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Project 2.2: Genetic diversity in Posidonia Sinuosa

Understanding the genetic diversity of WA's Posidonia sinuosa seagrasses

21 May 2025

Westport has partnered with the Western Australian Marine Science Institution (WAMSI) to deliver the $13.5 million WAMSI-Westport Marine Science Program. This 3-year program is developing the latest data, information and modelling on the complex environmental systems and community values associated with Cockburn Sound.

Project 2.2: Population genomic of Posidonia sinuosa

Research theme: Benthic habitats and community

Researchers: J Whale, C Webster, N Said, A Frouws, D Field, E Sinclair and K McMahon

Publication date:  March 2025

 

Understanding the genetic diversity of seagrass

Posidonia sinuosa is a seagrass variety found across along the western coast of Australia.

As part of understanding how to improve and support resilience of seagrass communities within Cockburn Sound, this research looked to understand the genetic diversity and connectivity of these seagrass meadows between Geraldton (northern range edge) and Geographe Bay.

Questions included whether the meadows were interlinked by genetics and whether there was any local variations or adaptations to differing environmental conditions along the coastline.

Adult seagrass shoots were taken from across 30 different locations.

 

What the study found

  • There were four key genetic ‘pools’ identified, from which there was a high level of ‘mixing’ across the locations.
  • Most seagrass populations in Cockburn Sound are of one genetic cluster, with some variation in the south of Cockburn Sound.
  • Across all the samples, levels of inbreeding were high, suggesting seed dispersal is limited.

 

What the report recommended

The report suggested resilience building activities to support seagrass health in Cockburn Sound. Seeds or transplants from more northern waters could be used in southern waters to improve diversity and increase resilience to warming environmental conditions within Cockburn Sound.

 

How Westport will use this report

Westport will use this report to inform its resilience building strategies for the port development, with the intent of supporting the long-term health and recovery of seagrass communities within Cockburn Sound.

 

You can read the full report here.

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