Brownification increases winter mortality in fish

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• 作者：Per Hedström ; David Bystedt ; Jan Karlsson ; Folmer Bokma ; Pär Byström
• 关键词：Brownification ; Winter mortality ; Light limitation ; Feeding efficiency ; Metabolism
• 刊名：Oecologia
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：183
• 期：2
• 页码：587-595
• 全文大小：548KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Ecology; Plant Sciences; Hydrology/Water Resources;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-1939
• 卷排序：183

文摘

In northern climates, winter is a bottleneck for many organisms. Low light and resource availability constrains individual foraging rates, potentially leading to starvation and increased mortality. Increasing input of humic substances to aquatic ecosystems causes brownification of water and hence a further decrease of light availability, which may lead to further decreased foraging rates and starvation mortality during winter. To test this hypothesis, we measured the effects of experimentally increased humic water input on consumption and survival of young-of-the-year three-spined stickleback (Gasterosteus aculeatus) over winter in large outdoor enclosures. Population densities were estimated in autumn, and the following spring and food availability and consumption were monitored over winter. As hypothesized, mortality was higher under humic (76%) as compared to ambient conditions (64%). In addition, body condition and ingested prey biomass were lower under humic conditions, even though resource availability was not lower under humic conditions. Light conditions were significantly poorer under humic conditions. This suggests that increased mortality and decreased body condition and ingested prey biomass were not due to decreased resource availability but due to decreased search efficiency in this visual feeding consumer. Increased future brownification of aquatic systems may, therefore, negatively affect both recruitment and densities of fish.