Application of bio-indicators assess aquatic ecosystem changes in the upper Ewaso Nyiro River, Kenya

Humans affect wetland ecosystems by changing cover, depleting resources, introducing waste and changing natural communities. In Laikipia, local resource managers have adopted expensive methods for monitoring ecosystem health... [ view full abstract ]

Humans affect wetland ecosystems by changing cover, depleting resources, introducing waste and changing natural communities. In Laikipia, local resource managers have adopted expensive methods for monitoring ecosystem health whose maintenance is not cost effective in the long term. A study carried out between October 2012 and April 2013 examined the potential use of mesocarnivores found in Laikipia as bio indicators of this change. Six sites were selected for sampling during the period with camera traps been strategically placed on the selected foraging sites so as to obtain round the clock data on mesocarnivore frequency of occurrences. Other related riparian and aquatic fauna were sampled at each site. Physicochemical characteristics of the water were assessed using standard probes and instruments. There was a general lack of significant relationships between mesocarnivore frequency of occurrence and all riparian and water fauna parameters sampled. Food availability seemed to be the only factor that affected their frequency of occurrence as indicated by the significant regression relationship between fish biomass and mesocarnivore frequency of occurrence (r2=0.928, P<0.05). Correlations tests to determine association of fish biomass and physicochemical water characteristics yielded no significant relationships. Therefore, the only environmental parameter that mesocarnivore frequency of occurrence indicates with significant accuracy is fish biomass. Mesocarnivores appeared to have limited sensitivity to environmental variability. This is because they did not respond directly but via food resources, which were directly influenced by variability in habitat conditions. The study therefore recommended the following for future studies attempting to use bio-indicators for monitoring aquatic ecosystem health (1). Future attempts should consider finer indicator variables such as diet specialization. This is because the generalist mesocarnivore species actually demonstrate remarkable tolerance to human disturbance (2). the specific taxa should ideally not be cryptic, since this may make the study more laborious and expensive shortchanging the earlier objective of making aquatic ecosystem health cost effective because it is difficult to collect adequate data. 3). finally, from the above criteria (1, 2) species such as the African fish eagle (Haliaeetus vocifer) which is found in Laikipia would be suitable candidates because of their numbers and their specialized diets.