Strong spatial differentiation of N and P deficiency, primary productivity and community composition between Nyanza Gulf and Lake Victoria (Kenya, East Africa) and the implications for nutrient management

2013 ◽  
pp. n/a-n/a ◽  
Author(s):  
P. Gikuma-Njuru ◽  
S. J. Guildford ◽  
R. E. Hecky ◽  
H. J. Kling
Keyword(s):  
East Africa ◽  
Community Composition ◽  
Primary Productivity ◽  
Nutrient Management ◽  
Lake Victoria ◽  
Spatial Differentiation ◽  
P Deficiency

scholarly journals Prolific Lightning and Thunderstorm Initiation over the Lake Victoria Basin in East Africa

2020 ◽  
Vol 148 (5) ◽  
pp. 1971-1985 ◽  
Author(s):  
Katrina S. Virts ◽  
Steven J. Goodman
Keyword(s):  
East Africa ◽  
Hot Spots ◽  
Seasonal Cycle ◽  
Lake Victoria ◽  
Intertropical Convergence Zone ◽  
Lake Victoria Basin ◽  
The Earth ◽  
Total Lightning ◽  
Average Cluster

Abstract The Lake Victoria basin of East Africa is home to over 30 million people, over 200 000 of whom are employed in fishing or transportation on the lake. Approximately 3000–5000 individuals are killed by thunderstorms yearly, primarily by outflow winds and resulting large waves. Prolific lightning activity and thunderstorm initiation in the basin are examined using continuous total lightning observations from the Earth Networks Global Lightning Network (ENGLN) for September 2014–August 2018. Seasonal shifts in the intertropical convergence zone produce semiannual lightning maxima over the lake. Diurnally, solar heating and lake and valley breezes produce daytime lightning maxima north and east of the lake, while at night the peak lightning density propagates southwestward across the lake. Cluster analysis reveals terrain-related thunderstorm initiation hot spots northeast of the lake; clusters also initiate over the lake and northern lowlands. The most prolific clusters initiate between 1100 and 1400 LT, about 1–2 h earlier than the average cluster. Most daytime thunderstorms dissipate without reaching Lake Victoria, and annually 85% of clusters producing over 1000 flashes over Lake Victoria initiate in situ. Initiation times of prolific Lake Victoria clusters exhibit a bimodal seasonal cycle: equinox-season thunderstorms initiate most frequently between 2200 and 0400 LT, while solstice-season thunderstorms initiate most frequently from 0500 to 0800 LT, more than 12 h after the afternoon convective peak over land. More extreme clusters are more likely to have formed over land and propagated over the lake, including 36 of the 100 most extreme Lake Victoria thunderstorms. These mesoscale clusters are most common during February–April and October–November.

scholarly journals Differential arthropod responses to warming are altering the structure of Arctic communities

2018 ◽  
Vol 5 (4) ◽  
pp. 171503 ◽  
Author(s):  
Amanda M. Koltz ◽  
Niels M. Schmidt ◽  
Toke T. Høye
Keyword(s):  
Community Composition ◽  
Primary Productivity ◽  
Species Interactions ◽  
Ecosystem Processes ◽  
The Arctic ◽  
Individual Species ◽  
Freeze Thaw ◽  
Compositional Changes ◽  
Arctic Communities

The Arctic is experiencing some of the fastest rates of warming on the planet. Although many studies have documented responses to such warming by individual species, the idiosyncratic nature of these findings has prevented us from extrapolating them to community-level predictions. Here, we leverage the availability of a long-term dataset from Zackenberg, Greenland (593 700 specimens collected between 1996 and 2014), to investigate how climate parameters influence the abundance of different arthropod groups and overall community composition. We find that variation in mean seasonal temperatures, winter duration and winter freeze–thaw events is correlated with taxon-specific and habitat-dependent changes in arthropod abundances. In addition, we find that arthropod communities have exhibited compositional changes consistent with the expected effects of recent shifts towards warmer active seasons and fewer freeze–thaw events in NE Greenland. Changes in community composition are up to five times more extreme in drier than wet habitats, with herbivores and parasitoids generally increasing in abundance, while the opposite is true for surface detritivores. These results suggest that species interactions and food web dynamics are changing in the Arctic, with potential implications for key ecosystem processes such as decomposition, nutrient cycling and primary productivity.

scholarly journals Organic wastes from bioenergy and ecological sanitation as a soil fertility improver: a field experiment in a tropical Andosol

SOIL ◽  
2016 ◽  
Vol 2 (2) ◽  
pp. 147-162 ◽  
Author(s):  
Ariane Krause ◽  
Thomas Nehls ◽  
Eckhard George ◽  
Martin Kaupenjohann
Keyword(s):  
Zea Mays ◽  
Crop Yield ◽  
Nutrient Management ◽  
Chemical Properties ◽  
Nutrient Status ◽  
Crop Productivity ◽  
Exchange Capacity ◽  
Biogas Slurry ◽  
Crop Species ◽  
P Deficiency

Abstract. Andosols require the regular application of phosphorus (P) to sustain crop productivity. On an Andosol in NW Tanzania, we studied the short-term effects of amending standard compost, biogas slurry and CaSa compost (containing biochar and sanitized human excreta) on (i) the soil's physico-chemical properties, on (ii) biomass growth and crop productivity, and on (iii) the plants' nutrient status. The practice-oriented experiment design included the intercropping of seven locally grown crop species planted on 9 m2 plots with five repetitions arranged as a Latin rectangle. Differences in plant growth (biomass production and crop yield, e.g., of Zea mays) and crop nutrition (total C, N, P, K, Ca, Mg, Zn, etc.) were related to pH, CEC (cation exchange capacity), total C and the availability of nutrients (N, P, K, etc.) and water (water retention characteristics, bulk density, etc.) in the soil. None of the amendments had any significant effect on soil water availability, so the observed variations in crop yield and plant nutrition are attributed to nutrient availability. Applying CaSa compost increased the soil pH from 5.3 to 5.9 and the level of available P from 0.5 to 4.4 mg per kg. Compared to the control, adding biogas slurry, standard compost and CaSa compost increased the aboveground biomass of Zea mays by, respectively, 140, 154 and 211 %. The grain yields of maize on soil treated with biogas slurry, standard compost and CaSa compost were, respectively, 2.63, 3.18 and 4.40 t ha−1, compared to only 1.10 t ha−1 on unamended plots. All treatments enhanced crop productivity and increased the uptake of nutrients into the maize grains. The CaSa compost was most effective in mitigating P deficiency and soil acidification. We conclude that all treatments are viable as a substitute for synthetic fertilizers. Nevertheless, further steps are required to integrate the tested soil amendments into farm-scale nutrient management and to balance the additions and removals of nutrients, so that the cycle can be closed.

scholarly journals Imagining ‘Atlanta’: The Cultural Politics and Poetics of Experimental Medicine in East Africa

2014 ◽  
Vol 20 (1) ◽  
Author(s):  
Denielle Elliott
Keyword(s):  
East Africa ◽  
State Of The Art ◽  
Lake Victoria ◽  
Field Research ◽  
Experimental Medicine ◽  
Research Station ◽  
Scientific Practices ◽  
Global Science ◽  
Rural Town ◽  
The Social

In East Africa there is a field research station that locals call ‘Atlanta.’ It sits on the outskirts of a rural town, near Lake Victoria, equipped with ‘state-of-the-art’ biotechnological and entomological equipment for monitoring and exploring malaria, HIV, tuberculosis, rotavirus, and other tropical diseases. Drawn from ethnographic fieldwork with clinical trials in East Africa, this paper considers the stories people tell about the landscapes and spaces of experimental medicine to explore the uneven movement of knowledge, scientific practices, and scientists in global medicine. I begin this analytical journey at ‘Atlanta’ to consider what local idioms about such places might tell us about the encounters and travels of science and scientists in East Africa. Last, I draw attention to the social and material effects of global science projects on the lives and landscapes of East Africa.

Late Palæolithic Finds in East Africa

1924 ◽  
Vol 4 (2) ◽  
pp. 177-178
Author(s):  
M. C. Burkitt
Keyword(s):  
South Africa ◽  
East Africa ◽  
Lake Victoria ◽  
Stone Age ◽  
Upper Palaeolithic ◽  
Cambridge University ◽  
Group 2 ◽  
University Museum ◽  
Cultural Movement ◽  
Late Palaeolithic

Whilst engaged in arranging the Stone Age collections of the Cambridge University Museum of Archæology and Ethnology a series of implements from Naivasha “turned up.” This locality lies a little to the East of lake Victoria Nyanza. The tools shew certain Upper Palæolithic characters and it is therefore important to note their existence. Some folk consider the continent of Africa to be a museum of cultures, others a cradle. In either case it is necessary to collect any information as to the possible lines of cultural movement. The paintings of the Spanish group 2 in rock shelters in Eastern Spain are in all probability quaternary in age and date from some moment in Upper Palæolithic times; but the Bushman art of South Africa bears such a remarkable resemblance to this Eastern Spanish group, both generally and in detail, that some connection between the artists who made them seems probable—perhaps both were derived from the same late Palæolithic stock, the Bushman being a survival to our own day.

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