Nutrient limitation of phytoplankton in Chesapeake Bay: Development of an empirical approach for water-quality management

WATER RESEARCH

卷:188

Article

Zhang, Qian¹  Fisher, Thomas R.²  Trentacoste, Emily M.³  Buchanan, Claire⁴  Gustafson, Anne B.²  Karrh, Renee⁵  Murphy, Rebecca R.¹  Keisman, Jennifer⁶  Wu, Cuiyin⁷  Tian, Richard¹  Testa, Jeremy M.⁸  Tango, Peter J.⁹ 

[1] Univ Maryland, Ctr Environm Sci, Chesapeake Bay Program, 410 Severn Ave, Annapolis, MD 21403 USA

[2] Univ Maryland, Ctr Environm Sci, Horn Point Lab, 2020 Horns Point Rd, Cambridge, MD 21613 USA

[3] US EPA, Chesapeake Bay Program Off, 410 Severn Ave, Annapolis, MD 21403 USA

[4] Interstate Commiss Potomac River Basin, 30 West Gude Dr,Suite 450, Rockville, MD 20850 USA

[5] Maryland Dept Nat Resources, 580 Taylor Ave, Annapolis, MD 21401 USA

[6] US Geol Survey, MD DE DC Water Sci Ctr, 5522 Res Pk Dr, Catonsville, MD 21228 USA

[7] Chesapeake Res Consortium, Chesapeake Bay Program, 410 Severn Ave, Annapolis, MD 21403 USA

[8] Univ Maryland, Ctr Environm Sci, Chesapeake Biol Lab, 146 Williams St, Solomons, MD 20688 USA

[9] US Geol Survey, Chesapeake Bay Program, 410 Severn Ave, Annapolis, MD 21403 USA

关键词: Nutrient limitation;    Phytoplankton;    Bioassay;    Water quality;    Long-term monitoring;    Nutrient management;   

DOI  :  10.1016/j.watres.2020.116407

来源: Elsevier

【 摘 要 】

Understanding the temporal and spatial roles of nutrient limitation on phytoplankton growth is necessary for developing successful management strategies. Chesapeake Bay has well-documented seasonal and spatial variations in nutrient limitation, but it remains unknown whether these patterns of nutrient limitation have changed in response to nutrient management efforts. We analyzed historical data from nutrient bioassay experiments (1992-2002) and data from long-term, fixed-site water-quality monitoring program (1990-2017) to develop empirical approaches for predicting nutrient limitation in the surface waters of the mainstem Bay. Results from classification and regression trees (CART) matched the seasonal and spatial patterns of bioassay-based nutrient limitation in the 1992-2002 period much better than two simpler, non-statistical approaches. An ensemble approach of three selected CART models satisfactorily reproduced the bioassay-based results (classification rate = 99%). This empirical approach can be used to characterize nutrient limitation from long-term water-quality monitoring data on much broader geographic and temporal scales than would be feasible using bioassays, providing a new tool for informing water-quality management. Results from our application of the approach to 21 tidal monitoring stations for the period of 2007-2017 showed modest changes in nutrient limitation patterns, with expanded areas of nitrogen-limitation and contracted areas of nutrient saturation (i.e., not limited by nitrogen or phosphorus). These changes imply that long-term reductions in nitrogen load have led to expanded areas with nutrient-limited phytoplankton growth in the Bay, reflecting long-term water-quality improvements in the context of nutrient enrichment. However, nutrient limitation patterns remain unchanged in the majority of the mainstem, suggesting that nutrient loads should be further reduced to achieve a less nutrient-saturated ecosystem. (C) 2020 The Authors. Published by Elsevier Ltd.

【 授权许可】

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