Definition of picoplankton in English:
picoplankton
Pronunciation /ˈpiːkəʊˌplaŋ(k)tən/
noun
Biology
Plankton consisting of organisms between 0.2 and 2.0 microns in diameter, or having a wet weight of the order of 10−12 g.
Origin
1970s. From pico- + plankton.