This page last revised 12 May 2009 -- S. Falzarano
Introduction
Ecoregion
Conservation Targets
Viability
Goals
Portfolio
TNC Action Sites
Threats
Strategies
Acknowledgements
▫
Tables
Maps & Figures
CPT Database
Appendices
Glossary
Sources
.
Anchialine Pools
Anchialine pools are land-locked bodies of water of varying salinity that are adjacent to the ocean. These pools have indirect, underground connections to the sea, and show tidal fluctuations in water level. The term "anchialine" was first coined by Holthuis (1963) and is derived from the greek: [anchi] = near, and [halos] = the sea, referring to the proximity of anchialine pools to the ocean.
Found only in the coastal tropics and subtropics, anchialine pools support a unique biota which is still poorly understood. Hawaiian anchialine pools include at least seven aquatic species that are currently believed to be rare worldwide, and new species undoubtedly await discovery. Anchialine pool species are tolerant of varying salinity and include those adapted to a partially subterranean habitat offered by groundwater under the pools. Characteristic anchialine pool species include crustaceans (e.g., shrimps, prawns, amphipods, isopods, etc.), some of which seem restricted to anchialine habitat. Hawaiian anchialine pools are often occupied by small endemic red shrimp (Halocaridina and others) called ʻōpaeʻula. Other species are restricted to the surface waters of the pools, and include a few fish species, crustaceans and other invertebrates. Two endangered waterbirds (Hawaiian Stilt and Hawaiian Coot), and several species of migratory waterfowl also use these pools.
Distribution:
Globally, anchialine pools are found in a limited set of areas where fresh lava or limestone occurs adjacent to the sea. Anchialine pools are known from sites in the Indo-Pacific (as far west as the Red Sea) as well as the Caribbean. Some Hawaiian anchialine pools show extremely high invertebrate and algal diversity, among the highest in the Indo-Pacific, and perhaps the world.
ʻŌpaeʻula, Halocaridina
rubra is the signature animal of
Hawaiian anchialine pool habitat. Learn
more.
In
the Hawaiian High Islands ecoregion,
anchialine pools have been reported from five islands -- Hawaiʻi, Maui,
Molokaʻi,
Oʻahu, and Kahoʻolawe. The
island of Hawai`i clearly supports the majority of the state's
anchialine
resources: a total of more than 460 pools in about 80 sites have been
identified on the ground, and an additional 54 sites (about 170 pools)
have
been viewed or photographed from the air.
This agrees with another published conservative estimate of 600-650 pools for this island. On the other islands, an additional 15 sites have been reported. However, very few (such as ʻĀhihi-Kīnaʻu, Maui and Lua o Palahemo, Hawaiʻi) have been systematically surveyed.
Threats to Anchialine Pools
Threats to anchialine pools include contamination of water sources, introduction of alien species, especially alien fish, and direct modification of substrate or filling. However, the effects of these changes are difficult to monitor. There are relatively few protected examples of anchialine pools, but some are present in ʻĀhihi-Kīnaʻu Natural Area Reserve (Maui), Manukā Natural Area Reserve (Hawaiʻi), and Hawaiʻi Volcanoes National Park.
This agrees with another published conservative estimate of 600-650 pools for this island. On the other islands, an additional 15 sites have been reported. However, very few (such as ʻĀhihi-Kīnaʻu, Maui and Lua o Palahemo, Hawaiʻi) have been systematically surveyed.
Threats to Anchialine Pools
Threats to anchialine pools include contamination of water sources, introduction of alien species, especially alien fish, and direct modification of substrate or filling. However, the effects of these changes are difficult to monitor. There are relatively few protected examples of anchialine pools, but some are present in ʻĀhihi-Kīnaʻu Natural Area Reserve (Maui), Manukā Natural Area Reserve (Hawaiʻi), and Hawaiʻi Volcanoes National Park.
Alien
fish can greatly disrupt anchialine pools by suppressing native
invertebrates, adding nutrients, and triggering large changes in algal
communities.
Anchialine
Pools of the Ecoregional Portfolio
The vast majority of anchialine pools in the ecoregion occur on the island of Hawai'i. Because of the limited number of anchialine pools found on other islands, all of them are included in the coastal portfolio.
The vast majority of anchialine pools in the ecoregion occur on the island of Hawai'i. Because of the limited number of anchialine pools found on other islands, all of them are included in the coastal portfolio.
Anchialine pools on O'ahu and selected aquifers with pools
Anchialine pools on Moloka'i and selected aquifers with pools
Anchialine pools on Kaho'olawe
Anchialine pools on Hawai'i island and selected aquifers with pools
Anchialine pools on Maui and selected aquifers with pools
Anchialine pools statewide