I thought I would take a break from my usual subjects, software development, Hawaiʻi's tech industry and policy issues, to write a few thoughts about my favorite little ecosystems - anchialine pools. Scientists have identified about 150 unique ecosystems in our state ranging from the awe inspiring alpine deserts of Mauna Loa to the world's wettest rainforests on Kauaʻi. They are all fascinating, but my favorites have always been the anchialine pools of the Big Island and Maui.
Anchialine pools are located near the coast. They have subterranean connections to the ocean, but no surface connection. Hawaiʻi's anchialine pools are made from fresh groundwater mixed with ocean water that seeps in through porous lava to form unique brackish environments. We benefit from having the highest concentration of anchialine pools in the world. They are home to hundreds of organisms unique to Hawaii and, in some cases, to a single pool!
This weekend while exploring Kaloko-Honokōhau Park and the area around Waikoloa, we observed single ponds no larger than a dining room table with a dozen fish, mollusk and crustacean species. Three types of shrimp are found in these pools - Halocaridina rubra ('Opae'ula), Palemon debilis ('Opae'huna) and Metabetaeus lohena. These highly adapted shrimp are omnivorous, can tolerate greatly varying salinity, and are able to live in a dormant state deep underground for long periods of time. They have been found in wells as far as a mile inland.
The extreme colors of the biota juxtaposed against the jet black lava make Hawaiʻi's anchialine pools visually striking. Bright orange and green algae mats typically cover the bottom of the pools and the edges are often covered by green, red and orange succulent plants. Apparently the 'opae'ula's bright red color made it a popular bait for the ancient Hawaiians.
Like any small ecosystem, anchialine pools are delicate, and easily disrupted by humans. Something as simple as a group of sunblock covered tourists wading through a small pool could bring an end to a unique species, so its important we take great care when exploring these environments.
Mika is giving me stink eye, so I best get back to relaxing. We hope you enjoy the pictures. They were taken with an iPhone, so please excuse the quality.