Ohler Katharina, Schreiner Verena C, Martin-Creuzburg Dominik, Schäfer Ralf B
iES Landau Institute for Environmental Sciences, RPTU Kaiserslautern-Landau Fortstraße 7 76829 Landau in der Pfalz Germany.
Department of Aquatic Ecology BTU Cottbus-Senftenberg Research Station Bad Saarow Cottbus Germany.
Ecol Evol. 2023 Mar 24;13(3):e9927. doi: 10.1002/ece3.9927. eCollection 2023 Mar.
Aquatic and their adjacent terrestrial ecosystems are linked via the flux of organic and inorganic matter. Emergent aquatic insects are recognized as high-quality food for terrestrial predators, because they provide more physiologically relevant long-chain polyunsaturated fatty acids (PUFA) than terrestrial insects. The effects of dietary PUFA on terrestrial predators have been explored mainly in feeding trials conducted under controlled laboratory conditions, hampering the assessment of the ecological relevance of dietary PUFA deficiencies under field conditions. We assessed the PUFA transfer across the aquatic-terrestrial interface and the consequences for terrestrial riparian predators in two outdoor microcosm experiments. We established simplified tritrophic food chains, consisting of one of four basic food sources, an intermediary collector gatherer (, Chironomidae), and a riparian web-building spider ( sp.). The four basic food sources (algae, conditioned leaves, oatmeal, and fish food) differed in PUFA profiles and were used to track the trophic transfer of single PUFA along the food chain and to assess their potential effects on spiders, that is, on fresh weight, body condition (size-controlled measurement of nutritional status), and immune response. The PUFA profiles of the basic food sources, and spiders differed between treatments, except for spiders in the second experiment. The PUFA α-linolenic acid (ALA, 18:3n-3) and ɣ-linolenic acid (GLA, 18:3n-6) were major contributors to the differences between treatments. PUFA profiles of the basic food sources influenced the fresh weight and body condition of spiders in the first experiment, but not in the second experiment, and did not affect the immune response, growth rate, and dry weight in both experiments. Furthermore, our results indicate that the examined responses are dependent on temperature. Future studies including anthropogenic stressors would deepen our understanding of the transfer and role of PUFA in ecosystems.
水生生态系统及其相邻的陆地生态系统通过有机和无机物质的流动相互联系。水生昆虫被认为是陆地捕食者的优质食物，因为它们比陆地昆虫能提供更多生理上相关的长链多不饱和脂肪酸（PUFA）。膳食中PUFA对陆地捕食者的影响主要是在实验室控制条件下进行的喂养试验中进行探索的，这妨碍了对野外条件下膳食PUFA缺乏的生态相关性的评估。我们在两个室外微观实验中评估了PUFA在水陆界面的转移以及对陆地河岸捕食者的影响。我们建立了简化的三营养级食物链，由四种基本食物来源之一、中间收集者（摇蚊科）和河岸结网蜘蛛（蜘蛛属）组成。这四种基本食物来源（藻类、经处理的树叶、燕麦片和鱼食）的PUFA谱不同，用于追踪单个PUFA沿食物链的营养转移，并评估它们对蜘蛛的潜在影响，即对鲜重、身体状况（营养状况的大小控制测量）和免疫反应的影响。除了第二个实验中的蜘蛛外，不同处理间基本食物来源、摇蚊和蜘蛛的PUFA谱存在差异。PUFAα-亚麻酸（ALA，18:3n-3）和γ-亚麻酸（GLA，18:3n-6）是不同处理间差异的主要贡献者。基本食物来源的PUFA谱在第一个实验中影响了蜘蛛的鲜重和身体状况，但在第二个实验中没有，并且在两个实验中都没有影响免疫反应、生长速率和干重。此外，我们的结果表明，所检测的反应取决于温度。未来包括人为压力源的研究将加深我们对PUFA在生态系统中的转移和作用的理解。
