Temporal changes in settlement, lipid content and lipid composition of larvae of the spawning hermatypic coral Acropora tenuis

Abstract

Stored lipids in marine planktonic larvae play an important role in buoyancy and as an energy source and thus are a key to understanding the dispersal and settlement potential of larvae. However, little is known about lipid content and composition in different coral species or their temporal changes during larval dispersal. We examined the lipid content and composition of eggs and planula larvae of Acropora tenuis, a reef-building coral, and their temporal changes over the course of larval dispersal and settlement. The total content and composition of lipids in newly released planulae of the brooding corals A. brueggemanni, Pocillopora damicornis and Heliopora coerulea were also examined for comparison. A. tenuis eggs were positively buoyant; lipids accounted for 85% of their dry weight, but decreased to 50% of their dry weight within 30 d after spawning. Wax esters were a major component of lipids in the eggs; they decreased appreciably by 5 d after spawning and decreased thereafter. In contrast, the phospholipid content remained almost constant. The period of rapid decrease in wax esters occurred before settlement, suggesting that A. tenuis planulae consume mainly wax ester lipids as an energy source during the planktonic phase. In contrast, the lipid content of H. coerulea planulae, which have a shorter dispersal period, was lower (41% of dry weight) than that found in 5-d-old planulae of A. tenuis and newly released planulae of A. brueggemanni and P. damicornis (> 58% of dry weight). Triacylglycerols in lipids were detected in P. damicornis and H. coerulea planulae, which settle quickly after release, but not in A. tenuis or A. brueggemanni, suggesting that triacylglycerols are used for rapid energy. These findings suggest that lipids are used for buoyancy and as an energy source and are related to differences in the dispersal period of planulae among coral species.

Effects of thermal stress on early developmental stages of a gorgonian coral

“…Generally, long survival of larvae implies the availability of large initial energy reserves that the larva is either able to supplement during its life, e.g. via symbiotic zooxanthellae or potentially even through the uptake of dissolved organic matter (DOM), or that it is able to control its metabolic rates (Richmond 1987, Manahan 1990, Ben-David-Zaslow & Benayahu 2000, Harii et al 2007, Okubo et al 2008). The red gorgonian P. clavata is aposymbiotic and there is no evidence of DOM uptake by its larvae, although the latter cannot be excluded.…”

Butterflyfishes feed on externally brooded larvae of the blue coral, Heliopora coerulea

“…comm.). For the butterflyfishes, the consumption of high lipid content (41% dry wt., Harii et al 2007) blue coral larvae may provide a fitness advantage, similar to the enhanced larval quality in damselfish that have consumed coral spawn (McCormick 2003). For the corals, this observation highlights a potentially significant source of larval mortality and a disadvantage of external benthic brooding.…”

Coral Distribution on Artificial Structures in Bonaire, Leeward Antilles

“…3). Although this difference is not as pronounced as the difference between the inshore and the offshore block faces, it could be sufficient for coral larvae to settle preferentially on the right rather than the left halves as they explore quality of attachment sites by probing, crawling, bouncing and swimming across them [14,[32][33][34].…”