“An Unique Anchialine Pool in the Hawaiian Islands”, 1998 ():
The Sailor’s Hat crater was artificially formed on the south coast of Kaho’olawe Island in 1965 with explosives. The explosion formed a crater about 50m from the shoreline, which penetrates the watertable to a 5m depth.
The pool at the bottom of the crater meets the criteria of an anchialine pond because it shows tidal fluctuation, has measurable salinity, and lacks surface connections to the sea. The water chemistry of this pool is similar to the ocean except silica is elevated and salinity is slightly depressed suggesting a small groundwater influence. The fauna is dominated by water boatmen, an endemic shrimp and tubeworm, polychaetes, amphipods, an ostracod, gastropod, solitary ectoproct. anemone, flatworm and sponge. The atyid shrimp, Halocaridina rubra, is a characteristic species of Hawaiian anchialine systems and probably colonized this 32-year old pool by active migration via the watertable. Colonization by the remaining fauna may have occurred by storm surf (for marine species) or with the wind. Most predators are unable to inhabit anchialine ponds because of difficult access due to physical barriers, or to unsuitable ecological conditions. The anchialine habitat and life history strategy of the atyid shrimp have probably been important influences on the adaptive success of H. rubra in the Hawaiian Islands, and may be important characteristics of hypogeal anchialine species elsewhere.
[Keywords: anchialine, shrimp, colonization, watertable, Hawaiian]
…The life history and behavior of Halocaridina rubra suggests that it is a fugitive species that cannot tolerate the high level of predation that is present in most Hawaiian aquatic systems. Thus H. rubra colonizes and is successful in marginal habitats that most predators are either unable to colonize because of physical barriers or the ecological conditions are inappropriate. Sailor’s Hat pool probably represents such a marginal habitat and may be the only site on Kaho’olawe where this shrimp species has sufficient food resources and protection from predators to sustain a viable population level. Given the ecological characteristics of this pool and barring further disturbance from humans or predators, it may be colonized and serve as a habitat for other rare Hawaiian anchialine species in the future.