Paper No. 64-1
Presentation Time: 1:30 PM
BIOTURBATORS—AGENTS OR RECIPIENTS OF WARMING-INDUCED BIOGEOCHEMICAL CHANGE? (Invited Presentation)
Bioturbators—burrowing and sediment-mixing animals—are among the foremost ecosystem engineers in today’s oceans. In particular, by mixing oxygenated bottom waters into seafloor sediments and reshaping the vertical distributions of reduced sedimentary species such as organic matter and sulfide minerals, bioturbators can substantially influence nutrient regeneration and seafloor and seawater redox state over both ecological and geologic time scales. Given their importance for seafloor ecology and biogeochemical cycling, reconstructing the impacts of major extinction episodes and climatic perturbations on burrowing animals has long been a critical concern. However, considerable uncertainties remain regarding how not only different groups of burrowing animals but also different bioturbator ecologies will respond to environmental and climatic stressors such as rapid warming. Similarly, to what extent bioturbators keep pace with or lag behind climate-mediated shifts in seafloor microbial activity, or whether the impacts of bioturbation are likely to be swamped by other environmental factors, are currently largely undetermined. Therefore, we have few constraints on the magnitude—or even the sign—of bioturbation-mediated biogeochemical changes in the wake of environmental perturbations. There is not, for instance, consensus on whether these are likely to aggravate or ameliorate delays in ecosystem recovery. I will present results, drawn from a combination of field-based bioturbation analyses, geochemical data, incubation experiments and numerical modeling, exploring the impact of environmental and climatic perturbations—both ongoing and ancient—on bioturbator behaviors and associated biogeochemical change. I will focus on the effects of warming events on bioturbators and associated shifts in phosphorus and carbon cycling, with implications for marine productivity, redox state and ecosystem health.