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The Helix experiment: Differential localized dispersal and recruitment patterns in Great Barrier Reef corals
Author(s) -
Sammarco Paul W.,
Andrews John C.
Publication year - 1989
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1989.34.5.0896
Subject(s) - reef , biological dispersal , oceanography , fringing reef , coral reef , coral , cnidaria , biology , ecology , plankton , geology , population , demography , sociology
In a large‐scale oceanographic study, we attempted to determine whether reefs of the central Great Barrier Reef are primarily self‐seeded with respect to corals. Twenty‐four moorings were deployed for 7 months around the small, relatively isolated Helix Reef (diam ≃ 800 m). Settling plates were placed on moorings 15–18 m below the surface. Moorings were placed 0, 0.3, 0.6, 1.2, 2.5, and 5.0 km from the reefs perimeter. Water movements were recorded concurrently via current meters and tide gauges. Most larvae settled on or within 300 m of the reef; settlement was generally lower in pocilloporids than acroporids. Most spat in the far field (acroporids) were derived from corals utilizing externally fertilized eggs with an obligate planktonic larval development period of 24–72 h, implying higher effective dispersal capabilities. Densities of settling pocilloporids (obligate brooders), however, were highest directly on the reef. Postsettlement mortality of recruits decreased significantly with distance from the reef. Coral spat were concentrated in two areas where water residence times were high and flushing rates were low. Highly localized circulation patterns appear to retain larvae near the reef. Effective larval dispersal in corals seems to be a small‐scale phenomenon, although measurable far‐field dispersal indicates sufficient gene flow between reefal populations to prevent allopatric speciation.