Interagency Ecology Program: Generalized Random Tesselation Stratified (GRTS) sampling of the benthic community of the upper San Francisco Estuary, 2007-2019.

The Interagency Ecological Program’s (IEP) Environmental Monitoring Program (EMP) conducted a special study of benthic invertebrates from 2007-2019, minus 2013 and 2016, in the upper San Francisco Estuary (SFE) as an extension to the long-term monitoring program EMP has been conducting since 1975. The objective of this study was to provide context to the ten sites that currently comprise EMP’s benthic invertebrate monitoring program, and to obtain spatially-intensive but temporally limited data to complement the EMP’s long-term program which is spatially-limited but temporally intensive. This special study sampled invertebrate communities across the benthos of the SFE by collecting dredge samples with a standard sized (0.052 m2) Ponar sampler. Sediment and particles smaller than 0.5mm were removed from the sample using a sieve table. The invertebrates present were preserved in formalin, identified to the lowest possible taxonomic level, and enumerated. Two species of non-native clam, Corbicula fluminea and Potamocorbula amurensis, were also measured and their biomass and grazing rate calculated. This study used a Generalized Random Tessellation Stratified (GRTS) design (Stevens and Olsen 2004) to select a spatially balanced set of fifty sites that were visited in May and October for every year of this study, and an additional 1174 sites that were visited in May and October in only one year. Portions of this data have been published in the following reports and data publications: Shrader, K.H., Zierdt Smith, E.L, Parchaso, F., Thompson, J.K., 2020, Benthic Community and Bivalve Metrics Data in the Sacramento - San Joaquin Delta from 2015 to 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9JJOL3W. Zierdt Smith, E.L., Shrader, K.H., Pearson S.A., Crauder, J.S., Parchaso, F., and Thompson, J.K., 2021, Bivalve metrics in the North San Francisco Bay and Sacramento-San Joaquin Delta: U.S. Geological Survey data release, https://doi.org/10.5066/P9Q57NL0. Zierdt Smith, E.L., Shrader, K.H., Parchaso, F., and Thompson, J.K., 2021, A spatially and temporally intensive sampling study of benthic community and bivalve metrics in the Sacramento-San Joaquin Delta (ver. 2.0, May 2021): U.S. Geological Survey data release, https://doi.org/10.5066/P93BAY64. References: Stevens Jr, Don L., and Anthony R. Olsen. "Spatially balanced sampling of natural resources." Journal of the American statistical Association 99.465 (2004): 262-278.