Zooplankton grazing

In addition to their role in chemical defense, DMSP-lyase products may also function as chemical cue in more complex trophic cascades. In the natural environment DMS-production is related to zooplankton herbivory [60] and can thus act as an indicator for the availability of food for planktivorous birds. Indeed, some Antarctic Procellariiform seabirds can detect DMS (22) and are highly attracted to the cue, as was shown with DMS-scented oil slicks on the ocean surface [61]. The odors released during zooplankton grazing (DMS) as well as those of zooplankton itself (e.g., trimethylamine and pyrazines) are attractive to birds [62], thus assisting vertebrate search behavior. 

Dacey JWH, Wakeham SG (1986) Oceanic dimethylsulfide production during zooplankton grazing on phytoplankton. Science 233 1314-1316 Davison IR, Pearson GA (1996) Stress tolerance in intertidal seaweeds. J Phycol 32 197-211 De Souza MP, Yoch DC (1996) Dimethylsulfoniopropionate lyase from the marine macroalga Ulva curvata purification and characterization of the enzyme. Planta 199 433—138 Dicke M, Agrawal AA, Bruin J (2003) Plants talk but are they deaf Trends Plant Sci 9 403-105... 

Hygum, B. H., J. W. Petersen, and M. Sondergaard. 1997. Dissolved organic carbon released by zooplankton grazing activity — A high-quality substrate pool for bacteria. Journal of Plankton Research 19 97-111. 

Bochdansky, A. B., S. Puskaric, and G. J. Herndl. 1995. Influence of zooplankton grazing on free dissolved enzymes in the sea. Marine Ecology Progress Series 121 53—63. 

In general, the mechanism(s) and reasons for the release of DMS by phytoplankton are unknown. Direct release of DMS is likely, as is release upon cell disruption. It has been demonstrated that zooplankton grazing on phytoplankton results in the release of DMS to the surrounding water (30). The release of DMS increases with increasing time in cultures of phytoplankton to which zooplankton have been added. Thu increase was shown to be linear over the time of the experiments (24 hours). 

Figure 3. DMS production during zooplankton grazing on phytoplankton ...

Dimethyl sulphide (DMS) is produced in sea-water as a consequence of enzymatic action in phytoplankton and zooplankton grazing. Measurements of DMS indicate an average global sea-to-air flux of 40 Tg of sulphur per year (1.3). Instantaneous emission rates to the atmosphere, however, can vary considerably, and depend on the nature and concentration of the phytoplankton, the time of year and the prevailing meteorology. For example, nigh concentrations of Phaeocystis, a prolific producer of DMS, have been found in the North Sea and when it blooms, emissions of DMS may increase by a factor of 40-60 over those in the absence of blooms (4). The sea-to-air flux is also dependent on the depth at which the phytoplankton is found since DMS is slightly soluble in water and can be oxidized in aqueous solution. 

Dacey, J.W.H., and Wakeham, S.G. (1986) Oceanic dimethylsulfide Production during zooplankton grazing on phytoplankton. Science 233, 1314-1316. 

Desvilettes, C., Bourdier, G, Amblard, C., and Barth, B. (1997) Use of fatty acids for the assessment of zooplankton grazing on bacteria, protozoans, and microalgae. Freshwat. Biol. 38, 629-637. 

Welschmeyer, N.A., and Lorenzen, C.J. (1985) Chlorophyll budgets zooplankton grazing and phytoplankton growth in a temperate fjord and the Central Pacific Gyres. Limnol. Oceanogr. 30, 1-21. 

Stelmakh LV (2006) Phytoplankton growth and zooplankton grazing in the western part of the Black Sea during September and October 2005. Black Sea Ecosystem 2005 and Beyond. Abstracts Istanbul Turkey, p 94... 

Zooplankton grazing on Phaeocystis a quantitative review and future challenges... 

Reports on copepods and other crustaceans dominate available zooplankton grazing data on Phaeocystis spp. These data show a wide range of rates, even for similar predator-prey combinations. We therefore attempt to summarize available quantitative data in relation to some of the mechanisms proposed to control the feeding on Phaeocystis. The shortage of quantitative feeding studies on microzooplankton and Phaeocystis was pointed out already a decade ago (Weisse et al. 1994), and the number of such studies is still limited, especially for protozoan microzooplankton, whether using laboratory cultures (Table 3)... 

Crustacean zooplankton grazing on Phaeocystis is there a general pattern ... 

Copepods may feed selectively based on nutritional quality of the prey (e.g., Houde and Roman 1987). However, it is not clear how food quality of the different forms of Phaeocystis affects zooplankton grazing. It has been suggested that Phaeocystis spp. are of low nutritional value due to their low content of polyunsaturated fatty acids (PUFA) (Al-Hasan et al. 1990 Claustre et al. 1990 Rogers and Lockwood 1990 Nichols et al. 1991 Cotonnec et al. 2001 Tang et al. 2001 Turner et al. 2002). This contrasts with the high survival and development rates observed in other... 

Hansen E, Ernstsen A, Eilertsen HC (2004) Isolation and characterisation of a cytotoxic polyunsaturated aldehyde from the marine phytoplankter Phaeocystis pouchetii (Hariot) Lagerheim. Toxicology 199 207-217 Hansen FC (1992) Zooplankton-Grazing an Phaeocystis mit be-sonderer Beriicksichtigung der Calanoiden Copepoden. 

Hansen PJ, Bjprnsen PK, Hansen BW (1997) Zooplankton grazing and growth scaling within the 2-2,000-pm body size range. Limnol Oceanogr 42 687-704 Hay ME, Fenical W (1988) Marine plant-herbivore interactions the ecology of chemical defense. Annu Rev Ecol Syst 19 111-145... 

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