The effects of Phaeocystis globosa bloom on the dynamics of the mineralization processes in intertidal permeable sediment in the Eastern English Channel (Wimereux, France)
Rauch, M.; Denis, L.; Dauvin, J.C. (2008). The effects of Phaeocystis globosa bloom on the dynamics of the mineralization processes in intertidal permeable sediment in the Eastern English Channel (Wimereux, France). Mar. Pollut. Bull. 56(7): 1284-1293. dx.doi.org/10.1016/j.marpolbul.2008.04.026 In: Marine Pollution Bulletin. Macmillan: London. ISSN 0025-326X; e-ISSN 1879-3363, more |  |
| Keyword | Phaeocystis globosa Scherffel, 1899 [WoRMS]
| | Author keywords | Phaeocystis globosa bloom; benthic mineralization; permeable sediment; |
| Abstract | In the Eastern part of the English Channel, high biomasses of the phytoplankton prymnesiophyceae Phaeocystis globosa (reaching biomasses over 20 µg Chla l-1) are a recurrent spring event (March-June). A significant part of the pelagic Phaeocystis-derived organic matter can be broken down in the sandy permeable sediment that makes up most of the intertidal zone in this part of the Channel. Sediment characteristics, macrolaunal distribution, bacterial biomass, organic carbon content, sediment oxygen demand (SOD), and the sediment-water flux of dissolved inorganic nitrogen and silicates were calculated for an exposed sandy beach (Wimereux, France) over a two-year period (2004-2006). According to the data collected, the SOD remains relatively low throughout the whole survey (64-306 µmol m-2 h-1), indicating limited mineralization. However, the same data reveals a temporal variability in the flux, with a sharp increase in the SOD and ammonium released in spring when Phaeocystis-derived phytodetritus was deposited. The organic carbon content and bacterial biomass values indicate similar patterns of increase in response to the phytodetritus deposit. The nitrogen cycle also appears to be modified during the Phaeocystis bloom, with a clear stimulation of nitrification. The influence of various factors (e.g., temperature, nutrient concentrations, and bacterial activity) on the temporal fluctuations of the exchanges is discussed, as are the direct effects of spring bloom. A synthesis of the annual cycle of the mineralization dynamics in this permeable sediment type is also presented. |
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