Abstract:
Oso Bay, Texas is a secondary bay in the Nueces Estuary that is characterized by high nutrient loading from wastewater treatment plants and high salinities caused by hypersaline water pumped into an upstream area of the Oso Bay. Benthic macrofauna and water quality were sampled from 2012-11-15 to 2014-01-25 to assess the effect of spatio-temporal changes in water quality on the benthic community.
This dataset is associated with the publications: Wetz, Michael S., Kenneth C. Hayes, Kelsey V. Fisher, Lynn Price, and Blair Sterba-Boatwright. Water quality dynamics in an urbanizing subtropical estuary (Oso Bay, Texas). Marine Pollution Bulletin. 2016; 104(1-2):44-53. doi:10.1016/j.marpolbul.2016.02.013.
De Santiago, K., Palmer, T., Wetz, M., & Beseres Pollack, J. (2020). Response of macrobenthic communities to changes in water quality in a subtropical, microtidal estuary (Oso Bay, Texas). Experimental Results, 1, E34. doi:10.1017/exp.2020.44
Suggested Citation:
De Santiago, Kevin, Jennifer Beseres Pollack, Terry Palmer, and Michael Wetz. 2020. Benthic macrofauna and water quality of Oso Bay, Texas, 2012-2014. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/D3PCKJSF
Purpose:
The aim of this study was to analyze macrobenthic communities across a spatiotemporal gradient of conditions and anthropogenic inputs. This study focuses on spatial differences in land cover and the influence of nutrient inputs on macrobenthic communities to inform ongoing management activities by the state of Texas (Texas Commission on Environmental Quality) and federal (U.S. Environmental Protection Agency) environmental management agencies.
Data Parameters and Units:
Latitude and Longitude (decimal degrees); Date (ddMMMyyyy); Taxa (Taxa/Species name); Number of organisms (n/sample); Number of organisms per meter square (n/m^2); Temperature (degrees C); Dissolved Oxygen (mg/l); Salinity; pH; Dissolved organic carbon (μM/L); Total dissolved nitrogen (μM/L); Ammonia (μM/L); Nitrate + nitrite (μM/L); Nitrite (μM/L); Dissolved organic nitrogen (μM/L); Silicate (μM/L); Orthophosphate (μM/L); Sediment chlorophyll (mg/L); and Grain size (% sand, % silt, % clay, % rubble).
Methods:
Benthic infaunal communities were sampled on a monthly basis, weather permitting, on the following sampling dates 2013-02-25; 2013-03-22; 2013-04-19; 2013-05-17; 2013-06-14; 2013-07-12; 2013-08-23; 2013-09-11; 2013-10-22; 2013-12-04; and 2014-01-25, using a 6.7-cm diameter core tube (35.4 cm^2 area). Two replicate cores were taken at each site, of which, the top 0-3 cm section of the core was collected and stored in 10% buffered formalin. Organisms were extracted using a 500 μm sieve, sorted using a stereo microscope, identified to lowest possible taxonomic level, and enumerated. Infaunal abundances (n/m^2) were calculated by multiplying species abundance (n/core) by 259.6 (m^2/core sampler area).
The top 3 cm of two additional replicate cores were collected for benthic chlorophyll analysis at each site throughout the study period. After sediment samples were manually homogenized using a stainless steel spatula, approximately 10 g was subsampled and frozen at <15 °C in 15 mL centrifuge tubes. Upon processing, 10 mL of 90% acetone was added to sediment samples, vortexed at 2,500 rpm for 30 seconds, and placed back into the freezer for 18-24 hours. Benthic chlorophyll samples were allowed to reach room temperate in the dark and centrifuged for 5 minutes at 4000 rpm. Because of high chlorophyll concentrations, 1 mL of sample was diluted with 9 mL of 90% acetone.
Samples were mixed and used to determine relative fluorescence units (RFU) without acidification using a Turner Trilogy Fluorometer. RFU was converted to mg/L chlorophyll-α using a linear curve based on values of established reference chlorophyll-α standards.
Sediment grain size samples were collected in January 2014 using a 6.7 cm diameter core tube (35.4 cm^2 area). Two replicate cores were taken at each site, of which, the top 0-3 cm section of the core was analyzed. Percent contribution by weight was measured for four components: rubble (e.g., shell hash), sand, silt, and clay following standard geologic procedures (Folk, 1964; E.W. Behrens, personal communication).
Water quality sampling occurred a few days prior to benthic sampling. Surface and bottom water samples were collected when water depth was greater than 1 m. Salinity, dissolved oxygen, pH and temperature were measured at each site using a calibrated YSI ProPlus sonde. Water samples were collected and analyzed for chlorophyll a, inorganic nutrients (silicate; ammonium; nitrate plus nitrite, N+N; nitrite; orthophosphate, PO43-), dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). For further details on water sample processing and analyses see Wetz et al. 2016.
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