Levels of some toxins found in fish aren’t currently a concern, according to a new study from Indian River Lagoon Association for Marine Research and Conservation (ORCA).
The study is called the One Health Fish Monitoring Project (OHFM) and is examining the transfer of toxins and toxins from the Indian River Lagoon and connecting waterways into fish commonly consumed by humans.
cadmium is is considered the seventh most toxic non-essential heavy metal and is released into the environment naturally through mineral deposits and anthropogenically through metal production, phosphate fertilizers, pesticides, herbicides and fungicides.
While the use of many cadmium-based herbicides and pesticides is banned, cadmium persists in the environment through bioaccumulation in the food chain and adsorption in soil and sediment, creating a continuous source of exposure to fish and other aquatic organisms.
Out of 100 analyzed samples, only two had measurable levels of cadmium – a Mayan cichlid (0.045 mg/kg) from Indian River County and a hardhead catfish (0.16 mg/kg) from St. Lucie County. These data indicate that cadmium is not currently bioaccumulating in the IRL at levels of concern.
Mercury is a toxic heavy metal that is released into the environment by coal combustion plants, volcanic activity, and mining, but has also been historically used in antifouling paints.
Over 700 fish in four counties (Brevard, Indian River, St. Lucie and Martin) were analyzed for mercury. Fish in Martin County had significantly higher mercury concentrations (0.293 mg/kg, ANOVA, p=0.00000000006) compared to other counties where fish were found Indian River County with the lowest average concentration (0.150mg/kg).
Compared to the literature, mercury concentrations in fish appear to be similar to what they were 10 to 20 years ago, suggesting that Mercury in fish has not increased in the Indian River Lagoon.
microplastic is Are defined as plastic particles
Of the 380 analyzed fish 53% of the stomachs contained microplastics with a range of 1-14 pieces. Fish from Brevard County had significantly fewer microplastic counts in their guts compared to fish from other counties (ANOVA, p=0.03).
Microplastics are also characterized and quantified by their type and color. Microplastics are a good indicator of their source, whether it’s clothing fibers or toy fragments entering the ecosystem. ORCA identified 90% of all microplastics as fibres, compared to 8.4% fragments, 0.8% granules and 0.8% other.
Currently, blue, black, and transparent microplastics are most commonly found in fish samples from the Indian River Lagoon and adjacent waterways. This summer, ORCA will expand its microplastic analysis to fish fillets to better understand the potential exposure of people consuming these fish.
Sources of microplastics:
- Fibres: Clothing and other textiles, fishing nets/line, plastic bags, tyres, sails
- Fragments: plastic bags, textiles, paints, packaging materials, toys, balloons
- Granules: cosmetics, plastic pellets, cleaning products
- Other: plastic bags, toys, balloons, textiles
Additional data for this project will be made available through ORCA’s Citizen Science Data website, launching this fall!