Water Quality of Selected Fishing Beaches of Lake Victoria Kenyan Gulf

Lake Victoria the second largest fresh water body in the world located in East Africa is a shared resource between Kenya, Tanzania and Uganda and enjoys a wide range of streams and rivers from as far as Burundi and Rwanda. The lake has environmentally undergone physical, chemical and biological changes in the last four decades, particularly rise in its trophic condition and decline in oxygen level, which affects the water quality and fish population dynamics. This study therefore set out to determine the quality of water in selected fishing beaches of Lake Victoria, Kenya with a view to report the possible pollution levels. pH was highest at Nyamasari and Kotieno (9.3 ± 0.1) and lowest at Nyachebe and Kichinjio (7.08 ± 0.1) whereas temperature was highest at Nyamasari (29.5°C ± 0.0°C) and lowest at Kichinjio (23.4°C ± 0.2°C). DO was highest at Kotieno (10.3 ± 0.2 mgL) and lowest at Seka (2.4 ± 0.1 mgL). Turbidity was highest at Uyoga (125.5 ± 0.90 NTU) and lowest at Osieko (2.7 ± 0.1 NTU). Ammoniacal nitrogen was highest at Dunga (1278.3 ± 0.8 μ∙gl-1) and lowest at Nyamasari (12.4 ± 0.8), all a factor of human activities, lake substratum and effluents from rivers and surface runoff. All parameters assessed showed significant differences across sampling sites and depth except pH which did not vary significantly with distance from lakeshore. Further, all parameters did not show a clear pattern with respect to distance from the lakeshore possibly due to adequate mixing in the gulf. There is a need for further water quality monitoring by seasons to inform policy decisions towards sustainable lake exploitation.

Lake Level Changes Recorded by Tree Rings of Lakeshore Shrubs： A Case Study at the Lake West-Juyan, Inner Mongolia, China

Variation in water resources is a main factor influencing ecohydrological processes and sustainable development in arid regions. Lake level changes are a useful indicator of the variability in water resources. However, observational records of changes in lake levels are usually too short to give an understanding of the long-term variability. In the present study, we investigated the tree rings of shrubs growing on the lakeshore of Lake West-Juyan, the terminus of the Heihe River in western China, and found that Lake West-Juyan had undergone degradation three times over the past 200 years. The lake level decreased from 904.3 to 896.8 m above sea level （a.s.1.） during the period 1800-1900, to 892.0 m a.s.1, from around 1900 to the late 1950s, and the lake dried out in 1963. The trend for changes in lake levels, which was represented by the composite chronology of three beach bars, showed that the phases of increasing lake levels over the past 150 years were during the periods 1852-1871, 1932-1952, 1973-1982, and 1995-1999. Comparison with the history of regional economic development showed that human activity has played an important role in regulating the water resources of the lower reaches of the Heihe watershed over the past 200 years.

Soil fauna diversity at different stages of reed restoration in a lakeshore wetland at Lake Taihu,China

Introduction:Wetland soil fauna support material cycling and restoration processes in wetland ecosystems.In our study,we observed variations in wetland soil fauna on the shores of Lake Taihu,China.We examined the relationships between fauna and major environmental factors,and looked at the short-and long-term changes in reed wetlands under restoration and in the natural reed lakeshore.Outcomes:We identified 93 groups of soil fauna in different wetlands and found significant differences in the lakeshore wetlands’soil fauna assemblages,depending on the length of the restoration period.By analyzing the soil fauna community evenness,dominance,number of taxa,and diversity,we found minimal seasonal variation in the soil fauna community diversity and abundance.The abundance of soil fauna in the sites under restoration decreased with depth below the soil surface.The reed restoration was obvious in the succession of the soil fauna groups in the long-term site.Although the restoration had an overall positive long-term effect on the soil fauna communities,there were no obvious short-term changes in the number of individuals.Conclusion:The study explored various potential measures to restore soil fauna in the Lake Taihu wetland and developed a theoretical basis for restoring the lakeshore wetland ecosystem.

Genetic composition,genetic diversity and small-scale environmental variation matter for the experimental reintroduction of a rare plant

Aims Reintroduction has become an important tool for the management of endangered plant species.We tested the little-explored effects of small-scale environmental variation,genotypic composition(i.e.identity of genotypes)and genotypic diversity on the population survival of the regionally rare clonal plant Ranunculus reptans.For this species of periodically inundated lakeshores,genetic differentiation had been reported between populations and between short-flooded and long-flooded microsites within populations.Methods We established 306 experimental test populations at a previously unoccupied lakeshore,comprising either monocultures of 32 genotypes,mixtures of genotypes within populations or mixtures of genotypes between populations.In 2000,three years after planting out at the experimental site,a long-lasting flood caused the death of half of the experimental populations.In 2003,an extreme drought resulted in the lowest summer water levels ever measured.Important Findings Despite these climatic extremes,27%of the established populations survived in December 2003.The success of experimental populations largely differed between microsites.Moreover,the success of genotype monocultures depended on genotype and source population.Genetic differentiation between microsites played a minor role for the success of reintroduction.After the flood,populations planted with genotypes from different source populations increased in abundance,whereas populations with genotypes from single source populations and genotype monocultures decreased.In 2014,several small patches of Ranunculus clones were still present,but plants were strongly intermingled,which precluded their assignment to the original treatments.We conclude that sources for reintroductions need to be selected carefully.Moreover,mixtures of plants from different populations appear to be the best choice for successful reintroduction,at least in unpredictably varying environments.