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Organohalogen compounds in blubber of Indo-Pacific bottlenose dolphin (Tursiops aduncus) and spinner dolphin (Stenella longirostris) from Zanzibar, Tanzania
Stockholm University, Faculty of Science, Department of Zoology. (Marine Mammal)
Stockholm University, Faculty of Science, Department of Zoology. (Marine Mammal)
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2010 (English)In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 158, no 6, 2200-2207 p.Article in journal (Refereed) Published
Abstract [en]

Blubber samples of Indo-Pacific bottlenose (Tursiops aduncus) and spinner (Stenella longirostris) dolphins from Zanzibar, East Africa, were analysed for a wide range of organohalogen compounds. Methoxylated polybrominated diphenyl ethers (MeO-BDEs), presumably biogenic, were found at higher concentrations than anthropogenic organochlorine pesticides (OCPs). Only traces of industrial pollutants, such as polychlorinated biphenyls, were detected. The OCP levels found off Zanzibar were lower than those reported from other regions while MeO-BDE levels were higher. The relative composition of the OCPs indicated recent use of lindane (γ-hexachlorocyclohexane) and aged residues of DDT and technical HCH. Placental transfer was estimated to 2.5% and 0.5% of the total burden of OCPs and MeO-BDEs, respectively. Overall transfer from mother to calf in Indo-Pacific bottlenose dolphins was estimated to 72% and 85% for the OCPs and MeO-BDEs burdens, respectively. Health effects of MeO-BDEs are not known, but structural similarities with well-known environmental toxins are cause for concern.

Place, publisher, year, edition, pages
2010. Vol. 158, no 6, 2200-2207 p.
Keyword [en]
Methoxylated polybrominated diphenyl ethers, MeO-BDEs, organochlorine pesticides, maternal transfer
National Category
Pharmacology and Toxicology
Research subject
Animal Ecology
Identifiers
URN: urn:nbn:se:su:diva-34468DOI: 10.1016/j.envpol.2010.02.027ISI: 000278343000028OAI: oai:DiVA.org:su-34468DiVA: diva2:284860
Available from: 2010-01-08 Created: 2010-01-08 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Biology, ecology and anthropogenic threats of Indo-Pacific bottlenose dolphins in east Africa
Open this publication in new window or tab >>Biology, ecology and anthropogenic threats of Indo-Pacific bottlenose dolphins in east Africa
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis examines the biology, ecology and anthropogenic threats of Indo-Pacific bottlenose dolphins (Tursiops aduncus) off Zanzibar, Tanzania, based on research conducted and samples collected between 2000 and 2008. Distribution and occurrence are described based on incidental catches (bycatch) in gillnet fisheries. Biology and ecology are examined by ageing and studying the reproductive biology and stomach contents of collected specimens. The composition of organohalogen compounds is determined in blubber samples, and assessment and mitigation of bycatch are conducted using observers onboard fishing vessels. Fisheries bycatch data showed that Indo-Pacific bottlenose dolphins occur year round in all areas around Zanzibar. Sexual maturity was attained between 7 and 8 years and body length 190-200 cm in females and at 16 years and body length 213 cm in males. The gestation period was estimated to be 12.3 months, with calving occurring throughout the year, peaking November-March and with an interval of 2.7 years. The estimated pregnancy rate was between 0.10 and 0.58 depending on methods used. Stomach contents revealed a relatively large number of prey species, but that only a few small- and medium-sized neritic fish and cephalopods contribute substantially to the diet. Estimates of total annual bycatch were >9% which is not considered sustainable. An experiment showed that pingers can be a short term mitigation measure to reduce bycatch of dolphins in both drift- and bottom set gillnets. Methoxylated polybrominated diphenyl ethers (Meo-BDEs) were found at higher concentrations than anthropogenic organic pesticides (OCPs), with only traces of polychlorinated biphenyls (PCBs) detected. This study reveals the magnitude and apparent susceptibility of Indo-Pacific bottlenose dolphins off Zanzibar to anthropogenic threats, especially fisheries bycatch, and it is clear that immediate conservation and management measures are needed to reduce bycatch.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2010. 31 p.
Keyword
Growth, reproduction, feeding ecology, bycatch, organohalogen compounds, dolphins, Tursiops aduncus, Zanzibar, East Africa
National Category
Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-34472 (URN)978-91-7447-002-4 (ISBN)
Public defence
2010-02-12, Ahlmansalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
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Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: Manuscript. Paper 5: Submitted. Available from: 2010-01-21 Created: 2010-01-08 Last updated: 2010-10-14Bibliographically approved

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