Plankton blooms

It is feasible to capture a large volume of seawater in the range of 65 000 1 by the CEPEX approach for the purpose of sampler intercomparison. It is possible by artificial stimulation of a plankton bloom and detritus removal to produce a reasonably homogeneous body of seawater for the study. Proximity of the in situ enclosure for the experiment and the on-shore, clean laboratory facilities eliminate errors introduced by shipboard contamination under less than ideal conditions on cruises. 

Labile and refractory DOM undergo abiotic photochemical reactions in the photic zone, especially in the sea surfece microlayer where physical processes concentrate DOM into thin films. Some of these reactions appear to be important in the formation of refractory DOM and others in its degradation. For example, DOM exuded by diatoms during plankton blooms has been observed to be transformed into humic substances within days of release into surfece seawater. Laboratory experiments conducted in seawater have demonstrated that photolysis of labile LMW DOM promotes the chemical reactions involved in humification and produces chemical structures foimd in marine humic substances. 

At mid-latitudes (Westerlies domain), seasonal changes in light availability, mixed layer depth, and temperature support two plankton blooms, one in the spring and a lesser one in the fall (Figure 24.10). In the winter, phytoplankton growth is light limited. (The carbon fixation reaction is also slower at lower temperatures.) Thus as heterotrophic microbes remineralize detrital POM, DIN concentrations rise. 

Model of plankton blooms date back to the classical work of Riley et al. (19microbial organisms was incorporated in models of the pelagic plankton by Pomeroy (1979), Pace et al. (1984) and Fasham (1985). The above works have all treated plankton communities on a seasonal scale. In the model described below, we deal with a simple model of phytoplankton and micro-organisms concerned with the "microbial loop" (Azam et al., 1983) on a daily time scale appropriate to the turnover time of these organisms. The model is based on biomass data collected by Holligan et al. 

Several studies have reported detailed investigations in the variability of DMS concentration is surface waters around the UK (50-521. As in other studies they found large spatial variability in the concentration of DMS. A seasonal trend was observed, with a peak in DMS concentration coincident with the second annual plankton bloom in the summer. These studies are summarized in more detail in a subsequent chapter (531. 

The North Sea is assumed to be a source of DMS only. Measurements of the concentration of DMS in the North Sea (1) suggest a mean value of 10 ng (S) l 1 rising to 300 ng (S) l 1 during bloom periods. Two annual plankton blooms occur. These are often in early May and towards the end of June (4) but deviations by more than a month are not unknown. A transfer velocity of 3.5 x 10-5 m s 1 as used by Andreae and Raemdonck (1) has been adopted in the... 

Eutrophication Processes in Coastal Systems Origin and Succession of Plankton Blooms and Effects on Secondary Production in Gulf Coast Estuaries, Robert J. Livingston Handbook of Marine Mineral Deposits, David S. Cronan Handbook for Restoring Tidal Wetlands, Joy B. Zedler Intertidal Deposits River Mouths, Tidal Flats, and Coastal Lagoons, Doeke Eisma... 

Ittekkot, V., Degens, E.T., and Brockmann, U. (1982) Monosaccharide composition of acid-hydrolyzable carbohydrates in particulate matter during a plankton bloom. Limnol. Oceanogr. 27, 770-776. 

The Halobacteriaceae, commonly referred to as the halobacteria, are a family of extremely halophilic archaebacteria [113]. As in other archaebacteria, their membranes contain ether-linked lipids. The primary lipids present are diphytanyl phospholipids [113]. Their cell walls are also unique in structure and lack muramic acid. There are several species of halobacteria that vary considerably in their physiological characteristics. The halobacteria are unicellular rods or cocci. More recently flat, square and box-shaped cells have been described. Halobacteria are found growing in salterns or natural salt lakes and on the surface of salted fish. They often form dense planktonic blooms and can form massive accumulations on solid substrates. They may be involved in mat communities in hypersaline environments. 

Bode, A., Gonzalez, N., Rodriquez, C., Varela, M., and Varela, M. M. (2005). Seasonal variabflity of plankton blooms in the Ria de Ferrol (NW Spain). I. Nutrient concentrations and nitrogen uptake rates. Estuar. Coast. Shelf Sci. 63, 269—284. 

McGiUicuddy, D. J., Anderson, L., Bates, N., Bibby, T., Buesseler, K., Carlson, C., Davis, C., FaUcowski, P., Goldthwaite, S., HanseU, D. A., Jenkins, W., Johnson, R., et al. (2007). Eddy-wind interactions stimulate extraordinary mid-ocean plankton blooms. Science 316, 1021—1026. 

Ittekkot, V. (1982). Variations of dissolved organic matter during a plankton bloom Qualitative aspects, based on sugar and amino acid analyses. Mar. Chem. 11, 143—158. 

Hollander D. J., McKenzie J. A., and Hsii K. J. (1993) Carbon isotope evidence for unusual plankton blooms and fluctuations of surface water CO2 in Strangelove Ocean after terminal Cretaceous event. Palaeogeogr. PalaeocUmat. Palaeoecol. 104, 119-Til. 

However, as inorganic nutrients are taken up rather rapidly by phytoplankton—especially in plankton blooms—their concentrations are low during long periods of the year and increased inputs and effects of eutrophication cannot be properly described for the whole Baltic Sea area if only concentrations of inorganic nutrients are taken into consideration. To get a better understanding of the processes involved in eutrophication it is necessary to follow the track of inorganic nutrients in the biogeochemical cycle. 

For most of the stations shown in Fig. 12.12 times series have been established for POC and PON and for DOC and DON. As an example, time series are shown in the surface layer (Fig. 12.13) and bottomlayer (Fig. 12.14) of station 271 in the central Eastern Gotland Basin. POC and PON concentrations near the surface show a pronounced seasonal signal with maximum summer concentrations close to 50 pmol/l C for POC and 5 pmol/1 N for PON. The minimum in winter is below 10 pmol/1 C for POC and below 2 pmol/1 N for PON, respectively. The time series of nitrogen species also reveals that DIN, which accumulates during wintertime, is almost completely converted into PON during plankton blooms in summer (Fig. 12.13 below). 

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