Effects of anthropogenic activities on aquatic macro- invertebrate composition and water quality in lumemo river, Morogoro Tanzania
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Date
2022
Authors
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Publisher
Sokoine University of Agriculture
Abstract
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.
Description
Dissertation
Keywords
Anthropogenic, aquatic, macro- invertebrate, composition, water, quality, lumemo river, Morogoro, Tanzania