Manomet Intertidal Green Crab Project - Powered by Anecdata.org

Data Records

The data in this occurrence resource has been published as a Darwin Core Archive (DwC-A), which is a standardized format for sharing biodiversity data as a set of one or more data tables. The core data table contains 11 records.

This IPT archives the data and thus serves as the data repository. The data and resource metadata are available for download in the downloads section. The versions table lists other versions of the resource that have been made publicly available and allows tracking changes made to the resource over time.

Versions

The table below shows only published versions of the resource that are publicly accessible.

Rights

Researchers should respect the following rights statement:

The publisher and rights holder of this work is The Community Environmental Health Laboratory at MDI Biological Laboratory. This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.

GBIF Registration

This resource has been registered with GBIF, and assigned the following GBIF UUID: 3151231f-0ad5-480d-8529-456dd4a74e55.  The Community Environmental Health Laboratory at MDI Biological Laboratory publishes this resource, and is itself registered in GBIF as a data publisher endorsed by GBIF-US.

Keywords

Occurrence

Contacts

Geographic Coverage

Maine, United States

Temporal Coverage

Project Data

Anecdata is a free online citizen science platform developed by the Community Lab at the MDI Biological Laboratory in Bar Harbor, Maine. Anecdata is used by hundreds of individuals and organizations to gather and access citizen science observations and provides a platform to easily collect, manage, and share their citizen science data. How Anecdata works: Project managers create projects, creating datasheets that participants fill out to share their observations. Participants join projects and use the Anecdata website or mobile app to share their observations with the project. Project data is now available for anyone to view and download!

The personnel involved in the project:

Sampling Methods

Collecting data using quadrat surveys.

Method step description:

1. 1) Timing of survey work: 1.1) Conduct surveys between May-November, during the height of productivity in the intertidal zone. 1.2) Schedule surveys around negative or zero tides (generally new and full moon cycles) to allow for adequate time in the low intertidal zone (i.e., at least 2 hours).
2. 2. Pre-survey preparation: 2.1) Locate and print all field guides and data collection sheets (see Appendices) prior to conducting the survey if that is the preferred method. If using the Anecdata app for field guides and data collection, visit the Anecdata website and join the Intertidal Green Crab Project. The data collection sheet and Anecdata collection categories are identical.
3. 4. Conducting survey 4.1) Prior to arriving at the survey site, record the following information on the Intertidal Survey Data Sheet (Appendix 3) or directly into the Intertidal Green Crab Project on Anecdata: site name, sampling date, participants, time and height of low tide at the location/date you will be sampling (determined using the NOAA Tide Predications website, or an app such as Tides), and lunar phase (determined using a lunar calendar such as www.moongiant.com). 4.2) Upon arriving at the survey site, locate the 100 m section of low intertidal shoreline where the survey will be conducted, unpack gear, and organize data sheets and field guides. 4.3) *Optional: Measure water temperature using a waterproof digital thermometer in the shallow water adjacent to the sampling area. Measure salinity by placing several drops of water collected adjacent to the sampling area onto the refraction prism of a salinity refractometer. Record water temperature in ℃ and salinity in parts per thousand (ppt) on the Intertidal Survey Data Sheet or directly into the Intertidal Green Crab Project on the Anecdata app. 4.4) Begin the survey by haphazardly tossing the 1 m2 quadrat within the predefined low intertidal zone area that runs parallel to the shoreline (a transect tape is not needed to conduct the survey because the sample area has already been defined). Record a visual estimate of the percent of both moveable rock (i.e., cobble/gravel that you can look underneath) and algae canopy cover (e.g. Ascophyllum or Fucus spp.) within the quadrat to the nearest quarter percent (i.e., 0, 25, 50, 75, or 100%). Rocky intertidal habitat is often patchy and can contain areas of sand, mud, ledge, or other habitats where green crabs are not found. To avoid skewing density estimates by sampling unsuitable habitat, only sample quadrats with greater than 50% movable rock, or greater than 50% algal canopy. Also avoid sampling areas where boulders or ledges are noticeably elevated above the profile of the shoreline within the low intertidal zone, as this habitat may be more representative of the mid intertidal zone. 4.5) Within each quadrat, lift moveable rocks or cobble and carefully move aside algae to look for crabs. Be sure to replace all rocks and algae as you found them. Collect all of the crabs you find and store them in a bucket until the entire quadrat has been searched. 4.6) Identify the species of each crab using the Intertidal Crab Field Guide (Appendix 1, or source on Anecdata project platform) and record using the species codes listed on the Intertidal Survey Data Sheet (Appendix 3) or on the Intertidal Green Crab Project on the Anecdata app. 4.7) Measure the carapace width (CW) of each crab across the widest part of the carapace, spanning from tip to tip of the terminal spines, to the nearest 1 mm using Vernier calipers. 4.8) Use the abdomen (or ‘apron’) on the ventral side of the crab to determine sex. Male crabs tend to have a narrow, pointed abdomen and female crabs tend to have a wider, beehive shaped abdomen (Appendix 1). Only record sex for crabs ≥ 10 mm CW. 4.9) For all crabs, record number of claws, number of legs, shell condition (i.e., hard- or soft-shell as determined by whether the carapace resists (hard) or gives (soft) when finger pressure is applied), and the presence (i.e., ovigerous) or absence of extruded eggs for females. 4.10) *Optional: Record color for green crabs, but not other crab species, using the color protocol developed by Young and Elliot (Appendix 2). This protocol should only be used if the actual paint chips can be sourced and brought into the field, as printed versions can vary substantially. Identify pre-molt shell condition for green crabs using external pre-molt indicators (Appendix 4, or source on Anecdata project platform). Pre-molt green crabs are within 3 weeks of molting and are of particular interest to the emerging soft-shell green crab fishery. 4.11) Return all crabs to the habitat within the quadrat once all measurements and characteristics have been recorded. 4.12) Continue haphazardly tossing the quadrat within the predefined low intertidal area until you have sampled a total of 10 m2. Continually move forward along the low intertidal area of shoreline and ensure that quadrats are separated by a minimum of 1 m so that resampling does not occur and a maximum of 10 m so that the survey area does not exceed 100 m.
4. 5. Data management and analysis 5.1) If using data sheets, check all raw data sheets for errors and legibility post-survey, photocopy, scan, and archive. Use the photocopy for data entry into an excel spreadsheet (see Appendix 5 for example) or into the Intertidal Green Crab Project on Anecdata. Store scanned data sheets electronically. 5.2) Conduct data analyses appropriate to the design of the study. Useful population metrics include crab density (total number of crabs divided by total number of quadrats sampled), sex ratio, cumulative size frequency, injury rate, shell condition ratio, and overall species encounter rates (e.g., % of native vs. invasive crabs).

Additional Metadata