Alterations of visual structures in Artemia salina: a new biomarker for environmental contamination

Contamination of coastal marine areas is a matter of major concern: many big cities are located along flat shores or protected bays where contaminants accumulate, in sediments and in the water column. Therefore, it has become essential to know all the possible targets of the different xenobiotic so to assess associated environmental risk. From this point of view, the larval stages of marine organisms represent very useful model organisms to test toxicity responses. Among those, Artemia salina nauplii are a perfect choice since easy to breed and observe and their widespread use in lab toxicity tests is a confirm. Mortality and mobility are the two common end-point used; however, others might be equally cheap, sensitive and simple. For this reason, in this study we focus on the possibility of introducing pigmented naupliar and paired eyes as a new end-point and tested this hypothesis by investigating responses to two heavy metals (nickel and cadmium) and two antibiotics (amoxicillin and gentamicin). Results indicate that naupliar eyes morphology is affected by the four contaminants (asymmetry and/or hypopigmentation) and that evidences can be collected as early as 12 hours following contamination. At the same time, the experiments revealed that the two heavy metals induce a delay in paired eyes formation; the information, however, is only available from day 5 post hatching. In conclusion, these preliminary experiments indicate that naupliar eyes are a potentially good new end-point in toxicity test even though further researches are required to clarify specificity and sensitivity. Results also indicate that naupliar visual structures are a target for common xenobiotic, as already demonstrated in other terrestrial and aquatic organism. Therefore, the environmental contamination might severely impair visual performances and, eventually, threaten animal survival.