Watershed Export Events and Ecosystem Responses in the Mission–Aransas National Estuarine Research Reserve, South Texas
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While inputs from land are recognized as important resources supporting production in estuaries, the role that storm events play in resource delivery and the response of estuarine systems to pulsed inputs are less well appreciated. Temporal variations in (1) watershed export via the Mission and Aransas rivers and (2) nutrient and organic matter dynamics in Copano Bay were examined in the Mission–Aransas National Estuarine Research Reserve, south Texas. Inorganic nutrient, dissolved organic matter (DOM), and particulate organic matter (POM) concentrations in the rivers varied substantially with discharge, as did carbon and nitrogen stable isotope ratios of POM. Accounting for these variations was critical for calculating robust watershed export estimates. In Copano Bay, soluble reactive phosphorus, POM, and DOM remained elevated for several months following major runoff events, whereas inorganic nitrogen was rapidly depleted. Chlorophyll-a concentrations and POC-δ13C in Copano Bay showed that increased POM concentrations were linked to enhanced in situ production.
KeywordsNitrogen Nutrients Storm events River export Stable isotopes NERR
This work was supported by the National Oceanic and Atmospheric Administration’s National Estuarine Research Reserve Graduate Research Fellowship (NA07NOS4200020) and a grant from the National Aeronautics and Space Administration (NASA-NNX07AL79G). We would like to acknowledge K.H. Dunton, D.R. Maidment, and two anonymous reviewers for comments on this work. Special thanks to P. Garlough for help with isotope analyses, field work, and lab support. Thanks are also due to the Mission–Aransas NERR staff: E.J. Buskey, C. Hyatt, S. Morehead, K.M. Madden, and C. Cook. We also would like to thank K. Jackson, G.C. Shank, S. Hamman, S. Diaz, M. Barajas, K. Swanson, L. Upchurch, L. Hurley, A.D. Evans, A.N. Evans, B. Gemmell, R. Withall, C. Smith, G. Hensgen, R. Mills, S. Bulloch, N. Klein, J. Stachelek, and S. Johnson.
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