The health of our oceans is under increasing threat—not just from visible pollutants like plastics, but from chemical compounds that are much harder to trace. These emerging contaminants (ECs)—including pharmaceuticals, personal care products, and industrial chemicals—are now being detected in coastal waters globally, including along South Africa’s shores. Yet, we know very little about their ecological impacts on local marine life.
In our recently accepted paper in Discover Environment, we present a breakthrough in developing a standardised marine bioassay using Haliotis midae, a native South African abalone species of both ecological and economic significance. This work represents the first local adaptation of the USEPA Whole Effluent Toxicity (WET) embryo–larval development test for a South African marine organism.
Why Haliotis midae?
South Africa’s National Toxicity Monitoring Programme (NTMP) currently has no marine ecotoxicology tools—yet our oceans support critical industries such as mariculture, tourism, and fisheries. H. midae offered a promising candidate due to its accessibility from local aquaculture farms and its ecological relevance. What was missing was a standardised method that could demonstrate its utility in pollution testing.
The Challenges We Faced
Working with marine organisms at early life stages is not easy. Ensuring reliable gamete quality, maintaining controlled seawater conditions, and adapting international protocols for a local species all presented challenges. Additionally, the five ECs we tested—Acetaminophen, Atrazine, Benzotriazole, Carbamazepine, and Emtricitabine—were chosen based on both local occurrence data and their potential for harm, yet toxicity thresholds in abalone were previously unknown.
What We Found
Our findings were eye-opening: even the lowest tested concentrations (25 µg/L) caused significant developmental delays and abnormalities in H. midae embryos and larvae. This highlights the species’ sensitivity to chemical pollution and validates its potential use in routine monitoring. The assay also passed all USEPA acceptance criteria, confirming its reproducibility and robustness.
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Broader Impact
This work goes beyond a single species or location. It directly contributes to Sustainable Development Goals:
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SDG 6 – Clean Water and Sanitation
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SDG 14 – Life Below Water
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SDG 15 – Life on Land
By establishing a cost-effective and scalable marine toxicity testing tool, we provide a pathway for evidence-based decision-making in environmental policy and coastal water management.
The Story Behind the Scenes
This project was a true team effort, combining methodological adaptation, local ecological knowledge, and toxicological testing. Somien Venter led the assay development and testing, while I (Hendrik Brink) and Evans Chirwa provided project supervision, conceptual guidance, and Andrew Witte provided industry context. The work was supported by a team of collaborators committed to sustainable ocean stewardship.
We hope this research provides a foundation for integrating marine bioassays into national monitoring frameworks, not just in South Africa, but in other regions facing similar challenges.