Abstract
In paleoecological studies, molecular markers are being used increasingly often to reconstruct community structures, environmental conditions and ecosystem changes. In this work, nodularin, anabaenopeptins and selected DNA sequences were applied as Nodularia spumigena markers to reconstruct the history of the cyanobacterium in the Norwegian fjords. For the purpose of this study, three sediment cores collected in Oslofjorden, Trondheimsfjorden and Balsfjorden were analyzed. The lack of nodularin in most recent sediments is consistent with the fact that only one report on the sporadic occurrence and low amounts of the cyanobacterium in Norwegian Fjords in 1976 has been published. However, analyses of species-specific chemical markers in deep sediments showed that thousands of years ago, N. spumigena constituted an important component of the phytoplankton community. The content of the markers in the cores indicated that the biomass of the cyanobacterium increased during the warmer Holocene periods. The analyses of genetic markers were less conclusive; they showed the occurrence of microcystin/nodularin producing cyanobacteria of Nostocales order, but they did not allow for the identification of the organisms at a species level.
Highlights
In Norwegian coastal waters, the phytoplankton community is mainly composed of diatoms, dinoflagellates, cyanobacteria, prymnesiophytes and raphidophytes [1,2,3]
The chemical analysis of deep sediment cores performed with the application of long core (LC)-MS/MS did not reveal the presence of saxitoxin (STX), okadaic acid (OA) or dinophysiotoxin
We analyzed sediment samples from the short (SC) and long (LC) cores collected in Norwegian fjords, namely in Oslofjorden (336 cm), Trondheimsfjorden (136 cm) and Balsfjorden
Summary
In Norwegian coastal waters, the phytoplankton community is mainly composed of diatoms, dinoflagellates, cyanobacteria, prymnesiophytes and raphidophytes [1,2,3]. In Lindaspollene, a land-locked fjord system on the west coast of Norway (north of Bergen), revealed the sporadic occurrence of heterocystous Nodularia sp This cyanobacterium was found there in small amounts, and no data on its toxicity was reported. In many brackish water bodies, N. spumigena regularly develops into toxic blooms, threatening public health and decreasing the recreational value of bathing sites [5]. This planktonic cyanobacterium, among others, was reported in the Baltic Sea [6], estuaries, rivers and lakes in Australia [7], New Zealand [8], the North Sea [9] and the Black Sea [10]. The chemical analysis of deep sediment cores performed with the application of LC-MS/MS did not reveal the presence of saxitoxin (STX), okadaic acid (OA) or dinophysiotoxin
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