We conducted a series of experiments in Monterey Submarine Canyon to examine potential ecological impacts of deep-ocean CO2 sequestration. Our focus was on responses of meiofaunal invertebrates (< 1 mm body length) living within the sediment at depths ranging between 3000-3600 m. Our particular emphasis was on harpacticoid copepods and nematodes. In the first phase of our DOE funding, we reported findings that suggest substantial (~80%) mortality to harpacticoid copepods. In the second phase of our funding we published additional findings from phase one and conducted follow-up experiments in the Monterey Canyon and in the laboratory. In one experiment we looked for evidence that meiofauna seek to escape areas where CO2 concentrations are elevated. “Emergence traps” near the source of the CO2-rich seawater caught significantly more harpacticoids than those far from it. The harpacticoids apparently attempted to escape from the advancing front of carbon dioxide-rich seawater and therefore presumably found exposure to it to be stressful. Although most were adversely affected, species differed significantly in the degree of their susceptibility. Unexpectedly, six species showed no effect and may be resistant. The hypothesis that harpacticoids could escape the effects of carbon dioxide-rich seawater by moving deeper into the seabed was not …