Collection of Groundwater and Freshwater Fauna on the Islands of the South Pacific. Operation Raleigh -- Pacific Crossing

During this project about 150 groundwater habitats were sampled on a number of islands in the South Pacific. The main habitats sampled were: wells, springs, caves, beaches and streams. Groundwater fauna was only found on two islands. On Easter Island we found a new species belonging to the Isopoda (Crustacea), living in marine groundwater interstitia. On Tongatapu a new species of groundwater Amphipoda (Crustacea) was found in Anahulu Cave. Fragments which possibly belong to the same species were found in some wells on the island. Many samples have not yet been sorted out. Therefore it is possible that more groundwater species will be found, particularly in the beach samples from the Cook Islands, and in the spring, cave, well, and beach samples of the Samoa’s. The absence of groundwater fauna on most volcanic islands was expected, but the lack of groundwater fauna on the uplifted coral islands, such as the outer Cooks, was surprising. Tongatapu and the other Tongan islands seem to be more promising as far as groundwater fauna is concerned. As a side-study many freshwater shrimps have been collected on the Cook Islands and the Samoa’s. On Robinson Crusoe Island, Henderson, Pitcairn, Atiu, and ’Eua, terrestrial Amphipoda belonging to the family Talitridae (sandhoppers or beach fleas) have been found.