Collaborative size frequency surveys by commercial urchin divers

This metadata record documents the size frequency surveys for subtidal community surveys. Size frequency sampling consists of recording the number and size of target invertebrate species (urchins of the genus Strongylocentrotus and red abalone Haliotis rufescens). Individuals are encountered and recorded as separate swath surveys in the vicinity of the main swath survey site. Completed as part of a collaborative sampling by commercial urchin fisherman at a few select study sites in the summer of 2016. Subtidal community structure surveys are conducted annually at all sites during the summer or early fall, and quantify substrate type and relief, benthic cover, abundance of major groups of macroalgae and invertebrates, and abundance and size of fishes. Spatial allocation of sampling is designed to measure year-to-year site-wide variability in community structure and the spatial scales at which such variation occurs. A site is defined as a fixed area of coastline comprised of 3 cells, each occupying approximately 500m. Each cell is comprised of 4 benthic transects stratified across the two zones described below.

本元数据记录针对潮下带群落调查的粒径频率采样工作进行归档。粒径频率采样的内容为记录目标无脊椎动物类群的数量与个体尺寸，目标类群包括球海胆属（Strongylocentrotus）海胆以及红鲍（Haliotis rufescens）。调查对象于主条带调查点位周边以独立条带调查的方式被发现并记录。本次采样为2016年夏季商业海胆捕捞从业者于若干选定研究点位开展的合作采样项目的组成部分。
所有研究点位均于每年夏季或初秋开展潮下带群落结构调查，以量化底质类型与地形起伏、底栖覆盖度、大型藻类及主要无脊椎动物类群的丰度，同时记录鱼类的丰度与个体尺寸。
采样的空间布设方案旨在评估群落结构逐年的点位整体变异情况，以及该类变异发生的空间尺度。
研究点位被定义为一段固定的岸线区域，由3个采样单元组成，每个单元覆盖长度约500米。每个采样单元包含4条底栖样线，按照下文所述的两个区域进行分层布设。