Identification of impacts, some biology of water hyacinth (Eichhornia crassipes) and its management options in Lake Tana, Ethiopia

Abstract

The study was conducted from July, 2013 to July, 2015 in the North-Eastern part of lake Tana. Six sites were selected from Fogera, Libokemkem and Dembia districts based on water hyacinth infestation and free area. Plant sample was collected from infested areas using quadrant and different parameters were recorded using sensitive balance and tape meter. The physical parameters were measured in situ using YSI 556 multi-probe system, while the chemical parameters were carried out using a portable water analysis kit. Zooplankton and phytoplankton samples were collected by 80 and 50 µm mesh net filtering device. Moreover, structured questionnaire, focuses group discussion, key informant interview has been used to collect some quantitative and qualitative data. 104 plants/m 2 and 8.216 ± 0.45 kg fresh weight/m 2 which equals 82,160 kg/ha or 82.16 tones/ha fresh weight can be harvested during the dry season of a year. But 583 plants/m 2 which equals 270,000 kg/ha = 270 tones/ha fresh weight can be harvested during the wet season of a year. The present assessment also noted that no major management strategy had been employed in the infested water body areas, despite many efforts had been applied by the community and the government. Water hyacinth poses serious problems on the community living around Lake Tana by affecting fishing process, farmland, livestock and the environment of in a variety of ways.

Determinants of manual control of water hyacinth expansion over the Lake Tana, Ethiopia

“…For instance, it is altering the growth and reproduction of the native flora and fauna diversity through reducing sunlight penetration, nutrient supply, oxygen availability and water access to native aquatic organisms. Agricultural input depositions and residues transported from upslope areas are intensifying the weed expansion (Asmare, 2017;Tewabe, Asmare, Zelalem & Mohamed, 2017).…”

“…Clearing the farmlands from water hyacinth and land preparation demands more labour and time which is difficult to cover by the poor farmers. Tewabe et al (2017) noted that about 19 manual workers are required to clear the water hyacinth from 0.25 ha lands. The collected weed heaps then left the farmlands fragmented and complicated to manage.…”

“…The collected weed heaps then left the farmlands fragmented and complicated to manage. Water hyacinth also affects livestock rearing in the lake adjacent villages through reducing the growth of hippo grasses (water submerging grasses) that are used for feeding cattle (Tewabe et al, 2017).…”

“…Losses of fishing tools and instruments are also reported in past literatures. Water hyacinth thus not only diminishes the fish population but also the efficiency of fish production (Asmare, Sewmehon, Tewabe & Mihret, 2016;Tewabe et al, 2017).…”

“…Absence of proper soil conservation practices on the upper watersheds, expanded cultivation in the wetlands bordering the Lake, weather variability and lack of firm concern and strict focus among the concerned stakeholders have also constrained the weed removing efforts of the local community (Anteneh et al, 2015;Asmare, 2017). Lack of knowhow on the life scale of the weed, poor storage of the harvested weeds and the spread of the weed fragments to adjacent waters through disturbances and waves make less effective the manual control efforts of the people (Tewabe et al, 2017).…”