RAPID: The effects of wildfire on salmonid olfaction and behavior

嗅觉，也就是嗅觉，对水生动物感知周围环境至关重要。环境中的有毒化合物可能会干扰这种能力。野火已成为西部景观的主要特征。当森林燃烧时，它们会释放出有毒的重金属，最终流入溪流。这些化合物可能会干扰动物闻到周围环境的能力，从而改变它们的行为。这项研究考察了最近加州野火对太平洋鲑鱼嗅觉和行为的影响。鲑鱼用它们的嗅觉来探测捕食者。如果这种能力被破坏，它们可能很快成为捕食者的午餐。在海上生活多年后，鲑鱼还利用嗅觉找到返回家乡溪流的路进行繁殖。这个过程被称为嗅觉印记，是小鲑鱼在溪流中经历的一种特殊的学习形式。如果这种印记被破坏，它们就无法在成年后找到回家的路。这项研究使用行为实验来测试受火灾影响的溪流中的鱼是否不太能闻到捕食者的气味。它使用行为实验和嗅觉功能的细胞研究来测试来自受火灾影响的溪流的鱼是否不能识别并在其家乡水域留下印记。该项目将培训学生，扩大科学参与，促进对感官污染物对野生种群影响的一般理解，并为在更干燥、更容易发生火灾的地区管理鲑鱼提供关键信息。在水生环境中，嗅觉线索提供了动物用来做出行为决定的重要信息。野火可能对水生化学环境造成大规模干扰，从而影响整个生态系统的嗅觉和行为。火灾将有机和无机化合物释放到溪流中。其中一些化合物，包括重金属，可能会扰乱嗅觉并改变行为。这项拟议的研究将行为实验与基因表达分析相结合，提出以下问题：野火如何影响自然溪流中幼年鲑鱼的嗅觉和行为？最近发生在2020年8月的加州中部海岸的野火形成了一个由燃烧和未燃烧的流域组成的马赛克。本项目采用配对采样设计，将四个流域内燃烧和未燃烧的溪流配对。在每个流域内选择空间隔离的地点，以确保幼鲑不能在燃烧和未燃烧的地点之间移动。该项目将测量每个流域内燃烧和未燃烧的河流中河流水和鱼类肌肉组织中的重金属浓度。从燃烧和未燃烧的溪流幼鲑的行为将比较在捕食者的回避和识别出生溪流的水。与正常嗅觉功能和出生归巢相关的基因的表达将在燃烧和未燃烧的溪流中进行比较。如果火灾释放的重金属破坏了幼年鲑鱼的嗅觉，那么来自被烧毁溪流的鱼可能会表现出较弱的捕食者躲避能力，对出生溪流水的识别能力受损，以及与嗅觉印迹相关的基因表达减少。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Olfaction, the sense of smell, is critical for aquatic animals to sense their surroundings. Toxic compounds in the environment may interfere with this ability. Wildfire has become a dominant feature of Western landscapes. When forests burn, they can release toxic heavy metals, which ultimately end up in streams. These compounds may interfere with the ability of animals to smell their surroundings, thereby changing behavior. This research examines the effects of recent California wildfires on the olfaction and behavior of Pacific salmon. Salmon use their sense of smell to detect predators. If this ability is disrupted, they may quickly become a predator’s lunch. Salmon also use smell to find their way back to their home streams to reproduce after years at sea. This process, called olfactory imprinting, is a specialized form of learning that juvenile salmon experience in streams. If this imprinting is disrupted, they are unable to find their way back to their home stream as adults. This research uses behavioral experiments to test whether fish from fire-impacted streams are less able to smell predators. It uses behavioral experiments and cellular studies of olfactory function to test whether fish from fire-impacted streams are less able to recognize and imprint on their home watersheds. This project will train students, broaden participation in science, advance a general understanding of the effects of sensory pollutants on wild populations, and contribute critical information to inform salmon management in a drier, more fire-prone landscape.In aquatic environments, olfactory cues provide important information that animals use to make behavioral decisions. Wildfires may cause large-scale disturbance to aquatic chemical environments that may impact olfaction and behavior at the scale of entire ecosystems. Fires release organic and inorganic compounds into streams. Some of these compounds, including heavy metals, may disrupt olfaction and alter behavior. This proposed research combines behavioral experiments with gene expression assays to ask: How does wildfire impact juvenile salmonid olfaction and behavior in natural streams? Recent wildfires that occurred in August 2020 along the Central California Coast have generated a mosaic of burned and unburned watersheds. This project uses a paired sampling design, pairing burned and unburned streams within four watersheds. Spatially isolated sites within each watershed have been selected to ensure juvenile salmonids cannot move between the burned and unburned sites. This project will measure the concentrations of heavy metals in stream water and in fish muscle tissue from burned and unburned streams within each watershed. The behavior of juvenile salmonids from burned and unburned streams will be compared in terms of predator avoidance and recognition of natal stream water. The expression of genes associated with normal olfactory function and natal homing will be compared between fish from burned versus unburned streams. If the release of heavy metals by fire disrupts juvenile salmonid olfaction, then fish from burned streams are expected to exhibit weaker predator avoidance, impaired recognition of natal stream water, and reduced expression of genes associated with olfactory imprinting.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.