Sediment toxicity on the survival of Capitella capitata (Fabricius, 1780) and early life stages of Echnometra mathaei (Blainville, 1825) in Dar es Salaam coastal marine waters, Western Indian Ocean
Journal Title: Journal of Aquatic Research and Sustainability - Year 2025, Vol 2, Issue 1
Abstract
Coastal marine pollution is a growing problem worldwide and ascertaining its impacts to aquatic biota is a growing concern. This study investigated the toxicity effects of sediments from Dar es Salaam harbor on the survival of Capitella capitata (Fabricius, 1780), fertilization and embryo development of Echinometra mathaei (Blainville, 1825) benthic biota along Dar es salaam harbor. Dar es salaam harbor is the main effluent receiving area along Tanzanian coastal marine waters associated with port operations. Sediment samples were collected at 35 sampling stations, C. capitata were collected at Msasani bay, 40 km from the harbor and E. mathaei were collected at Oysterbay rock shore about 10 km from the harbor. Sediments were collected along Dar es Salaam harbor using 50 cm long light piston corer and analyzed for heavy metals and total petroleum hydrocarbon levels and were used for toxicity testing. Higher concentrations of Cu, Cd, Pb, Zn, Cr, As, Ni, Fe, Ba, Mn were observed in the southern and central part of the harbor as compared to the northern par. However, Pb, Cr, Cd and Zn had the highest concentrations at the center of the harbor. Hydrocarbons included tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane and total petroleum hydrocarbons (TPH), their levels were low though was higher in the southern part of the harbor than in the central and northern part. Survival toxicity bioassay of C. capitata was conducted in sediments and seawater made from 1:4 sediments: seawater and 1:20 ratio, in a static and 48 hours’ replaceable seawater, similarly fertilization and embryo development bioassay of E. mathaei were conducted in elutriates made from similar sediment – seawater ratios in a static and 24 hours’ replaceable seawater. Higher mortality of C. capitata, lower fertilization and embryo development of E. mathaei were observed in sediments from the central part of the harbor and in the southern part, corresponding with the observed higher heavy metals and hydrocarbons levels. Revealing that higher heavy metal and hydrocarbons levels were the cause of the observed toxic effects. Comparison of the observed toxic effects showed that fertilization bioassay is the most sensitive test, thus making it suitable as bioindicator for the tropical costal marine pollution monitoring.
Authors and Affiliations
Benard Mwakisunga, Pratap Harishchandra Bhagwanj
Keywords
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- EP ID EP762841
- DOI https://doi.org/10.69517/jars.2025.02.01.0004
- Views 21
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Sediment toxicity on the survival of Capitella capitata (Fabricius, 1780) and early life stages of Echnometra mathaei (Blainville, 1825) in Dar es Salaam coastal marine waters, Western Indian Ocean
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