scholarly journals The Assessment of Phytoplankton Dynamics in Two Reservoirs in Southern Africa with Special Reference to Water Abstraction for Inter-Basin Transfers and Potable Water Production

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3045
Author(s):  
Johannes Sirunda ◽  
Paul Oberholster ◽  
Gideon Wolfaardt ◽  
Marelize Botes ◽  
Christoff Truter
Keyword(s):  
Phytoplankton Community ◽  
Temporal Dynamics ◽  
Phytoplankton Assemblages ◽  
Water Abstraction ◽  
The Public ◽  
Toxic Phytoplankton ◽  
Cyanobacteria Blooms ◽  
Toxic Cyanobacteria ◽  
Dry Seasons ◽  
Depth Ranges

Toxic phytoplankton in the aquatic ecosystems are dynamic, affecting water quality. It remains unclear as to how possible toxic phytoplankton assemblages vary vertically and temporally in Swakoppoort and Von Bach dams, located in a dry subtropical desert region in central Namibia. The following variables were analyzed: pH, Secchi depths, turbidity, water temperature, total phosphorus, orthophosphate, chlorophyll-a, phytoplankton cells, and water depths. Cyanobacteria dominated the phytoplankton community in the autumn, winter and spring (dry) and summer (wet) seasons, at all the depth ranges in both dams. Microcystis dominated the vertical and temporal dynamics, followed by Dolichospermum. In the dry seasons, higher cyanobacteria cell numbers were observed in comparison to the rainy season in both dams. Spring blooms of cyanobacteria were evident in the Von Bach Dam while autumn and spring cyanobacteria blooms were observed in the Swakoppoort Dam. In the Swakoppoort Dam, the preferable depth ranges for toxic cyanobacteria species were at 5 to 10 m while in the Von Bach Dam at 0 to 5 m range. The findings of the current study indicate that the traditional selective withdrawal of water in the two dams should be performed with vertical and temporal dynamics of possible toxic cyanobacteria accounted for to aid the abstraction of water with the lowest possible toxic phytoplankton numbers, which could lower the public health risk.

scholarly journals Phytoplankton temporal dynamics in the coastal waters of the north-eastern Adriatic Sea (Mediterranean Sea) from 2010 to 2017

2019 ◽  
Vol 34 ◽  
pp. 343-372 ◽  
Author(s):  
Federica Cerino ◽  
Daniela Fornasaro ◽  
Martina Kralj ◽  
Michele Giani ◽  
Marina Cabrini
Keyword(s):  
Mediterranean Sea ◽  
Seasonal Cycle ◽  
Phytoplankton Community ◽  
Spring Bloom ◽  
Temporal Dynamics ◽  
Late Winter ◽  
Research Station ◽  
Phytoplankton Assemblages ◽  
The North ◽  
Long Term Ecological Research

Phytoplankton community structure was analysed from 2010 to 2017 at C1-LTER, the coastal Long-Term Ecological Research station located in the Gulf of Trieste, which is the northernmost part of the Mediterranean Sea. Phytoplankton abundance and relevant oceanographic parameters were measured monthly in order to describe the seasonal cycle and interannual variability of the main phytoplankton taxa (diatoms, dinoflagellates, coccolithophores and flagellates) and to analyse their relationship with environmental conditions. Overall, phytoplankton abundances showed a marked seasonal cycle characterised by a bloom in spring, with the peak in May. During the summer, phytoplankton abundances gradually decreased until September, then slightly increased again in October and reached their minima in winter. In general, the phytoplankton community was dominated by flagellates (generally <10 µm) and diatoms co-occurring in the spring bloom. In this period, diatoms were also represented by nano-sized species, gradually replaced by larger species in summer and autumn. Phytoplankton assemblages differed significantly between seasons (Pseudo-F = 9.59; p < 0.01) and temperature and salinity were the best predictor variables explaining the distribution of the multivariate data cloud. At the interannual scale, a strong decrease of the late-winter bloom was observed in recent years with the spring bloom being the main phytoplankton increase of the year.

scholarly journals Permanent occurrence of Raphidiopsis raciborskii and cyanotoxins in a subtropical reservoir polluted by domestic effluents (Itupararanga reservoir, São Paulo, Brazil)

2021 ◽  
Author(s):  
Leila Dos Santos Machado ◽  
Fabiane Dörr ◽  
Felipe Augusto Dörr ◽  
Daniele Frascareli ◽  
Darllene S. Melo ◽  
...  
Keyword(s):  
Thermal Stratification ◽  
Phosphorus Limitation ◽  
Climatic Variations ◽  
Cyanobacteria Blooms ◽  
Toxic Cyanobacteria ◽  
Sampling Locations ◽  
Average Biomass ◽  
Dry Seasons ◽  
Domestic Effluents ◽  
Frequent Problem

Abstract Toxic cyanobacteria blooms are a frequent problem in subtropical reservoirs and freshwater systems. The purpose of this study was to investigate the occurrence of potentially toxic cyanobacteria and the environmental conditions associated with the presence of cyanotoxins in a Brazilian subtropical reservoir. Five collections were carried out at seven sampling locations in the reservoir, during the rainy and dry seasons, between the years 2016 and 2017. There was permanent occurrence of Raphidiopsis raciborskii (Woloszynska) Aguilera, Berrendero Gómez, Kastovsky, Echenique & Salerno, ranging between dominant and abundant, with an average biomass of 38.8 ± 29.9 mg L− 1. Also abundant were D. solitarium, D. planctonicum, P. isothrix, and A. gracile. Saxitoxin (STX) was detected in all the collected samples (0.11 ± 0.05 µg L− 1). Microcystin (MC) was also detected, but at lower concentrations (0.01 ± 0.0 µg L− 1). Low availability of NO3− and phosphorus limitation had significant effects on the R. raciborskii biomass and the levels of STX and MC. It was observed that R. raciborskii was sensitive to thermal stratification, at the same time that STX levels were higher. This suggested that STX was produced under conditions that restricted the growth of R. raciborskii. These are important findings, because they add information about the permanent occurrence of STX and R. raciborskii in an aquatic ecosystem limited by phosphorus, vulnerable to climatic variations, and polluted by domestic effluents.

scholarly journals Identification of Bacillus Anthracis, Brucella Spp., and Coxiella Burnetii DNA Signatures From Bushmeat

2021 ◽  
Author(s):  
Robab Katani ◽  
Megan Schilling ◽  
Beatus Lyimo ◽  
Ernest Eblate ◽  
Andimile Martin ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Coxiella Burnetii ◽  
Wildlife Diseases ◽  
Middle Income ◽  
The Public ◽  
Middle Income Countries ◽  
Close Proximity ◽  
Disease Risks ◽  
Potential Risks ◽  
Dry Seasons

Abstract Meat from wildlife species (bushmeat) represents a major source of dietary protein in low- and middle-income countries where humans and wildlife live in close proximity. Despite the occurrence of zoonotic pathogens in wildlife, their prevalence in bushmeat remains unknown. To assess the risk of exposure to major pathogens in bushmeat, a total of 3,784 samples were collected from three major regions in Tanzania during both rainy and dry seasons, both fresh and processed and screened by real-time PCR for the presence of DNA signatures of Bacillus anthracis, Brucella spp and Coxiella burnetii (Coxiella). The analysis identified DNA signatures of B. anthracis (0.48%), Brucella (0.9%), and Coxiella (0.66%) in a total of 77 samples. Highest prevalence rates of B. anthracis, Brucella, and Coxiella were observed in wildebeest, dik-dik, and impala, respectively. Fresh samples, those collected during the rainy season, and samples from Selous or the Serengeti had a greater relative risk of being positive. Microbiome characterization identified Firmicutes and Proteobacteria as the most abundant phyla. The results highlight and define potential risks of exposure to endemic wildlife diseases from bushmeat and the need for future investigations to address the public health and emerging infectious disease risks associated with bushmeat harvesting, trade, and consumption.

scholarly journals Temporal distribution of fruit-feeding butterflies (Lepidoptera, Nymphalidae) in the eastern extreme of the Amazon region

2020 ◽  
Vol 50 (1) ◽  
pp. 12-23
Author(s):  
Elias da Costa ARAUJO ◽  
Lucas Pereira MARTINS ◽  
Marcelo DUARTE ◽  
Gisele Garcia AZEVEDO
Keyword(s):  
Temporal Dynamics ◽  
Abiotic Factors ◽  
Temporal Structure ◽  
Temporal Distribution ◽  
Amazon Region ◽  
Influential Factors ◽  
Northeastern Brazil ◽  
Amazon Forest ◽  
Dry Seasons ◽  
Species Richness And Abundance

ABSTRACT Rainfall is one of the most influential factors driving insect seasonality in the Amazon region. However, few studies have analyzed the temporal dynamics of fruit-feeding butterflies in the Brazilian Amazon, specially in its eastern portion. Here, we evaluated the diversity patterns and temporal distribution of fruit-feeding butterflies in a remnant of eastern Amazon forest in the Baixada Maranhense, northeastern Brazil. Specifically, we tested whether fruit-feeding butterflies are temporally structured and whether rainfall influences species richness and abundance. Butterflies were collected with baited traps in both the rainy and dry seasons for two consecutive years. In total, we captured 493 butterflies belonging to 28 species, 15 genera and eight tribes. Three species comprised about half of the overall abundance, and Satyrinae was the most representative subfamily. The fruit-feeding butterfly assemblage showed a strong temporal structure during the second year of sampling, but not during the first year. Species composition and richness did not differ between rainy and dry seasons, and neither abundance nor richness was influenced by rainfall. Our results indicate that seasonality is not a strong environmental filter in this region, and that other biotic and abiotic factors are probably driving the community structure. The predominance of palms in the Baixada Maranhense, which are used as host plants by larvae of several lepidopteran species (specially satyrines) and are available year-round, might have contributed to the observed patterns of temporal diversity.

Spatial variability and temporal dynamics of cyanobacteria blooms and water quality parameters in Missisquoi Bay (Lake Champlain)

2019 ◽  
Vol 19 (5) ◽  
pp. 1500-1506 ◽  
Author(s):  
I. Melendez-Pastor ◽  
E. M. Isenstein ◽  
J. Navarro-Pedreño ◽  
M-H. Park
Keyword(s):  
Total Phosphorus ◽  
Temporal Dynamics ◽  
Secchi Depth ◽  
Spatial Association ◽  
Phosphorus Concentration ◽  
Lake Champlain ◽  
Total Phosphorus Concentration ◽  
Cyanobacteria Bloom ◽  
Explanatory Variables ◽  
Cyanobacteria Blooms

Abstract Cyanobacteria bloom events have been associated with eutrophication processes, along with hydrologic and climate factors. Missisquoi Bay is a portion of Lake Champlain (USA–Canada) that is highly eutrophic and prone to cyanobacteria blooms and cyanotoxins. This study assessed the spatial–temporal influence of nutrients, turbidity and temperature in cyanobacteria distributions during a bloom event in the summer of 2006. Correlations, generalized linear models (GLMs), geostatistics and local indications of spatial association (LISA) autocorrelation analysis tested the influence of nutrient and non-nutrient explanatory variables in cyanobacteria biovolume. Total phosphorus exhibited a high direct correlation with cyanobacteria biovolume. The best performing GLMs included total phosphorus, total nitrogen, Secchi depth (as turbidity) and temperature as explanatory variables of cyanobacteria biovolume. Variogram analysis of those variables resulted in a better understanding of the underlying spatial variation process of the cyanobacteria bloom event. The LISA test revealed a moderate but stable autocorrelation between cyanobacteria biovolume and total phosphorus from 180 to 1,000 m of weight distance, suggesting the possibility of up-scaling the current results to coarse-resolution satellite imagery for more frequent monitoring of bloom events. The LISA test also revealed the spatial–temporal dynamic (movement of cyanobacteria scums) of high cyanobacteria blooms with high total phosphorus concentration.

scholarly journals Analysis of the phytoplankton community emphasizing cyanobacteria in four cascade reservoirs system of the Iguazu River, Paraná, Brazil

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Clarisse Teixeira Adloff ◽  
Carla Cristina Bem ◽  
Gabriela Reichert ◽  
Júlio César Rodrigues de Azevedo
Keyword(s):  
Phytoplankton Community ◽  
Abiotic Factors ◽  
Longitudinal Axis ◽  
Cascade Reservoirs ◽  
Biological Communities ◽  
Cyanobacteria Blooms ◽  
Ecological Changes ◽  
Great Relevance ◽  
Physical And Chemical ◽  
Intense Process

ABSTRACT Knowing the ecological changes in a reservoir is of great relevance to study environmental impacts and assess water quality. Among these studies, the knowledge about the structure of the phytoplankton community is essential, once they represent a fundamental component of aquatic ecosystems, responding immediately to physical and chemical alterations in water. The objective of this work was to analyze the phytoplankton community and the influence of abiotic factors, along the longitudinal axis in four cascade reservoirs system of the Iguazu River, Paraná, Brazil, emphasizing the importance of cyanobacteria. Foz do Areia, Salto Segredo, Salto Santiago and Salto Caxias reservoirs were the objects of this study. The phytoplankton counting was made tubular sedimentation chamber using an inverted microscope. The results showed that the four reservoirs are under eutrophication processes, presenting intense cyanobacteria blooms, dominated mainly by Microcystis aeruginosa and Sphaerocavum brasiliense. There was no evident longitudinal gradient related to phytoplankton, as expected for reservoirs in a cascade system. The dominance of cyanobacteria shows that the Iguazu River is undergoing an intense process of environmental degradation, threatening the integrity of biological communities and causing serious damage to the ecosystem as a whole.

scholarly journals Spatial autocorrelation of phytoplankton biomass is weak in the rivers of Lake Taihu Basin, China

2019 ◽  
pp. 35
Author(s):  
Zhaoshi Wu ◽  
Ming Kong ◽  
Yamin Fan ◽  
Xiaolong Wang ◽  
Kuanyi Li
Keyword(s):  
Community Structure ◽  
Spatial Autocorrelation ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Lake Taihu ◽  
Total Biomass ◽  
Phytoplankton Community Structure ◽  
River Systems ◽  
Toxic Cyanobacteria ◽  
The Mean

We investigated the characteristic of phytoplankton community structure across the entire Lake Taihu Basin (LTB), one of the most developed areas in China. A morphologically based functional group (MBFG) proposed by Kruk et al. (2010), especially potential toxic cyanobacteria (group III and VII), was also illustrated. Samples were collected at 96 sites along main rivers throughout the four seasons from September 2014 to January 2016. Significant differences in the phytoplankton community structure were observed at spatial (particularly between Huangpu/Tiaoxi and the other 4 river systems) and seasonal scales. On a spatial basis, high variability was observed in the mean phytoplankton biomass, with a relatively high value of 3.13 mg L−1 in Yanjiang system and a relatively low value in Huangpu (1.23 mg L−1) and Tiaoxi (1.44 mg L−1) systems. The mean biomass of potential toxic cyanobacteria accounted for 18.28% of the mean total biomass spatially, which was more abundant in Nanhe and Yanjiang systems. Spatial autocorrelation was weak for the total biomass and its four main components (bacillariophyta, chlorophyta, euglenophyta, and cyanobacteria) at whole basin scale regardless of season. Regarding the river system, significant autocorrelation was scarcely observed in all the river systems except Huangpu, especially in the inflows. The characteristic in terms of hydrological and environmental conditions may determine the community structure of the 6 river systems. Our study highlighted the importance of monitoring based on a large spatial scale, and more attention should be paid to potential toxic cyanobacteria for water quality management purposes.

Sign in / Sign up

Export Citation Format

Share Document