FIGURE 15.1 Regression of ecosystem respiration and ecosystem gross primary production across many types of aquatic ecosystems. Gross production and respiration tend to be balanced across many ecosystems types, including estuaries, but note that some ecosystems deviate from the 1:1 line substantially. Metabolic rates collected from various literature sources: nonestuarine systems (Odum, 1956), estuaries (Randall and Day, 1987; Day et al., 1988; Flores-Verdugo et al., 1988; Teague et al., 1988; Twilley, 1988; Hoppema, 1991; Heath, 1995), MERL nutrient enrichment experiment (Oviatt et al., 1986), blackwater river (Caffrey, 2004), shallow, eutrophic lagoon (D’Avanzo et al., 1996). Source: Based on Figure 8 in Odum (1956). 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 ~

FIGURE 15.2 Measuring planktonic metabolism. 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 ~

FIGURE 15.3 Measuring diel fluctuations in O 2 and computing metabolic parameters from O 2 time series. 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 ~

FIGURE 15.4 Plots of binned means (±SD) of (a) net daytime production (P a ) versus photosynthetically active radiation (PAR) and (b) nighttime respiration (R n ) versus water temperature in the Corsica River estuary, a subtributary of Chesapeake Bay. Metabolic rates were calculated from short-term changes in water column O 2 and represent whole-ecosystem metabolism. P a correlates with PAR, but saturates at 30–40 E/m 2 /day with high variability at high PAR, because of turbidity-induced reductions in P a. R n increases exponentially with temperature and does not appear to saturate up to 30 °C. Source: O 2 and temperature data from Maryland Department of Natural Resources ( and PAR data from the Horn Point Laboratory weather station in Cambridge, Maryland, USA ( 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 ~

FIGURE 15.5 Comparative analysis of net ecosystem metabolism for estuarine systems in relation to the loading ratio of DIN/TOC (dissolved inorganic nitrogen/total organic carbon). Data from experimental marine ecosystems (green, filled circles, MERL, Oviatt et al. (1986), C = control and 1X, 2X, etc. are scales of nutrient enrichment relative to control), selected estuaries for which sufficient information is available (blue, open circles, Kemp et al. (1997)); Moreton Bay from Eyre and McKee (2002), and the case study systems from this chapter (red squares), including the Patuxent River estuary (Testa et al., 2008), Chesapeake Bay (Kemp et al., 1997), the Scheldt (Hofmann et al., 2008), Tomales Bay (as in Kemp et al., 1997), and the Parker River-Plum Island Sound ecosystem (Vallino et al., 2005). 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 ~

FIGURE 15.6 Relationships of freshwater residence time (FRT) with net ecosystem production (P n = productionrespiration) in two regions of the Patuxent River estuary (±SE; FRT from Hagy et al. (2000) and P n data from Testa and Kemp (2008)). The data indicate that P n is positively related to FRT in the upper estuary but that they are negatively correlated in the lower estuary. 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 ~

FIGURE 15.7 Average diel ranges (daily maximum–daily minimum) in water temperature and O 2 in 0.5-m depth categories in several Texas coastal bays during summer (Odum, 1967). 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 ~

FIGURE 15.8 Maps of ecosystem metabolism case study estuaries and adjacent watersheds. Source: Areal maps from Google ®. 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 ~

FIGURE 15.9 Time series of measurements of (a) P g and (b) R for planktonic communities and both unvegetated and seagrass-dominated benthic communities in Tomales Bay, California, USA. Source: Data from Smith and Hollibaugh (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 ~

FIGURE Time series of (a) 1-year moving averages for an upwelling index on the Pacific coast and (b) net ecosystem respiration (R − P) in the Tomales Bay, California, USA. Data from Smith and Hollibaugh (1997) and reprinted with permission. The correlation between the upwelling index and R − P from 1991– 1996 (and lack of correlation between watershed POC and R − P over the same time period) suggests that upwelling-derived organic inputs fuel net heterotrophy in this ecosystem. 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 ~

FIGURE (a) Model-estimated instantaneous gross primary production (P g ) and community respiration (R) at noon along the estuarine transect of the Parker River-Plum Island Sound estuarine system in northeastern Massachusetts, USA. Model data from Vallino et al. (2005). (b) Contributions of benthic and pelagic metabolism at three stations along the salinity gradient of the Parker River-Plum Island Sound estuarine system. The lower value in the range of benthic percentage contribution to total respiration is based on the fraction of total ecosystem metabolism (measured via nighttime water column O 2 consumption) that is contributed by benthic uptake of TCO 2 (converted to O 2 units using an RQ = 1). The upper range is the fraction of benthic respiration that contributes to benthic + water column respiration (measured in BOD bottles). Source: Data from Hopkinson et al. (1999). 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 ~

FIGURE (a) Steady state organic carbon budget for the main stem of the Chesapeake Bay, including biogeochemical rates and physical transports (Data from Kemp et al., 1997). (b) Seasonal distribution of P g and R for the main stem of the Chesapeake Bay in the upper, middle, and lower regions of the Bay. The upper estuary is net heterotrophic, while the middle and lower Bay are progressively net autotrophic, with March to May (the spring diatom bloom) and July to September (picoplankton dominated) periods dominating the net production. 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 ~

FIGURE Correlations between net ecosystem production and indexes of organic particle formation in (a) the Chesapeake Bay, where net plankton production is highly correlated to sediment trap collection rates (Boynton and Kemp, unpublished data) and (b) MERL mesocosms, where net ecosystem production is highly correlated to the accumulation of organic flocs (Oviatt et al., 1993). 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 ~

FIGURE Distribution of P g and P n (of plankton community) along the salinity gradient of the Scheldt estuary. Open, maroon squares are measured P n in 2003 (Gazeau et al., 2005c) and are compared to modeled P n rates (filled, red squares) from Soetaert and Herman (1995). Blue circles are the measured P g rates from Kromkamp and Peene (1995) and green circles are the measured P g rates from 2003 (Gazeau et al., 2005c). Source: Figure adapted from Gazeau et al. (2005c). 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 ~

FIGURE (a) Annual mean components of metabolism in the inner Scheldt estuary (data from Gazeau et al., 2005c). The data indicate a high level of community respiration, because of high organic matter inputs rates to this system and also a nonnegligible contribution of nitrification (a chemoautotrophic process) to organic carbon production in the estuary. (b) Time series of NH + and chlorophyll a concentrations averaged over the tidal freshwater region of the Scheldt estuary from 1967 to 2008 (inset is correlation between the annual data, which are from Cox et al. (2009) and sources cited within). High NH + concentrations prevailed through the mid-1990s, until management actions dramatically reduced NH + concentrations after 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 ~

FIGURE Frequency distribution of P n derived from computations of the net nonconservative production rates of dissolved inorganic phosphorus from budget estimates for coastal systems around the world. Rates are from Smith et al. (2005) based on the LOICZ biogeochemical budget model analysis. 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 ~

FIGURE Relationships between net ecosystem production (P n ) and gross primary production (P g ) for ecosystems under various land use and anthropogenic impacts. Source: Data from reported values in the literature (Nixon and Pilson, 1984; Oviatt et al., 1986; Smith and Hollibaugh, 1993; Ver et al., 1994; Kemp et al., 1997; Caffrey, 2004; and Testa, unpublished). 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 ~