Agricultural impact on the pelagic ecosystem of the small temporarily open/closed Seteni Estuary, South Africa

2013 ◽  
Vol 64 (10) ◽  
pp. 938 ◽  
Author(s):  
N. K. Carrasco ◽  
R. Perissinotto ◽  
A. Whitehead
Keyword(s):  
South Africa ◽  
Inorganic Nitrogen ◽  
Land Use Changes ◽  
Agricultural Practices ◽  
Zooplankton Community ◽  
Inorganic Phosphorus ◽  
Zooplankton Abundance ◽  
Microalgal Biomass ◽  
Chl A ◽  
The Impact

The encroachment of agriculture and human population is placing increasing levels of stress on estuarine ecosystems worldwide. The catchment of the Seteni Estuary, a small temporarily open/closed estuary in South Africa, has been under extensive sugar cultivation for over 60 years. The present study reports on the impact of agricultural practices on the structure and dynamics of its pelagic communities over a 1-year period, from April 2008 to March 2009. The physico-chemical characteristics of the system were strongly linked to seasonality, with the system exhibiting a distinct open- and closed-mouth phase in response to rainfall. Concentrations of dissolved inorganic nitrogen (DIN) were exceptionally high in comparison to concentrations of dissolved inorganic phosphorus (DIP), resulting in high DIN : DIP ratios. Despite this, microalgal biomass remained relatively low, exhibiting maximum values of 91.7 mg chl a m–2 and 18.0 mg chl a m–3 for microphytobenthos and phytoplankton, respectively. Zooplankton abundance and biomass were significantly higher during the dry phase, with Pseudodiaptomus hessei dominating the zooplankton community both in terms of abundance and biomass throughout the study period. The ichthyofaunal community was dominated by Ambassis ambassis and Myxus capensis in terms of abundance and biomass, respectively. Results suggest that the system remains functional, but there is potential for deterioration, should the catchment become more nutrient-rich through poor management or land-use changes.

scholarly journals Can land use changes alter carbon, nitrogen and major ion transport in subtropical brazilian streams?

2007 ◽  
Vol 64 (4) ◽  
pp. 317-324 ◽  
Author(s):  
Daniela Mariano Lopes da Silva ◽  
Jean Pierre Henry Balbaud Ometto ◽  
Gré de Araújo Lobo ◽  
Walter de Paula Lima ◽  
Marcos Augusto Scaranello ◽  
...  
Keyword(s):  
Land Use ◽  
Sugar Cane ◽  
Dissolved Inorganic Carbon ◽  
Comprehensive Evaluation ◽  
Land Use Changes ◽  
Agricultural Practices ◽  
Major Ion ◽  
Se Brazil ◽  
Tropical Watersheds ◽  
The Impact

Several studies in tropical watersheds have evaluated the impact of urbanization and agricultural practices on water quality. In Brazil, savannas (known regionally as Cerrados) represent 23% of the country's surface, representing an important share to the national primary growth product, especially due to intense agriculture. The purpose of this study is to present a comprehensive evaluation, on a yearly basis, of carbon, nitrogen and major ion fluxes in streams crossing areas under different land use (natural vegetation, sugar cane and eucalyptus) in a savanna region of SE Brazil. Eucalyptus and sugar cane alter the transport of the investigated elements in small watersheds. The highest concentration of all parameters (abiotic parameters, ions, dissolved organic carbon DOC - and dissolved inorganic carbon - DIC) were found in Sugar Cane Watersheds (SCW). The observed concentrations of major cations in Eucalyptus Watersheds (EW) (Mg, Ca, K, Na), as well as DIN and DOC, were found frequently to be intermediate values between those of Savanna Watersheds (SW) and SCW, suggesting a moderate impact of eucalyptus plantations on the streamwater. Same trends were found in relation to ion and nutrient fluxes, where the higher values corresponded to SCW. It is suggested that sugar cane plantations might be playing an important role in altering the chemistry of water bodies.

Characterising and predicting algal blooms in a subtropical coastal lagoon

2014 ◽  
Vol 65 (3) ◽  
pp. 191 ◽  
Author(s):  
Kwee Siong Tew ◽  
Pei-Jie Meng ◽  
David C. Glover ◽  
Jih-Terng Wang ◽  
Ming-Yih Leu ◽  
...  
Keyword(s):  
Coastal Lagoon ◽  
Algal Blooms ◽  
Algal Bloom ◽  
Coastal Lagoons ◽  
Inorganic Nitrogen ◽  
Inorganic Phosphorus ◽  
Reliable Measure ◽  
Exponential Relationship ◽  
Outlet Channel ◽  
Chl A

Algal bloom is a major concern worldwide. In this study, we characterised the physical and biochemical parameters during an algal bloom event in a coastal lagoon in an attempt to predict local blooms in the future. Results showed that the highest concentrations of dissolved inorganic phosphorus (DIP), chlorophyll a (chl a) and phytoplankton abundance were found in the inner area, whereas the highest dissolved inorganic nitrogen (DIN) concentration occurred near the inlet-outlet channel. Chl a was correlated with DIP, and there was a significant exponential relationship between chl a and the nitrogen to phosphorus ratio (N/P ratio) across all sampling stations and times. A higher proportion of the variation in chl a was explained by the N/P ratio than either DIP or DIN. We found that a N/P ratio <2.38 will likely trigger an algal bloom (chl a ≥ 10 µgL–1) in the lagoon. Our results suggest that the N/P ratio could be used as an expedient and reliable measure of the potential eutrophic status of coastal lagoons.

scholarly journals Effect of agricultural practices on terrestrial isopods: a review

ZooKeys ◽  
2018 ◽  
Vol 801 ◽  
pp. 63-96
Author(s):  
Catherine Souty-Grosset ◽  
Ariel Faberi
Keyword(s):  
Land Use ◽  
Land Use Changes ◽  
Agricultural Practices ◽  
Sustainable Land Use ◽  
Soil Tillage ◽  
Chemical Pollution ◽  
Soil Biodiversity ◽  
Tropical Regions ◽  
Terrestrial Isopods ◽  
The Impact

Terrestrial isopods (approximately 3700 known species in the world) are encountered in temperate and tropical regions, from the seashore to high altitudes and from floodplain forests to deserts. They are known to contribute to soil biodiversity. Environmental factors and anthropogenic actions, particularly land use changes such as primarily agricultural practices, and urbanization affect soil biodiversity and their functions. Human practices, such as soil tillage, pesticide application, chemical pollution, along with soil acidification adversely affect isopod abundance and diversity. It is thus important to recognise the vital contributions of soil biodiversity in support of environmental quality protection through maintaining soil functions and their significance to sustainable land use. This review will also deal with recent studies attempting to evaluate the impact of returning to an environmentally friendly agriculture by restoring refuge habitats such as grass strips, hedges, and woodlands for terrestrial isopods.

scholarly journals Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and landuse alteration

2012 ◽  
Vol 9 (9) ◽  
pp. 13211-13241 ◽  
Author(s):  
T.-Y. Lee ◽  
J.-C. Huang ◽  
S.-J. Kao ◽  
C.-P. Tung
Keyword(s):  
Nitrogen Saturation ◽  
Inorganic Nitrogen ◽  
Phosphate Transport ◽  
Inorganic Phosphorus ◽  
Fertilizer Application ◽  
Temporal Variations ◽  
Phosphorus Transport ◽  
Headwater Catchments ◽  
High Level ◽  
The Impact

Abstract. Oceania Rivers are hotspots of high DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphorus) transport. However, the effects of hydrologic controls and land use alternation on the temporal variations of DIN and DIP are rarely documented. In this study, we monitored the nitrate and phosphate concentrations from three headwater catchments with different cultivation gradients at a 3-day interval. This sampling scheme was supplemented with a 3-h interval monitoring during typhoon periods. The results showed that the DIN and DIP yields in the pristine, moderately cultivated, and intensively cultivated watersheds were 7.52/0.31, 31.17/0.30, and 40.96/0.52 kg ha−1 yr−1, respectively. The high DIN yields are comparable to the intensively and extensively disturbed large rivers around the world. These N yields may be due to a high level of nitrogen deposition, rainfall-runoff, and fertilizer application. The importance of event sampling was indicated by the contribution of the three typhoons to the annual DIN and DIP fluxes, which were 30% and 60%, respectively. Both DIN and DIP fluxes significantly increased as the cultivation gradient increased. The DIN and DIP ratio varied from 54 to 230 depending on the decrease of the cultivation gradient. This value is higher than the global mean of ~18. Thus, we speculate that nitrogen saturation occurs in the headwater catchments of Oceania Rivers. The results obtained provide fundamental clues of DIN and DIP yield of Oceania Rivers, which are helpful in understanding the impact of human disturbance on headwater watersheds.

scholarly journals Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and land use alteration

2013 ◽  
Vol 10 (4) ◽  
pp. 2617-2632 ◽  
Author(s):  
T.-Y. Lee ◽  
J.-C. Huang ◽  
S.-J. Kao ◽  
C.-P. Tung
Keyword(s):  
Land Use ◽  
Inorganic Nitrogen ◽  
Land Use Changes ◽  
Phosphate Transport ◽  
Inorganic Phosphorus ◽  
High Ratio ◽  
Tectonic Activity ◽  
Phosphorus Transport ◽  
High Background ◽  
Headwater Catchments

Abstract. Oceania rivers are hotspots of DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphorus) transport due to humid/warm climate, typhoon-induced episodic rainfall and high tectonic activity that create an environment favorable for high/rapid runoff and soil erosion. In spite of its uniqueness, effects of hydrologic controls and land use on the transport behaviors of DIN and DIP are rarely documented. A 2 yr monitoring study for DIN and DIP from three headwater catchments with different cultivation gradient (0 To 8.9%) was implemented during a ~ 3 day interval with an additional monitoring campaign at a 3 h interval during typhoon periods. Results showed the DIN yields in the pristine, moderately cultivated (2.7%), and intensively cultivated (8.9%) watersheds were 8.3, 26, and 37 kg N ha−1 yr−1, respectively. For the DIP yields, they were 0.36, 0.35, and 0.56 kg P ha−1 yr−1, respectively. Higher year-round DIN concentrations and five times larger in DIN yields in intensively cultivated watersheds indicate DIN is more sensitive to land use changes. The high background DIN yield from the relatively pristine watershed was likely due to high atmospheric nitrogen deposition and large subterranean N pool. The correlations between runoff and concentration reveals that typhoon floods purge out more DIN from the subterranean reservoir, i.e., soil, by contrast, runoff washes off surface soil resulting in higher suspended sediment with higher DIP. Collectively, typhoon runoff contributes 20–70% and 47–80%, respectively, to the annual DIN and DIP exports. The DIN yield to DIP yield ratio varied from 97 to 410, which is higher than the global mean of ~ 18. Such a high ratio indicates a P-limiting condition in stream and the downstream aquatic environment. Based on our field observation, we constructed a conceptual model illustrating different remobilization mechanisms for DIN and DIP from headwaters in a mountainous river, which is analogous to typical Oceania rivers and the headwater of large rivers in similar climate zones. Our study advanced our understanding about the role of cyclones, which exert hydrological control, and land use on nutrient export in the Oceania region, benefiting watershed management under the context of climate change.

scholarly journals Water quality and sustainability of Merdada Lake, Dieng, Indonesia

2019 ◽  
Vol 76 ◽  
pp. 02003
Author(s):  
Sudarmadji ◽  
Slamet Suprayogi ◽  
Sri Lestari ◽  
Mukhamad Ngainul Malawani
Keyword(s):  
Water Quality ◽  
Environmental Degradation ◽  
Land Use Changes ◽  
Agricultural Practices ◽  
Quality Standard ◽  
Physical Parameters ◽  
Volcanic Lake ◽  
Volcanic Lakes ◽  
Value Range ◽  
The Impact

The volcanic lakes in Dieng Plateau offer some unique phenomena, which interest not only tourists but also scientists. However, as the land use changes, the lakes are now facing environmental degradation especially from agricultural practices. This research aims to study the impact of agricultural practices on the environmental degradation of the lakes especially the water quality and analyze the sustainability of the lakes to support water needs. Merdada Volcanic Lake, one of the lakes in Dieng Plateau was selected as the focus of this research. Method conducted on this research are fields survey to collect the physical parameters temperature and conductivity also chemical parameters like pH, Nitrate, BOD, phosphate, and coliform. A complementary data was acquired using interviews method for defining the sustainability of the lake. Based on observation, water level of the lake is gradually decreased, especially during the dry season. At the same time, the agricultural practices in the surrounding area led to soil erosion, which involved surface runoff that transporting sediments into the lake. This research found that the practices of potato cultivation pumped out the water from Merdada Volcanic Lake and distributed over the plantation area. This practice caused a dramatic decrease in the water surface. Besides that, the agricultural practices had several adverse effects on the volcanic lakes in Dieng Plateau especially eutrophication and decrease of water quality in Merdada Lake where nitrate is over from water quality standard class II. Coliform also has an over expected value, range from 3–11 MPN/100 ml.

Evaluation of Factors Related to the Unusually Low Chlorophyll Levels in Prairie Saline Lakes

1986 ◽  
Vol 43 (4) ◽  
pp. 846-854 ◽  
Author(s):  
C. E. Campbell ◽  
E. E. Prepas
Keyword(s):  
Phytoplankton Biomass ◽  
Saline Lakes ◽  
Inorganic Nitrogen ◽  
Algal Growth ◽  
Dry Weight ◽  
Inorganic Phosphorus ◽  
Total Dissolved Solids ◽  
Empirical Models ◽  
Phytoplankton Primary Production ◽  
Chl A

Prairie saline lakes in Canada have remarkably low chlorophyll a (Chl a) levels relative to total phosphorus (TP) and total nitrogen (TN) levels. To evaluate factors related to low Chl a levels, three Alberta saline lakes (total dissolved solids > 5 g∙L−1) were studied in 1983 and 1984. Mean summer phytoplankton Chl a ranged from 3 to 10 μg∙L−1, mean summer periphyton Chl a was less than 70 mg∙m−2, while mean summer TP and TN ranged from 2 to 13 and from 4 to 11 mg∙L−1, respectively. Chl a and phytoplankton primary production were extremely low relative to predictions from measured TP and TN levels and empirical models for freshwaters. Bioassays indicated that inorganic phosphorus was not limiting, whereas inorganic nitrogen was limiting algal growth. Bacterial densities and zooplankton dry weight were high (> 107 cells∙mL−1 and > 1.0 mg∙L−1, respectively) relative to predictions from Chl a and empirical models for freshwaters. Phytoplankton biomass was insufficient to maintain the zooplankton populations; bacteria and detritus were likely a major food source for zooplankton. This study suggests that freshwater models are not applicable to prairie saline lakes.

scholarly journals INFLUENCE OF STRONG MONSOON-DOMINATED CLIMATE ON BIOGEOCHEMISTRY OF THE HEAVILY ANTHROPOGENIC IMPACTED BRANTAS RIVER ESTUARIES AND MADURA STRAIT COASTAL WATER, EAST JAVA, INDONESIA

2015 ◽  
Vol 36 (2) ◽  
pp. 37-49
Author(s):  
M.S. Nugrahadi
Keyword(s):  
River Basin ◽  
Coastal Water ◽  
Inorganic Nitrogen ◽  
N:P Ratio ◽  
Inorganic Phosphorus ◽  
Dry Season ◽  
Mixing Zone ◽  
Populated Area ◽  
Chl A ◽  
Agriculture Industry

Brantas River basin and Madura Strait in East Java Indonesia, are subject to heavily change in land use and land cover, and Brantas River Basin is a very important densely populated area in East Java, Indonesia for agriculture, industry as well as for settlement. The aim of the research is to elucidate the fate of transformation of bio-elements (organic carbon, Nitrogen (N), Phosphorus (P), and Silicate (Si)) and its seasonal variability. The contrast river discharge combined with tide generates the distinctive mixing zone during rainy and dry season. Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphorus (DIP) concentrations in the river are high and decrease to the very low value seaward. N:P ratio has seasonal variation due to large discrepancy of DIN and DIP supply from land to the sea. Dissolved Inorganic Silicate (DSi) in river and estuaries is extremely higher than the average in the world (> 150 mM). Chlorophyll-a (Chl-a) in dry season in the coastal water is higher than the rainy season. Due to high Total Suspended Matter (TSM), the primary production is limited by the light in the coastal water.

Some Reflections on Reparation in Post-Apartheid South Africa, using a Couple Therapy Intervention as a Microcosm of South African Society

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Andrea Hill ◽  
Sylvia Poss
Keyword(s):  
South Africa ◽  
South African ◽  
Couple Therapy ◽  
South African Society ◽  
Depressive Position ◽  
Central Hypothesis ◽  
Transference And Countertransference ◽  
Constructive Engagement ◽  
The Impact ◽  
Therapy Intervention

The paper addresses the question of reparation in post-apartheid South Africa. The central hypothesis of the paper is that in South Africa current traumas or losses, such as the 2008 xenophobic attacks, may activate a ‘shared unconscious phantasy’ of irreparable damage inflicted by apartheid on the collective psyche of the South African nation which could block constructive engagement and healing. A brief couple therapy intervention by a white therapist with a black couple is used as a ‘microcosm’ to explore this question. The impact of an extreme current loss, when earlier losses have been sustained, is explored. Additionally, the impact of racial difference on the transference and countertransference between the therapist and the couple is explored to illustrate factors complicating the productive grieving and working through of the depressive position towards reparation.

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