Temporal variability in summertime bottom hypoxia in shallow areas of Mobile Bay, Alabama

Park, Kyeong; Kim, Choong‐Ki; Schroeder, William W.

doi:10.1007/bf02782967

Cited by 82 publications

(63 citation statements)

References 25 publications

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“…In the Bilbao estuary, as in many other estuaries (Park et al 2007, Nezlin et al 2009), salt stratification was markedly stronger than thermal stratification at all sampling sites and seasons and, in agreement with results from Urrutia (1986), the strength of stratification increased longitudinally from the outer to the inner estuary (Table 1, Fig. 2).…”

Section: Vertical Temperature and Salinity Gradients And Eutrophicatisupporting

confidence: 77%

Dissolved oxygen in contrasting estuaries of the Bay of Biscay: effects of temperature, river discharge and chlorophyll a

Iriarte¹,

Aravena²,

Villate³

et al. 2010

Mar. Ecol. Prog. Ser.

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Section: Vertical Temperature and Salinity Gradients And Eutrophicatisupporting

confidence: 77%

Dissolved oxygen in contrasting estuaries of the Bay of Biscay: effects of temperature, river discharge and chlorophyll a

Iriarte¹,

Aravena²,

Villate³

et al. 2010

Mar. Ecol. Prog. Ser.

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“…In very shallow (1-5 m) tidal rivers and lagoons with well-mixed water columns that are enriched with inorganic nutrients, hypoxic conditions tend to appear and disappear on short (hours-days) time-scales (D'Avanzo and Kremer, 1994;Tyler et al, 2009). Slightly deeper (3-8 m) microtidal systems typically experience periodic stratification that may allow episodic hypoxia to occur on dailyto-weekly scales with changes in wind-driven mixing (Park et al, 2007). In deeper (10-50 m) estuaries and shelf systems with stratified water columns, hypoxia often occurs during much of the summer (2-4 mo) season (e.g., Kemp et al, 1992;Rabalais and Gilbert, 2008).…”

Section: Introductionmentioning

confidence: 99%

Temporal responses of coastal hypoxia to nutrient loading and physical controls

et al. 2009

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Abstract. The incidence and intensity of hypoxic waters in coastal aquatic ecosystems has been expanding in recent decades coincident with eutrophication of the coastal zone. Worldwide, there is strong interest in reducing the size and duration of hypoxia in coastal waters, because hypoxia causes negative effects for many organisms and ecosystem processes. Although strategies to reduce hypoxia by decreasing nutrient loading are predicated on the assumption that this action would reverse eutrophication, recent analyses of historical data from European and North American coastal systems suggest little evidence for simple linear response trajectories. We review published parallel time-series data on hypoxia and loading rates for inorganic nutrients and labile organic matter to analyze trajectories of oxygen (O 2 ) response to nutrient loading. We also assess existing knowledge of physical and ecological factors regulating O 2 in coastal marine waters to facilitate analysis of hypoxia responses to reductions in nutrient (and/or organic matter) inputs. Of the 24 systems identified where concurrent time series of loading and O 2 were available, half displayed relatively clear and direct recoveries following remediation. We explored in detail 5 well-studied systems that have exhibited complex, non-linear responses to variations in loading, including apparent "regime shifts". A summary of these analyses suggests that O 2 conditions improved rapidly and linearly in systems where remediation focused on organic inputs from sewage treatment plants, which were the primary drivers of hypoxia. In larger more open systems where diffuse nutrient loads are more important in fueling O 2 depletion and where Correspondence to: W. M. Kemp (kemp@umces.edu) climatic influences are pronounced, responses to remediation tended to follow non-linear trends that may include hysteresis and time-lags. Improved understanding of hypoxia remediation requires that future studies use comparative approaches and consider multiple regulating factors. These analyses should consider: (1) the dominant temporal scales of the hypoxia, (2) the relative contributions of inorganic and organic nutrients, (3) the influence of shifts in climatic and oceanographic processes, and (4) the roles of feedback interactions whereby O 2 -sensitive biogeochemistry, trophic interactions, and habitat conditions influence the nutrient and algal dynamics that regulate O 2 levels.

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“…When discharge is high, Mobile Bay can be almost completely fresh water, but low discharge can result in saline waters reaching more than half way up the bay. Although shallow, Mobile Bay often stratifies during the summer months owing to a combination of winds and tides (Park et al 2007). Combined with diel patterns in photosynthesis, stratification can result in hypoxic to anoxic conditions in the eastern sections of Mobile Bay.…”

Section: Introductionmentioning

confidence: 99%

Grazing and viral lysis vary for different components of the microbial community across an estuarine gradient

Ortmann¹,

Metzger²,

Liefer³

et al. 2011

Aquat. Microb. Ecol.

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The balance between grazing and viral lysis of both photosynthetic and heterotrophic microbes determines the food resources that are available, and how much of each resource is present, for higher trophic levels. Mobile Bay is the fourth largest estuary in the USA, based on river discharge, and is home to a variety of nursery habitats for larvae and juveniles of economically important species which depend for their food on production of organisms of microbial size. To characterize the patterns of growth and removal rates of this fraction of organisms in Mobile Bay, we carried out modified dilution experiments in summer and winter at 3 stations along a salinity and nutrient gradient. Rates of growth, grazing and viral lysis for prokaryotes and dominant phytoplankton (cyanobacteria, diatoms and dinoflagellates) were determined for each experiment. Grazing and viral lysis of prokaryotes did not appear to be related to season or location, and both processes were detected within the bay as well as on the shelf. For phytoplankton, grazing was the dominant removal process inshore in the summer, while viral lysis of phytoplankton was detected in the fall and in winter. In winter, an apparent increase in dinoflagellates, and in the overall biomass of phytoplankton, was concurrent with increased viral lysis, suggesting that recycling by viruses may be an important source of nutrients in coastal waters.KEY WORDS: Grazing · Viral-mediated mortality · Phytoplankton · Prokaryotes · Estuarine · Microbial food web Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 65: [143][144][145][146][147][148][149][150][151][152][153][154][155][156][157] 2011 Landry et al. 1995) for several years in a range of environments. In many instances, growth and grazing appear to be nearly balanced (Juhl & Murrell 2005, Palomares-García et al. 2006, Putland & Iverson 2007, Paterson et al. 2008, suggesting a strong top-down control of phytoplankton abundance. Viral lysis has been measured in fewer systems, but in many studies, lysis also appears to be a factor controlling the abundance of prokaryotes (Wilhelm et al. 2002, Boras et al. 2009, Karuza et al. 2010) and, in a few instances, phytoplankton (Baudoux et al. 2006(Baudoux et al. , 2008. There are fewer studies in which both grazing and viral lysis have been measured, but often grazing appears to be the dominant process in controlling host abundances (Guixa-Boixereu et al. 1999, Pedrós-Alió et al. 2000, Evans et al. 2003, Kimmance et al. 2007, Baudoux et al. 2008. It has been suggested that, as grazing is less specific and occurs at higher rates, grazing controls the abundance of prey while viral lysis -being a species-or strain-specific interaction -controls community diversity (Weinbauer 2004, Longnecker et al. 2010.When both grazing and viral lysis have been estimated, it is often observed that grazing increases both host productivity and viral lysis, with the grazers and viruses acting synergistically and producing results that are no...

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Temporal variability in summertime bottom hypoxia in shallow areas of Mobile Bay, Alabama

Cited by 82 publications

References 25 publications

Dissolved oxygen in contrasting estuaries of the Bay of Biscay: effects of temperature, river discharge and chlorophyll a

Dissolved oxygen in contrasting estuaries of the Bay of Biscay: effects of temperature, river discharge and chlorophyll a

Temporal responses of coastal hypoxia to nutrient loading and physical controls

Grazing and viral lysis vary for different components of the microbial community across an estuarine gradient

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