escape control by microzooplankton grazing and bloom (reviewed by Sherr & Sherr
2009).
Fig. 9.8 Micrograph of a heterotrophic dinoflagellate, Gyrodinium, that has ingested a
diatom chain that is much longer, 165 μm, than its original body dimensions.
(^) (Photo by Evelyn and Barry Sherr, published by Calbet 2008.)
Fig. 9.9 Abundances of chlorophyll, ciliated protists, and heterotrophic dinoflagellates
(Gymnodinium sp.) during four seasons in nearshore waters of the Gulf of Trieste. The
intense phytoplankton bloom was a strong increase of diatoms (Lauderia spp.)
Data are from Fonda Umani, S. & Beran, A. (2003). (Figure after Calbet 2008.)
(^) The proportional level of Hdino grazing as blooms decline is likely more significant
than recognized until lately, but is also strongly variable. Figure 9.9 was drawn by
Calbet (2008) from data in Fonda Umani and Beran (2003), which specifies that the
peak in chlorophyll was attributable to a massive and unusual bloom of Lauderia
species. Fonda Umani confirmed for us from her data sheets that the “Protozoa non-
Ciliophora” listed in the 2003 paper were heterotrophic Gymnodinium spp. So, very
likely the increase of dinoflagellates (to >7 μg C liter−1) was supported by the
Lauderia as food. However, the Lauderia stock came to exceed 1000 μg C liter−1(!).
Fonda Umani et al. (2005) extended the Gulf of Trieste data-set to four years; the
second greatest diatom bloom was 300 μg C liter−1, not Lauderia , with no substantial