Macro Invertebrate Diversity And Physicochemical Factors As Indicators Of Water Quality Within Nzoia Sugarcane Company Nucleus In Western Kenya

ABSTRACT

Sugarcane production is important in our day to day life though it causes water

pollution which reduces the water quality. Despite its threat to water quality, not much

is known about the impacts of agronomic inputs on macro invertebrates in Nzoia sugar

Company Nucleus ecosystem. Nzoia sugar company nucleus receives water from

Kuywa River which is a tributary of Nzoia River and discharges a diverse array of

pollutants to the river. Studies on Nzoia sugar company nucleus to determine the

physicochemical parameters and macro-invertebrate diversity as indicators of water

quality are limited. This study therefore, assessed agro-industrial activities within the

Nzoia Sugar Company nucleus plantations on the water quality and macro invertebrate

diversity. Surface water from canals and River Kuywa within Nzoia Sugar Company

nucleus was collected from 23 sites and analyzed for pH, electrical conductivity,

nitrates, ammonia and Ortho-phosphates according to standard methods. Aquatic

organisms were collected using fish nets and sweep nets. Larger aquatic organisms were

immobilized using chloroform while smaller animals were immobilized in absolute

alcohol and kept in sampling bottles and preserved in 70 percent alcohol. The data was

analyzed using descriptive and inferential statistics using SPSS version 18 and Statistica

version 10. Shannon Weiner diversity and evenness indices were calculated for macroinvertebrate

communities and macro invertebrate populations correlated with

physicochemical parameters. Student-Neuman-Keuls test for turbidity, salts and pH was

computed. A total of 1591 macro-invertebrates comprising 18 genera were collected:

826 during long rain season (May-August 2011), 299 during short rain season

(September-November 2011) and 466 during dry season (December 2011-February

2012). The class Insecta was the most abundant. There were significant differences in

all water quality parameters between seasons except temperature. Nitrites, soluble

reactive phosphates, total phosphates were higher during long rainy season. Total

I nitrates, ammonia, and conductivity were higher in the short rainy season while total

salts and total dissolved solids were high during dry season. Total nitrites, soluble

reactive phosphates and total phosphates showed a positive correlation (r = 0.2332,

0.5067 and 0.1771, respectively) with macro invertebrates during long rainy season but

they all gave a negative correlation in both short rain and dry seasons (r = -0.2383,-

0.1678 and -0.1178, respectively). Shannon Weiner diversity index of 0.44 was

recorded. There is significant differences (p

conductivity, total dissolved solids and temperature levels between control and

experimental sites. Based on the findings of this study, it can be concluded that

agricultural and industrial activities have significant impacts on water quality in

irrigation canals in Nzoia Sugar Company Nucleus in Western Kenya. This is shown in

this study by the high nitrogen and phosphate content in the runoff from sugar cane

agricultural fields that drain into water canals in the nucleus estate.