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- Lundholm, Nina, et al.
(författare)
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Buried alive - Germination of up to a century-old marine protist resting stages
- 2011
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Ingår i: Phycologia. - : Informa UK Limited. - 0031-8884 .- 2330-2968. ; 50:6, s. 629-640
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Tidskriftsartikel (refereegranskat)abstract
- report on the survival and germination of up to a century-old marine protist resting stages naturally preserved insediments from Koljö Fjord on the west coast of Sweden. This work has focused on germination of dinoflagellate cysts,but diatom resting stages were also observed. We record the longest known survival of dormant dinoflagellate cells. Weindividually isolated more than 1200 cysts of the three most abundant dinoflagellate taxa: Pentapharsodinium dalei,Lingulodinium polyedrum and Scrippsiella spp. Germination success decreased with core depth, and all successfulgerminations took place within the first 2 wk of incubation. Pentapharsodinium dalei had the highest germination successrate, with a maximum of up to 80% in 28-yr-old sediment, and could successfully germinate from core sediments datedto 1920 ± 12. Scrippsiella spp. cysts with cell contents occurred down to c. 90-yr-old sediment and could germinate fromdown to ca. 40-yr-old sediments, with a maximum germination rate of 50-60% in recent sediments. Cysts of L.polyedrum germinated frequently down to 20 yr and rarely to c. 80 yr, with a maximum of 20-50% germination successin recent sediments. Cyst isolation under cooled conditions rather than at room temperature resulted in a significantlyhigher germination success in P. dalei, while no effect was observed for L. polyedrum. The time elapsed since slicing ofthe core affected survival of L. polyedrum cysts negatively, most likely due to the effect of oxygen. The long-termsurvival potential of benthic resting stages that we report here has important implications, as viable resting stagesaccumulated in bottom sediments can be transported back to the water column by, for example, bioturbation andhuman-mediated sediment dredging. Hence, the sediment may to a higher degree than previously considered play a roleas seed bank. This is important in a changing climate and might have particularly severe impacts in the case of harmful species.
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| 2. |
- Mertens, Kenneth Neil, et al.
(författare)
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A review of recent freshwater dinoflagellate cysts: taxonomy, phylogeny, ecology and palaeocology
- 2012
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Ingår i: Phycologia. - : Informa UK Limited. - 0031-8884 .- 2330-2968. ; 51:6, s. 612-619
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Forskningsöversikt (refereegranskat)abstract
- Resting stages (e.g. cysts) play an important role in the life history and ecology of phytoplankton, e.g. the survival, reproduction, genetic recombination, and dispersal of many species. Marine dinoflagellates cysts have been intensively studied by both geologists and biologists, but freshwater cysts have received less attention. There are approximately 350 freshwater dinoflagellate species, and resting cysts have been described for 84 species. We evaluated the descriptions, and we reproduced images for each cyst type. The review highlighted the importance of cyst characters for taxonomy and phylogeny. We suggested that shape, wall ornamentation and possibly the archeopyle and color were important morphological characteristics at the generic level and above. The ecology of freshwater dinoflagellate cysts was reviewed, and the ecological role of cysts was discussed. The potential of freshwater cysts for Quaternary palaeoecological reconstructions was highlighted, revealing that these could serve as useful indicators of temperature, pH and productivity.
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