Pelagic Larval Duration and Settlement Size of Apogonidae, Labridae, Scaridae, and Tripterygiidae Species in a Coral Lagoon of Okinawa Island, Southern Japan

Pelagic larval duration and settlement sizes in species of Apogonidae, Labridae, Scaridae, and Tripterygiidae in a coral lagoon in southern Japan were examined. Sampling was conducted monthly from July 2004 to June 2005 in the coral lagoon and channel of the Oh-do Beach on Okinawa Island, Japan. Pelagic larval duration was estimated by the number of otolith increments. Mean standard length at settlement of apogonids ranged from 7.7 to 13.9 mm, and mean pelagic larval duration ranged from 14.0 to 30.6 days (14 species, 418 individuals). In labrids, mean standard length at settlement and pelagic larval duration varied greatly (mean standard length: 5.4–11.0 mm; pelagic larval duration: 18–57 days, four species, four individuals). Scarids showed consistent mean standard length at settlement and pelagic larval duration (mean standard length: 7.1–7.6 mm; pelagic larval duration: 29–42 days, five species, 25 individuals). In tripterygiids, pelagic larval duration was more consistent (range: 18–29 days, mean: 22.2e 2.1 days), but mean standard length at settlement ranged from 7.8 to 10.3 mm (six species, 32 individuals). These results suggest that the pelagic larval duration of Apogonidae and Tripterygiidae (nonpelagic egg spawning) is shorter than that of Labridae and Scaridae (pelagic egg spawning), and the dispersal strategy of labrids and scarids may include wider dispersal than that of apogonids and tripterygiids. The life history of most coral reef fishes includes a pelagic larval phase (Leis 1991). Hatched larvae inhabit open water and grow to become pelagic larvae. These pelagic larvae search for suitable benthic habitats on coral reefs using visual, acoustic, chemical, or other senses before settlement (Montgomery et al. 2001). The length of the pelagic larval duration influences the survival and dispersal of coral reef fishes (Wellington and Victor 1989, Doherty 1991, Cowen 2002). Pelagic larval duration and size at settlement are basic life history characters of coral reef fishes and are important in understanding coral reef ecosystems. Pelagic larval duration can be determined by examining otoliths of fish larvae that reach settlement sites. Pannella (1971) showed that microincrements of otoliths form daily. Many studies have shown that increments in otoliths form daily in both temperate (Kingsford and Milicich 1987) and tropical (Thresher et al. 1989, Moreno and Morales-Nin 2003) reef fishes. Researchers have estimated the pelagic larval durations of some coral reef fishes by the number of otolith increments of larvae and juveniles just before or after settlement (Brothers et al. 1983, Pacific Science (2011), vol. 65, no. 1:87–93 doi: 10.2984/65.1.087 : 2011 by University of Hawai‘i Press All rights reserved 1 This study was partially supported by the 21st Century Center of Excellence (COE) Program of the University of the Ryukyus. Manusucript accepted 1 May 2010. 2 Graduate School of Engineering and Science, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami-gun, Okinawa 903-0213, Japan (e-mail: [email protected]). 3 Laboratory of Fisheries Biology and Coral Reef Studies, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami-gun, Okinawa 903-0213, Japan. 4 Corresponding author (e-mail: [email protected]