| The
collection of living
ostracodes with their associated environmental and hydrochemical data
from different environments in North America is an ongoing task of the
NANODe project. To simplify a complex problem of where to
collect, and to maximize our chances of gaining a diverse assemblage of
samples and species, we decided to focus on sites located in distinct
environmental or climate gradients. For example, the steep
effective moisture gradients in the U.S. were of particular interest
because of their significance to paleoclimate studies. In
addition, topographic gradients, areas with diverse lithologies and
diverse hydrologic environments were also of interest. We still
have many areas within the U.S. that have not yet been sampled, as well
as Canada and Mexico. The lack of coverage in those areas simply
denotes the limit of sampling at the time of the release of NANODe
version 1. A standard sampling procedure was used to collect the NANODe data, which involved ostracode sampling, water sampling, and site description. 1) Ostracode sampling was done using a D-frame net, Hongve, and/or Bola sampler, depending on the substrate conditions. Ostracode collections were made in the littoral zones of lakes, ponds, and streams, as well as at depth in sublittoral or profundal areas at each site. In wetlands, seeps, and other extremely shallow water conditions, the D-frame net was the primary collecting tool. Samples were stored in Ziplock® bags in ice chests, and shipped at once back to the lab for processing. 2) Water sampling for the purpose of major ion hydrochemical analysis was done in the following way: Three subsamples were prepared from a single raw water sample, including a subsample of the raw water, a filtered subsample (0.2 micron filter) and a filtered acidified subsample (acidified with HNO3). Temperature, specific conductance, pH, and alkalinity titration were done in the field, and then again in the lab. In many cases, one water sample at the time of ostracode collection for a locality was sufficient, in other cases, more than one sample was prepared. 3) A brief site description was prepared for all sites at the time of collection, noting presence of groundwater seeps or streams associated with lakes, ponds and wetlands, as well as types of human impact and the characteristics of the local geology. |