The Communities at Sea maps use Vessel Trip Report location point data as input to create density polygons representing visitation frequency ("fisherdays"). The data show total labor including crew time and the time spent in transit to and from fishing locations. They do not show other variables such as vessel value or number of pounds landed. The results can be interpreted as maps of "community presence." This layer shows data for the dredge fishing gear group for Chatham, MA from 2011-2015.

Seagrass beds are critical wetlands components of shallow marine ecosystems along the Massachusetts coastline. Seagrass beds provide food and cover for a great variety of commercially and recreationally important fauna and their prey. The leaf canopy of the seagrass bed calms the water, filters suspended matter and together with extensive roots and rhizomes, stabilizes sediment. Seagrasses are often referred to as "Submerged Aquatic Vegetation" or SAV. This distinguishes them from algae, which are not classified as plants by biologists (rather they are often placed in the kingdom protista), and distinguishes them from the "emergent" saltwater plants found in salt marshes.

In Massachusetts, the dominant SAV is Zostera marina or eelgrass. The other species found in the embayments of the Massachusetts coast is Ruppia maritima, commonly called “widgeon grass,” which is present in areas of less salinity along Cape Cod and Buzzards Bay. Widgeon grass, found in the upper reaches of embayments, has a thread-like morphology that makes it difficult to identify using remotely sensed data. It can only be identified and located by on-site survey.

The Massachusetts Department of Environmental Protection (MassDEP) began a program to map the state's SAV resources in the early 1990s and since 1995 the MassDEP Eelgrass Mapping Project has produced multiple surveys of SAV along the Massachusetts coastline, as listed here:

PhaseProject YearsProject Area11995Entire MA Coast22001Coast-wide MA Coast except Elizabeth Islands (Gosnold) and Mount Hope Bay32006/07Selected embayments, coast-wide including Elizabeth Islands42010-20132010 - South Shore of Cape Cod: Woods Hole to Chatham, selected embayments, Pleasant Bay;2012 - North Shore, Boston Harbor, South Shore to Provincetown;2013 - Buzzards Bay, Elizabeth Islands, Martha's Vineyard and Nantucket52015-20172015 - South Shore of Cape Cod, Pleasant Bay, Nantucket;2016 - North Shore, Boston Harbor, South Shore to Canal;2017 - Buzzards Bay, North Shore of Cape Cod, Elizabeth Islands and Martha's Vineyard62019-20232019 - South Shore of Cape Cod, Pleasant Bay, North Shore of Nantucket2020 - Martha’s Vineyard, Buzzards Bay and Elizabeth Islands 2021 - Cape Cod Bay (Provincetown through Duxbury) 2022 - South Shore, Boston Harbor, North Shore (Marshfield through Rockport)2023 - Cape Ann to the New Hampshire border (Essex through Newburyport)

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BenchmarksThis feature layer, utilizing National Geospatial Data Asset (NGDA) data from the National Oceanic and Atmospheric Administration (NOAA), displays the Center for Operational Oceanographic Products and Services (CO-OPS) locations of present and historical stations in the United States at which benchmarks have been derived from oceanographic observations. According to NOAA, a bench mark is "a fixed physical object or mark used as reference for a horizontal or vertical datum. A tidal bench mark is one near a tide station to which the tide staff and tidal datums are referred. A primary bench mark is the principal mark of a group of tidal bench marks to which the tide staff and tidal datums are referred."Chatham, Lydia Cove (MA) & Chatham, Stage Harbor (MA)Data currency: This cached Esri federal service is checked weekly for updates from its enterprise federal source (Benchmarks) and will support mapping, analysis, data exports and OGC API – Feature access.NGDAID: 178 (Sea Level Trends: Sea Level Variations of the United States Derived from National Water Level Observation Network Stations)OGC API Features Link: (CO-OPS Benchmarks - OGC Features) copy this link to embed it in OGCFor more information: Bench Mark Data Sheets - Station Selection; Tides & Currents ProductsFor feedback please contact: Esri_US_Federal_Data@esri.comNGDA Data SetThis data set is part of the NGDA Water - Oceans & Coast Theme Community. Per the Federal Geospatial Data Committee (FGDC), Water - Oceans & Coast is defined as "features and characteristics of salt water bodies (i.e. tides, tidal waves, coastal information, reefs) and features and characteristics that represent the intersection of the land with the water surface (i.e. shorelines), the lines from which the territorial sea and other maritime zones are measured (i.e. baseline maritime) and lands covered by water at any stage of the tide (i.e. Outer Continental Shelf ), as distinguished from tidelands, which are attached to the mainland or an island and cover and uncover with the tide."For other NGDA Content: Esri Federal Datasets