Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Im Technologiepark 5, 26129 Oldenburg, Germany; Alfred-Wegener-Institute, Helmholtz-Centre for Polar and Marine Research (AWI), Am Handelshafen 12, 27570 Bremerhaven, Germany.
GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1-3, 24148 Kiel, Germany.
Sci Total Environ. 2024 Nov 25;953:175659. doi: 10.1016/j.scitotenv.2024.175659. Epub 2024 Aug 22.
Fish early life stages are particularly vulnerable and heavily affected by changing environmental factors. The interactive effects of multiple climate change-related stressors on fish larvae remain, however, largely underexplored. As rising temperatures can increase the abundance and virulence of bacteria, we investigated the combination of a spring heat wave and bacterial exposure on the development of Atlantic herring larvae (Clupea harengus). Eggs and larvae of Western Baltic Spring-spawners were reared at a normal and high temperature ramp and exposed to Vibrio alginolyticus and V. anguillarum, respectively. Subsequently, mRNA and miRNA transcriptomes, microbiota composition, growth and survival were assessed. Both high temperature and V. alginolyticus exposure induced a major downregulation of gene expression likely impeding larval cell proliferation. In contrast, interactive effects of elevated temperature and V. alginolyticus resulted in minimal gene expression changes, indicating an impaired plastic response, which may cause cellular damage reducing survival in later larval stages. The heat wave alone or in combination with V. alginolyticus induced a notable shift in miRNA expression leading to the down- but also upregulation of predicted target genes. Moreover, both increased temperature and the Vibrio exposures significantly altered the larval microbiota composition, with warming reducing microbial richness and diversity. The outcomes of this study highlight the high sensitivity of herring early life stages towards multiple climate change-related stressors. Our results indicate that interactive effects of rapidly changing environmental factors may exceed the larval stress threshold impairing essential acclimation responses, which may contribute to the ongoing recruitment decline of Western Baltic Spring-Spawning herring.
鱼类早期生活阶段特别脆弱，受到环境变化因素的影响较大。然而，多种与气候变化相关的胁迫因素对鱼类幼体的相互作用影响仍在很大程度上尚未得到充分探索。由于温度升高会增加细菌的丰度和毒性，我们研究了春季热浪和细菌暴露对大西洋鲱（Clupea harengus）幼鱼发育的综合影响。我们在正常和高温斜坡下饲养了来自西波罗的海春季产卵的鲱鱼的卵和幼鱼，并分别将其暴露于Alg 弧菌（Vibrio alginolyticus）和鳗弧菌（V. anguillarum）中。随后，评估了 mRNA 和 miRNA 转录组、微生物群落组成、生长和存活率。高温和 Alg 弧菌暴露都显著下调了基因表达，这可能阻碍了幼鱼的细胞增殖。相比之下，高温和 Alg 弧菌的相互作用导致基因表达的变化最小，表明其可塑性反应受损，这可能导致细胞损伤，从而降低后期幼鱼阶段的存活率。热浪单独或与 Alg 弧菌结合会引起 miRNA 表达的显著变化，导致预测靶基因的下调和上调。此外，温度升高和弧菌暴露都显著改变了幼鱼的微生物群落组成，升温降低了微生物的丰富度和多样性。本研究的结果强调了鲱鱼早期生活阶段对多种与气候变化相关的胁迫因素的高度敏感性。我们的研究结果表明，快速变化的环境因素的相互作用可能超过幼鱼的应激阈值，损害其重要的适应反应，这可能导致西波罗的海春季产卵鲱鱼的捕捞量持续下降。
