Occurrence and density of Halobates micans (Hemiptera: Gerridae) in the eastern South Indian Ocean

Two species of ocean skaters, Halobates germanus and Halobates micans, live in the tropical and subtropical waters of the Indian Ocean. From December 1992 to December 1993, Halobates was intensively sampled in the easternmost region of the South Indian Ocean (13 - 18.5 degrees S, 114 - 121 degrees E), from which there have been a small number of records of Halobates. No H. germanus was caught, but a total of 1190 H. micans were collected, with densities estimated at 13 900 - 28 100 individuals/km(2). This suggests that H. micans lives in the study area at high densities comparable to those in the Atlantic and the Pacific Oceans. We also discuss the possible effects of ocean currents and winds on the geographic distributions of the two Halobates species in the eastern South Indian Ocean.