Potential for trophic transfer of microplastics in the smallspotted catshark’s food web: insights from Portuguese coastal ecosystems

Pica, Rodrigo; Fernandes, João; Seixas, Sónia; Martins, Marta

http://hdl.handle.net/10400.2/20404

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Abstract(s)

Microplastics (MPs) are increasingly prevalent pollutants in marine environments, raising concerns about their potential to transfer across trophic levels. However, the extent and significance of such transfer remain uncertain. This study aimed to (i) characterise MPs in the digestive tracts (GITs) of three ecologically connected species — the small-spotted catshark (Scyliorhinus canicula), pouting (Trisopterus luscus), and Henslow’s swimming crab (Polybius henslowii); and (ii) assess the potential for trophic transfer, as S. canicula is a known predator of the other two species. Thirty individuals from each species were collected by bottom-trawling off Figueira da Foz, Portugal. GITs were digested using 10% potassium hydroxide (KOH), filtered, and analysed by Fourier-transform infrared (FTIR) spectroscopy. A total of 88 MPs were identified, primarily in S. canicula (0.89 ± 1.19 MP.ind-1) and P. henslowii (0.54 ± 0.74 MP.ind-1). No MPs were found in T. luscus, possibly due to its juvenile stage or short retention time. Frequencies of occurrence were 57% for S. canicula and 43% for P. henslowii, representing the first record of MPs in the latter. The predominant MP types were fragments (51%) and fibres (47%), mainly green (32%), black (20%), and transparent (16%), with polyvinyl acetate (32%) and polyethene terephthalate (27%) identified as the main polymers. Significant differences in MP colour and polymer composition between species suggest distinct exposure routes. Although the presence of MPs in a known prey species of S. canicula suggests potential trophic transfer, further research is needed to confirm bioaccumulation. These findings provide a valuable baseline for understanding plastic pollution in coastal ecosystems and highlight the need for ongoing investigation into MP dynamics within marine food webs.

Keywords

Bioaccumulation Biomagnification Scyliorhinus canicula Trisopterus luscus Polybius henslowii

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http://hdl.handle.net/10400.2/20404

Citation

Pica, R; Fernandes, J; Seixas, S; Martins, M. 2025. Potential for trophic transfer of microplastics in the smallspotted catshark’s food web: insights from Portuguese coastal ecosystems. Book of Abstracts. ICYMARE 2025. p. 195.