HABITAT USE, FEEDING AND REPRODUCTIVE TRAITS OF ROCKY-SHORE INTERTIDAL MITES FROM BERMUDA (ORIBATIDA: FORTUYNIIDAE AND SELENORIBATIDAE)

Ecological aspects of the intertidal fortuyniid oribatid mites Alismobates inexpectatus and Fortuynia atlantica and the selenoribatid Carinozetes bermudensis and Carinozetes trifoveatus were studied in the Bermuda islands. All species are stenotopic inhabitants of the marine littoral zone. Fortuynia atlantica and C. trifoveatus dwell predominantly in the lower eulittoral zone of rocky shores, A. inexpectatus prefers the median eulittoral area of exposed rocky coasts and C. bermudensis inhabits median and upper ranges of boulder beaches and mangrove forests. All species are algivorous showing certain food preferences but they are also opportunistic feeders. Indirect sperm transfer could be demonstrated in A. inexpectatus and C. bermudensis. Both species typically produce stalked spermatophores, although A. inexpectatus deposits spermatophores singly and C. bermudensis in groups. Occasional spermatophagy could be observed by specimens of A. inexpectatus. Oviposition was observed for all species and time from deposition to eclosion ranged from 15 to 30 days. Egg shell structure differs considerably between Fortuyniidae and Selenoribatidae. Fortuynia atlantica and A. inexpectatus showed aggregation behaviour, but no direct function or triggering stimulus could be detected. All species are fast-moving and excellent climbers. Fortuynia atlantica exhibits a special floating behaviour and C. bermudensis exhibits levitation; both phenomena are likely to facilitate hydrochorous dispersal.