Marine microbes are vital to oceanic ecosystems and influence the global climate through their paramount role in Earth’s biogeochemical cycles. With this intricate role in ecosystems, it is important to understand the effect of increasing ocean temperatures on the cycling of organic matter (OM). We experimentally investigated the temperature sensitivity of microbial consumption of marine particulate OM focused in the rapidly warming Gulf of Maine during the 2019 and 2020 Fall bloom. The overall rate and quantity of microbial OM (C, N, and P pools) consumption at in situ versus elevated temperatures were quantified within bottle incubations over the course of two weeks. The results indicate that OM incubated at warmer temperatures (+5 – 6°C) was significantly different and consumed at a faster rate with an overall larger quantity consumed compared to cooler temperatures (12 – 14°C). Overall, more nitrogen-rich OM was primarily consumed in both incubation temperatures for the 2019 experiment and in the cooler incubation temperature for the 2020 experiment, leaving behind carbon-rich OM. Whereas at warmer temperatures in the 2020 experiment, carbon-rich OM was primarily consumed presumably due to it being a bioavailable energy source to fuel elevated metabolic rates. The temperature coefficient (Q10) ranges from 2.66 – 3.42 in 2019 versus 0.94 – 1.21 in 2020, dependent on the OM elemental pool, suggesting temperature plays an important role in OM consumption, but is not the only factor contributing to faster rates and overall quantities.
