A tidal flat is a flat area of coastal land with a sandy or clayey bottom that is covered by seawater at high tide but exposed as land at low tide.
Biology and ecological characteristics of tidal flats
Tidal flats are one of the most productive ecosystems in the ocean. The productivity of tidal flats is 10 to 20 times higher than that of the open ocean, and it is known to have higher productivity than agricultural areas and forest areas. In addition, tidal flats are spawning grounds and habitats for a wide variety of organisms.
In tidal flats, some terrestrial plants, such as seaweed and plantain, have adapted to the marine environment and appear as saline plants, while microscopic, invisible benthic diatoms and phytoplankton cover the surface of the tidal flats.
The high productivity of tidal flats is primarily due to the high organic matter production capacity of these benthic diatoms through photosynthesis. In some places, land-derived saline plants appear in large quantities on the upper part of the tidal flats, resulting in high primary production, but most tidal flats in Korea maintain high primary production by benthic microalgae such as benthic diatoms, euglena, and blue-green algae.
In addition to the above primary producers, the high productivity of tidal flats is also maintained by organic matter that is transported from the land and deposited on the tidal flats and organic debris that falls from the water column. The organic matter accumulated in the mudflats is directly utilized by a variety of benthic animals, but most of it is broken down by bacteria and cycled through the sediment and water column as inorganic nutrients.
This high productivity of bacteria serves as the primary food source for microscopic zooplankton. Smaller ciliates prey on tidal flatworms, which in turn feed on larger benthic animals. The complex benthic microbial food web of benthic diatoms, bacteria, flagellates, and ciliates contributes to the basic energy flow of many benthic organisms in tidal flats.
Ecological and socioeconomic values
In addition to their high primary productivity, tidal flats are also important as nurseries for valuable fish and shellfish, so the destruction of tidal flats can adversely affect fish stocks in neighboring waters and lead to a reduction in fisheries yields.
Like the ecological value of tidal flats, the types of marine ecosystem services for assessing tidal flats’ productivity can be divided into two categories: market goods and non-market goods. Market goods include goods and services that are traded in markets, such as seafood consumption. For these goods, it is relatively easy to determine their economic value because price information is actually available.
半 Non-market goods, such as access to beaches or marine parks, are not market-traded goods or services, so economic valuation of these goods requires the use of non-market valuation methods. Tidal flats are very valuable because they provide both market and non-market goods such as seafood production, habitat for marine life, ecosystem balance, flood control, and typhoon damage reduction.