Abundance and distribution of planktonic coral larvae in Kaneohe Bay, Oahu, Hawaii

Abstract

A plankton sampling program was designed for the capture of coral planulae. More than 250 surface tows were made with a small, fine-mesh net along 5 transects established near the southeast fringing reef of Coconut Island, Oahu, Hawaii. Time between collection and sorting was minimized, and low temperature storage was employed in lieu of chemical fixation to prevent decomposition of the planulae prior to identification. More than 20,000 cnidarian larvae were collected and sorted, of which 90 % were scleractinian planulae. Twelve different types of cnidarian larvae were recognized. Six were identified as the planulae of the corals Pocillopora damicornis, Porites compressa, Montipora verrucosa, M. dilitata, Cyphastrea ocellina and Fungia scutaria. Two appear to be the zoanthina larvae of the zoanthids Palythoa vestitus and Zoanthus pacificus. Peak recovery of planulae generally occurred 3 to 7 d after onset of spawning or planulation. Limited data indicate that some coral planulae may undertake diurnal migration, residing near the surface at night and moving to several meters depth during the day. The potential for the export of large numbers of coral planulae from Kaneohe Bay is considered high, but whether this export is significant to recruitment on reefs outside the bay remains to be determined.

Response of the microbial community to coral spawning in lagoon and reef flat environments of Hawaii, USA

“…While large, rapid variations in microbial cell abundances, nutrients and chl a concentrations were observed during high frequency, diurnal sampling in the Kaneohe Bay lagoon, no systematic microbial response was detected during post-spawning sam- Several factors may contribute to the differences in microbial response between previous studies from the Great Barrier Reef and the present study from Kaneohe Bay, Hawaii. For example, the magnitude of spawning likely contributes to the differential observations between studies: the number of synchronous spawning coral species is considerably higher in the Great Barrier Reef compared to Kaneohe Bay (Hodgson 1985, Babcock 1986. A second factor is that the present study characterized the natural variability in microbial communities during non-spawn conditions, and considered the impact of tides.…”

“…The volume of water clearing the net was quantified using a mechanical flow meter (General Oceanics). Nets which had been towed were stored on ice to maintain the structural stability of coral eggs and planulae (Hodgson 1985) for no more than 2 h before analysis. Coral eggs and planulae were identified to genus and counted; the dominant zooplankton and phytoplankton groups were also noted, but not quantified.…”

“…1). Kaneohe Bay is an ideal location for this study because it harbors an abundance of coral with known spawning periods (Hodgson 1985), and a number of studies have examined various aspects of microbial functioning in this environment (Landry et al 1984, Ringuet & Mackenzie 2005, Cox et al 2006, Hoover et al 2006. We surveyed reef flat and lagoon sites in Kaneohe Bay over 18 mo in order to understand the factors driving the structure of the bacterioplankton community, microbial abundances and rates of bacterial production during non-spawning conditions.…”

Timing of reproduction in Montastraea annularis: relationship to environmental variables

“…However, spawning may not even be annual, and is not always as synchronized as the Australian spawning events which were the first to be reported (Harrison et al 1984, Babcock et al 1986). For example, in Japan synchronous multispecies spawnings occur over several months from May until September (Heyward et al 1987), while in Hawaii and the Red Sea many species have separate spawning times staggered throughout the summer (Hodgson 1985, Schlesinger & Loya 1985, Heyward 1986). Corals which deviate from annual periodicity include several species in Papua New Guinea that show evidence of bi-annual spawning, with 2 gametogenic cycles a year (Oliver et al 1988).…”

Larval settlement rates and gene flow of broadcast-spawning (Acropora tenuis) and planula-brooding (Stylophora pistillata) corals

“…broadcastspawning versus planula-brooding, may influence the dispersal potential of their larvae (reviewed in Harrison & Wallace 1990). While brooded planulae generally settle within a few hours of release (Atoda 1947, Harrigan 1972, Richmond 1987a, Harrison & Wallace 1990, planulae originating from spawning require 4 to 6 d after gamete release before they settle (Hodgson 1985, Harrison & Wallace 1990. This suggests that the dispersal potential of brooded planula is more restricted than that of planulae originating from spawning, because of the shorter pre-competency period in brooders versus spawners.…”