Last week I attended a talk given by a federal biologist who, before her funding was cut, worked with Hawaii’s anchialine shrimp, known as opae ula. Although these shrimp inspire nearly endless questions, I had a specific one in mind: Is it OK for a conservation-minded person to buy anchialine shrimp, sold in jars at Shirokiya and also online?
"Anchialine" (AN-key-ah-lin) is a Greek term meaning near the sea, and describes pools with indirect connections to the ocean. The coastal pools are found in limestone and lava deposits where fresh water and seawater both percolate through the porous rock.
The salt content of anchialine pools varies from pool to pool and from top to bottom. Most pools fluctuate with the tides, but the water doesn’t always mix. Often the deepest part of a pool contains seawater, the middle is brackish and the top is fresh.
At least seven aquatic species thrive in Hawaii’s anchialine pools. Some found in Hawaii are also found in pools of Egypt and Japan, but Hawaii’s most famous inhabitant is the endemic opae ula, the Methuselah of shrimp. Most live from one to six years. No one knows how long the half-inch opae ula can live, but some are still going strong after 20 years in captivity.
Opae ula can also live in fresh to supersalty water and tolerate a 20-degree water temperature change.
Opae ula are "Field of Dreams" creatures in that if you dig it, they will come. Individuals somehow survive for decades in aquatic underground cracks and crevices. But if someone digs a hole above their caves to the surface and cleans all soil and clay from the pores, up come the shrimp.
Life in the sun is grand, with food growing on rocks. With ample algae and bacteria to graze on, the shrimp thrive and multiply.
Oahu, Maui, Kahoolawe and Hawaii island all have anchialine pools containing opae ula. Most are hard to find or visit, but a couple on Hawaii island are easy. Owners of the Kona sea horse farm, Ocean Rider, dug their own pool, and it’s so loaded with opae ula that managers feed the shrimp to their baby sea horses. The Four Seasons Resort at Hualalai also has attractive pools, black lava speckled in bright red.
So. Should admirers of opae ula buy them?
No, the biologist told me. Although the shrimp aren’t officially listed as endangered, their habitat is in trouble. Alien fish introduced to the few remaining anchialine pools eat the shrimp, and hole-filling for development destroys their homes. Also, she said, the shrimp don’t do as well as advertised in those closed ecosystems.
But the government program that enabled this biologist to study the shrimp and restore several of Oahu’s anchialine pools was eliminated by budget cuts. Perhaps by sharing details about their special pets, informed opae ula owners help inspire support to fund studies and protect pools.
To buy or not to buy is just one more opae ula unknown. But one thing I do know. Whether gazing at these creatures in a glass jar, an open aquarium or an anchialine pool, the tiny red crustaceans give a person a lot to think about.
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Reach Susan Scott at www.susanscott.net.
