Study finds ways to avoid hidden dangers of accumulated stresses on seagrass

December 7, 2017 by Debra Nowland, Queensland University of Technology
Credit: Queensland University of Technology

A new QUT-led study has found ways to detect hidden dangers of repeated stresses on seagrass using statistical modelling.

The research, published by the Journal of Applied Ecology, found cumulative maintenance which affected the light on the increased risks on survival.

It found, globally, can be at risk of collapse from accumulated effects of repeated dredging and natural stress.

  • Seagrass provide shelter and food to marine life, including at-risk species like dugongs and green turtles
  • Globally, hundreds of millions of cubic metres of sediment are dredged annually
  • Dredging repeated every 1, 2 or 3 years, or for three months or more duration, needs careful management to avoid a loss of resilience
  • Latest research builds on recently released research pinpointing 'ecological windows' for timing of dredging

"Our model predicts ahead of time how much repeated stress is too much," Dr Wu said.

"Our results show dredging can be successfully managed to maintain healthy seagrass meadows in the absence of other disturbances.

"The research isn't about stopping dredging.

"It's about being able to predict how resilient the seagrass will be by incorporating environmental conditions such as storms, cyclones and run-off from agriculture."

Credit: Queensland University of Technology

Dr Wu said port authorities and coastal developers could use the research to support a risk-informed management strategy.

Coastal development is commonly associated with dredging, which presents a hazard to ecosystem health via stressors including light degradation and water quality reduction.

"Generally, dredging repeated every one, two or three years, or of three months duration or more, needs careful management to avoid a loss of seagrass resilience," Dr Wu said.

Dr Wu said the development of a risk modelling approach, based on a Bayesian Network, was a tool increasingly applied in ecology.

The findings of the study are specific to hazards and for individual sites.

"For instance, dredging repeated every one, two or three years on a Halophila meadow at Hay Point was predicted to be at risk of losing resilience," he said.

"We developed 960 hazard scenarios including frequency of dredging durations of between one to six months and the level of light stress and the month when dredging occurred."

Explore further: Saving seagrasses from dredging—new research finds solutions

More information: Paul Pao-Yen Wu et al. Managing seagrass resilience under cumulative dredging affecting light: Predicting risk using dynamic Bayesian networks, Journal of Applied Ecology (2017). DOI: 10.1111/1365-2664.13037

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