The limnology of a naturally acidic tropical water system in Australia I. General description and wet season characteristics

Morley, A. W.; Brown, T. E.; Koontz, D. V.

doi:10.1080/03680770.1983.11897635

Cited by 3 publications

(2 citation statements)

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“…Descriptions of the region's climate and billabong limnology are given by Hart & MacGregor (1980), Walker & Tyler (1982, Morley et al (1985) and Brown et al (1985), and will be only summarized here.…”

Section: Description Of Study Areamentioning

confidence: 99%

“…Over the ensuing dry season, the profundal community was more diverse than the littoral (Outridge, in review), and the billabong as a whole was more diverse than any other (Table 2). Rainfall records indicate that floods of similar magnitude occur several times each decade (see Morley et al 1985). Catastrophic floods, coupled with marked dry season reductions in species numbers and abundance which are correlated with declining water quality (Outridge, in review), may maintain benthic populations at relatively low densities, thereby encouraging increased diversity.…”

Section: Possible Causes Of High Diversity In the Magela Creek Benthosmentioning

confidence: 99%

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Possible causes of high species diversity in tropical Australian freshwater macrobenthic communities

Outridge¹

1987

Hydrobiologia

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A total of 133 benthic macroinvertebrate species was recorded in four permanent freshwater lagoons (billabongs) and a stream riffle in the Magela Creek catchment, Northern Territory, Australia. 101 species were lentic in occurrence. Each billabong supported at least as many species as larger tropical and Australian temperate lakes, and was an exception to the species-poor status of Australian lentic macrobenthic communities.> 98% of the total benthic biomass was contributed by a mussel species; the remaining species' combined standing crop was an order of magnitude lower than in other lentic systems, further highlighting the diversity of the Magela benthos. Rarefaction (removal of organisms) and predictable environmental heterogeneity, both related to monsoonal variations in flow and water quality, were probably important determinants of the high diversity of these communities.

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Section: Description Of Study Areamentioning

confidence: 99%

Section: Possible Causes Of High Diversity In the Magela Creek Benthosmentioning

confidence: 99%

Possible causes of high species diversity in tropical Australian freshwater macrobenthic communities

Outridge¹

1987

Hydrobiologia

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Seasonal and spatial variations in benthic macroinvertebrate communities of Magela Creek, Northern Territory

Outridge¹

1988

Mar. Freshwater Res.

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This study examined seasonal and spatial patterns of benthic macroinvertebrate communities in four billabongs and a perennial stream riffle in the Magela Creek catchment, Northern Territory. Chironomids, coleopterans, trichopterans and hydracarina were the most diverse and abundant taxa, although the mussel Velesunio angasi contributed over 98% of total standing crop in most billabongs. Diversity and standing crop were usually higher in littoral than in profundal areas of two shallow billabongs, probably because of the presence of macrophytes. Diversity, abundance and biomass declined sharply over the dry season, from maxima in May-July to minima in December. Recovery in the early wet season was rapid, commencing after the first creek flows in December. The decline and recovery were closely associated with the availability of sediment organic matter, which reflected inputs of mainly allochthonous (terrestrial) detritus over the wet season followed by losses due to intense microbial breakdown. Microbial respiration also seemed related to declines in benthic communities in the latter half of the wet season, by producing hypolimnetic anoxia during periods of reduced creek flow.

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Manganese speciation in Magela Creek, northern Australia

Hart¹,

Noller²,

Legras³

et al. 1992

Mar. Freshwater Res.

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The speciation of Mn has been studied in Magela Creek, a tropical river in northern Australia containing water characterized by low pH, high temperature and extremely low ionic strength. Low concentrations (about 2-5�g L-1) of soluble Mn (i.e. filtration size <0.02�m) are typically found in these waters during the wet season, the main natural sources apparently being rainwater and groundwater. An additional source of soluble Mn has been identified, possibly being seepage from a mine retention pond. Rather surprisingly, the concentration of colloidal Mn (0.4-0.02�m) was almost three times higher than that of soluble Mn and was correlated with it. The primary process controlling the concentration of soluble Mn in this system appears to be rapid adsorption of soluble Mn to existing colloidal matter, followed by slower transfer of part of this surface-bound Mn to the interior of the colloid. Colloidal Mn is postulated to have a particularly long lifetime in this system because the removal process (aggregation to form particulate Mn) would be slow due to the extremely low concentrations of Ca and Mg ions during the wet season. A mixing experiment, undertaken to provide information on the possible fate of Mn in a mine retention pond if this wastewater should be discharged to the creek, clearly showed that Mn would be rapidly removed from the water column via colloidal and particulate forms. The precise mechanism was shown to be complex, depending upon the amount and characteristics of the colloidal and particulate matter present at the time of discharge, the changes in the Ca and Mg concentrations (which would influence the rate of aggregation), and the amount of turbulence in the creek.

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The limnology of a naturally acidic tropical water system in Australia I. General description and wet season characteristics

Cited by 3 publications

References 1 publication

Possible causes of high species diversity in tropical Australian freshwater macrobenthic communities

Possible causes of high species diversity in tropical Australian freshwater macrobenthic communities

Seasonal and spatial variations in benthic macroinvertebrate communities of Magela Creek, Northern Territory

Manganese speciation in Magela Creek, northern Australia

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