Detection of contaminants in local fish : anisakis parasites and heavy metals

Abstract

The Mediterranean Sea which is rich in biodiversity may also be vulnerable to harmful contaminants such as parasites and toxic heavy metal pollutants that may contaminate the fish and lead to serious threats to the marine ecosystem and to human health when consumed. A recent study was conducted on fish samples to determine any contaminants such as Anisakis parasite and seven heavy metal contaminants that included mercury (Hg), nickel (Ni), lead (Pb), arsenic (As), copper (Cu), zinc (Zn) and chromium (Cr) within local marine fish species found particularly in the south-eastern region around Malta. The aim of this project was to determine these contaminants on four native marine fish found around Malta waters, which are Trachurus trachurus, Scomber colias, Boops boops and Sardinella aurita. For the detection of Anisakis parasite, visual inspection and the Digestion Method according to ISO 23036-2:2021 was performed. The method used to perform a quantitative analysis on heavy metals was by using a Microwave Plasma-Atomic Emission Spectroscopy (MP-AES). This study demonstrated that Boops boops was the least infested species by Anisakis parasite, while Scomber colias was the most infested one, with Sardinella aurita and Trachurus trachurus, showing a lower infestation rate. Pearson Correlation statistics revealed that Anisakis infestation correlated with fish size but not with maturity or fish sex. Principal Component analysis demonstrated that the carnivorous fish species were more prone to Anisakis infestation than the omnivorous species. Seven metals were analysed in this study on fish samples collected from the skin, muscle, viscera and bones. Results of Hg content in fish and different tissues was undetectable. The Ni content in fish tissues ranged between 2.6±0.10 µg/g and 19.5±0.02 µg/g, Pb content ranged between 9.0±0.05 µg/g and 28.8±0.09 µg/g, As content between 20.1±1.37 µg/g and 73.0±2.31 µg/g, Cu content ranged from undetectable quantities to 13.2±0.11 µg/g, Zn content ranged from non-detectable quantities to 184.87±0.63 µg/g and Cr content ranged between 15.1±0.01 µg/g and 19.9±0.01 µg/g. Principal Component Analysis revealed that heavy metal contamination does not discriminate between fish species and sex, but it showed differences between tissue type and location of catch. Some metals, such as Zn and Pb seem to accumulate more in muscle rather than the other tissues. These findings indicate that Anisakis infestation and heavy metal analysis should be monitored and extended beyond the current EU requirements.