The role of platelet ice microalgae in seeding phytoplankton blooms in Terra Nova Bay (Ross Sea,Antarctica): a mesocosm experiment |
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Authors: | Olga Mangoni Maria Saggiomo Monica Modigh Giulio Catalano Adriana Zingone Vincenzo Saggiomo |
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Institution: | (1) Dipartimento delle Scienze Biologiche, Università di Napoli Federico II, Via Mezzocannone 8, 80134 Naples, Italy;(2) Stazione Zoologica Anton Dohrn, Villa Comunale I, 80121 Naples, Italy;(3) CNR, Istituto di Scienze Marine, Viale Romolo Gessi 2, 34123 Trieste, Italy |
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Abstract: | The aim of this study was to assess the role of platelet ice microalgal communities in seeding pelagic blooms. Nutrient dynamics,
microalgal biomass, photosynthetic parameters, cell densities and species succession were studied in two mesocosm experiments,
designed to simulate the transition of microalgal communities from platelet ice habitat to pelagic conditions. The microalgal
assemblages were dominated by diatoms, 70% of which were benthic species such as Amphiprora kufferathii, Nitzschia stellata, and Berkeleya adeliensis. Photoacclimation of benthic species was inadequate also at relatively low irradiances. Exceptional growth capacity at different
light levels was observed for pelagic species such as Fragilariopsis cylindrus and Chaetoceros spp. which may be important in seeding blooms at ice breakup. Fragilariopsis cylindrus showed high growth rates both at 65 and 10% of incident light and in nutrient replete as well as in nutrient depleted conditions.
Five days after inoculation, phytoplankton biomass increased and nutrient concentrations decreased in both light conditions.
Nutrient uptake rates were up to 9.10 μmol L−1 d−1 of TIN in the high light tank and 6.18 μmol L−1 d−1 in the low light tank and nutrient depletion in the high light tank occurred 3 days prior to depletion in the low light tank.
At nutrient depletion, biomass concentrations were similar in both tanks, 30 and 34 μg Chla L−1.
This article belongs to a special topic: Five articles on Sea-ice communities in Terra Nova Bay (Ross Sea), coordinated by
L. Guglielmo and V. Saggiomo, appear in this issue of Polar Biology. The studies were conducted in the frame of the National
Program of Research in Antarctica (PNRA) of Italy. |
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Keywords: | Ross Sea Terra Nova Bay Platelet ice Diatoms Species composition Seeding |
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