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Abstract In the global ocean, more than 380 species are known to ingest microplastics (plastic particles less than 5 mm in size), including mid-trophic forage fishes central to pelagic food webs. Trophic pathways that bioaccumulate microplastics in marine food webs remain unclear. We assess the potential for the trophic transfer of microplastics through forage fishes, which are prey for diverse predators including commercial and protected species. Here, we quantify Northern Anchovy ( Engraulis mordax ) exposure to microplastics relative to their natural zooplankton prey, across their vertical habitat. Microplastic and zooplankton samples were collected from the California Current Ecosystem in 2006 and 2007. We estimated the abundance of microplastics beyond the sampled size range but within anchovy feeding size ranges using global microplastic size distributions. Depth-integrated microplastics (0–30 m depth) were estimated using a depth decay model, accounting for the effects of wind-driven vertical mixing on buoyant microplastics. In this coastal upwelling biome, the median relative exposure for an anchovy that consumed prey 0.287–5 mm in size was 1 microplastic particle for every 3399 zooplankton individuals. Microplastic exposure varied, peaking within offshore habitats, during the winter, and during the day. Maximum exposure to microplastic particles relative to zooplankton prey was higher for juvenile (1:23) than adult (1:33) anchovy due to growth-associated differences in anchovy feeding. Overall, microplastic particles constituted fewer than 5% of prey-sized items available to anchovy. Microplastic exposure is likely to increase for forage fishes in the global ocean alongside declines in primary productivity, and with increased water column stratification and microplastic pollution.
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This content will become publicly available on June 1, 2026
Stratification intensity structures zooplankton functional trait composition in a continental shelf system
Abstract Zooplankton composition and distribution influence prey quality and availability for higher trophic levels, yet ecological forces structuring communities are not often resolved on spatial scales relevant to predator–prey encounters (1–10 m). Because continental shelf water columns are often vertically stratified, fine-scale interactions may influence overall biological productivity. Using a towed imaging system, we measured meso- and macrozooplankton abundances (>2.2 mm equivalent spherical diameter) in the South Atlantic Bight between the 25 and 45 m isobaths in August 2021. Zooplankton were parsed into four key traits (size, carbon content, trophic strategy, and swimming speed), and buoyancy frequency was used to identify discrete vertical oceanographic zones. Trait diversity was less variable in mixed waters due to the dominance of low carbon content zooplankton or passive swimmers. Upwelling intrusions generated high chlorophyll-a and sharp stratification, which favoured high-carbon, fast swimming zooplankton. Trait group abundances were often higher in these deeper, sharply stratified waters, suggesting that intrusions generally favour secondary production, with gelatinous organisms gradually becoming more dominant as the pycnocline weakens. The distribution of size classes, however, did not change among water masses. Stratification and mixing generate distinct environments and consistent trait assemblages, potentially improving predictions of community responses to oceanographic structure.
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- PAR ID:
- 10658213
- Editor(s):
- Andersen, Ken
- Publisher / Repository:
- ICES Journal of Marine Science
- Date Published:
- Journal Name:
- ICES Journal of Marine Science
- Volume:
- 82
- Issue:
- 6
- ISSN:
- 1054-3139
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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