Microfibers Accumulation within a Mediterranean Submesoscale Cyclone

TL;DR

This study shows that small ocean whirlpools in the Mediterranean trap microfibers, acting as temporary pollution reservoirs.

Contribution

The paper reveals that submesoscale cyclones efficiently accumulate microfibers, a previously underappreciated transport mechanism for marine pollution.

Findings

Submesoscale cyclones in the Mediterranean trap microfibers at 0.34 MF l–1 in their core.

Microfiber enrichment persists in a secondary cyclone after the main one fragments.

Elevated chlorophyll-a suggests biological activity linked to physical ocean dynamics.

Abstract

Cyclonic eddies are
widespread upper ocean features known to enhance
primary productivity via nutrient upwelling; yet, their role in the
transport and retention of anthropogenic contaminants remains poorly
understood. Here, we present high-resolution oceanographic measurements
from a submesoscale cyclone in the Western Mediterranean Sea, revealing
a pronounced subsurface accumulation of textile microfibers (MFs)
within the eddy core (0.34 MF l–1) relative to surrounding
waters (0.09 MF l–1). This enrichment persisted
in a secondary, smaller cyclone that detaches following the main cyclone’s
fragmentation. Elevated chlorophyll-a concentrations in the upper
40 m, driven by isopycnal uplift, point to a coupled biological response
to physical forcing. Spatial heterogeneity in pollution sources, vertical
circulation, and mixing likely explains the observed microfiber distribution.
Our findings demonstrate that submesoscale cyclones can function as
transient yet efficient reservoirs of man-made contaminants, with
potential consequences for pollutant exposure pathways and trophic
transfer in marine ecosystems.

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