「炭鉱のカナリア」:乾燥気候に適応した魚でさえ、気温上昇と干ばつの中で苦戦している(‘A canary in the coal mine’: Even fish adapted to dry climates are struggling amid rising temps, droughts)

2025-09-17 バッファロー大学(UB)

バッファロー大学を中心とする研究チームは、米国とオーストラリアの乾燥地帯にある約1,500の河川・渓流の42年間のデータを解析し、魚類多様性の減少を報告した。調査では降水量の減少(米国で年0.137mm、豪州で年0.083mm)や無流期間の増加(年0.62日)など水資源の悪化が確認され、特に小型で食性が流量に依存する魚種で影響が顕著だった。ただし解析モデルは水資源減少と種数減少の直接的因果関係を示さず、外来種や人間活動など複合的要因の影響も示唆された。研究者は「乾燥地の魚は気候変動のカナリア」として、生態系への早期警告的存在であると強調した。本研究はEcology and Evolution誌に掲載された。

「炭鉱のカナリア」:乾燥気候に適応した魚でさえ、気温上昇と干ばつの中で苦戦している(‘A canary in the coal mine’: Even fish adapted to dry climates are struggling amid rising temps, droughts)
A desert sucker sampled from the Gila River, New Mexico, in 2011. Photo: Corey Krabbenhoft/University at Buffalo

<関連情報>

人為的ストレス要因と気候ストレス要因による乾燥生態地域の淡水魚群集における長期的な群集構成の変化 Long-Term Regime Shifts in Xeric Ecoregion Freshwater Fish Assemblages due to Anthropogenic and Climate Stressors

Corey A. Krabbenhoft, Jane S. Rogosch, Freya E. Rowland
Ecology and Evolution  Published: 01 September 2025
DOI:https://doi.org/10.1002/ece3.72067

ABSTRACT

Shifting climate regimes are projected to increase the area of xeric regions and result in more pronounced intermittency across river networks. Given these projected changes, we aim to understand the factors contributing to species persistence under increasing aridity. To investigate how changing flow regimes are related to changes in fish richness and assemblage composition, we compiled data from 1473 xeric stream sites in the United States and Australia. The temporal coverage of this dataset is more than 40 years, from 1980 to 2021. Our focus was on fishes occurring in xeric streams and included 191 species. We compiled climate, hydrologic, and fish species trait data to identify relationships between environmental drivers of species persistence and corresponding characteristics common to species in these systems and traits eliciting the strongest responses to environmental change. Our data show declines in overall precipitation in concert with increasing temperatures over the last several decades. Climatic shifts were accompanied by declines in discharge, increased zero-flow days, and longer durations of no-flow periods. In these same systems, an overall linear decline in fish species richness was observed, but it was not directly correlated with any hydrologic predictors. However, xeric species of conservation concern were small-bodied and occupied lower trophic levels than those not of concern. Listed species were primarily affected by multiple stressors, including habitat degradation and invasive species, compounded by a small geographic range. We thus propose a multiple stressors argument for the declines in xeric fish assemblages, something that may be exacerbated by climate alterations in the future. This work highlights a critical conservation need for xeric fishes and identifies taxa that are especially vulnerable to a combination of anthropogenic stressors and changing climates.

1903自然環境保全
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