AN INVESTIGATION OF THE SOURCES AND SEASONAL-VARIATIONS OF HIGHLY BRANCHED ISOPRENOID HYDROCARBONS IN INTERTIDAL SEDIMENTS OF THE TAMAR ESTUARY, UK

Citation
Sj. Hird et Sj. Rowland, AN INVESTIGATION OF THE SOURCES AND SEASONAL-VARIATIONS OF HIGHLY BRANCHED ISOPRENOID HYDROCARBONS IN INTERTIDAL SEDIMENTS OF THE TAMAR ESTUARY, UK, Marine environmental research, 40(4), 1995, pp. 423-437
Citations number
19
Categorie Soggetti
Marine & Freshwater Biology","Environmental Sciences",Toxicology
ISSN journal
01411136
Volume
40
Issue
4
Year of publication
1995
Pages
423 - 437
Database
ISI
SICI code
0141-1136(1995)40:4<423:AIOTSA>2.0.ZU;2-I
Abstract
The concentrations and distributions of highly branched isoprenoid (HB I) hydrocarbons in the surficial sediments of an intertidal mudflat in the Tamar Estuary, UK, were examined at monthly intervals throughout 1990. C-20 and C-25 HBIs were present all the year round and their con centrations covaried, maximising at several times in the year, notably in April-June. Since C-25 HBIs are known to be produced by a species of diatom (Haslea ostrearia) in culture, it seemed likely that the sed imentary maxima were also due to production from sediment diatoms. It was interesting therefore that the April-June HBI maximum did not coin cide with the (August) maximum concentration of the common diatom hydr ocarbon n-heneicosahexaene (HE), even though HE is also produced by th e diatom species which produces C-25 HBIs in culture. Diatoms isolated om the sediments in August produced abundant HE and only a small prop ortion of C-25 HBIs. These results suggest that HBI and HE production maximise at different diatom growth stages, or that the major sources of HBIs in the sediments ave as yet unidentified diatom species. The d iatoms isolated from the sediment did not produce C-20 HBIs and to dat e no organism has produced these in culture. Nonetheless, the delta(13 )C values of the sedimentary C-20 HBIs were consistent with an algal s ource.