نتایج جستجو برای: lake victoria
تعداد نتایج: 51390 فیلتر نتایج به سال:
Lake Victoria, East Africa, is the site of the world’s most productive freshwater fishery. Mercury in muscle tissue of the 2+ and 3+ year old Nile perch (Lates niloticus), presently the largest constituent of the fishery, was 90 to 250 ng /g wet weight. This is similar to the range of mercury in fish muscle reported for the commercial fish of the Laurentian Great Lakes (140 to 320 ng/g). The av...
The approximately 700 species of cichlids found in Lake Victoria in East Africa are thought to have evolved over a short period of time, and they represent one of the largest known examples of adaptive radiation. To understand the processes that are driving this spectacular radiation, we must determine the present genetic structure of these species and elucidate how this structure relates to th...
The flocks of cichlid fishes in the African Great Lakes are a fascinating system for studies of visual ecology. Separate radiations have produced a diverse flock of several hundred closely related cichlid species in each of the three large lakes (Malawi, Tanganyika and Victoria). Closely related species exhibit a diverse range of color patterns. The three lakes have dramatically different photi...
Western Kenya is well known for abundant early Miocene hominoid fossils. However, the Wasiriya Beds of Rusinga Island, Kenya, preserve a Pleistocene sedimentary archive with radiocarbon age estimates of >33-45 ka that contains Middle Stone Age artifacts and abundant, well-preserved fossil fauna: a co-occurrence rare in eastern Africa, particularly in the region bounding Lake Victoria. Artifacts...
This paper presents new calculations of Lake Victoria's water balance. Evaporation is estimated using both the Penman formula and the energy balance approach, and sensitivity studies are performed to determine the influence of input data on the estimates. Rainfall over the lake is estimated from catchment rainfall using a relationship between the two that was derived using satellite data. The r...
In Lake Nabugabo, Uganda, a satellite of Lake Victoria, approximately 50% of the indigenous fishes disappeared from the open waters subsequent to the establishment of the introduced predatory Nile perch, Lates niloticus. This pattern is similar to the faunal loss experienced in the much larger Lake Victoria. Several of these species persisted in wetland refugia (e.g. ecotonal wetlands, swamp la...
Nile perch (Lates niloticus) suddenly invaded Lake Victoria between 1979 and 1987, 25 years after its introduction in the Ugandan side of the lake. Nile perch then replaced the native fish diversity and irreversibly altered the ecosystem and its role to lakeshore societies: it is now a prised export product that supports millions of livelihoods. The delay in the Nile perch boom led to a hunt fo...
Human activities, such as species introductions, are dramatically and rapidly altering natural ecological processes and often result in novel selection regimes. To date, we still have a limited understanding of the extent to which such anthropogenic selection may be driving contemporary phenotypic change in natural populations. Here, we test whether the introduction of the piscivorous Nile perc...
About 14, 000 years ago, Lake Victoria contained 500 species. Of these original species, 200 have become extinct and 200 are on the endangered species list (DuHamel, 2004). Predation coupled with poor harvesting methods has caused a big economic loss on most Ugandan lakes in particular and the world at large. In this study, we formulate a model based on a standard Lotka-Volterra prey-predator m...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید