ANTHROPOCENE TRIPLE STRESS: IMPACT OF EXPERIMENTALLY INDUCED OCEAN ACIDIFICATION, DEOXYGENATION, AND WARMING ON BENTHIC FORAMINIFERAL COMMUNITY COMPOSITION AND GROWTH

Since the beginning of industrialization, carbon dioxide (CO₂) concentrations have increased in the atmosphere, causing an increase in oceanic pCO₂ that drives a decrease in oceanic pH, a process called ocean acidification (OA). Higher CO₂ concentrations have been linked to rising global temperatures, which can result in more stratified surface waters, reducing the exchange between surface and deep waters and leading to an expansion of oxygen-depleted zones (so called hypoxia or deoxygenation). Many studies have assessed the impact of these stressors individually or as pairs; fewer studies have assessed the impact of all three. We conducted a long-term experiment (>10 months) with different treatments of pCO₂, O₂, and temperature to determine the sole or combined impact of these stressors on the abundance and survival of a continental-shelf benthic foraminiferal community. Inoculation materials were collected from a ~75-m deep site south of Woods Hole, MA. The agglutinated Bathysiphon cf. B. minuta grew in each pseudoreplicate of each treatment. Calcareous species had more restricted occurrences, some being most common in oxygen-depleted treatments. Multidimensional scaling analysis (Primer) indicates that of the three factors, pCO₂ was least influential and that the triple stressor treatment (warm, hypoxic, high pCO₂) differed from all other treatments, suggesting a compounded impact from multiple stressors. Additional results on assemblage composition and growth will be presented. Supported by NSF OCE-1219948 and the Investment in Science Fund at WHOI.