Production 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. 

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

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

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Overview Heterotrophs represent a major sink for primary production, and thus a critical part of the marine N cycle. In the pelagic realm, there have been attempts to estimate zooplankton grazing (both micro- and macro-zooplankton) using two major enzymatic approaches activities of digestive enzymes (especiaUy proteases in the case of N) (e.g., Gonzalez et al, 1993) and the activity of GDH, the... 

The relative impact of zooplankton grazing on primary production decreases with increasing production levels the proportion of primary production that is consumed by zooplankton decreases exponentially as productivity levels increase (Calbet, 2001). This supports the observation that the ratio of export production to total production is higher in areas of high productivity. Globally, 12% of marine primary production, or 5.5 Pg C (0.5 Pmol C), is consumed by mesozoo-plankton each year (Calbet, 2001). 

We further developed this model to include zooplankton interactions (38) by including algal losses to zooplankton grazing, zooplankton production of fecal pellets that can interact with other particles, and zooplankton population growth with the model of Fasham et al. (49). 

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