“…For example, microbes may exploit zooplankton as a nutrient-and carbonenriched microhabitat by colonizing its exoskeleton and/ or gut (Carman and Dobbs, 1997;Tang et al, 2010). Additionally to the nutrient-enriched conditions, the zooplankton's gut provides a hypoxic environment that may facilitate marginal but important anaerobic processes such as denitrification, dissimilatory nitrate or nitrite reduction and methanogenesis in the oxygenated open waters (De Angelis and Lee, 1994;Tang et al, 2011;Glud et al, 2015;Stief et al, 2017). Finally, the zooplankton's acidic digestive tract may promote iron recycling and solubilization via multiple pathways involving microbes (Tang et al, 2011;Nuester et al, 2014;Schmidt et al, 2016).…”