Efficient, fast and inexpensive bioassay to monitor benthic microalgae toxicity: Application to Ostreopsis species

Abstract

Even though HPLC-MS is commonly used to quantify the toxin content of Ostreopsis spp. cells, there is a need to develop easy-to-use toxicological tests to set thresholds during Ostreopsis spp. blooms. The crustacean Artemia has been widely used to evaluate the presence and toxicity of chemicals and biological contaminants and we anticipated that it could also be useful to test Ostreopsis spp. toxicity. Its relevance was first assessed by investigating the variability of the toxic effects among Ostreopsis spp. strains and throughout the dinoflagellate life cycle in combination with chemical analyses of the toxinic content by UHPLC-HRMS. After testing the toxicity of fractions prepared from Ostreopsis spp. cells, the known ova-and paly-toxins were not the only toxic metabolites to Artemia franciscana, indicating that other toxic compounds synthesized by Ostreopsis spp. still remain to be identified. To extend the bioassay to in situ monitoring, the toxicity of the benthic microalgal consortium was tested during a natural bloom of Ostreopsis cf. ovata in the NW Mediterranean Sea. The results highlight the accuracy and sensitivity of the ecotoxicological assay with Artemia franciscana to assess the toxicity of Ostreopsis spp. blooms. Highlights► Artemia bioassay is relevant to evaluate Ostreopsis spp. Toxicity ► Ostreopsis spp. produce other toxic compounds than known ovatoxins ► Artemia bioassay could be used for bio-guided fractionation approach

Progress on the Link between Nutrient Availability and Toxin Production by Ostreopsis cf. ovata: Field and Laboratory Experiments

“…These toxin contents on a per-cell basis were higher than the values reported for other Mediterranean O. cf. ovata strains (7.5 to 75 pg tox cell −1 ) [ 4 , 58 , 70 , 71 ] and quite similar to those found for a French Mediterranean strain (up to 300 pg tox cell −1 ) [ 18 ] and the NW Mediterranean strain studied in García-Altares et al (2015) (up to 250 pg tox cell −1 ) [ 72 ]. Furthermore, it should be noted that the NW O. cf.…”

“…Impacts on marine fauna associated with Ostreopsis spp. blooms have been documented [ 2 , 3 ], and ecotoxicology studies are underway to elucidate the essential noxious mechanisms involved [ 4 , 5 ]. Palytoxin (PLTX) analogues (namely, putative or isobaric PLTX (isoPLTX) and ovatoxins (OVTXs)) synthesized by Ostreopsis species have been associated with sporadic but dramatic seafood-borne poisonings in the tropics [ 6 , 7 , 8 ] and, most commonly, with cutaneous and respiratory irritations in users of temperate beaches [ 9 , 10 , 11 ].…”

Exploring the Role of Macroalgal Surface Metabolites on the Settlement of the Benthic Dinoflagellate Ostreopsis cf. ovata

“…ovata's growth or physiology, bidirectional effects may also be considered since some macroalgae have been shown to rely on microbial metabolites for cell division and differentiation (Wichard and Beemelmanns, 2018). The bioactive metabolites produced by the benthic dinoflagellate (Pavaux et al, 2020) may be detrimental or beneficial to the macroalgal host.…”

Chemical Ecology of the Benthic Dinoflagellate Genus Ostreopsis: Review of Progress and Future Directions

“…exposed to toxins produced by Ostreopsis sp. are not specific since our studies (Pavaux et al, 2020). The Artemia bioassay can be a prescreening test of Ostreopsis strains toxicity for OVTX analogues and other toxic metabolites produced by these dinoflagellates.…”

“…The Artemia bioassay can be a prescreening test of Ostreopsis strains toxicity for OVTX analogues and other toxic metabolites produced by these dinoflagellates. Indeed, the production of other toxic compounds that do not belong to the OVTX family was suggested by Ternon et al (2018) and confirmed by Pavaux et al (2020) because toxicity on Artemia was caused by Ostreopsis cf. ovata's fractions free of OVTXs.…”