Dynamics of the Swan River Estuary: The seasonal variability

Stephens, Rohan; Imberger, J.

doi:10.1071/mf9960517

Cited by 64 publications

(41 citation statements)

References 13 publications

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“…For example, during the summer dry season river flow nearly ceases while tidally driven, marine waters can reach 60 km upstream (Stephens and Imberger 1996). As river discharge increases with winter rainfall, the shallow regions of the upper and middle estuary are flushed but stratification can persist in the deep basins of the middle estuary (Hodgkin 1987).…”

Section: Methodsmentioning

confidence: 99%

“…The Swan-Canning is a salt-wedge estuary that is permanently open to the Indian Ocean at its mouth in Fremantle, and has a small diurnal tidal amplitude of , 0.6 m. The low tidal influence and seasonally variable river discharge often result in a high degree of stratification in the estuary (Hodgkin 1987;Stephens and Imberger 1996). For example, during the summer dry season river flow nearly ceases while tidally driven, marine waters can reach 60 km upstream (Stephens and Imberger 1996).…”

Section: Methodsmentioning

confidence: 99%

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Source, biogeochemical cycling, and fluorescence characteristics of dissolved organic matter in an agro‐urban estuary

Fellman¹,

Petrone²,

Grierson³

2010

Limnology & Oceanography

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Seasonal measurements of dissolved organic matter (DOM) fluorescence characteristics were combined with weekly to bi-weekly measurements of carbon (C), nitrogen (N), and phosphorus (P) (including particulate, dissolved organic and inorganic forms) and chlorophyll to determine how riverine inputs and autochthonous production influence DOM and nutrient dynamics in the Swan-Canning estuary, Western Australia. Estuarine concentrations of C, N, and P were influenced by multiple factors, including the seasonal riverine flux of DOM, N, and P, the regeneration of mainly inorganic N and P from benthic anoxia, and the delivery of DOM and nutrients from urban drains. Parallel factor analysis of excitation-emission matrices identified eight fluorescence components that were used to fingerprint three distinct sources of estuarine DOM: (1) riverine DOM derived mainly from vascular plant material, (2) autochthonous DOM recently produced within the estuary (indicated by tryptophan-like fluorescence), and (3) autochthonous DOM originating from within the lower estuary or coastal marine environment enriched in marine humic-like and tyrosine-like fluorescence. Overall, fluorescence DOM characteristics shifted from humic-like in the upper and mid-estuary to protein-like in the lower estuary, which likely reflects the increased contribution of autochthonous relative to terrigenous DOM closer to the estuary mouth. Our findings show that DOM composition varies with season and estuary position as riverine DOM inputs, mainly from terrestrial plant material, are supplemented by autochthonous DOM contributions associated with discrete inputs of inorganic nutrients.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Source, biogeochemical cycling, and fluorescence characteristics of dissolved organic matter in an agro‐urban estuary

Fellman¹,

Petrone²,

Grierson³

2010

Limnology & Oceanography

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“…During the last 20 years, this permanently-open microtidal estuary, and particularly its riverine upper reaches, has become increasingly eutrophic (Stephens and Imberger, 1996;Hamilton and Turner, 2001; Thomson et al, 2001;Robson and Hamilton, 2003). Thus, while phytoplankton blooms were rarely observed in the 1980s (Zammit et al, 2005), they occurred intermittently in the 1990s (Viney and Sivapalan, 2001) and in most years in the 2000s (Robson and Hamilton, 2003;Hallegraeff et al, 2010;Kristiana et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Marked deleterious changes in the condition, growth and maturity schedules of Acanthopagrus butcheri (Sparidae) in an estuary reflect environmental degradation

Cottingham

Hesp

Hall

et al. 2014

Estuarine, Coastal and Shelf Science

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Keywords:estuarine fish biological characteristics plasticity eutrophication hypoxia density dependence a b s t r a c t As Acanthopagrus butcheri typically completes its life within its natal estuary and possesses plastic biological characteristics, it provides an excellent model for exploring the ways and extent to which a fish species can respond to environmental changes over time. The environment of the Swan River Estuary in south-western Australia has deteriorated markedly during the last two decades, reflecting the effects of increasing eutrophication and hypoxia in the upper regions, where A. butcheri spends most of the year and spawns. In this study, the biological characteristics of A. butcheri in 2007e11 were determined and compared with those in 1993e95. Between these two periods, the condition factor for females and males of A. butcheri across their length ranges declined by 6 and 5%, respectively, and the parameters k and L ∞ in the von Bertalanffy growth curves of both sexes underwent marked reductions. The predicted lengths of females and males at all ages !1 year were less in 2007e11 than in 1993e95 and by over 30% less at ages 3 and 6. The ogives relating maturity to length and age typically differed between 1993e94 and 2007e10. The L 50 of 161 mm for females and 150 mm for males in 2007e10 were less than the corresponding values of 181 and 170 mm in 1993e94, whereas the A 50 of 2.3 years for females and 2.2 years for males in 2007e10 were greater than the corresponding values of 1.6 and 1.1 years in 1993e94. The above trends in condition, growth and maturity parameters between periods are consistent with hypotheses regarding the effects of increasing hypoxia on A. butcheri in offshore, deeper waters. However, as the density of A. butcheri declined in offshore, deeper waters and increased markedly in nearshore, shallow waters, density-dependent effects in the latter waters, although better oxygenated, also probably contributed to the overall reductions in growth and thus to the changes in the lengths and ages at maturity.

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“…The Swan River estuary is influenced by mostly diurnal tides with a mean tidal range at the mouth of the estuary of 0.8 m. At the same time, the estuary is seasonally forced with a large discharge of freshwater from the tributaries during the wetter winter months (May-September), and little freshwater discharge during dry summers. This leads to fresh-to-brackish water in parts of the estuary in winter with a freshwater lens overlying saltwater, and an inland progression of the saltwater wedge, making the estuary a saltwater habitat during drier months (Stephens and Imberger, 1996). The Swan River estuary is permanently open to the ocean and has two major freshwater tributaries, the Swan River and the Canning River ( Fig.…”

Section: Study Sitesmentioning

confidence: 99%

“…1). While MC and SCC are situated at the deeper part of the estuary (depth < 17 m), all other sites are located in the shallower part (depth < 10 m) (Stephens and Imberger, 1996). The jetty at Cl is situated in a shallow bay (depth approximately 2 m) with established seagrass meadows and abundant macroalgae and macrophytes (Department of Water, 2010).…”

Section: Study Sitesmentioning

confidence: 99%

Can mussels be used as sentinel organisms for characterization of pollution in urban water systems?

Reichwaldt¹,

Ghadouani²

2016

Hydrol. Earth Syst. Sci.

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Abstract. Urbanization strongly impacts aquatic ecosystems by decreasing water quality and altering water cycles. Today, much effort is put towards the restoration and conservation of urban waterbodies to enhance ecosystem service provision, leading to liveable and sustainable cities. To enable a sustainable management of waterbodies, the quantification of the temporal and spatial variability of pollution levels and biogeochemical processes is essential. Stable isotopes have widely been used to identify sources of pollution in ecosystems. For example, increased nitrogen levels in waterbodies are often accompanied with a higher nitrogen stable isotope signature (δ 15 N), which can then be detected in higher trophic levels such as mussels. The main aim of this study was to assess the suitability of nitrogen stable isotopes as measured in mussels (Mytilus edulis), as an indicator able to resolve spatial and temporal variability of nitrogen pollution in an urban, tidally influenced estuary (Swan River estuary in Western Australia). Nitrogen concentrations were generally low and nitrogen stable isotope values of nitrate throughout the estuary were well within natural values of uncontaminated groundwater, organic nitrate from soils, or marinederived sources, indicating groundwater inflow rather than pollution by human activity was responsible for differences between sites. The δ 15 N signature in mussels was very stable over time within each site which indicated that mussels can be used as time-integrated sentinel organisms in urban systems. In addition, our study shows that the nature of the relationship between δ 15 N in the mussels and the nitrate in the water can provide insights into site-specific biogeochemical transformation of nutrients. We suggest that mussels and other sentinel organisms can become a robust tool for the detection and characterization of the dynamics of a number of emerging anthropogenic pollutants of concern in urban water systems.

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Dynamics of the Swan River Estuary: The seasonal variability

Cited by 64 publications

References 13 publications

Source, biogeochemical cycling, and fluorescence characteristics of dissolved organic matter in an agro‐urban estuary

Source, biogeochemical cycling, and fluorescence characteristics of dissolved organic matter in an agro‐urban estuary

Marked deleterious changes in the condition, growth and maturity schedules of Acanthopagrus butcheri (Sparidae) in an estuary reflect environmental degradation

Can mussels be used as sentinel organisms for characterization of pollution in urban water systems?

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