DMSP in corals and benthic algae from the Great Barrier Reef

In this study the first measurements of DMSP in six species of corals and ten species of benthic algae collected from four coral reefs in the Great Barrier Reef are reported, together with DMSP measurements made on cultured zooxanthellae. Concentrations ranged from 21 to 3831 (mean=743) fmol DMSP zooxanthellae⁻¹ in corals, 0·16 to 2·96 nmol DMSP cm⁻² (mean=90) for benthic macroalgae, and 48–285 fmol DMSP zooxanthellae⁻¹ (mean=153) for cultured zooxanthellae. The highest concentrations of DMSP in corals occurred in Acropora formosa (mean=371 fmol DMSP zooxanthellae⁻¹) and Acropora palifera (mean=3341 fmol DMSP zooxanthellae−1) with concentrations in A. palifera the highest DMSP concentrations reported in corals examined to date. As well as inter-specific differences in DMSP, intra-specific variation was also observed. Adjacent colonies of A. formosa that are known to have different thermal bleaching thresholds and morphologically distinct zooxanthellae, were also observed to have different DMSP concentrations, with the zooxanthellae in the colony that bleached containing DMSP at an average concentration of 436 fmol zooxanthellae⁻¹, whilst the non-bleaching colony contained DMSP at an average concentration of 171 fmol zooxanthellae⁻¹. The results of the present study have been used to calculate the area normalized DMSP concentrations in benthic algae (mean=0·015 mmol m⁻²) and corals (mean=2·22 mmol m⁻²) from the GBR. This data indicates that benthic algae and corals are a significant reservoir of DMSP in GBR waters.