Hawaiʻi's Anchialine Ponds

A Hands-on Guide to Hawaiʻi’s anchialine pond habitat

Grade Level: Kindergarten

Purpose: This curriculum is designed to communicate:

How the anchialine ponds of Hawaiʻi are physically and biologically structured.
What the major natural and human induced impacts to the anchialine pond habitat are.
How we use science to study the anchialine pond habitat and manage the people and resource within the habitat.
How anchialine ponds are culturally important and who uses them.

Rationale: Anchialine ponds are one of Hawaiʻi’s most threatened ecosystems. There are about 700 known anchialine ponds in Hawaiʻi. Most Hawaiian anchialine ponds are in the youngest lava areas of the Big Island of Hawaiʻi and Maui. They exist in inland lava depressions near the shore and contain brackish (a mixture of freshwater and saltwater) water. Freshwater id fed to the ponds from ground water that moves downslope and from rainwater. Ocean water seeps into the ponds through underground crevices in the surrounding lava rock. Fresh ground water forms a cold freshwater lens floating on top of the warmer ocean water because freshwater is less dense than salt water. As ocean water level rises and falls with the tide, the salinity of the pond varies, exemplifying an ecosystem always in flux.

Common plants that grow within anchialine ponds include seaweeds, blue-green algae, and native grasses. Native plants such as pickleweed, sedges (makaloa), and herbs (ʻakulikuli) also grow around the edges of anchialine ponds. Damselflies, eels, crustaceans, mollusks, and fish such as mullet and gobies can be found in ponds that are closer to the ocean. Inland ponds are typically dominated by tiny, endemic shrimp called ʻopae ‘ula.

This unit includes demonstrations of the physical properties of saltwater and freshwater via the scientific method, observations of live ʻopae ʻula in the classroom, and a visit to an anchialine pond to survey the flora-fauna. The lessons are inquiry-based with connections to art, reading, writing, and critical thinking throughout. The lessons stress both the biological and cultural importance of this ecosystem. It is estimated that 98% of anchialine ponds are no longer pristine and cannot support ʻopae ʻula. Therefore, lessons also facilitate discussions on the issues that threaten the ponds today, such as development and introduced species. These discussions bring students in touch with these systems to help preserve these fragile ecosystems.

Downloadable Lessons

This unit was created and piloted by Jackie Gaudioso, Bobby Hsu & Diane Duke