Gut Fluorescence measurements of mesozooplankton grazing on autotrophic prey. Samples collected in the CCE-LTER region on Process Cruises from 2006 to the present. Summaries for each Lagrangian Cycle.

Mesozooplankton are collected with plankton nets (typically a 71-cm diameter, 202-um mesh Bongo net) and samples flash frozen at sea in liquid N2 for subsequent shore-based measurements of ingested phytoplankton chlorophyll-a. Measurements of mesozooplankton gut fluorescence are done by fluorometric analysis on a Turner Designs fluorometer of gut pigments extracted in 90% acetone. Analyses are done on mesozooplankton size-fractionated into 5 different categories on Nitex mesh (> 0.2 mm, 0.5 mm, 1.0 mm, 2.0 mm, 5.0 mm). The pigment content (as Chl-a and phaeopigments) is then expressed as mass of pigment ingested per m3 of water filtered, or divided by the dry weight biomass of the mesozooplankton in the same sample in order to obtain mass-specific ingestion per m3 of water. Application of published values of the temperature-dependent gut passage time are used to estimate the mesozooplankton grazing rate, as pigments ingested per m3 per unit time, or the corresponding mass-specific rate of ingestion. Samples for gut fluorescence assays have been collected on CCE-LTER Process Cruises since 2006 and these collections are ongoing.