Introduction

Ciguatoxins (CTXs), produced by certain marine microalgae, can bioaccumulate and biomagnify through the marine food web, ultimately posing a health risk to humans. Previous studies have identified a high prevalence of CTX-producing microalgae in the coastal areas of Risco Verde and Sardina del Norte (Gran Canaria, Spain). These findings prompted a focused investigation of fish species from these regions over two consecutive years, 2023 and 2024.

Methodology

Fish specimens representing various trophic levels were collected from both areas, a total of 72 fish in 2023 (35 from Risco Verde and 37 from Sardina del Norte) and 82 in 2024 (41 from each area). Liver and muscle tissues were selected for CTX extraction and analysed using a neuro-2a MTT cell-based assay.

Results and conclusion

In 2023, 35 specimens from Risco Verde comprised 10 species, with 8 testing positive for CTXs. All of them showed liver toxicity, and only 3 of them also showed muscle toxicity. From Sardina del Norte, 37 specimens representing 11 species were analysed, of which 6 species were CTX-positive. All of them showed liver toxicity, and only 3 of them also showed muscle toxicity.

In 2024, 41 specimens from Risco Verde included 18 species, with 10 testing positive. Similarly, the 41 specimens from Sardina del Norte represented 15 species, of which 9 tested positive. At both locations, the Parrotfish tested positive for CTXs. Redporgy showed toxicity to CTXs in the liver at both sites as well.

The results demonstrate the widespread presence of CTXs across various fish species and trophic levels in both locations. These findings underscore the importance of ongoing monitoring to assess the risk of ciguatera poisoning in the Canary Islands.