Superstars of STEM: The hero of the half-shell

Home to the iconic green sea turtle (Chelonia mydas), the Great Barrier Reef stretches close to the cities of Australia’s eastern coastline. Chemical pollution from agriculture, industry, and urban centres passes through farms, cities and along waterways, ultimately ending up in the ocean. What impact is human activity having on this World Heritage Area and the vulnerable species that call it home? 

The turtles forage in coastal areas close to human activity, where they are exposed to land-based pollutants via contaminated water, sediment and sea grass. The Rivers to Reef to Turtles project, led by the World Wide Fund for Nature Australia, brings together a group of scientists from different fields to investigate their effects.

The four-year project combines environmental monitoring, turtle health and toxicology to understand the effects of chemical pollutants on green sea turtles foraging in three areas – one remote, offshore site far removed from human activities, and two coastal sites impacted by industrial and agricultural activities. 

One of these scientists is analytical chemist, Amy Heffernan, who specialises in mass spectrometry, a tool to map the chemical fingerprint of different types of samples, including turtle blood.{%recommended 7318%}

Using this approach, Heffernan discovered that the organic chemical profile was distinct for each foraging site on the reef, and that it reflected nearby land use patterns. For example, turtles from the coastal sites had been exposed to a wide range of chemicals, including human heart and gout medication, pesticides and industrial compounds such as sulfonic acids. 

Turtles, seagrass and algae, the main sea turtle diet, were also found to have high levels of particular metals, including cobalt.

In addition to measuring the levels of chemical pollutants, the researchers also looked at overall turtle health. Many of the coastal specimens showed signs of systemic stress, including liver dysfunction and neurological inflammation. This was not seen in animals from the remote site.

The major challenges for this project have been to find an ethical way to study sea turtles in the wild, to develop new scientific tools to collect information, and then to try to understand what the data mean for long-term turtle health. As a result, the researchers now better understand the relationship between external pollutant dose from the water, sediment and seagrass; internal exposure via blood measurements; and the observed health effects in the turtles.  

“Understanding the impact of chemical pollution on turtle health is crucial, as green sea turtles can paint a broader picture of the health of the entire reef ecosystem,” Heffernan says.

“This information is critical for effective species conservation, reef catchment restoration, and sustaining the health of the Great Barrier Reef.”

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Amy Heffernan is one of 30 Superstars of STEM featured in this weekly series, prepared by Science and Technology Australia (STA). To learn more about the program, visit the STA website.