Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 4

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1

Integrating aquaculture with traditional farming system: socioeconomic assessment in the Amhara Region, Ethiopia

100%
Adugna B. T., Goshu G.
International Journal of Ecohydrology and Hydrobiology
|
2010
|
tom 10
|
nr 2-4
Semi-intensive aquaculture practice started in 2005 in the Amhara region of Ethiopia. An evaluation survey was undertaken in September 2009. Beneficiaries, key informants and various groups were interviewed. Constructed aquaculture ponds were different in source of water, structure, age, original purpose, level of integration and the type of fish stocked. Farming households integrated aquaculture with different production subsystems and increased the flow of nutrients. At the same time they gained different benefits. However, the practice has been also constrained by various challenges. Farmers’ research extension group approach, provision of gillnets, appropriate fish species and mono-sex culture, capacity building of the research and extension system, and proper follow up are the recommendations for integrated aquaculture expansion.
2

A preliminary survey of the ecohydrological management challenges faced by Lake Gudera, Sekela woreda, West Gojjam, Ethiopia

81%
Endalew M., Goshu G., Zelalem W.
International Journal of Ecohydrology and Hydrobiology
|
2010
|
tom 10
|
nr 2-4
Lake Gudera, a highland lake, is highly degraded by agricultural activity, but still serves the local community for irrigation and livestock watering. Preliminary investigations indicated chemical composition of NO3 (0.7 mg dm-3), turbidity (26 NTU) and conductivity (78 μs cm-1) with poor floristic and faunistic composition. The Community Elders explained that the wetland encroachment started in 1986/1987, was aggravated in 2002/2003 and now had resulted in 25% littoral zone macrophyte loss. Wetlands had been converted for agriculture, leaving reduced filtering capacity of the lake which impacted on the ecosystem services. Now there are growing calls for sustainable management for the various values and functions, involving different stakeholders to alleviate negatively impacting factors.
3

Spatial and temporal distribution of commercially important fish species of Lake Tana, Ethiopia

81%
Goshu G., Tewabe D., Adugna B. T.
International Journal of Ecohydrology and Hydrobiology
|
2010
|
tom 10
|
nr 2-4
The distribution of Lake Tana fish species was studied from January 2000 to December 2003. Samples were collected monthly using gill-nets of 60, 80, 100, 120 and 140 mm stretched mesh size. Labeobarbus spp., Oreochromis niloticus, Claris gariepinus and Varicorhinus beso are commercially important fish species and form 77%, 13%, 9% and 1% of the pooled experimental fish catch. There was significant variability among years and sampling sites encompassing both temporal and spatial aspects. Population densities of Labeobarbus spp. and V. beso were significantly declining, in contrast, the abundance of O. niloticus and C. gariepinus did not change. The most likely explanations for the decline in Labeobarbus spp. are the increase of the commercial gill-net fishery targeting their spawning aggregations in the river mouths, use of poisonous plant materials and the increasing trend of the disconnectivity and channelisation of rivers. The results stress the need for urgent development of a management plan focusing on ensuring river connectivity, fishing effort and gear restrictions, and control in the river mouths and major tributaries during the breeding seasons.
4

A pilot study on anthropogenic faecal pollution impact in Bahir Dar Gulf of Lake Tana, Northern Ethiopia

71%
Goshu G., Byamukama D., Manafi M., Kirschner A. K. T., Farnleitner A. H.
International Journal of Ecohydrology and Hydrobiology
|
2010
|
tom 10
|
nr 2-4
The anthropogenic effect on faecal and chemical pollution at Bahir Dar Gulf of Lake Tana, Ethiopia was investigated in the period of October 2006 to February 2007. Faecal and physicochemical pollution levels were significantly increased and clearly discernible in the Bahir Dar Gulf locations as compared to presumptively anthropogenic uninfluenced reference locations near the outlet of the Blue Nile River of Lake Tana. One directly sewage influenced lake site at Bahir Dar Gulf was found to be excessively faecally polluted. The total pooled data set from the study for faecal coliforms, Escherichia coli and Clostridium perfringens spores ranged from not detectable (n.d.) to log 6.2 CFU, n.d. to log 6.1 CFU and n.d. to log 1.7 CFU per 100 ml, respectively. A high variation was also observable for the physicochemical parameters including the spectral absorption coefficient at 254 nm, ammonia, nitrite, nitrate, total dissolved solids, total suspended solids and pH values. Although the data have to be considered preliminary, it strongly points to the need for systematic water quality monitoring of Lake Tana and its potential impact sources. This is all the more important as the lake is the largest freshwater body in the country serving a multipurpose role and being identified as a growth corridor of the country.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.