definitions and examples of the types of wetlands found on Maui:
|Mangroves||Mangrove forests are tropical coastal wetlands characterized by the presence of mangrove trees. These trees are adapted to grow in saltwater and are important habitats for a variety of species.||The mangrove forests of Kahului Bay on Maui are home to a diverse array of plant and animal species, including fish, crabs, and birds.|
|Salt Marshes||Salt marshes are wetlands that are characterized by the presence of salt-tolerant plants and are often found in coastal areas. These wetlands provide important habitats for a variety of species and serve as a buffer against coastal erosion and storms.||The salt marshes of Maalaea Bay on Maui are home to a diverse array of plant and animal species, including grasses, crabs, and shorebirds.|
|Anchialine Pools||Anchialine pools are small, shallow bodies of water that are found in coastal areas and are connected to the ocean through underground channels or conduits. These pools are often found in lava tubes or other geologically formed depressions in the ground and are home to a diverse array of flora and fauna.||The anchialine pools of Waianapanapa State Park on Maui are home to a variety of unique species, including shrimp, crabs, and snails.|
|Paulistrine wetlands||Paulistrine wetlands are a type of palustrine wetland, which refers to wetlands that are not directly connected to a body of standing water, such as a lake or river. These wetlands typically have soil that is saturated with water for at least part of the year, and are characterized by the presence of hydrophytic (water-loving) vegetation, such as sedges, rushes, and marsh grasses.||Waihe’e Coastal Dunes and Wetlands Sanctuary: This wetland is located on the north shore of Maui, and is home to a variety of rare plants and animals, including the endangered Hawaiian stilt and Hawaiian coot.|
|Riverine wetlands||Riverine wetlands are a type of wetland that is directly connected to a river or stream, and are characterized by the presence of flowing water. These wetlands may be subject to fluctuating water levels, depending on the flow of the river or stream. Riverine wetlands are often home to a variety of plants and animals, including fish, amphibians, and birds.||Waikamoi Preserve: This wetland is located on the eastern side of Maui, and is home to a variety of native plants and animals, including the endangered Hawaiian hawk and Hawaiian hoary bat.|
|Estuarine wetlands||Estuarine wetlands are a type of wetland that is located where fresh water from rivers and streams mixes with salt water from the ocean. These wetlands are often characterized by their brackish (slightly salty) water and the presence of both freshwater and saltwater plants and animals. Estuarine wetlands are important habitat for a variety of species, including fish, shellfish, and birds.||Kanaha Pond State Wildlife Sanctuary: This wetland is located on the north shore of Maui, and is home to a variety of birds, including the endangered Hawaiian coot and Hawaiian stilt.|
|Lacustrine wetlands||Lacustrine wetlands are a type of wetland that is directly connected to a lake or other body of standing water. These wetlands are typically characterized by the presence of hydrophytic (water-loving) vegetation, such as sedges, rushes, and marsh grasses. Lacustrine wetlands are important habitat for a variety of plants and animals, including amphibians, fish, and birds.||Keālia Pond NWR is named after the main body of water that provides all 200 acres of lacustrine wetlands on the Refuge.|
|Marine wetlands||Marine wetlands are wetlands that are located in the marine (saltwater) environment, and are typically characterized by the presence of saltwater plants and animals. These wetlands may be found along the coast, in estuaries, or on coral reefs. Marine wetlands are important habitat for a variety of species, including fish, shellfish, and birds.||Honolua Bay: This marine wetland is located on the west side of Maui, and is home to a variety of marine plants and animals, including coral reefs and endangered sea turtles.|
|Fishpond wetlands||Fish pond wetlands are man-made wetlands that are used for the cultivation of fish, shellfish, or other aquatic organisms. These wetlands are typically constructed by building a dam or levee to create a pond or lake, and are often used for both commercial and recreational purposes. Fish pond wetlands may be fed by a source of fresh water, such as a river or stream, or may be supplied with seawater.||Ke’anae Fishpond: This fish pond wetland is located on the east side of Maui, and is used for the cultivation of a variety of aquatic species, including tilapia, shrimp, and oysters.|
Source: “Anchialine Pools in Hawaii: A Review of Their Ecology, Biogeography, and Conservation” by J.E. Briggs and K.G. Johnson (Hydrobiologia, 2002)
Source: “Wetlands of Hawaii: Types and Functions.” Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlife, www.dlnr.hawaii.gov
Paulistrine wetlands are a type of palustrine wetland, which refers to wetlands that are not directly connected to a body of standing water, such as a lake or river. These wetlands typically have soil that is saturated with water for at least part of the year, and are characterized by the presence of hydrophytic (water-loving) vegetation, such as sedges, rushes, and marsh grasses.
In Maui County, there are several examples of palustrine wetlands, including:
- Waihe’e Coastal Dunes and Wetlands Sanctuary: This wetland is located on the north shore of Maui, and is home to a variety of rare plants and animals, including the endangered Hawaiian stilt and Hawaiian coot.
- Honokōhau Wetland: This wetland is located on the west side of Maui, and is home to a variety of native plants and animals, including the endangered Hawaiian hoary bat.
- Kanaha Pond State Wildlife Sanctuary: This wetland is located on the north shore of Maui, and is home to a variety of birds, including the endangered Hawaiian coot and Hawaiian stilt.
Source: “Wetlands of Hawaii: Types and Functions.” Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlife, www.dlnr.hawaii.gov/ecosystems/wetlands/types-functions/.