Metabolism in a groundwater-fed river system in the Australian wet/dry tropics: tight coupling of photosynthesis and respiration

Townsend, Simon A.; Webster, Ian T.; Schult, Julia

doi:10.1899/10-066.1

Cited by 41 publications

(51 citation statements)

References 54 publications

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“…Sampling dates on the x axis: EW08 early-wet-08, MW09 mid-wet-09, ED09 early-dry-09, MD09 mid-dry-09, LD09 late-dry-09, LLD09 late-late-dry-09, and MW10 mid-wet-10 freshwater systems. Our metabolism dome results also contrast with findings from measuring open water metabolism in Australian tropical main river channels (Webster et al 2005;Townsend et al, 2011;Hunt et al, 2012), which have been found to be net heterotrophic for much of the dry season. Our findings of autotrophic stream conditions are not surprising as the metabolism domes used have measured benthic primary productivity of epilithic algae and phytoplankton and excluded measurement of subsurface respiration.…”

Section: Discussioncontrasting

confidence: 99%

“…At the end of the dry season, as available habitat contracted, GPP and algal biomass in both the benthos and the water column peaked. In the transition from the wet to the dry season, discharge, fluvial scour , and sediment loads are reduced and water clarity greatly improves (Townsend et al, 2011), but nutrient delivery is maintained by Hydrobiologia sustained low flows, leading to another peak in benthic chl a. Similar patterns have been observed in the tropical Cinaruco River in Venezuela and lowland, Pampean streams in Argentina (Leggieri et al, 2013), where the annual flood regime creates strong patterns of seasonal and spatial variation in benthic periphyton production.…”

Section: Discussionsupporting

confidence: 55%

“…Low dissolved nutrient levels but increasing GPP and chl a through the dry season in our oligotrophic streams suggest that rapid recycling and uptake of nutrients take place in the pools. In the Cinaruco River in South America, GPP was not correlated with nutrient concentrations due to extremely rapid nutrient cycling rates , while Townsend et al (2011) suggested that rapid recycling of nutrients by microorganisms may contribute to primary production in the Daly River, northern Australia. Nutrient recycling may also be a result of macroinvertebrate and fish grazer/algae interactions whereby nutrients regenerated by algal grazers are rapidly assimilated by algae so that rapid growth by algae more than makes up for loss to consumers.…”

Section: Discussionmentioning

confidence: 97%

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Temporal variation in benthic primary production in streams of the Australian wet–dry tropics

et al. 2015

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In the Australian wet-dry tropics, seasonal changes in hydrology can influence abiotic conditions and consequently influence standing stocks of benthic biomass and production. While there is some understanding of these processes at riverscape scales, effects of seasonal hydrology on benthic biomass and production in low-order streams remain largely unquantified. We observed changes in water quality, algal and macroinvertebrate biomass, and stream benthic primary productivity over a 15-month period in three low-order streams with contrasting flow regimes in the wet-dry tropics of northern Australia. Water quantity and quality showed a distinct seasonal signature reflected in seasonal peaks in algal (maximum 1.29 lg cm -2 ) and macroinvertebrate biomass (maximum 0.24 g m -2 ), and productivity (maximum 0.41 g C m -2 days -1 ). In particular, transitional periods between dry and wet seasons were key times of elevated production and algal biomass. Overall, variation in biomass and benthic primary production was greater between seasons than among streams indicating that extrapolation between seasons may not be appropriate.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 97%

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Temporal variation in benthic primary production in streams of the Australian wet–dry tropics

et al. 2015

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“…At our focal streams, estimated rates of GPP ranged from 0.00026 g O 2 m À2 d À1 to 13 g O 2 m À2 d À1 , exceeding the range of GPP recorded across six tropical studies (0.10-4.6 g O 2 m À2 d À1 ) [Gücker et al, 2009;Hunt et al, 2012;Mulholland et al, 2001;Oliver and Merrick, 2006;Ortiz-Zayas et al, 2005;Townsend et al, 2011]. Available light has been identified as a strong contributing factor to high GPP, especially in reference streams [Bernot et al, 2010;Mulholland et al, 2001;Young and Huryn, 1999].…”

Section: Stream Metabolic Dynamicsmentioning

confidence: 48%

“…High stream respiration rates were particularly surprising because they occurred in a nonforest catchment. Previous studies suggest that forested catchments produce the greatest respiration rates as a result of high organic matter inputs from riparian vegetation and a tendency for pristine streams to retain organic matter [Delong and Brusven, 1994 [Gücker et al, 2009;Hunt et al, 2012;Mulholland et al, 2001;Oliver and Merrick, 2006;Ortiz-Zayas et al, 2005;Townsend et al, 2011]. In the mature oil palm stand in August 2009, low flow rates resulted from little antecedent precipitation.…”

Section: Stream Metabolic Dynamicsmentioning

confidence: 99%

Influence of watershed‐climate interactions on stream temperature, sediment yield, and metabolism along a land use intensity gradient in Indonesian Borneo

et al. 2014

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Oil palm plantation expansion into tropical forests may alter physical and biogeochemical inputs to streams, thereby changing hydrological function. In West Kalimantan, Indonesia, we assessed streams draining watersheds characterized by five land uses: intact forest, logged forest, mixed agroforest, and young (<3 years) and mature (>10 years) oil palm plantation. We quantified suspended sediments, stream temperature, and metabolism using high-frequency submersible sonde measurements during month-long intervals between 2009 and 2012. Streams draining oil palm plantations had markedly higher sediment concentrations and yields, and stream temperatures, compared to other streams. Mean sediment concentrations were fourfold to 550-fold greater in young oil palm than in all other streams and remained elevated even under base flow conditions. After controlling for precipitation, the mature oil palm stream exhibited significantly greater sediment yield than other streams. Young and mature oil palm streams were 3.9°C and 3.0°C warmer than the intact forest stream (25°C). Across all streams, base flow periods were significantly warmer than times of stormflow, and these differences were especially large in oil palm catchments. Ecosystem respiration rates were also influenced by low precipitation. During an El Niño-Southern Oscillation-associated drought, the mature oil palm stream consumed a maximum 21 g O 2 m À2 d À1 in ecosystem respiration, in contrast with 2.8 ± 3.1 g O 2 m À2 d À1 during nondrought sampling. Given that 23% of Kalimantan's land area is occupied by watersheds similar to those studied here, our findings inform potential hydrologic outcomes of regional periodic drought coupled with continued oil palm plantation expansion.

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The importance of climatic variability and human influence in driving aspects of temporarily open‐closed estuaries

Brooker

Scharler

2020

Ecohydrology

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Freshwater availability is a major topic in scientific literature and the public domain.Estuaries are complex and dynamic ecosystems that depend on freshwater inflow from their catchments and exchange with the marine environment. Catchment forcings are subject to shifts in frequency and intensity due to regional hydrological variability over time. Human manipulation of freshwater regimes may further alter this beyond natural variability through flow abstraction and additional inputs in the form of wastewater. To elucidate the effect of climate variability and human activities, we conducted a time series investigation on hydrological drivers into a small South African estuary (uMdloti), representative of temporarily open-closed estuaries. Subsequently, we investigated the ability of the hydrological variables to drive physical parameters and microalgae in the estuary. Freshwater abstraction caused a disconnect between rainfall and river flow, and increased lag times during dry spells, peaking at 115 days. Annual seasonal peaks in rainfall were not represented in river flow due to the dam. Wastewater discharges equate to 4% of the mean annual runoff from the catchment, which has reduced from a natural runoff of 85.8 to 71.9 Mm −3 year −1 . Due to this and damming of catchment flows, wastewater discharging into the estuary was the most important driver of water quality in the system, resulting in increased nutrient and decreased dissolved oxygen concentrations, whereas river flow was an important driver at high flow volumes. An understanding of interaction effects between climatic variability and catchment flow manipulation is vitally important to estuarine management and their ecological viability. K E Y W O R D S climatic variability, estuarine water quality, freshwater abstraction, hydrological drivers, intermittently open-closed lagoons, temporarily open-closed estuaries, wastewater treatment works

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Metabolism in a groundwater-fed river system in the Australian wet/dry tropics: tight coupling of photosynthesis and respiration

Cited by 41 publications

References 54 publications

Temporal variation in benthic primary production in streams of the Australian wet–dry tropics

Temporal variation in benthic primary production in streams of the Australian wet–dry tropics

Influence of watershed‐climate interactions on stream temperature, sediment yield, and metabolism along a land use intensity gradient in Indonesian Borneo

The importance of climatic variability and human influence in driving aspects of temporarily open‐closed estuaries

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