Estimating rates of gross TEP production and heterotrophic consumption from natural assemblages

Aggregation aided by transparent exopolymer particles (TEP) is the most common mechanism facilitating marine carbon export. However, the mechanisms that mediate TEP accumulation difficu-lt to parameterize. Here, we present a novel adaptation the dilution method, to quantify in situ rates of biological community (< 200 m) instantaneous gross TEP production, TEP consumption, and net TEP production. We examined TEP under two different nutrient regimes in a mesocosm experiment in Bergen, Norway. TEP concentrations ranged from 37.7 6.6 247 22 g XG eq. L-1 under replete conditions and 37.8 12 195 27 g XG eq. L-1 under P-limited conditions. We observed decoupling of TEP and chlorophyll-a, with 3-4x increases in magnitude of TEP:Chla ratio coinciding with shifts in measured rates of TEP consumption and production. This research reinforces the idea that variation in rates of TEP production and consumption alter TEP accumulation, potentially impacting biological pump efficiency.