Microplastics in bloom-forming macroalgae: Distribution, characteristics and impacts

Area of Science:

• Marine Biology
• Environmental Science
• Oceanography

Background:

• Macroalgal blooms and marine microplastics (MPs) are escalating global ocean challenges.
• The Yellow Sea faces severe green tides and significant MPs pollution.
• The interaction between macroalgal blooms and MPs remains largely unknown.

Purpose of the Study:

• To investigate the trapping of MPs by drifting macroalgae (Ulva prolifera) in the Yellow Sea.
• To quantify the abundance of MPs associated with macroalgae.
• To understand the mechanisms and implications of this interaction.

Main Methods:

• Tracking drifting Ulva prolifera during green-tide periods in the Yellow Sea.
• Quantifying MPs in both macroalgae and surrounding seawater.
• Laboratory experiments to assess the impact of MPs on Ulva prolifera growth and physiology.
• Identifying mechanisms of MP trapping by the macroalgae.

Main Results:

• MPs abundance in drifting Ulva prolifera was 595–3917 times higher than in seawater.
• MP concentration increased along the macroalgae's drifting path from south to north.
• Four trapping mechanisms were identified: twining, attachment, embedment, and wrapping.
• Ulva prolifera exhibited high tolerance to MPs, with no significant impact on growth or photosynthesis until extremely high concentrations.

Conclusions:

• Drifting macroalgae act as significant vectors for marine microplastics.
• The trapping capacity of macroalgae can substantially alter the spatio-temporal distribution of MPs in oceans.
• This interaction has critical implications for understanding and managing marine pollution.