Plum Island Ecosystems LTER Database

Acceptance and utilization of LTER data requires that:

(1) The Principal Investigator be sent a notice stating reasons for acquiring any data and a description of the publication intentions.
(2) The Principal Investigator of the data set be sent a copy of the report or manuscript prior to submission and be adequately cited in any resultant publications.
(3) A copy of any resultant publications should be sent to:

Principal Investigator
Ecosystems Center
Marine Biological Laboratory
7 MBL St.
Woods Hole, MA 02543

Dataset URLs:METADATA: HTML, Rich Text, XML(EML compliant)
DATA: Comma Delimited, Excel file with Metadata and data
Dataset ID:HTL-EST-Clam-densitysediment.01
Dataset Title:Sediment grain characteristics and clam densities for clam flat surveys during 2010 in the Plum Island Sound estuary, Newbury, Rowley and Ipswich, MA.
Investigator 1: 
First Name:Chuck
Last Name:Hopkinson
Address line 1:University of Georgia
Address line 2:229 Marine Sciences
Address line 3:
Zip Code:30602
Associate Investigators:Kyung-Ah Koo, Emily Davenport
Keywords:LTER, PIE, Plum Island Ecosystems, population dynamics, sediment, grain size, softshell clam
Abstract:In 2010 a study was conducted at five sites in the Rowley and Parker Rivers, Northeast Massachusetts, to determine the distribution and density of soft shell clams along a transect from the high to low tide line, as well as the sediment grain size distribution a t each of the sites.
Contact: Plum Island Ecosystems LTER Information Manager
The Ecosystems Center
Marine Biological Lab
7 MBL St
Woods Hole, MA 02543
Phone (508) 289 7485
Online URL:
Data File URL
Data File Name HTL-EST-Clam-densitysediment
Beginning Date 5/11/2010
End Date 8/6/2010
Number of Data Records 116
Other Files to Reference HTL-EST-Clam-growth, HTL-EST-Clam-chlorophyll, HTL-EST-Clam-isotopes, HTL-EST-Clam-lengthweight
Availability Status Typw 1
Quality Control Information
Maintenance Description Data complete for 2010
Log of Changes: Version 01: September 29, 2015, data and metadata created to comply with importation to Drupal and LTER PASTA. Used MarcrosExportEML_HTML (working)pie_excel2007_Jan2015.xlsm 1/15/15 4:26 PM for QA/QC to EML 2.1.0
RESEARCH LOCATION: HTL-PR-MR-Clams HTL-SO-GF-Clams HTL-SO-Stackyard-Clams HTL-RO-RM-Clams HTL-RO-RowleyHouse-Clams  
Geographic Description Site of clam surveys at confluence of Mill River with Parker River, Newbury, MA Site of clam surveys, alias "Grandkids Flat", southeast of Cape Merrill in Plum Island Sound, Newbury, MA Site of clam surveys, end of Stackyard Rd, east of Nelson Island, in Plum Island Sound, Newbury, MA. Site of clam surveys, near kite flag pole, mouth of Rowley River, Rowley, MA Site of clam surveys, tidal flat near PIE LTER Rowley field station, Rowley, MA.  
Location Bounding Box            
West Bounding Coordinate            
East Bounding Coordinate            
North Bounding Coordinate            
South Bounding Coordinate            
OR if single point location            
Latitude 42.755183 42.7483 42.74625 42.727133 42.725367  
Longitude -70.872083 -70.810983 -70.8219 -70.81515 -70.85495  
Taxonomic Protocols
Organisms studied Mya arenaria
Methods:At each site, three transects were measured out from the marsh edge to the low tide line (marked as 1 ,2 and 3 in the data file ) Each transect was divided into 5 (sometimes 6 depending on the length of the transect) points (marked as A-E, sometimes F in the data file) and at each point the elevation of the point was calculated. The elevation for each sampling point was extracted from the digital elevation model (DEM) of Plum Island Sound, 2 m spatial resolution, developed using LIDAR data (Zhao, Chen et al. 2010). A one square foot quadrat was placed on the sediment and any clams residing in that section of sediment were counted to determine the density of clams living at that specific elevation in the sediment (density data is reported as number of clams per square meter). Each clam found was measured for length and weight. Midtransect sediment samples were taken to determin e the sediment grain size at each site/transect.

Sediment samples were analyzed in the lab to determine the percentage of pebbles, (phi size 0 to -6) sand (phi size 0 to 5), clay (phi size 6-9) and silt (phi size >9) in each .A detailed procedure for determining sediment grain size and the theory behind the calculations can be found at the following:

Briefly, a homogenized subset of sediment was taken from each bagged sample and dried in a drying oven. The driedsediment was then shaken through a series of mesh sieves and the sediment remaining in each sieve was weighed. Anything larger than 2000um was considered gravel/pebbles, and anything smaller than 2000umand larger than 63um was considered part of the sand fraction. Anything that ended up in the smallest mesh size sieve (<63um, the clay + silt fraction) was placed into a 1000ml graduated cylinder with some dispersant (sodium hexametaphosphate, 50g/L) The cylinder was shaken through inversion for 1 minute and then allowed to settle over a 24hr time period. During that time frame the cylinder was subsampled at set intervals using a volumetricpipette at a specific measured depth in the cylinder. This liquid was put into a pre-tared beaker and the beakers were dried in a drying oven and then weighed . Calculations outlined in and were used to determine the percentage of pebbles, sand, clay and silt in each sample.

Data Table

Variable Name Variable Description Units Measurement Scale Code Information Number Type DateTime Format Missing Value Code Missing Value Code Explanation
Date Date of sampling   datetime     DD-MON-YYYY NA NA = not available
Station_ID Name of sampling station   nominal       NA NA = not available
Transect_name Name of transect at each sampling station   nominal       NA NA = not available
Latitude Latitude of sampling station (decimal degrees) degree ratio   real   NA NA = not available
Longitude Longitude of sampling station (decimal degrees) degree ratio   real   NA NA = not available
Elevation Elevation of specific transect in meters meter ratio   real   NA NA = not available
Pebble_% Sediment pebble fraction percent ratio   real   NA NA = not available
Sand_% Sediment sand fraction percent ratio   real   NA NA = not available
Clay_% Sediment clay fraction percent ratio   real   NA NA = not available
Silt_% Sediment silt fraction percent ratio   real   NA NA = not available
Density Number of clams found per square meter numberPerMeterSquared ratio   real   NA NA = not available
Clam_ID Individual ID of clam(s) found on each transect   nominal       NA NA = not available
Length Length of individual clam millimeter ratio   real   NA NA = not available
Weight Weight of individual clam gram ratio   real   NA NA = not available