Plastic-associated harmful microalgal assemblages in marine environment

Area of Science:

• Marine Biology
• Environmental Science
• Microbiology

Background:

• Plastic debris in marine environments acts as a substrate for various organisms.
• These colonizing organisms, including harmful microorganisms, can disperse invasive species and toxic compounds.
• The ecological and health impacts of these plastic-associated microbial communities are significant.

Purpose of the Study:

• To quantify microalgal taxa, particularly harmful species, colonizing marine plastics using molecular methods.
• To investigate the relationship between the abundance of harmful algal species and their toxin production on plastics.
• To determine the adhesion rates of microalgal species on plastic substrates.

Main Methods:

• Analysis of marine plastic surface samples using a molecular quantitative polymerase chain reaction (qPCR) assay.
• Quantification of attached microalgal taxa, including diatoms and dinoflagellates.
• Measurement of toxin levels and microalgal adhesion rates on plastic substrates.

Main Results:

• Diatoms were the most abundant colonizers (up to 8.2 × 10^4 cells cm^-2), followed by dinoflagellates (up to 1.1 × 10^3 cells cm^-2).
• Harmful species like Pseudo-nitzschia spp. and Ostreopsis cf. ovata were abundant, with toxin levels ranging from 10^1 to 10^2 ng cm^-2.
• Microalgal adhesion rates ranged from 0.3 to 1.8 day^-1, indicating rapid colonization of plastic surfaces.

Conclusions:

• This study provides the first molecular quantification of microorganisms, including toxin-producing species, colonizing plastics.
• Findings highlight the role of plastic debris as vectors for harmful algal species and their toxins.
• Improved monitoring of plastics is needed, as the epi-plastic community can exacerbate plastic pollution's harmful effects through dispersal and trophic transfer.