Abstract:

Dredge efficiency comparisons were conducted at 19 locations within four Texas estuaries (Mission-Aransas, Guadalupe, Lavaca-Colorado, San Jacinto) from 2018-07-02 to 2018-10-03. The locations encompassed a range of environmental conditions and oyster densities within and among estuaries. Oysters were sampled in triplicate using quadrat samples taken by scuba divers (0.5-m2), and then dredge tows (14.625 m2: 0.375-m wide dredge for 30 s at 1.3 m s-1) at each location. The proportion of mud, sand, shell hash and whole shell in each quadrat sample was estimated before the top 10 cm of each quadrat was excavated for oyster shells. The abundance and volume of live and dead oysters (>25 mm) were standardized to unit area, and all live oyster heights were measured (+/- 1 mm) in each sample. Shell volumes were determined by water displacement in a measuring bucket. Ancillary salinity and depth data were measured with a YSI ProDSS sonde at each location. Dataset associated with publication: Beseres Pollack, J., & Palmer, T. (2020). Crassostrea virginica dredge efficiency in Texas estuaries. Experimental Results, 1, E2. doi:10.1017/exp.2019.2.

Suggested Citation:

Jennifer Beseres Pollack, Terry Palmer, Natasha Breaux. 2019. Comparison of oyster populations sampled by dredge and quadrat at different locations within four Texas estuaries from 2018-07-02 to 2018-10-03. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/DRCEDRM3

Publications:

Beseres Pollack, J., & Palmer, T. A. (2020). Crassostrea virginica dredge efficiency in Texas estuaries. Experimental Results, 1. https://doi.org/10.1017/exp.2019.2

Purpose:

The purpose of generating this data was to determine the efficiency of using a dredge to sample oysters (Crassostrea virginica) and to develop a correction factor so that dredge-sample count data can be converted to density.

Data Parameters and Units:

Main parameters: Mud content (%), sand content (%), shell hash content (%), whole shell content (%), live oysters (n and L), dead oysters (n and L), temperature (deg C), specific conductance (mS/cm), salinity (PSU), dissolved oxygen (% and mg/L), pH, turbidity (NTU), secchi disc (m). Please note that the worksheet "Metadata" includes a description, units, and data source (where applicable) for all the variables/data in the worksheets - "Station Metadata", "OysterCounts", "OysterHeights", and "Hydro".

Individual Files: