Collaborative Research: Does larval transport or physiological tolerance set the southern range boundary of a northern blue mussel?

智力优点本项目将测试是否南部范围边界的北方蓝色贻贝，贻贝trossulus，是由限制的幼虫，或幼虫和/或少年的生理耐受性的扩散。紫贻贝Mytilustrossulus及其姊妹种M. edulis，共同出现在整个加拿大海洋省份和缅因州的北方海湾。而M. M. trossulus在加拿大边境以南突然减少。edulis分布在南至北卡罗来纳州。迄今为止的研究表明：1）成年M。在缅因州东北部的trossulus栖息在沿海地区，岛屿，和人造结构内的东缅因州沿海流（EMCC）的冷水。2)在EMCC释放的漂流物很少进入南部的近岸沃茨，这表明跨大陆架的运输极为有限。3)这两个物种的幼虫在耐热性上可能略有不同，一些证据表明，耐热性也可能受到营养状况的影响。4)在东北部缅因州地区，但在EMCC之外移植的紫贻贝trossulus青少年，有很高的存活率，而移植到西南部遭受高死亡率。结合，这些结果表明，幼虫运输设置在东北部缅因州（在10公里的规模）的近距离范围内的边界，但热耐受性将最终限制在一个更大的空间尺度（200公里）的分布。在M. trossulus幼虫扩散（6月中旬至8月中旬）将被用来量化的物理流场和温度制度在幼虫扩散。Drogues将使我们能够评估不同深度的幼虫是否会经历不同的流场。水文调查数据，结合定期的空间和时间采样贻贝幼虫和新的定居者，将被用来评估幼虫和定居后阶段和不同的水团之间可能的关联。新定居者的生理耐受性将通过移植到EMCC内外的地点进行测定。最后，实验室生长和存活实验将分析幼虫在不同温度和摄食条件下的表现。研究人员将使用分子标记来识别这些兄弟物种的形态学上无法区分的幼虫和定居者。更广泛的影响这个项目将为一名MS和一名博士生以及几名本科生提供培训。PI是在强调本科和研究生研究的机构，我们的项目将为海洋学和底栖生态学领域和实验室研究提供众多的学生机会。这样的研究机会可能会吸引一些学生，否则他们将从事生物医学研究。缅因州的海湾是一个繁荣的贻贝水产养殖业的家园。trossulus是一种商业上较低的物种--种植者担心它可能会蔓延。因此，更好地了解决定该物种分布区边界的因素将有助于种植者避免M。trossulus spat.将传播结果，以加强与缅因州水产养殖界的沟通。所有的实地考察将在面临巨大教育挑战的缅因州地区进行;将从地区学校招聘教师协助夏季实地考察和实验室工作。

Intellectual MeritThis project will test whether the southern range boundary of a northern blue mussel, Mytilus trossulus, is determined by limitations on the dispersal of larvae, or the physiological tolerance of larvae and/or juveniles. Mytilus trossulus and its sister species, M. edulis, co-occur throughout the Canadian maritime provinces and the northern Gulf of Maine. While the abundance of M. trossulus decreases abruptly south of the Canadian border, M. edulis ranges south to North Carolina. Work to date has demonstrated that: 1) Adult M. trossulus in northeastern Maine inhabit coastal sites, islands, and man-made structures that are within the colder water of the Eastern Maine Coastal Current (EMCC). 2) Drifters released in the EMCC rarely enter nearshore waters to the south, suggesting that across-shelf transport is extremely limited. 3) Larvae of the two species may differ slightly in thermal tolerance, and some evidence suggests that tolerance may also be affected by nutritional status. 4) Mytilus trossulus juveniles transplanted within the northeastern Maine region, but outside of the EMCC, have high survivorship, while transplants further to the southwest suffer high mortality. In combination, these results suggest that larval transport sets the proximate range boundary within northeastern Maine (on a scale of 10 km), but thermal tolerance would ultimately limit the distribution on a larger spatial scale (200 km).This research project is designed to test this pair of hypotheses via a combination of field and lab experiments. Satellite drifters equipped with temperature loggers deployed in and out of the EMCC during the season of M. trossulus larval dispersal (mid-June to mid-August) will be used to quantify the physical flow fields and temperature regimes during larval dispersal. Drogues will allow us to assess whether larvae at different depths may experience different flow fields. Data from hydrographic surveys, combined with regular spatial and temporal sampling of mussel larvae and new settlers, will be used to assess possible associations between larval and post-settlement stages and different water masses. The physiological tolerance of new settlers will be assayed via transplants to sites in and out of the EMCC. Finally, laboratory growth and survival experiments will assay larval performance in different thermal and feeding regimes. The investigators will use molecular markers to identify the morphologically indistinguishable larvae and settlers of these sibling species.Broader ImpactsThis project will provide training for one MS and one PhD student, and several undergraduates. The PIs are at institutions that emphasize undergraduate and graduate research, and our project will provide numerous student opportunities for field and laboratory research in oceanography and benthic ecology. Such research opportunities are likely to attract a number of students who would otherwise pursue careers in biomedical research. The Gulf of Maine is home to a thriving Mytilis edulis aquaculture industry, and M. trossulus is a commercially inferior species - growers are concerned about its possible spread. Hence a better understanding of the factors determining the range boundary of this species will help growers avoid M. trossulus spat. Results will be disseminated to enhance communication with the Maine aquaculture community. All of the fieldwork will be conducted in a region of Maine facing great educational challenges; teachers from area schools will be recruited to assist with summer field and laboratory work.