scholarly journals Unusual massive phytoplankton bloom in the oligotrophic Lake Tanganyika

2021 ◽  
Vol 154 (3) ◽  
pp. 351-361
Author(s):  
Christine Cocquyt ◽  
Pierre-Denis Plisnier ◽  
N’sibula Mulimbwa ◽  
Muderhwa Nshombo
Keyword(s):  
Littoral Zone ◽  
Lake Tanganyika ◽  
Phytoplankton Bloom ◽  
Meteorological Data ◽  
Algal Species ◽  
Rare Event ◽  
Oligotrophic Lake ◽  
The North ◽  
High Solar Radiation ◽  
Relative Abundances

Background and aims – Massive algae growth resulting in a phytoplankton bloom is a very rare event in the meromictic and oligotrophic Lake Tanganyika. Such a bloom was observed in the north of the lake in September 2018. Phytoplankton species composition during this bloom is compared to a documented bloom in 1955, and to the composition in September 2011–2013. Meteorological observations suggest hydrodynamics could explain the occurrence of the 2018 bloom.Material and methods – Phytoplankton net samples were taken in the pelagic and littoral zone near Uvira during five consecutive days of the bloom in 2018. For the period 2011–2013, quantitative phytoplankton samples were obtained during a weekly sampling at the same sites. Samples were analysed with an inverted microscope and relative abundances of the algal species were compared. Key results – Dolichospermum flosaquae (Cyanobacteria) initially dominated the bloom followed by high relative abundance of Limnococcus limneticus (Cyanobacteria) on the third sampling day in September 2018. In the pelagic zone an increase of Nitzschia asterionelloides (Bacillariophyta), and Dictyosphaerium and Lobocystis (Chlorophyta) was observed while in the littoral zone increasing abundances of dinophytes were noted. Dolichospermum flosaquae was also responsible for the bloom reported in 1955, but was only sporadically observed in the 2011–2013 samples. Although Limnococcus limneticus was present in 2011–2013, it never reached relative abundances as high as during the 2018 bloom. Meteorological data indicate that 2018 experienced different conditions compared to previous years: strong south-east winds from May to September with a more eastern direction of the wind, and a well-marked drop in atmospheric pressure between August and September.Conclusion – After a very windy season, the combination of strong hydrodynamics, calmer lake conditions, and high solar radiation and air temperature in September 2018 was favourable for a massive Cyanobacteria bloom in the north of Lake Tanganyika.

Biochemical study of attached macroalgae from the Madeira Archipelago and beach-cast macroalgae from the Canary Islands: multivariate analysis to determine bioresource potential

2020 ◽  
Vol 63 (3) ◽  
pp. 283-298
Author(s):  
Nuno Nunes ◽  
Sofia Valente ◽  
Sónia Ferraz ◽  
Maria Carmo Barreto ◽  
Miguel A.A. Pinheiro de Carvalho
Keyword(s):  
Biochemical Study ◽  
Algal Species ◽  
Biochemical Properties ◽  
Total Phenolic ◽  
Total Carotenoids ◽  
The North ◽  
Madeira Archipelago ◽  
Total Carbohydrates ◽  
Beach Cast

AbstractFifteen attached macroalgae from the Madeira Archipelago, comprising three green, three red and nine brown algal species, as well as two beach-cast macroalgal samples, collected along the north shore of Gran Canaria, were assessed for their biochemical properties. The analysis included the determination of total minerals, total carbohydrates, protein, lipids, chlorophyll a, total carotenoids, total phenolic content, fucoxanthin and phycobilins (allophycocyanin, phycocyanin and phycoerythrin). The results showed a high variability of biochemical composition, allowing for the targetting of specific bioresources for particular purposes, including functional foods. This work provides the foundation for a biorefinery strategy implementation plan, for which specific macroalgae may be targeted for valuable and beneficial compounds.

Spatial distribution and temporal variability of open fire in China

2017 ◽  
Vol 26 (2) ◽  
pp. 122 ◽  
Author(s):  
Kunpeng Yi ◽  
Yulong Bao ◽  
Jiquan Zhang
Keyword(s):  
Meteorological Data ◽  
Fire Season ◽  
Spatial And Temporal Patterns ◽  
Burnt Area ◽  
The North ◽  
Temperature And Precipitation ◽  
North Eastern ◽  
Vegetation Fires ◽  
Precipitation Variation ◽  
Two Peaks

This study presents the spatial and temporal patterns of vegetation fires in China based on a combination of national fire records (1950–2010) and satellite fire data (2001–12). This analysis presents the first attempt to understand existing patterns of open fires and their consequences for the whole of China. We analysed inter- and intra-annual fire trends and variations in nine subregions of China as well as associated monthly meteorological data from 130 stations within a 50-year period. During the period 2001–12, an average area of 3.2 × 106 ha was consumed by fire per year in China. The Chinese fire season has two peaks occurring in the spring and autumn. The profiles of the burnt area for each subregion exhibit distinct seasonality. The majority of the vegetation fires occurred in the north-eastern and south-western provinces. We analysed quantitative relationships between climate (temperature and precipitation) and burnt area. The results indicate a synchronous relationship between precipitation variation and burnt area. The data in this paper reveal how climate and human activities interact to create China’s distinctive pyrogeography.

scholarly journals Assessment of diversity and physico-chemical parameters of cyanobacteria, diatoms and other algal species in the paddy fields of Belagavi district, Karnataka

2020 ◽  
Vol 7 (3) ◽  
pp. 378-382
Author(s):  
Santoshkumar Jayagoudar ◽  
Pradeep Bhat ◽  
Ankita Magdum ◽  
Duradundi Sakreppagol ◽  
Laxmi Murgod ◽  
...  
Keyword(s):  
Algal Species ◽  
Soil Samples ◽  
Chemical Parameters ◽  
Range Estimation ◽  
The North ◽  
Physico Chemical ◽  
Water And Soil Samples ◽  
Study Sites ◽  
Good Range

Algae are the diverse group of organisms in the soil and aquatic environment. The role of them in soil fertility enhancement has been extensively studied worldwide. Belagavi is a tropical agricultural belt in the North Karnataka region with highly fertile soil. Water and soil samples were collected randomly from the paddy field of 15–20 well-distributed spots in 4 selected locations viz Kusumali, Jamboti, Kinaye and Piranwadi. The identification revealed the presence of 94 species and 71 genera in the investigated sites. Among all, 62 species belonged to Bacillariophyceae, 14 species to Chlorophyceae, 10 species to Cyanophyceae, 3 to Xanthophyceae, followed by Trebouxiophyceae and Zygnematophyceae (2 species each) and one species of Ulvophyceae. The maximum number of 62 species was recorded from Kusamali, followed by 49 species in Kinaye, 44 in Jamboti and 35 in Piranwadi. The month of February had the highest number of species (61), decreased to 45 in March, 42 in April and 37 in May. Among the physicochemical parameters analysed for the soil samples, it was found that the pH of the soil is slightly acidic in all the study sites ranged between 5.03–5.85. Further, the electrical conductivity (EC) varied from 0.27–0.345 dS/m, found to be in a good range. Estimation of available micro and macronutrients of soil were measured, and it was found to be at low to moderate levels. The present study indicates the extensive distribution of different classes of algae in the rice fields of four study locations in Belagavi.

scholarly journals Destruction of chlorophyll in emerging seedlings of spring barley associated with environmental stresses

2010 ◽  
Vol 41 (No. 4) ◽  
pp. 165-170 ◽  
Author(s):  
V. Kůdela ◽  
B. Voženílková ◽  
R. Krejzarová ◽  
V. Krejzar ◽  
M. Janouch
Keyword(s):  
Solar Radiation ◽  
Meteorological Data ◽  
Spring Barley ◽  
Environmental Stresses ◽  
Plant Tissues ◽  
Chronological Order ◽  
Uv Index ◽  
High Solar Radiation

An unusual disorder occurred on spring barley seedlings in southern and central Bohemia in April 2005. Affected seedlings showed conspicuous bleached or straw-coloured areas on tips of the first leaves. There were very sharp, distinct, horizontal boundaries between the green basal and discoloured tip parts of the leaves. It was remarkable that these boundaries were at the same position on all affected first leaves of seedlings from the same field. Affected seedlings were randomly distributed in the fields, and their incidence ranged from about 20 to 70% according to location. Based on meteorological data it can be concluded that the colour abnormality in emerging seedlings was associated with specific environmental stresses, being effective in certain chronological order on sensitive plant tissues during the period from 6 to 8 days after seeding. These stresses include frosty mornings followed by clear days with high solar radiation with a high UV Index.

Spatial and temporal variability of the phytoplankton community structure in the North Water Polynya, investigated using pigment biomarkers

2004 ◽  
Vol 61 (11) ◽  
pp. 2038-2052 ◽  
Author(s):  
Francesca Vidussi ◽  
Suzanne Roy ◽  
Connie Lovejoy ◽  
Marie Gammelgaard ◽  
Helge Abildhauge Thomsen ◽  
...  
Keyword(s):  
Community Structure ◽  
Phytoplankton Community ◽  
Phytoplankton Bloom ◽  
Circulation Pattern ◽  
Spatial And Temporal Variability ◽  
Phytoplankton Community Structure ◽  
Southeastern Part ◽  
Chl A ◽  
The North ◽  
North Water

Phytoplankton taxonomic pigments were measured by high-performance liquid chromatography (HPLC) during a 3-month survey (April–June 1998) in the North Water (NOW) Polynya (Canadian Arctic) to investigate changes in phytoplankton biomass and composition and the physical–chemical factors that influence these changes. A phytoplankton bloom with high chlorophyll a (Chl a) concentrations (up to 17.45 mg·m–3 at 15 m) occurred in mid-May along the Greenland coast in the southeastern part of the NOW Polynya. The initiation of the phytoplankton bloom was linked to shallow mixed-layer depths. The contribution of the different phytoplankton groups to Chl a inferred using a factorization program (CHEMTAX) indicated that the bloom was diatom-dominated (maximum 94% diatoms). The phytoplankton community structure was influenced by the water mass characteristics and the surface circulation pattern. Autotrophic flagellates dominated in April and May along the Canadian coast, where cold Arctic waters with relatively deep mixed layers were found. In contrast, diatoms dominated in May along the Greenland coast in warmer water masses of Atlantic origin and during June in the whole polynya, except in the southernmost part.

scholarly journals Heavy Rainfall and Landslide Event in January 1831 at the Pedregoso Mountains (Cabeza Del Buey, SW Spain)

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 544 ◽  
Author(s):  
Juan Pedro García-Garrido ◽  
María Cruz Gallego ◽  
Teodoro Palacios ◽  
Ricardo M. Trigo ◽  
José Manuel Vaquero
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Meteorological Data ◽  
Triggering Mechanism ◽  
Sw Spain ◽  
The North ◽  
Nao Index ◽  
Landslide Event ◽  
High Precipitation ◽  
The North Atlantic Oscillation

In this work, a landslide event that took place on January 1831 at the Pedregoso Mountains, Cabeza del Buey, SW Spain, is described. This landslide had not been documented to date and was only described in the local press. This event involved an estimated amount of dislodged material in the order of 104 m3. The amount of meteorological data is very scarce as the event occurred before the setting up of the national meteorological service in Spain. However, data from the relatively near location of SW Iberia suggest that the landslide was preceded by a prolonged period of unusually high precipitation totals and that this intense wet period is compatible with the large-scale atmospheric configuration in the winter of 1829–1830. In fact, the North Atlantic Oscillation (NAO) index for that winter achieved one of the most negative values observed in the bicentennial period spanning 1821 to 2019. This multidisciplinary work represents the first attempt to report and describe the main triggering mechanism for an historical landslide in the Extremadura region that is similar to other great historical landslides which have already been documented for other locations in Spain.

scholarly journals Anomalous wind triggered the largest phytoplankton bloom in the oligotrophic North Pacific Subtropical Gyre

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chun Hoe Chow ◽  
Wee Cheah ◽  
Jen-Hua Tai ◽  
Sin-Fu Liu
Keyword(s):  
North Pacific ◽  
Phytoplankton Bloom ◽  
Subtropical Gyre ◽  
Velocity Shear ◽  
North Pacific Subtropical Gyre ◽  
The North ◽  
Large Eddy ◽  
Anomalous Wind ◽  
Anticyclonic Eddies

Abstract In summer 2010, a massive bloom appeared in the middle (16–25°N, 160–200°E) of the North Pacific Subtropical Gyre (NPSG) creating a spectacular oasis in the middle of the largest oceanic desert on Earth. Peaked in June 2010 covering over two million km2 in space, this phytoplankton bloom is the largest ever recorded by ocean color satellites in the NPSG over the period from 1997 to 2013. The initiation and mechanisms sustaining the massive bloom were due to atmospheric and oceanic anomalies. Over the north (25–30°N) of the bloom, strong anticyclonic winds warmed sea surface temperature (SST) via Ekman convergence. Subsequently, anomalous westward ocean currents were generated by SST meridional gradients between 19°N and 25°N, producing strong velocity shear that caused large number of mesoscale (100-km in order) cyclonic eddies in the bloom region. The ratio of cyclonic to anticyclonic eddies of 2.7 in summer 2010 is the highest over the 16-year study period. As a result of the large eddy-number differences, eddy-eddy interactions were strong and induced submesoscale (smaller than 100 km) vertical pumping as observed in the in-situ ocean profiles. The signature of vertical pumping was also presented in the in-situ measurements of chlorophyll and nutrients, which show higher concentrations in 2010 than other years.

scholarly journals Monitoring Phenology in the Temperate Grasslands of China from 1982 to 2015 and Its Relation to Net Primary Productivity

2019 ◽  
Vol 12 (1) ◽  
pp. 12
Author(s):  
Chaobin Zhang ◽  
Ying Zhang ◽  
Zhaoqi Wang ◽  
Jianlong Li ◽  
Inakwu Odeh
Keyword(s):  
Primary Productivity ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Net Primary Productivity ◽  
Meteorological Data ◽  
Temperate Grasslands ◽  
The North ◽  
Phenological Changes ◽  
Grass Growth ◽  
Global Inventory

Both vegetation phenology and net primary productivity (NPP) are crucial topics under the background of global change, but the relationships between them are far from clear. In this study, we quantified the spatial-temporal vegetation start (SOS), end (EOS), and length (LOS) of the growing season and NPP for the temperate grasslands of China based on a 34-year time-series (1982–2015) normalized difference vegetation index (NDVI) derived from global inventory modeling and mapping studies (GIMMS) and meteorological data. Then, we demonstrated the relationships between NPP and phenology dynamics. The results showed that more than half of the grasslands experienced significant changes in their phenology and NPP. The rates of their changes exhibited spatial heterogeneity, but their phenological changes could be roughly divided into three different clustered trend regions, while NPP presented a polarized pattern that increased in the south and decreased in the north. Different trend zones’ analyses revealed that phenology trends accelerated after 1997, which was a turning point. Prolonged LOS did not necessarily increase the current year’s NPP. SOS correlated with the NPP most closely during the same year compared to EOS and LOS. Delayed SOS contributed to increasing the summer NPP, and vice versa. Thus, SOS could be a predictor for current year grass growth. In view of this result, we suggest that future studies should further explore the mechanisms of SOS and plant growth.

Impact of climatic conditions on fumonisins in maize grown in Serbia

2019 ◽  
Vol 12 (2) ◽  
pp. 183-190 ◽  
Author(s):  
B. Udovicki ◽  
I. Djekic ◽  
S. Stankovic ◽  
A. Obradovic ◽  
A. Rajkovic
Keyword(s):  
Solar Radiation ◽  
Critical Parameter ◽  
Meteorological Data ◽  
Climatic Conditions ◽  
Chi Square ◽  
High Solar Radiation ◽  
Significant Difference ◽  
Chi Square Test ◽  
Low Humidity ◽  
Low Precipitation

The influence of climatic conditions on the levels of fumonisins in maize grown in Serbia was studied over eight years (2008 to 2015), investigating the possible relationship between the levels of fumonisins contamination in maize in relation to registered weather/climatic conditions. Presence of these mycotoxins in maize after harvest was evaluated based on climatic conditions within two periods: 10 days before and 10 days after 50% silking. Categories of fumonisins levels were transformed into classes. Chi-square test for association was used in analysing relationships between results of fumonisins levels and calendar years. Mann-Whitney U-test was used to compare differences between meteorological data of two subsets in years with high and low fumonisins level. There was a statistically significant association between the fumonisins levels and calendar years χ2=247.954; (P<0.05). This study identified low precipitation and low humidity combined with high solar radiation as a critical parameter combination for elevated levels of fumonisins. The statistically significant difference in relation to some of the examined parameters suggests that maize in Serbian agro-climatic conditions is more susceptible to fungal colonisation, and subsequent fumonisin production in the period of 10 days before 50% silking.

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