Gulf Watch Alaska Nearshore Component: Intertidal Mussel Site Data from Prince William Sound, Katmai National Park and Preserve, and Kenai Fjords National Park, 2008-2015

This data is part of the Gulf Watch Alaska (GWA) long term monitoring program, nearshore monitoring component. Specifically, these data describe mussel sampling and observations conducted in the northern Gulf of Alaska within the GWA program. The dataset consists of five comma separated files exported from a microsoft excel workbook. The data consists of 1. mussel sampling site layout information, 2. mussel count and 3. size measurements for mussels greater than 20 millimeters, 4. mussel count and 5. size measurements for all mussels collected from core samples. Samplers used transect tapes, quadrat frames, rulers, and core tools to sample mussels from mussel sites. Mussels greater than 20 millimeters were collected from a quadrat and measured with dial calipers to the nearest millimeter. Associated with the quadrat, but not within it, a small core sample was collected and all mussels greater than 1mm were counted and measured (measurements began in 2014). Sampling year, region, block, site, quadrat number, quardrat size (overall area sampled), and number of mussels in the core were recorded. Sites are in Alaska and include locations in Katmai National Park and Preserve, Kenai Fjords National Park and Prince William Sound. There are five mussel sites in each of those three regions. The time interval includes 2008-2015. Pacific blue mussels (Mytilus trossulus) are a conspicuous and abundant filter feeding marine invertebrate in the intertidal zone. Mussels are widely distributed, but also form relatively monotypic stands of larger individuals that are termed mussel beds. Although a number of factors such as environment, disturbance, predation and competition influence the abundance and distribution of mussels, they can be a competitively dominant intertidal species. Within the nearshore foodweb, mussels area a source of energy to a wide array of invertebrate, avian, and mammalian predators and are critically important prey for sea otters, black oystercatchers, harlequin ducks, Barrows goldeneye, and several species of sea stars.本数据集隶属于阿拉斯加海湾观测计划（Gulf Watch Alaska, GWA）长期监测项目的近岸监测子项目。具体而言，其记录了GWA计划在阿拉斯加湾北部开展的贻贝采样与观测工作。 本数据集包含5个由Microsoft Excel工作簿导出的逗号分隔值（Comma-Separated Values, CSV）文件，数据内容分为5个部分：1. 贻贝采样点位布局信息；2. 体长大于20毫米的贻贝计数数据；3. 体长大于20毫米的贻贝尺寸测量数据；4. 岩芯样本采集的所有贻贝计数数据；5. 岩芯样本采集的所有贻贝尺寸测量数据。 采样人员使用样带卷尺、样方框、直尺与岩芯采样工具开展贻贝采样工作。其中，体长大于20毫米的贻贝取自样方，使用游标卡尺测量至精确到1毫米。在样方周边（非样方内部）采集小型岩芯样本，自2014年起对其中所有体长大于1毫米的贻贝进行计数与尺寸测量。本次采样记录的参数包括：采样年份、区域、区块、点位、样方编号、样方面积（即总采样面积）以及岩芯样本中的贻贝数量。 所有采样点位均位于阿拉斯加境内，涵盖卡特迈国家公园与保护区、基奈峡湾国家公园以及威廉王子湾三个区域，每个区域各设5个贻贝采样点位。监测时段为2008年至2015年。 太平洋蓝贻贝（Mytilus trossulus）是潮间带中醒目且数量丰富的滤食性海洋无脊椎动物。该物种分布广泛，常形成以较大个体为主的单优群落，即贻贝床。尽管环境、扰动、捕食与竞争等诸多因素会影响贻贝的丰度与分布，但其仍是潮间带中具有竞争优势的物种。在近岸食物网中，贻贝为众多无脊椎动物、鸟类与哺乳类捕食者提供能量来源，是海獭、黑蛎鹬、丑鸭、巴氏鹊鸭以及多种海星的关键猎物。