Tracking pollution in the food chain

The Bay of Biscay is home to popular holiday resorts – and it’s the source of the regional Basque staple, squid. What are the effects of pollution and pathogens on the squid? And what could be the broader impacts of this?

A team of researchers are currently studying the anthropogenic (human-caused) impacts on squid in the Plentzia Estuary. BlueAdapt spoke with researchers Ionan MarigomezBelén González Gaya, and Juan Francisco Ayala Cabrera from the Centre for Experimental Marine Biology and Biotechnology (PiE-UPV/EHU), who are working on the case study.

This research is a collaborative investigation, involving a multi-perspective and multi-skilled team from across the science and ecotoxicology disciplines. Investigations into marine pollution and waterborne pathogens in this region are informing BlueAdapt’s pilot project for the development of a One Health Living Lab. The Living Lab is a research environment that takes a collaborative approach to problem-solving. The Lab is based on the One Health principle that by caring for the environment, animals, and humans, we are better protecting human health. And this is how Plentzia’s famous squid enters the picture.


Why squid?

Squids are of vital importance to this region, playing a significant part in local cuisine and also featuring on many restaurant menus.

From a scientific perspective, little is known about squid responses to pollutants, pathogens, and other environmental stressors that could serve as indicators of squid health. Squid are also significant from a bioaccumulation point of view, as they hunt fish and invertebrates and are consumed as seafood by people.

Squid skin is bioluminescent thanks to symbiotic bacteria of the species Vibrio fischeri (bacteria found globally in marine environments). Other types of Vibrio species are well-known pathogens that cause various diseases, including cholera, vibriosis, and gastroenteritis. By looking closely at different types of harmful bacteria called Vibrio in the sea, scientists are working hard to understand the connections between these bacteria and the squid.


Seasonal sampling challenges

The research team from PiE-UPV/EHU is carrying out a seasonal sampling program, which involves dealing with several different pollutants from a variety of environments (such as water and sediment) and marine organisms, including squid. This diversity is enriching from a research point of view – but it does pose challenges for the researchers, who have to disentangle the various effects of anthropogenic pollution.

Ionan Marigomez, one of BlueAdapt’s Principal Investigators, explains that sampling has been more challenging this year than expected:“Squid sampling has been tricky in the hot summer of 2023. Unseasonable changes occurred in the coastal area, with repeated episodes of sewage contamination in the water after unusually frequent extreme storms and with unremitting hordes of Portuguese man-of-war jellyfish invading the bay. In this scenario, the squid fishing ground remained without squid all summer. Once summer passed, the seawater remained unusually warm, and now squid is emerging in mid-autumn.” 

Belén explains: “Analytical chemistry is always challenging! You do not know how many chemicals could be there. And how can you look for something if you don’t even know what it is? This is what we call “non-targeted analysis”, where we look for known unknowns and unknown unknowns (it looks like a joke, doesn’t it!) then apply complex analytical techniques to identify them.”

The chemist team will be looking out for substances from daily human lives among the emerging pollutants. This includes pharmaceuticals, personal care products, food additives, and common industrial chemicals (like plasticizers, water repellents, and flame retardants).

Juan Francisco, says: “We would love to say that we didn’t find any of these pollutants in the environment! However, from previous experience, we presume that these chemicals will be present. Let’s just hope that at least we can explain their effects and help to prioritise their control and use.”


Identifying what pollutants are entering the food chain

The primary objective for the team of researchers from the PiE-UPV/EHU is to emphasize the importance of decisions and actions through the presentation of concrete evidence. Their research aims to uncover the chemical makeup of Plentzia Bay, to explain which pollutants are impacting both the environment and the people who interact with it.

Juan Francisco reflects on the One Health approach: “We need to take care of the environment to protect ourselves. If we ensure a healthy environment, there’ll be fewer sources for potential exposure to pollution, which could help to prevent infection and disease.” 

Studying Plentzia’s squid population is extremely time-consuming, and samples usually have a higher complexity of pollutants than expected. But, the team is dedicated to identifying exactly what pollutants are entering the food chain.