CAREER: Quantifying Western Atlantic Climate and Seasonality across the Plio-Pleistocene Regional Molluscan Extinction

在过去的400万年里，70-80%的软体动物物种（蛤，扇贝等）生活在大西洋海湾沿岸沃茨的鱼类已经消失。新物种的出现是为了取代那些灭绝的物种，软体动物的种群今天仍然相当多样化。物种大量更替的原因尚未确定。主要的假设是，不断下降的水温将喜欢温暖水域的物种驱逐出去，取而代之的是那些可以居住在较冷沃茨的物种。研究人员将对过去300万至500万年来东海岸上下的地点进行可靠的定量温度估计，并将其与海洋软体动物的灭绝模式进行比较，以验证这一假设。除了解决灭绝的根本原因外，这些数据还将揭示所研究的软体动物物种的耐热性信息，并确定这些信息是固定的还是灵活的（这意味着一个物种可以适应生活在与目前居住的不同的水温中）。这将对生活在美国沃茨的软体动物的生存产生影响（包括那些养殖的水产养殖，如蛤蜊和扇贝）在未来几十年和几个世纪的海洋温度变暖。研究人员将通过与Umich自然历史博物馆合作的一些外展项目和展览与公众分享他们的发现。他们将创建一个真实的研究体验课程，以降低进入障碍的方式向更多的本科生介绍研究，特别是对于代表性不足的群体。研究人员将使用集束同位素古温度计（D47）对化石软体动物进行同位素测量，包括现代海洋腹足类和双壳类的校准。使用这种新方法是至关重要的，因为初步的基于D47的温度估计与历史上基于氧同位素的估计有很大的不同，历史上基于氧同位素的估计是有缺陷的，因为它们对过去海水的氧同位素组成（d18 Osw）的限制很差。这里产生的数据将直接解决问题的生态位稳定性软体动物类群通过确定的变化（或缺乏）在耐热性随着时间和空间。这个奖项反映了NSF的法定使命，并已被认为是值得支持的评估使用基金会的知识价值和更广泛的影响审查标准。

Over the past ~4 million years, 70-80% of mollusk species (clams, scallops, etc.) living in the waters of the Atlantic & Gulf Coasts have disappeared. New species originated to replace those that went extinct, and the mollusk population remains quite diverse today. The cause of this great turnover in species has not been established. The primary hypothesis is that declining water temperatures pushed out warm-water-loving species and replaced them with those that could inhabit cooler waters. The researcher will produce robust, quantitative temperature estimates from sites up and down the East Coast over the past 3-5 million years and compare those to extinction patterns of marine mollusks to test this hypothesis. In addition to addressing the root cause of the extinction, these data will reveal information about the thermal tolerances of studied mollusk species and determine whether those are fixed or flexible (meaning a species could adapt to live in different water temperatures than it currently inhabits). This will have implications for the survival of mollusks living in American waters (including those farmed for aquaculture like clams and scallops) in the coming decades and centuries as ocean temperatures warm. The researcher will share their findings with the public through a number of outreach projects and exhibits in partnership with the UMich Museum of Natural History. They will create an authentic research experience course to introduce more undergraduates to research in a way that lowers barriers-to-entry, especially for underrepresented groups. The researcher will conduct a program of isotopic measurements on fossil mollusks using the clumped isotope paleothermometer (D47), including calibrations of modern marine gastropods and bivalves. Use of this new method is vital, as preliminary D47-based temperature estimates differ greatly from historical oxygen-isotope-based estimates which are flawed due to their poor constraints on past oxygen isotopic composition of seawater (d18Osw). Data generated here will directly address questions of niche stability in mollusk taxa through determination of changes (or lack thereof) in thermal tolerances over time and space.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.