Laboratory bioassay exploring the effects of anti-aging skincare products on free-living marine nematodes: a case study of collagen

Organic enrichment due to human impact is one of the major threats that affect benthic communities in semi-enclosed marine ecosystems, such as the Mediterranean Sea. However, many emerging sources of organic pollutants, such as those released to nature through human practices related to esthetics and cosmetics, remain underestimated, despite being an increasingly important source of organic matter input following a decade of expansion by the cosmetic industry. Therefore, an experiment was designed to explore the influence of collagen, the main component of commercialized skin anti-aging products, on a Mediterranean community of free-living marine nematodes from a beach in Rimel, northeast Tunisia. The effects of exposure for 30 days to a control treatment and three test treatments, corresponding to three levels of sedimentary enrichment with collagen (3, 6, and 12 ppm dry weight (DW)), were examined using a microcosm approach. Reductions in abundance and diversity were noted with an increase in collagen enrichment, together with a slight increase in individual weight. The presence of three species characteristic of control microcosms, Ptycholaimellus ponticus, Theristus modicus, and Kraspedonema reflectans, was clearly affected at the lowest dose; these were therefore classified as "collagen-sensitive." In contrast, the numbers of "collagen-tolerant" species, including Sigmophoranema rufum, Lauratonema hospitum, Enoploides spiculohamatus, and Trichotheristus mirabilis, increased significantly in the treated microcosms.