Planktonic Duration, Distribution and Population Structure of Western and Central Pacific Damselfishes (Pomacentridae)

Abstract

The duration of the planktonic larval stage of Indo-West Pacific damselfishes (Pomacentridae) is inferred from the microstructure of their otoliths and related to the development of morphologically distinct, localized populations and interspecific differences in geographic distribution. Mean duration of the planktonic stage varies between species from 0-37.4 d, differing significantly among species, among genera and among subfamilies. Both morphological and genetic data suggest localized sub-populations are most common in species with planktonic durations less than approximately 15 d. The breadth of a species distribution does not, however, correlate with its planktonic duration. Nonetheless, species with a longer than average planktonic duration are significantly more likely to be distributed on both sides of major barriers to dispersal, such as the western margin of the Pacific Plate. Pacific Plate endemics also tend to have long duration planktonic stages. THE life histories of most shallow-water tropical marine organisms consist of two very dissimilar stages: a planktonic egg and/or larval stage that, depending upon the species, lasts from a few hours to a few months; and a relatively sedentary juvenile and adult stage. It has been widely hypothesized that planktonic larvae are advected and dispersed from the site of spawning, and that this transport is fundamental to maintenance of species integrity. Evidence to support the latter hypothesis comes primarily from studies of marine invertebrates: species with planktonic larvae are reported to be more widely distributed than those that lack such larvae (Shuto, 1974; Scheltema and Williams, 1983; Perron and Kohn, 1985), to have genetically more homogeneous populations (Scheltema, 1977) and to persist longer in the