Microplastic particles (MPs) in the Mediterranean Sea are released mainly from coastal discharges and are colonized by a several of bacteria, including pathogens and antibiotic resistant bacteria (ARB), absent in seawaters. MPs are suggested to be novel substrates (spatial or ecological niches), allowing these bacteria to survive, or even to proliferate, in seawaters. We compared the bacterial communities in biofilms from MPs and natural organic particles with the planktonic community in samples collected in 3 sites in the Tyrrhenian Sea: V Terre (marine reserve, low coastal impact) and Forte Dei Marmi (city beach, diffuse anthropogenic impact) at 500 mt from the shore, and open sea, about 15 km east of Palmaria Island. We defined bacterial communities, antibiotic and heavy metal resistomes. We found large differences in the planktonic communities in comparison to the particles biofilm, and identify a number of human and animal pathogens finding a refuge on the particles, with a surprising prevalence of the latest on natural particles. The same was detected for antibiotic resistances, while heavy metal resistances were equally distributed between particles and water. We did not find a specific impact from the shores, independently from the level of anthropogenic pressure. The natural movement of water masses seems to rapidly reduce the impact of anthropogenic pollution. Our study highlights the plasticity of allochthonous bacteria (including potential pathogens and ARB) that can use as a refuge, or as source of nutrients, not only MPs, but also other organic substrates in waters.

Primary Presenter: Gianluca Corno, CNR-IRSA (gianluca.corno@cnr.it)

Authors:

Belen Sathicq,   ()

Raffaella Sabatino,   ()

Tomasa Sbaffi,   ()

Andrea Di Cesare,   ()