Phytoplankton composition and constraints to biomass in the middle reaches of an Australian tropical river during base flow

2012 ◽  
Vol 63 (1) ◽  
pp. 48 ◽  
Author(s):  
S. A. Townsend ◽  
M. Przybylska ◽  
M. Miloshis
Keyword(s):  
Rapid Growth ◽  
Phytoplankton Biomass ◽  
Dry Season ◽  
Base Flow ◽  
Nutrient Concentrations ◽  
Phytoplankton Composition ◽  
Tropical River ◽  
Transport Time ◽  
Tropical Australia ◽  
High Flows

Under high flows, the biomass of riverine phytoplankton can be constrained by short transport times and advective losses. However, under slower flows and longer transport times, secondary factors and sometimes their interaction with flow may constrain phytoplankton biomass. To contribute to a wider understanding of the riverine conditions that constrain phytoplankton biomass, we tested the hypothesis that phytoplankton of the Daly River (tropical Australia) was constrained by transport time during dry-season base flow. The river is virtually undisturbed, with oligotrophic nutrient concentrations during the dry season. The most frequently occurring taxa were planktonic, rather than benthic, and dominated by the dinoflagellate Peridinium inconspicuum which has r-strategist traits that favour rapid growth in a nutrient-deficient environment. Our hypothesis was not supported because increased downstream loads of Chlorophyll a and the domination of P. inconspicuum inferred phytoplankton net growth. Instead, phytoplankton biomass was more likely to be nutrient-limited, although transport time may limit phytoplankton growth over some reaches and for specific taxa. The present study demonstrated that even in the fast-flowing middle reaches of a river (~0.4 m s–1), a population of phytoplankton can be sustained.

An analysis of primary production in the Daly River, a relatively unimpacted tropical river in northern Australia

2005 ◽  
Vol 56 (3) ◽  
pp. 303 ◽  
Author(s):  
I. T. Webster ◽  
N. Rea ◽  
A. V. Padovan ◽  
P. Dostine ◽  
S. A. Townsend ◽  
...  
Keyword(s):  
Primary Production ◽  
Plant Biomass ◽  
Net Primary Production ◽  
Low Flow ◽  
Nutrient Concentrations ◽  
Tight Coupling ◽  
Tropical River ◽  
Rate Of Photosynthesis ◽  
Curve Method ◽  
Tropical Australia

In this paper, the dynamics of primary production in the Daly River in tropical Australia are investigated. We used the diurnal-curve method for both oxygen and pH to calculate photosynthesis and respiration rates as indicators of whole-river productivity. The Daly River has maximum discharges during the summer, monsoonal season. Flow during the dry season is maintained by groundwater discharge via springs. The study investigated how primary production and respiration evolve during the period of low flow in the river (April–November). The relationship between primary production and the availability of light and nutrients enabled the role of these factors to be assessed in a clear, oligotrophic tropical river. The measured rate of photosynthesis was broadly consistent with the estimated mass of chlorophyll associated with the main primary producers in the river (phytoplankton, epibenthic algae, macroalgae, macrophytes). A significant result of the analysis is that during the time that plant biomass re-established after recession of the flows, net primary production proved to be ~4% of the rate of photosynthesis. This result and the observed low-nutrient concentrations in the river suggest a tight coupling between photosynthetic fixation of carbon and the microbial degradation of photosynthetic products comprising plant material and exudates.

scholarly journals Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

2012 ◽  
Vol 63 (9) ◽  
pp. 788 ◽  
Author(s):  
N. E. Pettit ◽  
T. D. Jardine ◽  
S. K. Hamilton ◽  
V. Sinnamon ◽  
D. Valdez ◽  
...  
Keyword(s):  
Water Quality ◽  
Seasonal Changes ◽  
Aquatic Macrophyte ◽  
Plant Cover ◽  
Critical Role ◽  
Dry Season ◽  
Nutrient Concentrations ◽  
Wet Season ◽  
Dry Tropics ◽  
The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

scholarly journals Dry season habitat use of fishes in an Australian tropical river

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
K. Keller ◽  
Q. Allsop ◽  
J. Brim Box ◽  
D. Buckle ◽  
D. A. Crook ◽  
...  
Keyword(s):  
Habitat Use ◽  
Dry Season ◽  
Tropical River

Effect of Water Body Morphology on Phytoplankton Biomass and Species Composition

2013 ◽  
Vol 777 ◽  
pp. 375-379
Author(s):  
Yue Hong Zhang ◽  
Fei Peng Li ◽  
Hu Hu Zhao ◽  
Hai Ping Zhang
Keyword(s):  
Species Composition ◽  
Water Body ◽  
Environmental Variables ◽  
Phytoplankton Biomass ◽  
Population Variation ◽  
Nutrient Concentrations ◽  
Body Morphology ◽  
Key Factor ◽  
Lake Type ◽  
River Type

Environmental variables, phytoplankton biomass and species composition in Nanhu Lake in Yingdong Village, Chongming Island were monitored from August 2010 to September 2011. The relationship between environmental variables and population variation of phytoplankton was discussed. The results showed that water body morphology was the key factor leading to the variation of phytoplankton community. In river-type waters the level of phytoplankton biomass was generally higher than that in lake-type waters, especially in summer. During the period of seasonal change, in river-type waters Cyanophyta dominated longer with the succession from Cyanophyta to Chlorophyta and Bacillariophyta occurred later than that in lake-type waters. Redundancy analysis (RDA) indicated that the morphology of enclosed waters had influence on phytoplankton biomass and species composition. One of the mechanisms may be that water body morphology could have impact on the growth and species dynamics of phytoplankton indirectly by affecting nutrient concentrations.

scholarly journals Study on the Transport of Terrestrial Dissolved Substances in the Pearl River Estuary Using Passive Tracers

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1235
Author(s):  
Bo Hong ◽  
Guangyu Wang ◽  
Hongzhou Xu ◽  
Dongxiao Wang
Keyword(s):  
Water Resource Management ◽  
River Flow ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Dry Season ◽  
Pearl River ◽  
Transport Time ◽  
The Pearl River Estuary ◽  
Passive Tracers ◽  
The Pearl River

Highly populated river deltas are experiencing marine environment degradation resulting from the tremendous input of terrestrial dissolved substances (TeDS). The Pearl River Delta is one of the deltas with degradation of the water quality and ecological condition. The Pearl River Estuary (PRE) was investigated to reveal the fate and transport timescales of TeDS in order to provide guidance on water resource management and pollutant transport prediction. By using passive tracers in a calibrated 3D numerical model, the TeDS transports from five different outlet groups were investigated systematically. The TeDS transport time was computed by using the concept of water age, which is a measure of the time that has elapsed since the tracer was transported from the upstream boundary to the downstream concerned area. The tracer impacted area was defined by the area with tracer concentrations > 0.2 (arbitrary unit). The domains that were impacted by the tracer coming from each outlet group were identified separately. In the wet season, the impacted area was larger than in other seasons. The most prominent variations appeared in the Jiaomen–Hengmen–Hongqili (JHH) and Modaomen (MD) outlets. The hydrodynamic conditions controlled the offshore spreading of the TeDS. Assuming the TeDS were conservative, it took approximately 10–20 days for the TeDS to be transported from the head water to the entrance of the outlet. For the TeDS coming from the head water of the Humen outlet, it took approximately 40 (80) days for the TeDS to be transported out of the mouth of the Lingding Bay during the wet (dry) season. For the case of the TeDS coming from the head water of the JHH outlets, it took approximately 20 (40) days for the TeDS to be transported out of the Lingding Bay during the wet (dry) season. For the MD, Jiti and Yamen–Hutiao outlets, it usually took approximately 10 days for the TeDS to be transported from the head water to the inner shelf. The correlation coefficient between the river flow and tracer concentrations was 0.78, and between the river flow and transport time it was −0.70 at a station in the lower Lingding Bay. At the estuary mouth, the impacts of other forcing fields got stronger.

scholarly journals Quantification of Temporal Variations in Base Flow Index Using Sporadic River Data: Application to the Bua Catchment, Malawi

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 901 ◽  
Author(s):  
Laura Kelly ◽  
Robert M. Kalin ◽  
Douglas Bertram ◽  
Modesta Kanjaye ◽  
Macpherson Nkhata ◽  
...  
Keyword(s):  
Water Resources ◽  
River Flow ◽  
Temporal Variations ◽  
Dry Season ◽  
Base Flow ◽  
Flow Index ◽  
Wet Season ◽  
Data Application ◽  
Base Flow Index ◽  
Long Term Trends

This study investigated how sporadic river datasets could be used to quantify temporal variations in the base flow index (BFI). The BFI represents the baseflow component of river flow which is often used as a proxy indicator for groundwater discharge to a river. The Bua catchment in Malawi was used as a case study, whereby the smoothed minima method was applied to river flow data from six gauges (ranging from 1953 to 2009) and the Mann-Kendall (MK) statistical test was used to identify trends in BFI. The results showed that baseflow plays an important role within the catchment. Average annual BFIs > 0.74 were found for gauges in the lower reaches of the catchment, in contrast to lower BFIs < 0.54 which were found for gauges in the higher reaches. Minimal difference between annual and wet season BFI was observed, however dry season BFI was >0.94 across all gauges indicating the importance of baseflow in maintaining any dry season flows. Long term trends were identified in the annual and wet season BFI, but no evidence of a trend was found in the dry season BFI. Sustainable management of the investigated catchment should, therefore, account for the temporal variations in baseflow, with special regard to water resources allocation within the region and consideration in future scheme appraisals aimed at developing water resources. Further, this demonstration of how to work with sporadic river data to investigate baseflow serves as an important example for other catchments faced with similar challenges.

scholarly journals Phytoplankton Biomass Dynamics in Tropical Coastal Waters of Jakarta Bay, Indonesia in the Period between 2001 and 2019

2020 ◽  
Vol 8 (9) ◽  
pp. 674 ◽  
Author(s):  
Ario Damar ◽  
Franciscus Colijn ◽  
Karl-Juergen Hesse ◽  
Luky Adrianto ◽  
Yonvitner ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Temporal Dynamics ◽  
Inorganic Nitrogen ◽  
Outer Part ◽  
Middle Part ◽  
Nutrient Concentrations ◽  
Marine Biota ◽  
Chl A ◽  
Hypoxic Conditions

A study of nutrients, underwater light dynamics, and their correlation with phytoplankton biomass was conducted in the tropical estuary of Jakarta Bay, Indonesia, in the dry season during the period from 2001 to 2019. This study analyzed the spatial and temporal dynamics of phytoplankton biomass and its correlation with phytoplankton biomass. There was significant increase in nutrient concentration in Jakarta Bay, with annual means of 27.97 µM dissolved inorganic nitrogen (DIN) and 11.31 µM phosphates in 2001, increasing to 88.99 µM DIN and 25.92 µM phosphates in 2019. Increased mean nutrient concentrations were accompanied by increased mean phytoplankton biomass, from 15.81 µg Chl-a L−1 in 2001 to 21.31 µg Chl-a L−1 in 2019. The eutrophication status of Jakarta Bay waters was calculated using the Tropical Index for Marine Systems eutrophication index, which showed increased areas of hyper-eutrophic and eutrophic zones, while the mesotrophic area decreased. The hyper-eutrophic zone dominated the areas around river mouths and the inner part of the bay, while eutrophic status was observed in the middle part of the bay and mesotrophic status was found in the outer part of the bay. The area of hyper-eutrophic water increased 1.5-fold, from 75.1 km2 in 2001 to 114.0 km2 in 2019. Increasing eutrophication of the bay has had negative ecological consequences including algal blooms, hypoxic conditions, and mass mortality of marine biota, and it urgently requires remediation.

The instantaneous transport of inorganic and organic material in a highly polluted tropical estuary

2013 ◽  
Vol 64 (6) ◽  
pp. 562 ◽  
Author(s):  
Carlos E. D. Noriega ◽  
Marilene Felipe Santiago ◽  
Patrícia Façanha ◽  
Maria da Glória Gonçalves da Silva Cunha ◽  
Rodolfo Araújo da Silva ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Coastal Area ◽  
Rainy Season ◽  
Phytoplankton Biomass ◽  
Dry Season ◽  
Tropical Estuary ◽  
Liquid Transport ◽  
Water Renewal ◽  
Rainy Period ◽  
Dissolved Inorganic Nutrients

The contribution of the estuarine channel of Recife harbour to the eutrophication of the Recife coastal area was evaluated by quantifying the instantaneous transport of salt, dissolved inorganic nutrients (PO4–, SiOH4, NO3–, NO2– and, NH4+), material in suspension, Chlorophyll-a, pico–nanoplankton and microplankton during the rainy (June 2007) and dry (November 2007) seasons. The results showed that all of the dissolved nitrogenated nutrients, the silicate and the material in suspension had higher concentrations during the rainy season, whereas the phosphate and Chlorophyll-a (both the total and the pico–nanoplankton and microplankton fractions) showed greater concentrations during the dry season. All of the materials considered were exported to the sea except for Chlorophyll-a (pico–nanoplankton and microplankton fractions) during the dry season, when these materials were imported into the area. The total liquid transport in the rainy season was three times higher than that found for the dry season. Silicate represented nearly 85% of the total exported material during the rainy period, whereas during the dry season, phosphate and silicate represented 79% of the total exported material. The stratification and circulation processes indicated a well mixed environment. The water-renewal rate was low, as demonstrated by the input of phytoplankton biomass during November. The area was characterised as eutrophic during the months investigated.

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