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Long-term and seasonal variations of heavy metal concentrations in a brown macroalga, the case of Padina gymnospora in the Zanzibar Channel
Stockholm University, Faculty of Science, Department of Botany.
Manuscript (Other academic)
URN: urn:nbn:se:su:diva-24255OAI: diva2:197109
Part of urn:nbn:se:su:diva-6818Available from: 2007-05-03 Created: 2007-04-26 Last updated: 2010-01-13Bibliographically approved
In thesis
1. Heavy metal contamination and toxicity: Studies of Macroalgae from the Tanzanian Coast
Open this publication in new window or tab >>Heavy metal contamination and toxicity: Studies of Macroalgae from the Tanzanian Coast
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Concentrations of various metals are elevated above background levels in several intertidal areas along the Tanzanian coasts. However, there is little available information concerning the toxicity of these metals and how the uptake of these metals by bioindicators are influenced by external factors, such as heavy rains and increased coastal eutrophication, which tend to fluctuate.

The present study focused on the uptake and toxicity of Cu and Zn in two common macroalgal species, Padina gymnospora (Phaeophyta) and Ulva reticulata (Chlorophyta). Laboratory studies were performed where metal content, growth (DGR), maximal quantum yields (Fv/Fm) and protein expression patterns (in Ulva) were measured as a response to exposure to Cu and Zn. The levels of metals accumulated in algal tissues correlated well to exposure concentrations and the longer the exposure time, the greater the uptake. However, an increased nutrient load (tested on Padina) or dilution of the seawater (tested on Ulva) affected both uptake of metals and their toxic effects. Here, DGR was more affected than Fv/Fm, suggesting DGR to be the more sensitive indicator of Cu and Zn toxicity. As shown by 2-D gel electrophoresis, more than ten proteins were up-regulated in U. reticulata after being exposed to Cu (1μg/L), while at higher concentrations (10 and 100 μg/L) of Cu numerous proteins were down-regulated.

P. gymnospora was also used as a bioindicator to monitor long-term (1994–2005) and seasonal in-year variations in heavy metal concentrations in the Zanzibar Channel. No clear overall trends were revealed, but analysis of the combined dataset clearly pinpointed the most contaminated sites. It was concluded that seasonal and long-term variations, as well as environmental conditions need to be taken into consideration when using macroalgae as bioindicators.

Place, publisher, year, edition, pages
Stockholm: Botaniska institutionen, 2007. 48 p.
Heavy metals, Padina gymnospora, Ulva reticulata, salinity, nutrients, proteins, uptake, growth, Fv/Fm, Zanzibar Channel
National Category
Research subject
Plant Physiology
urn:nbn:se:su:diva-6818 (URN)91-7155-374-6 (ISBN)
Public defence
2007-05-23, föreläsningssalen, Botanicum, Lilla Frescativägen 5, Stockholm, 13:00
Available from: 2007-05-03 Created: 2007-04-26Bibliographically approved

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