A Comparative Study of Nutrient Behavior along the Salinity Gradient of Tropical and Temperate Estuaries

Eyre, Bradley D.; Balls, P.W.

doi:10.2307/1352987

Cited by 129 publications

(79 citation statements)

References 71 publications

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“…Our conceptual model reflects the importance of season (wet vs. dry) as a key climatological driver in the neotropical Florida Everglades. Eyre and Balls (1999) demonstrated a similar climatological forcing of biogeochemical cycling in tropical estuaries that was manifest primarily through variability in freshwater inputs. Figure 8 also demonstrates how managed inflows of freshwater drive dynamics in our estuaries.…”

Section: Discussionmentioning

confidence: 78%

Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Childers

Boyer

Davis

et al. 2006

Limnology & Oceanography

166

142

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We present 8 yr of long-term water quality, climatological, and water management data for 17 locations in Everglades National Park, Florida. Total phosphorus (P) concentration data from freshwater sites (typically Ͻ0.25 mol L Ϫ1 , or 8 g L Ϫ1 ) indicate the oligotrophic, P-limited nature of this large freshwater-estuarine landscape. Total P concentrations at estuarine sites near the Gulf of Mexico (average ഠ0.5 mol L Ϫ1 ) demonstrate the marine source for this limiting nutrient. This ''upside down'' phenomenon, with the limiting nutrient supplied by the ocean and not the land, is a defining characteristic of the Everglade landscape. We present a conceptual model of how the seasonality of precipitation and the management of canal water inputs control the marine P supply, and we hypothesize that seasonal variability in water residence time controls water quality through internal biogeochemical processing. Low freshwater inflows during the dry season increase estuarine residence times, enabling local processes to control nutrient availability and water quality. El Niño-Southern Oscillation (ENSO) events tend to mute the seasonality of rainfall without altering total annual precipitation inputs. The Niño3 ENSO index (which indicates an ENSO event when positive and a La Niña event when negative) was positively correlated with both annual rainfall and the ratio of dry season to wet season precipitation. This ENSO-driven disruption in seasonal rainfall patterns affected salinity patterns and tended to reduce marine inputs of P to Everglades estuaries. ENSO events also decreased dry season residence times, reducing the importance of estuarine nutrient processing. The combination of variable water management activities and interannual differences in precipitation patterns has a strong influence on nutrient and salinity patterns in Everglades estuaries.Nutrient enrichment and cultural eutrophication affect virtually all aquatic systems to some degree (Carpenter et al.

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Section: Discussionmentioning

confidence: 78%

Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Childers

Boyer

Davis

et al. 2006

Limnology & Oceanography

166

142

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“…In BC, the renovation rates for each tidal cycle are of the order of 12.9% in the spring and 24.4% in the neap tides, favoring the exportation of the high nutrient load of the brackish water toward the estuary´s lower reaches and the adjacent sea. In fact, despite being surrounded by mangrove forest, considered as an efficient nutrient sink (Alongi, 1996), the BC displays higher mean values of inorganic nutrients (Table 1) than those presented by Eyre & Balls (1999) for tropical Australian estuaries.…”

Section: Discussionmentioning

confidence: 91%

Short-term variability and transport of nutrients and Chlorophyll-a in Bertioga Channel, São Paulo State, Brazil

et al. 2005

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A B S T R A C TShort-term variability of nutrients, chlorophyll-a (Chl-a) and seston (TSS) concentrations were followed up at a fixed station in the Bertioga Channel (BC), Southeastern Brazil, over two full tidal cycles of neap and spring tides, during the winter of 1991. Simultaneous data on hydrographic structure, tidal level and currents allowed the computation of the net transport of those properties. Tidal advection and freshwater flow were the main forcing agents on the water column structure, nutrient availability and Chl-a distribution. Dissolved inorganic nitrogen and phosphate average values were high (16.88 and 0.98 µM, respectively, at neap tide and 10.18 and 0.77µM at spring tide). Despite N and P availability, Chl-a average values were low: 1.13 in the neap and 3.11 mg m -3 in the spring tide, suggesting that the renovation rate of BC waters limits phytoplankton accumulation inside the estuary. The highest Chl-a was associated with the entrance of saltier waters, while the high nutrient concentrations were associated with brackish waters. Nutrients were exported on both tides, TSS and Chl-a were exported on the spring tide and Chl-a was imported on the neap tide. The study of the main transport components indicated that this system is susceptible to the occasional introduction of pollutants from the coastal area, thus presenting a facet of potential fragility. R E S U M OVariações de curta escala das concentrações de nutrientes, clorofila-a (Cl-a) e séston foram acompanhadas em uma estação fixa no canal de Bertioga (CB), sudeste do Brasil, em dois ciclos completos de maré de quadratura e sizígia, no inverno de 1991. Dados simultâneos da estrutura hidrográfica, marés e correntes permitiram calcular o transporte resultante daquelas propriedades. A advecção por maré e o fluxo de água doce foram as principais forçantes da estrutura hidrográfica e da distribuição de nutrientes e Cl-a. As concentrações médias de NID e fosfato foram altas (respectivamente: 16,88 e 0,98 µM na quadratura e 10,18 e 0,77 µM na sizígia). Apesar da disponibilidade de N e P, os valores médios de Cl-a foram baixos: 1,13 mg m -3 (na quadratura) e 3,11 mg m -3 (sizígia), sugerindo que a alta taxa de renovação das águas do CB limitam o acúmulo de fitoplâncton. Os maiores valores de Cl-a relacionaram-se à entrada de águas costeiras enquanto que as altas concentrações de nutrientes foram relacionadas às águas salobras. Os nutrientes dissolvidos foram exportados em ambas as marés, séston e Cl-a foram exportados na sizígia e, na quadratura, a Cl-a foi importada. O estudo dos principais componentes do transporte indicou uma susceptibilidade desse sistema à introdução de poluentes oriundos da área costeira, revelando uma potencial fragilidade ambiental.

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“…Subsequently, the onset of the rainy season and higher river flow rates flushed out the estuary, reestablishing oxic conditions. Eyre and Balls (1999) proposed that one of the major differences between temperate and tropical estuaries is that whereas the former have reasonably constant flow rates and flushing throughout the year, tropical estuaries are characterized by periods with a very low flow in the dry season, interspersed with periods of high rainfall and strong flushing during the rainy season that ''reset'' the estuary, a situation apparently occurring in the Cisadane estuary.…”

Section: Discussionmentioning

confidence: 99%

Dissimilatory reduction of nitrate to ammonium, not denitrification or anammox, dominates benthic nitrate reduction in tropical estuaries

Dong

Sobey

Smith

et al. 2010

Limnology & Oceanography

214

119

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We measured benthic denitrification (DN) and dissimilatory reduction of nitrate to ammonium (DNRA) using the isotope-pairing technique in three tropical estuaries in Thailand (Mae Klong), Indonesia (Cisadane), and Fiji (Vunidawa-Rewa) during rainy, dry, and intermediate seasons along the salinity gradient of each estuary. DNRA dominated. Anammox (AN) was measured initially but neither AN activity nor AN bacteria-related 16S ribosomal RNA genes were detected in any of the estuaries. DN was either zero or extremely low, driven by water column nitrate and not from benthic nitrification-DN. N 2 O was not formed during DN. N 2 O saturations in estuary water were low, except in the nutrified Indonesian estuary, and tropical estuaries are therefore likely to be only small sources of N 2 O. Benthic nitrate reduction was nitrate limited; when nitrate was enhanced experimentally, DN increased slightly, but DNRA increased proportionately much more. Predominance of DNRA over DN in tropical estuaries may be due both to an energetic advantage (greater standard free energy change, DGu) of nitrate ammonifiers over denitrifiers when competing for limited nitrate, and also to higher affinity for nitrate by the nitrate ammonifiers. At tropical temperatures the three processes occur in the order DNRA . DN . AN. In contrast, temperate estuaries, at lower temperature and higher nitrate concentrations, exhibit proportionately greater levels of AN and DN. The Cisadane estuary became anoxic during the dry season, with high ammonium and sulfide, but no nitrate reduction because of lack of nitrate. Addition of nitrate stimulated high rates of autotrophic DN driven by sulfide, but not DNRA.

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A Comparative Study of Nutrient Behavior along the Salinity Gradient of Tropical and Temperate Estuaries

Cited by 129 publications

References 71 publications

Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Short-term variability and transport of nutrients and Chlorophyll-a in Bertioga Channel, São Paulo State, Brazil

Dissimilatory reduction of nitrate to ammonium, not denitrification or anammox, dominates benthic nitrate reduction in tropical estuaries

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