RUI: River and sediment-modulated stress in planktonic and early settlement Mya arenaria

河口因其渔业、生态系统服务和娱乐潜力而具有生产力、复杂性和巨大的经济价值。由于异养过程中产酸和来自陆地和大气的酸性输入的综合影响，它们对酸的缓冲作用通常不如开阔的海洋。在河口，重要的是要了解不同的酸负荷如何影响生物资源，特别是那些提供生态系统服务和/或产生收入的渔业资源。本研究的重点物种——双壳类沙螺就是这样一种资源，它维持着宝贵的沿海渔业，同时通过其过滤能力提供服务。由于Mya壳是由一种相对可溶的碳酸钙（文石）构成的，而且这种蛤蜊通常生活在富营养化水域，所以当pH值下降时，它们可能特别脆弱。浮游幼虫和底栖幼体是生命的关键阶段——即使它们的丰度稍有减少，也会大大减少成年种群。本研究提出了关于河流和沉积物相互作用对Mya幼虫和幼鱼生存能力的四个不同假设。研究活动包括以下内容。1. 实地考察将评估肯纳贝克河河口和卡斯科湾文石饱和状态的空间和季节变化。季节性采样将与每年产卵期间的高频采样相结合，观察和记录文石饱和度降低对Mya幼虫健康状况的影响。利用Mya幼虫，实验室实验将模拟卡斯科湾在高频巡航期间观察到的文石饱和状态。Mya的变质变化（veligers、pediveligers和变质幼虫）、生长率和存活率将作为文石饱和状态的函数进行评估。3. 对缅因州法尔茅斯潮间带泥滩进行空间密集的每日队列监测，将建立Mya集期间沉降幼鱼丰度变化与文石饱和状态之间的联系。将参考沉积物pH值和附近沉积物文石饱和状态对Mya沉降进行队列监测，以确定沉积物饱和状态是否是过渡幼虫的主要沉降线索。4. 将为贝类管理界开发一种诊断模型，用于检测水柱文石饱和状态。该模型将在常规的海洋学测量（盐度、温度、氧气和叶绿素荧光）上运行。研究的知识价值：大气中二氧化碳增加和由此产生的碳酸水解的化学后果已被充分了解，而由此产生的海洋酸化已被当前一代的全球环流模式准确地预测出来。这些预测加速了对海洋酸化对海洋生物影响的研究，特别是那些具有CaCO3外骨骼的海洋生物。河口水域的缓冲比海洋少得多，受到各种酸负荷的影响，很可能酸化的速度比开阔的海洋快。然而，这些地区在“酸化”研究中基本上被忽视了。酸化对钙化生物的影响是相似的，无论酸的来源是大气交换、净异养还是酸性河水的排放。同样，每一种酸通量都受到人为活动（如使用化石燃料、砍伐森林、农业）的干扰。本研究将进一步了解不同酸负荷对沿海水域钙化生物的综合和累积影响。更广泛的学习影响：缅因圣约瑟夫学院是一所本科院校，有许多潜在的机会向学生介绍科学研究和发现的兴奋。这个项目对圣约瑟夫学院70%的女性学生来说具有特殊意义，她们中的许多人将第一次体验科学研究。学生对研究的投入将效仿SJC的其他赞助研究，从而形成一个新的海洋科学专业，超过35名SJC本科生参加和/或在国家/国际会议上发表研究成果（12名作为共同作者），4名学生共同撰写了近期发表的论文。

Estuaries are productive, complex and have great economic value by virtue of their fisheries, ecosystem services and recreation potential. They are typically less buffered to acid than open oceans due to the combined effects of acid production during heterotrophy and acidic inputs from both land and atmosphere. Within estuaries, it is important to understand how varying acid burdens impact living resources, particularly those that provide ecosystem services and/or generate income as fisheries. The bivalve Mya arenaria, the focal species of this proposed research, is one such resource that sustains a valuable coastal fishery while providing service via its filtration capacity. Because Mya shells are constructed from a relatively soluble form of calcium carbonate (aragonite), and the clams often inhabit eutrophic waters, they may be particularly vulnerable as pH declines. Planktonic larvae and benthic juveniles are critical life stages -- even small reductions in theier abundances could substantially decrease adult populations. This proposed research addresses four distinct hypotheses concerning the roles of riverine and sediment interactions on the viability of larval and juvenile Mya. Research activities include the following. 1. Fieldwork will evaluate the spatial and seasonal changes in aragonite saturation state within the Kennebec River Estuary and Casco Bay. Seasonal sampling will be coupled with high-frequency sampling during the annual Mya spawn to observe and document the effect of lowered aragonite saturation state on the health status of larval Mya. 2. Using larval Mya, laboratory experiments will mimic the aragonite saturation state observed in Casco Bay during the high-frequency cruises. Metamorphic change (veligers, pediveligers, and metamorphosed juveniles), growth rate, and survivorship of Mya will be evaluated as a function of aragonite saturation state. 3. Spatially intensive daily cohort monitoring of the intertidal mud flats in Falmouth, Maine, will establish the link between changes in abundance of settling juveniles and aragonite saturation state during the period of Mya set. Cohort monitoring of settling Mya will be examined in reference to sediment pH and aragonite saturation state in nearby deposits to ascertain if sediment saturation state is a primary settlement cue for transitioning larvae. 4. A diagnostic model will be developed for the shellfish management community that can be used to detect aragonite saturation state of the water column. The model would run on routine oceanographic measurements (salinity, temperature, oxygen and chlorophyll fluorescence). Intellectual merit of study: The chemical consequences of increasing atmospheric CO2 and resulting hydrolysis of carbonic acid is well understood and resultant ocean acidification has been accurately predicted with the current generation of global circulation models. These predictions have accelerated research into the effects of ocean acidification on marine organisms, particularly those with CaCO3 exoskeletons. Estuarine waters are far less buffered than oceans, are subject to a variety of acid loadings, and are quite possibly acidifying at a faster rate than the open ocean. Yet, these regions have been largely ignored in 'acidification' research. Effects of acidification on calcifying organisms are similar regardless of whether of acid origin -- atmospheric exchange, net heterotrophy, or discharge of acidic river water. Likewise, each of these acid fluxes is being perturbed via anthropogenic activity (e.g. fossil fuel use, deforestation, agriculture). The proposed research will further understanding of the combined and cumulative impacts of varied acid burdens on calcifying organisms in coastal waters. Broader impacts of study: Saint Joseph's College of Maine is an undergraduate institution with many potential opportunities to introduce students to the excitement of scientific research and discovery. This project will have special significance to the 70% of women that make up the student body at Saint Joseph's College, many of whom will experience research science for the first time. The immersion of students into research will be modeled after other sponsored research at SJC, resulting in a new marine science major, in over 35 SJC undergraduates attending and/or presenting research results at national/international conferences (12 as co-authors), and in 4 students co-authoring recent papers for publication.