南ウェールズの塩性湿地は裸地海岸の約3倍の魚類を支えることを確認 (South Wales saltmarshes hold nearly three times more fish than unvegetated shores, Swansea University study shows)

2026-06-13 スウォンジー大学

スウォンジー大学の研究チームは、南ウェールズの塩性湿地(ソルトマーシュ)が、植生のない河口域沿岸と比べて約3倍の魚類密度を支えていることを明らかにした。研究では2023~2024年にかけてバリー湾とスリー・リバーズ河口の14地点を調査し、21種・8525匹の魚類を確認した。特に自然状態のソルトマーシュでは魚類の密度・生物量・生産量が高く、ニシン、ボラ、ヨーロッパヒラメ、サンドイールなど多くの幼魚が生息していた。調査では、英国の塩性湿地が通年型の育成場として機能することも初めて示された。復元湿地では生産量が低かったが、絶滅危惧種ヨーロッパウナギの高い生息数など回復傾向も確認された。研究者らは、塩性湿地が水産資源、生物多様性、沿岸防災に重要な役割を持つと指摘し、英国で進む湿地減少に対し保全と再生を急ぐ必要性を強調した。

南ウェールズの塩性湿地は裸地海岸の約3倍の魚類を支えることを確認 (South Wales saltmarshes hold nearly three times more fish than unvegetated shores, Swansea University study shows)
A graphical abstract of the study findings – Credit: Sasha Shute

<関連情報>

北東大西洋の塩性湿地における魚類の生息密度は、植生のない海岸の3倍である Fish density in NE Atlantic saltmarsh is three-fold higher than unvegetated shores

Sasha L. Shute, Lauren M. Pennack, Alex Scorey, Ida A. Nielsen, Richard K.F. Unsworth, Nicole Esteban
Estuarine, Coastal and Shelf Science  Available online: 2 November 2025
DOI:https://doi.org/10.1016/j.ecss.2025.109599

Highlights

  • The highest recorded saltmarsh fish diversity in the UK (n = 19) occurred in South Wales, UK.
  • Fish density in saltmarsh in South Wales, UK was three-fold higher than unvegetated habitat.
  • Variation in seasonality: dominant fish species varied each month of spring-summer.

Abstract

Atlantic saltmarshes are widely recognised as important and productive estuarine habitats, yet their role in supporting fish populations in northern Europe remains understudied. We used fyke and seine nets to assess fish assemblages at 14 sites across two estuaries in Carmarthen Bay, South Wales. Sampling took place in both saltmarshes and unvegetated estuarine shores monthly from October 2023 to September 2024. The age composition of the catch was predominantly juvenile (83 %). Fish density was significantly higher in saltmarshes (5972 ind/ha) compared to unvegetated shores (1806 ind/ha; p < 0.001). Six species were present in saltmarshes across all seasons, including Atlantic herring (Clupea herrangus) and European flounder (Platichthys flesus) not previously documented year-round in UK saltmarshes. Several species, were significantly more likely to be caught within saltmarsh, including lesser sandeel (Ammodytes tobianus) and grey mullet species (Chelon ramada, Chelon labrosus, Chelon aurata), while no species were significantly more likely to be caught in unvegetated shores, demonstrating saltmarshes enhanced nursery function. In total, 19 fish species were recorded in saltmarshes, representing the highest species richness documented for UK saltmarshes. Clear seasonal shifts in community composition were observed, with peaks in European flounder (Platichthys flesus) in May, European bass (Dicentrarchus labrax) in June and Atlantic herring (Clupea herrangus) in July, likely reflecting staggered recruitment strategies that minimise competition during early life stages. These findings provide the first year-round assessment of saltmarsh fish assemblages on the west coast of the UK and highlight the ecological value of saltmarshes in supporting coastal fish communities.

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