Composite sidescan sonar mosaic of National Oceanic and Atmospheric Administration (NOAA) survey H11044 in West-Central Long Island Sound off Milford, Connecticut (H11044_GEO_WGS84.TIF, geographic)

The U.S. Geological Survey, in cooperation with the National Oceanographic 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 sidescan sonar mosaics (complete-coverage acoustic images of the sea floor) within specific areas of special interest. The mosaic presented herein covers a section of the sea floor in west-central Long Island Sound off Milford, Connecticut. The mosaics 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 sidescan sonar mosaics 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）与美国国家海洋和大气管理局（National Oceanographic and Atmospheric Administration）、康涅狄格州环境保护部（Connecticut Department of Environmental Protection）合作，针对坐落于美国人口最密集区域周边的东海岸重要河口——长岛湾（Long Island Sound）的海底完成了详细地质填图。此项研究依托1982年启动的康涅狄格州合作研究项目推进。本研究计划当前阶段的研究方向为：海底沉积物分布、调控沉积物分布的过程、近岸环境问题，以及底栖生物群落结构与海底地质的关联。 人为废弃物、有毒化学品，以及由住宅、商业及休闲开发引发的土地利用格局变化，已对长岛湾的生态环境造成显著胁迫，引发底栖栖息地退化乃至潜在丧失（Koppelman等，1976；长岛湾研究项目，1994）。为精准评估此类负面影响的波及范围，并为未来的资源科学管理提供支撑，高精度海底填图成果不可或缺。因此，为持续深化对长岛湾的认知，研究团队针对若干重点关注区域构建并解析了侧扫声呐镶嵌图（sidescan sonar mosaics，即全覆盖式海底声学影像）。 本次披露的镶嵌图覆盖了康涅狄格州米尔福德市近海的长岛湾中西部海底区域。该镶嵌图及其解析成果具备多重应用价值：（1）明确海底地质变异性——该因素是调控底栖生境多样性的核心控制因子之一；（2）深化对调控海底沉积物分布与输运、底栖生境及相关底内生物群落（infaunal community）结构分布过程的认知；（3）为后续研究、监测与管理活动提供精细化框架。 侧扫声呐镶嵌图同时可作为后续沉积学、地球化学及生物学观测的基础底图，因环境背景的精准信息对于采样点位遴选及单点测量结果的准确解析具有重要意义。