The following is a description of the data files associated with Strayer, D.L., Hamilton, S.K., and H.M. Malcom. 2020. Long-term increases in shell thickness in Elliptio complanata (Bivalvia: Unionidae) in the freshwater tidal Hudson River.

Contact for questions about these data: David Strayer (strayerd@caryinstitute.org).

The dry shells of animals used in this study have been deposited in the Mollusk Collection of the University of Michigan Museum of Zoology.

OVERVIEW OF SAMPLING DESIGN AND METHODS

The sampling program consisted of an annual visit to 44 sites between South Troy and Newburgh (4 sites randomly arrayed along 11 cross-river transects, which were arrayed in a stratified design to concentrate sampling effort in the upper part of the river, where unionids were most abundant). Sampling usually occurred over 5-11 days between late June and early August. At each site, we took 5 grabs using a standard (23 x 23 cm) PONAR grab. We sieved the samples in the field through a 2.8 mm brass sieve and put any visible unionids into individual whirl-pak bags. We put these unionids plus the residue from the sieve into zip-lok bags on ice, and froze them upon returning to the lab.
Later that year, we thawed out the unionids, measured shell length, width, and height using calipers, and shucked the unionid body from the shell. We then dried the body at least overnight at 60˚C, and weighed it. Shells were air-dried and then weighed.

LIST OF INCLUDED DATA FILES (all are tables of data in .csv format)

One data file is included here: "elliptio_shell_dimensions_mass_figshare.csv"

DESCRIPTIONS OF DATA SET

Variables:
height = height of the shell (mm) measured by calipers
ID_code = individual code number for each individual unionid, usually of the form yy-nnn (where yy is the last two digits of the year and nnn is the number for the unionid), but beware of some differences in format among years; these ID codes are penciled onto the inside of the shells in the museum
length = length of the shell (mm) measured by calipers
shell_mass = dry mass (g) of the mussel shell, after air-drying
width = width of the shell (mm) measured by calipers
year = year of collection

Notes: missing data are indicated by '.'