Francoise, you are looking for something specific ? There are a lot of papers describing interaction between protists and marine snow. E.g. Thomas Kiørboe from DTU Aqua published many papers

Kiørboe, Thomas, et al. "Dynamics of Microbial Communities on Marine Snow Aggregates: Colonization, Growth, Detachment, and Grazing Mortality of Attached Bacteria." Applied and Environmental Microbiology 69.6 (2003): 3036.

http://www.adm.dtu.dk/upload/dfu/cv-publikationer/hoek/thomas_kioerboe/kioerboe%20et%20al%202003%20-%20aem.pdf

Kiørboe, Thomas, et al. "Particle-associated flagellates: swimming patterns, colonization rates, and grazing on attached bacteria." Aquatic microbial ecology 35.2 (2004): 141-152.

http://www.dtu-aqua.dk/upload/dfu/cv-publikationer/hoek/thomas_kioerboe/kioerboe%20et%20al%202004%20ame.pdf

Artolozaga, Itxaso, et al. "Grazing rates of bacterivorous protists inhabiting diverse marine planktonic microenvironments." Limnol. Oceanogr 47.1 (2002): 142-150.

http://72.48.224.78/lo/toc/vol_47/issue_1/0142.pdf

Please read:

http://www-mpl.ucsd.edu/people/dstramski/14_Stram.pdf

http://www.uibk.ac.at/limno/files/pdf/antonie_van_l.pdf

http://plankt.oxfordjournals.org/content/19/10/1429.full.pdf

you can try the following too-

https://sapientia.ualg.pt/bitstream/10400.1/1891/1/Montagnes%20et%20al%202008%20Aquat%20Microb%20Ecol.pdf