Coral reproduction at Hall Bank, a high latitude coral assemblage in Western Australia

Ah Baird,Dp Thomson

doi:10.3354/ab00696

Abstract

Research on coral reproduction has increased dramatically in recent times; however, there remain significant regions, in particular high latitude reefs, where research is limited. For example, the reproductive biology of species in the coral assemblage at Hall Bank, a high latitude site (32 degrees S) in southern Western Australia, remain unknown. Here, reproductive traits and the likely time of spawning for 12 of the approximately 16 species that occur at Hall Bank were established using histology between March 2009 and March 2011 at 7 discrete time points. Peak reproductive activity most likely occurs in February, as 7 of the 10 species sampled in this month had colonies with mature gametes. The sexuality, mode of larval development and transmission of symbionts were, as expected, consistent with previous work. The reproductive biology of the corals at Hall Bank is consistent with other regions of the Indo-Pacific, supporting the hypo thesis that reproductive traits such as sexuality and mode of larval development are evolutionarily conserved and do not vary biogeographically.

Highlights

Heightened interest in high latitude coral assemblages arose in the mid-1990s following the suggestion that high latitude reefs can provide potential sites of refuge from ocean warming (Glynn 1996)
There are still many marginal reef areas for which there is no information on coral reproductive biology
Coelastrea palauensis was sampled on 4 occasions and no gametes were observed in any colonies, including all 6 colonies sampled in February 2010

Summary

Introduction

Heightened interest in high latitude coral assemblages arose in the mid-1990s following the suggestion that high latitude reefs can provide potential sites of refuge from ocean warming (Glynn 1996). Glynn (1996) suggested that reefs at high latitudes, moderate depths or in areas with strong currents could provide respite from thermal stress associated with rising ocean temperatures, and allow for the persistence or expansion of tropical coral reef species. Rates of ocean warming since the mid-1990s have remained constant at 1.5°C per 100 yr (Hobday & Pecl 2014) and there is evidence of an associated poleward shift in some tropical and subtropical coral reef species (Verges et al 2014, Wernberg et al 2016), including scleractinian corals (Thomson 2010, Yamano et al 2011, Baird et al 2012). There are still many marginal reef areas for which there is no information on coral reproductive biology

Methods

Results

Conclusion