Anchialine pool

Anchialine pool in Maui, Hawaii, with the ocean in the background

Ecologists collecting organisms from an anchialine pool in Maui

An anchialine pool or pond (pronounced "AN-key-ah-lin", from Greek ankhialos, "near the sea") is a landlocked body of water with a subterranean connection to the ocean. Anchialine pools are a feature of coastal aquifers which are density stratified, with the water near the surface being fresh or brackish, and saline water intruding from the coast below at some depth. Depending on the site, it is sometimes possible to access the deeper saline water directly in the anchialine pool or sometimes it may be accessible by cave diving.^[1]

Water levels in anchialine pools often fluctuate with tidal changes due to the coastal location and the connection with the ocean.^[2] The range in water levels fluctuations will be decreased (damped) and delayed compared to the range and time observed for the adjacent tide. The primary controls on the damping and lag are the distance from the coast, and the hydraulic conductivity of the geological materials.

Anchialine pools are extremely common worldwide especially along neo-tropical coastlines where the geology and aquifer system are relatively young, and there is minimal soil development. Such conditions occur notably where the bedrock is limestone or recently formed volcanic lava. Many anchialine pools are found on the coastlines of the island of Hawaii, and on the Yucatán Peninsula, where they are locally called cenotes as well as Christmas Island.^[3]

Ecological studies of anchialine pools frequently identify regionally rare and sometimes endemic species living in them.

In Hawaii, the pools are home to mostly the ʻōpaeʻula (Hawaiian shrimp, Halocaridina rubra). The Sailor's Hat crater created by an explosives test in 1965 is an anchialine pool.^[4]

In karst anchialine pools and the caves these may be connected to, the fauna are diverse and include: crustaceans including remipedia and copepods, and among the vertebrates are several species of blind cave fish and eels.

See also

• Brackish water
• Cenote

References

External links

Wikimedia Commons has media related to Anchialine pools.

• Anchialine Pool Information United States Geological Survey, National Park Service 2005
• Anchialine Caves and Cave Fauna of the World

Ponds, pools and puddles
Ponds	Ash pond Balancing lake Ballast pond Beel Cooling pond Detention pond Dew pond Evaporation pond Facultative lagoon Garden pond Ice pond Immersion pond Kettle pond Log pond Melt pond Mill pond Raceway pond Retention pond Sag pond Salt evaporation pond Sediment pond Settling pond Solar pond Stabilization pond Stepwell Stew pond Stormwater management pond Polishing pond Tailings Tarn Treatment pond Waste pond
Pools	Anchialine pool Brine pool Natural pool Plunge pool Reflecting pool Spent fuel pool Stream pool Swimming pool Tide pool Vernal pool
Puddles	Bird bath Coffee ring effect Puddle Puddles on a surface Seep puddle
Biota	Beaver dam Duck pond Fish pond Goldfish pond Koi pond
Ecosystems	Freshwater ecosystem Lake ecosystem Lentic ecosystem Aquatic ecosystem
Related topics	Aerated pond Bakki shower Big fish–little pond Body of water Full pond Hydric soil Phytotelma Water aeration Pond of Abundance Pond liner Ponding Puddle (M C Escher) Spring Swimming hole Water garden Water Lilies (Monet) Water well

Coastal geography
Landforms	Anchialine pool Archipelago Atoll Avulsion Ayre Barrier island Bay Baymouth bar Bight Bodden Brackish marsh Cape Channel Cliff Coast Coastal plain Coastal waterfall Continental margin Continental shelf Coral reef Cove Dune cliff-top Estuary Firth Fjard Fjord Freshwater marsh Fundus Gat Geo Gulf Gut Headland Inlet Intertidal wetland Island Islet Isthmus Lagoon Machair Marine terrace Mega delta Mouth bar Mudflat Natural arch Peninsula Reef Regressive delta Ria River delta Salt marsh Shoal Shore Skerry Sound Spit Stack Strait Strand plain Submarine canyon Tidal island Tidal marsh Tide pool Tied island Tombolo Windwatt
Beaches	Beach cusps Beach evolution Coastal morphodynamics Beach ridge Beachrock Pocket beach Raised beach Recession Shell beach Shingle beach Storm beach Wash margin
Processes	Blowhole Cliffed coast Coastal biogeomorphology Coastal erosion Concordant coastline Current Cuspate foreland Discordant coastline Emergent coastline Feeder bluff Fetch Flat coast Graded shoreline Headlands and bays Ingression coast Large-scale coastal behaviour Longshore drift Marine regression Marine transgression Raised shoreline Rip current Rocky shore Sea cave Sea foam Shoal Steep coast Submergent coastline Surf break Surf zone Surge channel Swash Undertow Volcanic arc Wave-cut platform Wave shoaling Wind wave Wrack zone
Management	Accretion Coastal management Integrated coastal zone management Submersion
Related	Bulkhead line Grain size boulder clay cobble granule pebble sand shingle silt Intertidal zone Littoral zone Physical oceanography Region of freshwater influence
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