2-m ASCII Bathymetric Grid from National Oceanic and Atmospheric Administration (NOAA) Survey H11361 of the Sea Floor in Eastern Long Island Sound (H11361_2MUTM18_XYZ.TXT, UTM Zone18)

The U.S. Geological Survey, in cooperation with the National Oceanic and Atmospheric Administration and the Connecticut Department of Environmental Protection, has produced detailed geologic maps of the sea floor in Long Island Sound, a major East Coast estuary surrounded by the most densely populated region of the United States. These studies have built upon cooperative research with the State of Connecticut that was initiated in 1982. The current phase of this research program is directed toward studies of sea-floor sediment distribution, processes that control sediment distribution, nearshore environmental concerns, and the relation of benthic community structures to the sea-floor geology. Anthropogenic wastes, toxic chemicals, and changes in land-use patterns resulting from residential, commercial, and recreational development have stressed the environment of the Sound, causing degradation and potential loss of benthic habitats (Koppelman and others, 1976; Long Island Sound Study, 1994). Detailed maps of the sea floor are needed to help evaluate the extent of adverse impacts and to help manage resources wisely in the future. Therefore, in a continuing effort to better understand Long Island Sound, we have constructed and interpreted multibeam bathymetric data within specific areas of special interest. This bathymetric data layer presented herein covers a roughly 92 km square area of the sea floor in the area just west of Six Mile Reef, eastern Long Island Sound. The original multibeam bathymetric data were collected during 2004 as part of charting applications aboard the NOAA Survey Vessel Thomas Jefferson. A Simrad EM1002 multibeam system mounted on the hull of this vessel was used to acquire data along survey lines from the deeper water (>20 m) parts of the study area. Two 29-foot launches with hull-mounted Reson systems were deployed from the ship and were used to acquire data along survey lines from the shallower areas. Detailed bathymetric data and their interpretations serve many purposes, including: (1) defining the geological variability of the sea floor, which is one of the primary controls of benthic habitat diversity; (2) improving our understanding of the processes that control the distribution and transport of bottom sediments and the distribution of benthic habitats and associated infaunal community structures; and (3) providing a detailed framework for future research, monitoring, and management activities. The bathymetric data models also serve as base maps for subsequent sedimentological, geochemical, and biological observations, because precise information on environmental setting is important for selection of sampling sites and for accurate interpretation of point measurements.美国地质调查局（U.S. Geological Survey, USGS）联合美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）以及康涅狄格州环境保护部，针对美国东海岸重要河口——长岛湾（Long Island Sound）完成了详细的海底地质填图工作，该区域毗邻美国人口最稠密的城市群。 此项研究工作依托1982年启动的康涅狄格州合作研究项目开展。本研究计划当前阶段的研究方向包括：海底沉积物分布特征、控制沉积物分布的动力过程、近岸环境问题，以及底栖生物群落（benthic community）结构与海底地质的关联。 人为废弃物、有毒化学物质，以及由住宅、商业和休闲开发引发的土地利用模式变更，已对长岛湾的生态环境造成压力，导致底栖生境（benthic habitat）退化甚至潜在丧失（Koppelman等，1976；长岛湾研究项目，1994）。详细的海底填图数据有助于评估负面影响的波及范围，为未来的资源科学管理提供支撑。因此，为持续深化对长岛湾的认知，研究团队针对特定重点区域开展了多波束测深（multibeam bathymetric）数据的采集与解译工作。 本次发布的测深数据图层覆盖了长岛湾东部六英里礁（Six Mile Reef）西侧约92平方公里的海底区域。原始多波束测深数据采集于2004年，由美国国家海洋和大气管理局的“托马斯·杰斐逊号”调查船（NOAA Survey Vessel Thomas Jefferson）负责执行海图测绘任务期间获取。该船搭载的西姆拉德EM1002（Simrad EM1002）多波束系统，用于采集研究区深水（水深>20米）区域的测线数据。科研团队从母船部署了两艘29英尺的工作艇，艇载Reson多波束系统用于采集浅水区的测线数据。 详细的测深数据及其解译成果具备多重应用价值：（1）刻画海底地质异质性——这是控制底栖生境多样性的核心因素之一；（2）深化对控制海底沉积物分布与输运、底栖生境及相关底内生物（infaunal）群落结构分布的动力过程的认知；（3）为后续的研究、监测与管理活动提供精细化的空间框架。本次发布的测深数据模型同时可作为后续沉积学、地球化学与生物学观测的底图，因为环境背景的精准信息对采样点位选取与点位实测数据的准确解译至关重要。