Phytoplankton and environmental drivers at a long-term offshore station in the northern Adriatic Sea (1988–2018)
Francesca NeriTiziana RomagnoliStefano AccoroniAlessandra CampanelliMauro MariniFederica GrilliCecilia Totti
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Coccolithophore
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Emiliania huxleyi
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MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 126:247-265 (1995) - doi:10.3354/meps126247 Production and downward flux of organic matter and calcite in a North Sea bloom of the coccolithophore Emiliania huxleyi Van der Wal P, Kempers RS, Veldhuis MJW In July 1993, an extensive study was made of a large bloom of the coccolithophorid Emiliania huxleyi in the North Sea halfway between the Shetland Islands and Norway. Here we report on the hydrography, production and sedimentation of particulate organic carbon (POC) and calcite carbon (calcite-C) at 4 stations occupied for 24 h, 2 inside the bloom and 2 just outside. The coccolithophorid bloom was confined to North Sea waters, where a stable shallow mixed layer had been formed. Bloom development had entered the decaying phase, judged by the relatively low living cell number (maximally 1200 cells cm-3), the high number of loose coccoliths (up to 350000 coccoliths cm-3), and the fact that sedimentation of calcite-C exceeded production. In the top 15 m at the bloom stations, the mean daily production of coccoliths was 17 per cell. At the 2 stations outside the bloom, the dominant coccolithophore was a holococcolithophorid (up to 1400 cells cm-3), with insignificant amounts of calcite produced per cell. At these stations, nutrients were present in non-limiting concentrations and production of POC was twice as high as at the bloom stations. In the bloom, mixed layer nitrate levels were below 0.2 uM. Faecal pellets collected in the sediment traps contained large numbers of coccoliths of E. huxleyi. Although the numbers of grazers at the 2 stations outside the bloom were not lower than those in the bloom, the volume of faecal matter sedimenting at 50 m was about 70 times lower. It is hypothesized that faecal pellets outside the bloom were so light in weight that they did not sink very far before degradation, whereas the pellets produced in the E. huxleyi bloom in general were exported rapidly due to their heavy load of calcite. This implies that recycling of materials in the mixed layer of this bloom is relatively low due to high downward flux rate. The ratio at which POC and calcite-C were sedimenting amounted to 1.3 on average for the 2 bloom stations at 50 m water depth. Emiliania huxleyi . Coccoliths . Primary production . Calcification . Calcite dissolution . Sedimentation . Faecal pellets . North Sea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 126. Publication date: October 05, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.
Emiliania huxleyi
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Changes with time in the concentration of inorganic carbon in Lake Kinneret subsurface water were followed throughout two seasonal dinoflagellate blooms. The response of natural populations of the dominant dinoflagellate, Peridinium gatunense, to these changes was recorded by examining fluctuations over time in the activity of the enzyme carbonic anhydrase (CA) and in photosynthetic parameters. Our results show distinct fluctuations of both external and cytoplasmic CA activity in P. gatunense throughout the annual bloom. Higher levels of activity were triggered by the decline of total dissolved inorganic C below 1.8 mM and more specifically by low concentrations of dissolved CO 2 (1–10 µ M) during the seasonal bloom decline in May–June. Laboratory studies on cultured P. gatunense confirmed our field observations, suggesting that supplemental mechanisms are activated in P. gatunense that enhance inorganic C uptake when CO 2 is limiting for photosynthesis. Eventually, the cellular adaptations of P. gatunense to the declining CO 2 concentrations could not prevent decline of photosynthetic rates contributing to the subsequent decrease in P. gatunense biomass in May–June. In Lake Kinneret, P. gatunense is succeeded by Peridiniopsis spp., the photosynthetic rates and external CA activities of which were much higher under environmental conditions typical of the end of the bloom.
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Spatial and temporal distributions of Peridinium penardii were studied during a spring bloom. Blooms developed at the mouths of tributary streams after periods of high runoff and lasted for about 3 weeks. Allochthonous inputs may be necessary for the development of dinoflagellate blooms in this reservoir.
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We report surface observations of a mesoscale coccolithophore bloom at the shelf break of the Patagonian Shelf during December 2008, representing the densest coccolithophore population in the Southern Ocean. The bloom was most intense within the Falklands Current, northeast of the Falkland Islands. Emiliania huxleyi dominated bloom waters, with a mixed E. huxleyi and Prorocentrum sp. dinoflagellate bloom to the west and mixed assemblage of diatoms, dinoflagellates, and flagellates to the east. Optical measurements of coccolith light scattering, analytical measurements of their calcite, and microscopic counts all showed this to be an intense coccolithophore bloom. Average particulate inorganic carbon per coccolith in the bloom was low, typical of the B coccolith morphotype and in agreement with independent measurements made by scanning electron microscopy. Highest particulate inorganic carbon (measured optically and chemically) was observed when residual nitrate (defined as the difference, [NO 3 −1 ] − [Si(OH) 4 ]) was 10–17 µmol L −1 and nitrate to phosphate ratios were close to Redfield values. Elevated particle backscattering was observed in the E. huxleyi bloom, whereas the highest particle scattering occurred in the adjoining Prorocentrum sp. bloom. Backscattering from coccolithophores represented up to 50% of the total backscattering (from organic and inorganic particles) along the main axis of the E. huxleyi bloom. Chlorophyll‐specific absorption in the coccolithophore bloom was typical of marine phytoplankton. Residual nitrate plotted vs. temperature showed that the E. huxleyi bloom was associated with waters between 5°C and 15°C, with depleted silicate. Results suggest that previous drawdown of silicate by diatoms occurred prior to the densest E. huxleyi blooms over the Patagonian Shelf. We speculate that such conditions might also be important for annual development of the broader Great Calcite Belt and other coccolithophore blooms..
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Summary 1. The abundance of cysts of the bloom‐forming dinoflagellate Peridinium gatunense in the sediments of Lake Kinneret and the effects of environmental conditions on encystment were studied in relation to bloom dynamics. Peak cyst formation coincided with the highest growth rate of the population, prior to bloom peak. 2. Peridinium cysts were counted in water and sediment corer samples from 2000 to 2003 and in archived sediment trap samples collected during 1993–94. The cyst data were examined in relation to ambient temperature and nutrient records, and revealed no direct correlation. 3. In laboratory encystment experiments with Peridinium cells collected from the lake, 0.2–3% of the vegetative cells encysted. Temperature, light and cell density had no significant effect on the percentage of encystment. 4. Cysts were always present in the lake sediments but their abundance in ‘non Peridinium ’ years was much lower than after a massive bloom. Vegetative cells were always present in the water column after the collapse of the annual dinoflagellate bloom, potentially serving as the inoculum for the next bloom. We propose that the hardy cysts serve as an emergency ‘gene bank’ to initiate population build up following catastrophic die outs.
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Abstract This study examines an unprecedented bloom of Emiliania huxleyi along the California coast during the NE Pacific warm anomaly of 2014–2015. Observations of coccolithophore populations from microscopy and flow cytometry, surface current data derived from high‐frequency radar, and satellite ocean color imagery were used to track the population dynamics of the bloom in the Santa Barbara Channel. Results show a coastal bloom of mostly E. huxleyi that reached cell concentrations up to 5.7 × 10 6 cells per liter and a maximum spatial extent of 1,220 km 2 . We speculate that the rare cooccurrence of warm water, high water column stability, and an extensive preceding diatom bloom during the anomaly contributed to the development of this bloom. Flow cytometry measurements provided insight on the phases of bloom development (e.g., growth versus senescence) with calcified cells comprising up to 64% of particles containing chlorophyll a and detached‐coccolith:cell ratios ranging from 10 to >100. Lagrangian particle trajectories estimated during two nonoverlapping 48‐ and 72‐hr periods showed the changes in the surface structure of the bloom due to advection by surface currents and nonconservative biological and physical processes. Time rates of change of particulate inorganic carbon were estimated along particle trajectories, with rates ranging from −4 to 6 μmol·L −1 ·day −1 . The approach presented here is likely to be useful for understanding the evolution of coastal phytoplankton bloom events in a general setting.
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