Elskens, M.

Kochzius, M.

Leermakers, M.

Rumisha, C.

Open Marine Archive

 - 75 -
INFLUENCE OF TRACE METALS POLLUTION ON THE COMMUNITY 
STRUCTURE OF SOFT BOTTOM MACROFAUNA IN INTERTIDAL AREAS 
OF THE DAR ES SALAAM COAST, TANZANIA 
Rumisha Cyrus C.1, Marc Kochzius2, Marc Elskens3 and Martine Leermakers3 
1 Ecological Marine Management (ECOMAMA), Faculty of Science and Bioengineering Science 
Free University of Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium 
E-mail: crumisha@msn.com  
2 Marine Biology, Free University of Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium 
3 Laboratory of Analytical and Environmental Chemistry, Free University of Brussels (VUB), Pleinlaan 
2, 1050 Brussels, Belgium 
 
Dar es Salaam is the largest and a major industrial city in Tanzania with a population of about 2.5 
million people. Due to rapid increase in population, most open spaces have been converted to 
residential and industrial areas, resulting in uncontrolled disposal of domestic and industrial 
sewage.  Because sewage is rarely treated, pollution is usually transported by rivers and streams to 
coastal areas. Despite efforts undertaken to assess the level of pollution in sediments and or fauna 
of the Dar es Salaam coast, very little efforts have been made to try to address the influence of 
these pollutants on faunal community structure in Dar es Salaam coastal areas. Thus the main 
objective of the present study is to assess the influence of trace metal pollution on the community 
structure of soft bottom macrofauna in intertidal areas of the coast. 
 
Samples for this study were collected during a field trip in summer, 2010. Six stations along the 
coast were selected and at each station three replicate samples of sediments were collected by 
using a frame with surface area 0.0962m2 and height 0.20m. The sediments were well mixed and a 
small fraction of it placed in small plastic bottles for analysis of heavy metals, organic matter 
content and grain size distribution. The remaining sediments were sieved through a 0.5mm sieve 
and retained organisms preserved in plastic bottles with ethanol. Salinity of water at each station 
was determined by using a refractometer. The samples were transported to the Vrije Universiteit 
Brussel (VUB) for analysis. Currently, sediment samples are analysed in the Analytical and 
Environmental Chemistry Lab of the VUB and identification of macrofauna is going on in the APNA 
(Algemene Plantkunde en Natuurbeheer) Lab. After sediment analysis and species identifications, 
the total number of organisms, species number, and Shannon-Wiener diversity index will be 
calculated for each station. Statistical significance tests will be conducted in order to compare 
different stations. If the data show a normal distribution, a one way ANOVA (Analysis of Variance) 
will be conducted. Otherwise, a non parametric Kruskal-Wallis ANOVA by ranks will be used. A 
multivariate analysis of the community structure will be done with the software PRIMER 6.0. Samples 
will be compared using cluster analysis and multidimensional scaling (MDS). ANOSIM will be used to 
test for significant differences. Abiotic parameters will also be analysed with the same methods 
used for analysis of community structure. A BIOENV correlation analysis will be performed to 
determine which abiotic parameters best explain the changes in the assemblage of macrofauna. 


Influence of trace metals pollution on the community structure of soft bottom macrofauna in intertidal areas of the Dar es Salaam coast, Tanzania

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