Alternate Title

Microdebris Abundance, Distribution, and Ingestion by Sargassum-Associated Juvenile Fishes in the Gulf of Mexico

Document Type



Holopelagic Sargassum is a critical nursery habitat for the early life stages of many marine fishes, including several federally managed species in the United States and Caribbean. Sargassum is often aggregated along surface convergence features where microdebris (synthetic, semi—synthetic, and naturally—derived particles size) have also been found in relatively high concentrations. In this study, we collected microdebris from Sargassum and adjacent open water habitats (in 2018), and juvenile fishes from Sargassum (in 2017 and 2018) in the northern Gulf of Mexico to quantify habitat—specific microdebris concentrations and the degree to which Sargassum—associated juvenile fishes ingest microdebris. Microdebris concentrations within Sargassum habitats were, on average, 180 times greater than those found within adjacent open water habitats. Microdebris concentrations decreased with distance from shore in both Sargassum and open water habitats, and generally increased with Sargassum biomass. Microdebris ingestion by juvenile (9–320 mm SL) fishes (n = 846) varied by year (all taxa: 24.7% in 2017; 14.7% in 2018) and by taxa, and generally decreased with distance from shore. Small fibers were the dominant type of microdebris observed in stomach contents. The structural complexity of Sargassum provides a mechanism for microdebris capture and concentration in surface waters. Since 2011, massive blooms of Sargassum have inundated regions in the central Atlantic Ocean and Caribbean Sea. The role of Sargassum as a microdebris “sink” has major implications for the transport of microdebris as Sargassum drifts within and across basins and eventually strands on beaches and coastal habitats, or subsides to benthic environments.

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Lestrade and Hernandez Supplemental Figure S1.pdf (67 kB)
Supplementary Figure S1

Lestrade and Hernandez Supplemental Table S2.pdf (104 kB)
Supplementary Table S2

Lestrade and Hernandez Supplemental Table S3.pdf (142 kB)
Supplementary Table S3

Lestrade and Hernandez Supplementary Figure S2.pdf (53 kB)
Supplementary FIgure S2

Lestrade and Hernandez supplementary table S1.pdf (113 kB)
Supplementary Table S1