Abstract:

The lower Rio Grande is a river-dominated estuary that serves as the border between Texas, USA and Tamaulipas, Mexico. River estuaries encompass the section of the river influenced by tidal exchange with the Gulf of Mexico, but the connection with the Rio Grande is intermittent and can be temporarily open or closed. During the 4.8-year study period, the river mouth was closed 30% of the time, mostly during average or dry climatic conditions, with the temporary closing of the river mouth being linked to hydrology. When the Rio Grande estuary is closed, salinity is low, nitrate plus nitrite are low, and ammonium is high, but chlorophyll is similar. Benthic macrofaunal abundance and biomass are higher when the river mouth is closed than open. Benthic macrofaunal community structure divided into two groups: chironomid larvae and Oligochaeta dominated when the river mouth was closed, whereas polychaetes Mediomastus ambiseta and Streblospio benedicti dominated when the river mouth was open. The implications of these results for managing freshwater flows are that the open and closed conditions each have a characteristic benthic macrofaunal community that is strongly influenced by system hydrology.

Suggested Citation:

Montagna, Paul. 2023. Rio Grande water and sediment quality data affecting benthic macrofaunal community obtained from 2000-10-24 to 2005-08-06. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/xzyn67pf

Purpose:

Measure long-term dynamics of a river-estuary system and effects on benthic macrofaunal community.

Data Parameters and Units:

Date Daily Flow (m³/s) Average Flow 30 day (m³/s) Depth (m) Temperature (°C) Salinity (psu) Dissolved Oxygen (mg/L) pH Chl a (ug/L) Ammonium (μmol/L) Nitrite+Nitrate (μmol/L) Orthophosphate (μmol/L) Silicate SIO4 (μmol/L) Rubble (%) Sand (%) Silt (%) Clay (%) Porewater (%) δ 15Nitrogen (ppt) Nitrogen content (%) Total Carbon δ 13C (ppt) Total Carbon content (%) TOC δ 13C (ppt) TOC content (%) Biomass (g/m²) Abundance (ind./m²) Richness (S/sample) Diversity (N1/sample) Diversity (H'/sample) Evenness (J'/sample)

Methods:

Montagna, P.A., T.A. Palmer, and J. Beseres Pollack. 2007. Effect of Freshwater Inflow on Macrobenthos Productivity in Minor Bay and River-Dominated Estuaries – Synthesis. Final Report to the Texas Water Development Board, Contract No. 2006-483-026. Harte Research Institute, Texas A&M University-Corpus Christi, Corpus Christi, Texas, USA, 56 p. https://tamucc-ir.tdl.org/handle/1969.6/90047 Palmer, T.A., P.A. Montagna, J.B. Pollack, R.D. Kalke and H.R. DeYoe. 2011. The role of freshwater inflow in lagoons, rivers, and bays. Hydrobiologia 667: 49-67. http://dx.doi.org/10.1007/s10750-011-0637-0 Montagna, P.A., T.A. Palmer, J. Beseres Pollack. 2022. Effect of Temporarily Opening and Closing the Marine Connection of a River Estuary. Estuaries and Coasts 2022. https://doi.org/10.1007/s12237-022-01159-6

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