Adriana Humanes, Bette Willis, Katharina Fabricius and Andrew Negri A.Humanes@aims.gov.au Cumulative effects of sediments, nutrient enrichment and high temperatures compromise the early life history stages of the coral Acropora tenuis
Local changes in the Great Barrier Reef (GBR) Nutrient and sediment input in the GBR increased since 1823: Nitrogen Phosphorus Source: eAtlas Frequency of exposure Frequency of exposure to 2nd water types Plume exposure Suspended sediments Australia
Gamete collection and separation Acropora tenuis Temperature 27, 30, and 32°C Nutrient enrichment 0, 0.3 and 0.6 mg/l organic carbon Low Medium High National Sea Simulator (SeaSim) Suspended sediments 0, 5, 10, 30 and 100 mg/l
2. Embryo development % Settlement Suspended sediments (mg/l) Low enrichment Medium enrichment High enrichment Suspended sediments and nutrient enrichment Settlement decreased with suspended sediments and nutrient enrichment in an additive way 0 20 40 60 80 100 0 5 10 30 100
0 20 40 60 80 100 27 30 32 Temperature (°C) % Settlement 4. Larval settlement 5-day old larvae exposed for 24 h to treatments 0 20 40 60 80 100 27 30 32 Temperature (°C) % Settlement 3-day old larvae exposed for 48 h to treatments 27 30 32 Mechanism of action: Changes in physiological and metabolic functions
Conclusions • Management strategies should be directed to minimise dredging activities and improve water quality associated with river discharges during the periods of coral spawning. • The effects of individual stress factors varies between early life history stages of corals. • The co-occurrence of pressures can aggravate the impacts of single factors.
Volunteers: Catia de Carvalho Florita Flores Marion Hliscs Heidi Luter Helios Martinez Sam Noonan Joy Smith Staff of the National Sea Simulator (AIMS Townsville) Acknowledgements A.Humanes@aims.gov.au www.adrianahumanes.com