Waycott et al., 2007:

"The major vulnerability of seagrass to climate change is loss of seagrass in the coastal zone, particularly near river mouths and in shallow areas. The greatest impact is expected to result from elevated temperatures, initially during extreme events, eventually in a chronic manner. In addition, reduced light penetration from sediment deposition and re-suspension after severe storm and rainfall events will cause seagrass loss. However, additional research on thresholds and the combined impacts of different stressors is critical to understanding the specific vulnerability of seagrasses to climate change impacts.

In addition to losses, changes in species composition are expected to occur particularly in relation to disturbance and re-colonisation. Following such events, a shift to more ephemeral species and those with lower minimum light requirements is expected. If the period between events increases, it is expected that high-risk habitats will go through ‘boom-bust’ cycles. Such cycles pose significant risks to associated fauna such as dugong, turtle, and important fisheries species as habitat availability changes rapidly during events.

Finally, there is potential for seagrasses to increase in their extent, especially in currently low-nutrient reef habitats where cumulative changes result in elevated nutrient concentrations and lower competition due to the loss of herbivores. However, it is more likely that macroalgae are better placed to take advantage of such changes, although little direct data exists to make a strong case either way."

Table 8.1: Summary of major impacts on seagrass based on predicted climate change scenarios for the GBR where: predicted direction of change represents loss, gain or fluctuation compared to current state, including if a change in community might be expected; Vulnerability represents most likely habitats to be affected; Adaptability represents how resilient a seagrass community is to impacts; Significance represents an indication of the scale and likelihood of impact to seagrass meadows within the GBR.