Seagrass Ecology

Seagrass Microbiology

Microbes are everywhere and are central to the functioning of every organism on this planet. Despite their recognised importance, we have merely glimpsed into their roles in ecosystems. By gaining better understanding of microbes, we are able to more clearly understand and predict how our world operates and how it might change. This project examines how seagrass and microbes interact and how these interactions can help us understand and better protect seagrass systems. So far we have uncovered several novel findings including:

  • The first evidence that sulfide oxidising bacterial symbionts of clams are commonly present on seagrass roots, providing another mechanism for seagrasses to alleviate sulfide stress globally.
  • Light limitation in seagrasses leads to a reduction in beneficial microbes. Light not only negatively affects seagrass physiology and functioning, but also the microbes that live on and in their roots.
  • The first report of electrogenic sulfide oxidising cable bacteria in seagrass roots. These bacteria could be key players in helping seagrass survive unhealthy sediment conditions.
  • Changes in seagrass microbial community dynamics can be a useful tool for monitoring the health of seagrasses. This is a promising tool as it would allow us to mitigate stressors on seagrass before they cause death.

Seagrass Physiology

Plants, like all organisms, are in a constant flux of energy; transforming light and carbon dioxide into sugars and using those sugars in combination with nutrients and water that is drawn into the plant. Understanding the mechanisms of these reactions allows us to predict how they will behave in different environments and how they will respond to change. This project examines how seagrass physiology responds to environmental conditions. So far we have found:

  • Water currents are really important for maintaining sufficient oxygen inside seagrass tissues to prevent the tissues from becoming anoxic.
    • You can read about it here
  • Seagrasses increase exudation of root compounds when they are under low light stress. The compounds have the capacity to change biogeochemical cycling in the sediment.
    • You can read about it here

Seagrass Monitoring

Monitoring seagrass abundance, coverage and condition is an integral part of assessing not only the health condition of the seagrass, but also the health condition of marine environment. Seagrasses are relatively sensitive to ecosystem change, and are often considered as ocean sentinels – proving signals that the system may be in trouble. Some of the projects that we are involved in include:

  • Monitoring seagrass (Posidonia sinuosa) across Cockburn Sound in Perth, Western Australia
  • Monitoring seagrass (Halophila ovalis) in the Swan River in South-West Western Australian estuaries