Under pressure: Managing deep-water seagrasses of the Great Barrier Reef

This talk covers:

• Segrass Ecology Group (1:05)
• The Great Barrier Reef: Its' not just coral (4:40)
  • One of the world's largest seagrass ecosystems
  • 20% of world's seagrass species
  • Inter-reef, reef platform, nearshore
  • Intertidal, subtidal
  • Stable, ephemeral, seasonal
• Seagrass is important (5:36)
  • Food for iconic species
  • Connectivity
  • Fisheries habitat
  • Inter-reef habitat
  • Sediment stabilization
  • Primary production
• Management questions (6:01)
  • Where does it grow?
  • Where does it not grow?
  • How much is there?
  • What species is it?
  • Does it vary spatially/temporally?
  • What drives seagrass presence & productivity?
• GBR Deep-water Seagrasses - what we know: (6:55)
  • In Queensland more than 31,000 km² in GBR
  • Meadow turnover: 1.7 - 4.1 days
  • Dominated by Halophila species
• What we don't know: (8:30)
  • Drivers of seasonality and change
  • Species-specific information
  • Tolerance levels
  • How they re-establish after seasonal declines
• Aims of the Deep-water Seagrass Dynamics Project: (9:30)
  • Investigate seasonal dynamics, drivers of changes, role of seed banks and recruitment and light thresholds.
  • Undertaken at Lizard Island, Green Island and Keswick Island (Mackay)

Green Island Seagrass Biomass 2012 - 2015 (Halophila decipens)

This graph shows the biomass of seagrass (Halophila decipens) at Green Island from 2012 - 2015 along with matching total daily light (PAR), maximum temperature and rainfall. This graph is an extract from the video presentation Under pressure: Managing deep-water seagrasses on the Great Barrier Reef.

© courtesy JCU - TropWATER, Katie Chartrand

• Experimental design (14:30)
• Shoot Density results (17:14)
• Below-ground carbohydrate reserves (18:19)
• Sex and seed banks (24:00)
• Germination Trials - Role of light (25:26)