Ocean Acidification/Collaborative Research/RUI: Effects of Ocean Acidification on Larval Competence, Metamorphosis, and Juvenile Performance in a Planktotrophic Gastropod

现在空气中的二氧化碳水平比200年前工业革命开始时高出约40%。至少三分之一的过剩二氧化碳已经被海洋吸收，随着二氧化碳形成碳酸，海洋变得更加酸性。由于环境的其他特征预计也将发生显著变化(例如，海水温度将上升，食物可获得性和营养价值可能下降)，由于在早期发育过程中经历的压力可能会产生持久的影响，以及由于对反应的分子机制知之甚少，理解这种日益严重的海洋酸化对海洋动物和生态系统可能产生的影响是复杂的。这项研究考察了不同环境条件下的OA将如何影响海螺Crepidula forNicata的发育、扩散和变态，Crepidula forNicata是一种原产于美国东部的常见物种，现已在太平洋西北部、欧洲和其他地方定居。这项研究将包括：1)OA对幼虫组织和壳的相对生长速率的影响；2)幼虫暴露于OA对幼虫存活和生长的长期影响；3)OA对幼虫和幼体基因表达模式的影响；4)OA对变态时间和对环境诱导剂反应能力的影响；5)温度升高对OA反应的影响；6)幼虫对OA脆弱性的影响；以及7)OA对幼虫游泳能力和定居行为的影响。这种被研究的物种原产于美国东海岸，但现在已经成为世界许多其他地区的重要入侵物种。这一结果将对了解该物种的持续传播具有重要意义。此外，这项工作包括研究生和本科生培训的机会，与高中教师的接触，以及开发新的课堂练习。预计在未来几年，软体动物幼虫将特别容易受到海洋酸化(OA)的影响，因为它们的外壳很薄。此外，水温预计会放大OA的一些影响。一些影响，如潜在的生长速度减慢、壳厚度减少和扩散能力的改变可能是立竿见影的，而另一些(潜在影响)可能要到发育后期才会出现，也就是在变态发生之后很久。此外，无论有没有海洋变暖，海洋变暖都可能改变幼虫的行为和生理，从而影响变态的时间和幼虫的适应能力，从而改变扩散潜力和对捕食者的脆弱性。油酸还可能改变浮游植物的丰度和营养质量。我们将调查不同环境情景下OA对海产腹足类Crepidula forNicata幼虫的影响，这种易于养殖的物种作为轮虫发育的一般模型和底栖潮下群落中具有重要生态意义的入侵者正受到越来越多的关注。我们的研究将包括：1)OA对幼虫组织和贝壳生长速率的影响；2)幼虫暴露于OA对幼虫存活和生长的潜在影响；3)温度升高对幼虫对OA的反应的影响；4)OA升高对幼虫和幼虫基因表达的影响；5)OA对幼虫变态能力发展的影响；6)OA对适应幼虫对各种变态诱导剂的反应的影响；7)幼虫在幼虫阶段和变态后对OA易感性的影响(潜在影响)；(8)OA对幼虫游泳和定居行为的影响，以及这些行为的神经关系。

Levels of CO2 in the air are now about 40% higher than they were 200 years ago at the start of the Industrial Revolution. At least 1/3 of excess CO2 production has been absorbed by the ocean, making it more acidic as the CO2 forms carbonic acid. Understanding the likely impact of this increasing ocean acidification (OA) on marine animals and ecosystems is complicated by the fact that other features of the environment are also expected to change appreciably (e.g., seawater temperatures will increase and food availability and nutritional value may decline), by the fact that stresses experienced in early development can have lasting effects, and because the molecular mechanisms of the responses are poorly understood. This study examines how OA under different environmental conditions will impact the development, dispersal, and metamorphosis of the marine snail Crepidula fornicata, a common species native to the eastern U.S. that has now become established in the Pacific Northwest, Europe, and elsewhere. This study will include: 1) the impact of OA on relative rates of tissue and shell growth in larvae; 2) long-term impact of larval exposure to OA on the survival and growth of juveniles; 3) influence of OA on gene expression patterns in both larvae and juveniles; 4) impact of OA on time until metamorphosis and on the ability to metamorphose in response to environmental inducers; 5) effect of elevated temperature on responses to OA; 6) impact of larval diet on vulnerability to OA; and 7) impact of OA on larval swimming ability and settlement behavior. The study species is native to the East coast of the United States but has now become an important invasive in many other parts of the world. The results will have important implications for understanding the continued spread of this species. In addition, the work includes opportunities for graduate and undergraduate student training, outreach to high school teachers and development of new classroom exercises. Molluscan larvae are expected to be especially susceptible to the effects of ocean acidification (OA) in the coming years, due to their thinly calcified shells. In addition, water temperatures are expected to amplify some impacts of OA. Some effects, such as potentially reduced growth rates, reduced shell thickness, and altered dispersal capability are likely to be immediate, while others (latent effects) may appear only later in development, well after metamorphosis has taken place. In addition, OA--with or without ocean warming--may alter larval behavior and physiology in ways that affect the timing of metamorphosis and the fitness of juveniles,thus altering dispersal potential and vulnerability to predators. OA may also alter the abundance and nutritional quality of phytoplankton. We will investigate the consequences of OA under different environmental scenarios for larvae of the marine gastropod Crepidula fornicata, an easily cultured species that is receiving increasing attention both as a general model for lophotrochozoan development and as an ecologically significant invader in benthic subtidal communities. Our study will include: 1) impact of OA on rates of larval tissue and shell growth; 2) latent effects of larval exposure to OA on juvenile survival and growth; 3) effect of elevated temperature on responses to OA; 4) influence of elevated OA on larval and juvenile gene expression; 5) impact of OA on the development of competence for metamorphosis; 6) impact of OA on the response of competent larvae to a variety of metamorphic inducers; 7) impact of larval diet quality on vulnerability to OA, both in the larval stages and following metamorphosis (latent effects); and 8) impact of OA on larval swimming and settlement behaviors, and the neural correlates of those behaviors.