Phytoplankton production and nutrient distributions in a subtropical estuary: Importance of freshwater flow

Murrell, Michael C.; Hagy, James D.; Lores, Emile M.; Greene, Richard M.

doi:10.1007/bf02819386

Cited by 95 publications

(60 citation statements)

References 44 publications

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“…11). If T f in the SLE is < 10 d as it is much of the time (Ji et al, 2007), then the inputs of freshwater and nu- 1 d), both allochthonous and autochthonous materials are transported from the estuary to the coastal ocean (Doering et al, 2006;Murrell et al, 2007;Phlips et al, 2011). Reliable estimates of freshwater inflow and nutrients along with knowledge of flushing time offer a platform to quantify and link external loading to internal ecosystem metabolism (Fig.…”

Section: Discussionmentioning

confidence: 99%

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

et al. 2013

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Abstract. Interactions among geomorphology, circulation, and biogeochemical cycling determine estuary responses to external nutrient loading. In order to better manage watershed nutrient inputs, the goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River estuary (CRE) and the St. Lucie Estuary (SLE), from 2002 to 2008. The Land-Ocean Interactions in the Coastal Zone (LOICZ) approach was used to generate water, salt, and DIN and DIP budgets. Results suggested that internal DIN production increases with increased DIN loading to the CRE in the wet season. There were hydrodynamic effects as water column concentrations and ecosystem nutrient processing stabilized in both estuaries as flushing time increased to > 10 d. The CRE demonstrated heterotrophy (net ecosystem metabolism or NEM < 0.0) across all wet and dry season budgets. While the SLE was sensitive to DIN loading, system autotrophy (NEM > 0.0) increased significantly with external DIP loading. This included DIP consumption and a bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge to the SLE in 2005. Additionally, while denitrification provided a microbiallymediated N loss pathway for the CRE, this potential was not evident for the SLE where N 2 fixation was favored. Disparities between total and inorganic loading ratios suggested that the role of dissolved organic nitrogen (DON) should be assessed for both estuaries. Nutrient budgets indicated that net internal production or consumption of DIN and DIP fluctuated with inter-and intra-annual variations in freshwater inflow, hydrodynamic flushing, and primary production. The results of this study should be included in watershed management plans in order to maintain favorable conditions of external loading relative to internal material cycling in both dry and wet seasons.

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Section: Discussionmentioning

confidence: 99%

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

et al. 2013

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“…Freshwater Flow Flow has a strong influence on estuarine variability: It can influence nutrient loading (Nixon 2003), stratification (Cloern 1984), light penetration (Livingston et al 1997), residence time , and other factors (Drinkwater and Frank 1994;Kimmerer 2002) that influence chlorophyll and primary production (e.g., Mallin et al 1993;Murrell et al 2007). In many estuaries, freshwater flow is a key factor in stimulating primary production, most often through the correlation between flow and nutrient loading.…”

Section: Temporal Patternsmentioning

confidence: 99%

Short-Term and Interannual Variability in Primary Production in the Low-Salinity Zone of the San Francisco Estuary

Kimmerer

Parker

Lidström

et al. 2012

Estuaries and Coasts

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We measured primary production during springsummer 2006-2007 to determine the carbon supply to the low-salinity pelagic food web of the San Francisco Estuary (SFE). Weekly or biweekly samples were taken at three stations of fixed salinity for size-fractionated primary production and biomass, both as chlorophyll and from biovolume based on counts. Error variance in productivity estimates arose mainly from the depth integration of 14 C uptake, showing the importance of productivity measurements at high light levels for estimates of depth-integrated production. Temporal and spatial variability in production were surprisingly small. Combining data from this study with long-term monitoring data, productivity and biomass were variable in time and salinity but without persistent patterns and with infrequent blooms. Production within the lowsalinity zone was unresponsive to variation in freshwater flow, in contrast to findings in other estuaries where nutrient loading drives variability in production and other regions of the SFE where production responds to residence time or to stratification. Estimated annual primary production was only 25 and 31 gC m −2 year −1 during 2006 and 2007, only half of it in cells >5 μm. These results imply that phytoplankton provided poor food web support for higher trophic levels, probably contributing to the long-term decline in fish abundance in the brackish to freshwater region of the estuary.

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“…Tropical estuaries in regions experiencing monsoonal climates are influenced by highly seasonal river flows and are often characterized by enhanced fluxes of terrestrial derived organic matter, phytoplankton blooms and subsequent phyto-detritus deposition during the wet season (Eyre and Balls 1999, Eyre and Ferguson 2006, Murrell et al 2007). We postulate that such monsoonal events significantly influence the trophic dynamics in tropical estuarine systems.…”

Section: Introductionmentioning

confidence: 99%

Monsoons and habitat influence trophic pathways and the importance of terrestrial‐marine linkages for estuary sharks

Wai¹,

Yeung²,

Lam³

et al. 2012

Ecosphere

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Abstract. Tropical estuaries often receive enhanced fluxes of terrestrial derived organic matter and phytoplankton during the wet season, and such monsoonal events may significantly influence the trophic dynamics of these systems. This study examined spatio-temporal terrestrial-marine linkages in a tropical estuary, the Pearl River Estuary (PRE), southern China, by investigating trophic pathways leading to estuary sharks. We investigated spatial (inshore vs. offshore) and seasonal (wet vs. dry season) variation in the relative importance of terrestrial-and marine-derived carbon, so as to assess the contribution of detrital pathways to the pelagic spadenose shark, Scoliodon laticaudus; ontogentic changes in shark diets were also documented. Stable isotope analyses (SIA) and fatty acid (FA) profiling indicated that spadenose sharks assimilated both marine and terrestrial carbon via consumption of zooplantivorous fish and shrimps. Detrital carbon sources were more important to juvenile and pre-mature sharks at inshore locations, especially during the wet season when river discharge increased and terrestrial detritus was more abundant. Ontogenetic dietary shifts were evident: juvenile and pre-mature sharks had significantly higher levels of bacterial (detrital) FA than adults which contained more animal-derived FA. Inshore sharks, with more depleted d 13 C signatures, relied more on terrestrial carbon than sharks offshore. Comparison of spadenose shark FA profiles with those of the sympatric, white-spotted bamboo shark (Chiloscyllium plagiosum)-a benthic predator that acquires detrital carbon via consumption of polychaetes and crustaceans-revealed that they made greater use of detrital carbon sources. However, spadenose sharks in the inner estuary assimilated higher proportions of terrestrial detritus (44-56%) than bamboo sharks (31-45%). The importance of terrestrial detritus for both shark species demonstrated the important contribution of terrestrial detritus to both pelagic and benthic food webs in the PRE. Terrestrial-marine linkages are therefore of great significance, particularly during the wet season, in this estuarine system, which serves as feeding and nursery grounds for both shark species, and trophic subsidies from land are likely to be important for marine predators in other tropical estuaries.

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Phytoplankton production and nutrient distributions in a subtropical estuary: Importance of freshwater flow

Cited by 95 publications

References 44 publications

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

Short-Term and Interannual Variability in Primary Production in the Low-Salinity Zone of the San Francisco Estuary

Monsoons and habitat influence trophic pathways and the importance of terrestrial‐marine linkages for estuary sharks

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