Browsing by Author "Mremi, Joel Frank"

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Effects of anthropogenic activities on aquatic macro- invertebrate composition and water quality in lumemo river, Morogoro Tanzania
(Sokoine University of Agriculture, 2022) Mremi, Joel Frank
Biodiversity of freshwater ecosystems is declining faster than any other ecosystems due to various anthropogenic activities which result in changes in land use and water quality. However, the effects thereof on aquatic ecosystems are not well quantified and understood especially where small holder agriculture is a major economic activity and driver of changes on the status of ecosystems. This study investigates the effects of anthropogenic activities on water quality and aquatic macro-invertebrates in the Lumemo River Morogoro Tanzania. Aquatic macro-invertebrates, physio-chemical water variables and the health of the riparian vegetation were assessed in the upper, middle and lower reach of the River. A total of 30 sampling points were established, ten in each river reach segment. The distance between sampling points was 500 m. The abundance of aquatic macro- invertebrate was determined as the sum of all individuals in each sampling point. The diversity of macro-invertebrates was calculated using Shannon-Wiener Index. Anthropogenic activities were assessed based on the health of the riparian ecosystem by measuring the width and height of the vegetation strip, the structure of the vegetation strip and the extent of human-induced degradation (uses, vegetation clearing, and cultivation). The extent of use was determined using a scale of 1-5 where 1 = no/low use 5 = extensive use. Non-metric Multidimensional Scaling (NMDS) was used to determine the association between macro-invertebrates, physicochemical variables and anthropogenic activities. Macro-invertebrate diversity was lowest in the lower reach segment (H’ = 0.6228), with notable dominance of high pollution tolerant species than the middle reach (H’ = 1.299) and upper reach (1.593). There was statistically significant difference in water conductivity and pH across longitudinal sections of the river reaches. The lower reach had higher conductivity which infer higher amounts of suspended solids, followed by middle reach and the upper reach. Higher pH value was recorded in the upper reach (pH = 9);iii while the middle reach had almost similar pH values to the upper reach (pH = 8.83). The lower reaches recorded an acidic pH value of 4.23 an indication of potential pollution load from intensive human use. The health of the riparian vegetation as indicated by vegetation cover, vegetation width and height was highest in the upper reach of the river. Overall diversity and abundance of aquatic macro-invertebrates along the reaches of Lumemo River were negatively correlated with the physicochemical parameters (pH, conductivity and temperature). Minimizing anthropogenic activities is vital for maintaining the health, water quality and improving the diversity and stability of macro-invertebrate in the Lumemo River ecosystem. Maintenance of ecological integrity by controlling anthropogenic activities, protection of the river channel and its basin and increased public education and awareness on environmental integrity is recommended.