1. FIGURE 17.1 A simple nitrogen and water balance for ‘‘Dave the Sea Lion.’’ Both nitrogen and water flows are in units of grams per 40 days. See text for details of this budget development. Source: Data are from Pilson (1970). ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~

2. FIGURE 17.2 Schematic diagram of simple box-model computation for an estuary receiving freshwater from a single river and connected to the ocean by a single channel. Salt, water, and nutrient balances are represented by equations 1–3, respectively. Q F = freshwater input volume, Q E = water output from estuary, E E, O is diffusive/dispersive exchange between estuary and ocean, V E = the volume of the estuary, and P E = the net production rate of nutrient, O 2, or carbon in the estuary. s o = ocean salinity, s F = freshwater salinity = 0, and s E = estuary salinity. c O = ocean nutrient/O 2 /carbon concentration, c F = freshwater nutrient/O 2 /carbon concentration, and c E = estuary nutrient/O 2 /carbon concentration. ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~

3. FIGURE 17.3 Monthly mean rates of net biogeochemical production of surface and bottom-layer (top) O 2 (surface rate corrected for air–water exchange), (middle) DIN, and (bottom) DSi computed by the box-model for the surface and bottom layers in the Patuxent River estuary. Monthly means (± standard error) were calculated for the years 1985–2003. Horizontal dashed lines are drawn at net production rates equal to zero. Source: Data and figure are from Testa and Kemp (2008). ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~

4. FIGURE 17.4 Two nitrogen budgets developed for a New England, United States, salt marsh ecosystem. (A) An annual-scale budget for the mussel population for Great Sippewissett Marsh and (b) an annual-scale budget for the full marsh ecosystem with the mussel population highlighted. Nitrogen flows for both budgets have units of kg N/year, except for mussel standing stock, which has units of kg N. Source: These budget diagrams were adapted from Jordan and Valiela (1982). ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~

5. FIGURE 17.5 Estimated mean average values for major TOC fluxes in the mainstem Chesapeake Bay. Fluxes are grouped as Inputs (I), Outputs (E), Production (P), and Respiration (R). Net Ecosystem Metabolism (NEM) for the mainstem Bay is also provided. Source: Diagram was adapted from Kemp et al. (1997). ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~

6. FIGURE 17.6 Comparison of estimated annual inputs of dissolved inorganic N and P to Narragansett Bay, RI/MA during prehistoric and modern times. Source: modified from Nixon, 1997. Units are 10 6 moles/year. ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~

7. FIGURE 17.7 The fraction of total N input from land and atmosphere that is exported to near-shore shelf waters from a sample of estuaries and other coastal systems as a function of mean annual water residence time. Mean water residence time was calculated by the freshwater fraction method (mean fresh water contained in the estuary calculated from salinity divided by the inflow of fresh water; see Sheldon and Alber, 2006). Source: Figure was adapted from Nixon et al. (1996). ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~

8. FIGURE 17.8 A map of the Patuxent River basin and estuary (a) with summary nitrogen budget results for the middle basin (tan color) and the portion of the estuary associated with the middle basin and (b) a photograph of the tidal marsh at high tide typical of this section of the estuary. Source: Data were adapted from Boynton et al. 2008. ESTUARINE ECOLOGY, Second Edition. John W. Day JR, Byron C. Crump, W. Michael Kemp, and Alejandro Yánez-Arancibia. Copyright © 2013 by Wiley-Blackwell. All rights reserved ~