Effects of abiotic stressors on infaunal burrowing and associated sediment characteristics

Infauna play key roles in nutrient cycling and bioturbation by facilitating exchange across the sediment-water interface, but the effects of environmental stressors on the behavior of infauna are poorly studied compared to epifauna. Here we used laboratory experiments to examine the effects of temperature (15, 21, and 32°C), salinity (16, 22, 28, and 34), and food availability (low, moderate, high) on the burrowing activity of the opportunistic deposit-feeding polychaete Capitella sp. 1. We also used pH and O₂ fluorosensors to investigate the effects of burrowing on marine sediment chemistry. Worms buried significantly deeper at 21 than at 15°C, and they died at 32°C. Salinity only marginally affected the area of burrowing activity, with greater area at 35 than at 22. Burrows in highly enriched treatments were significantly more shallow than those in moderate and low food treatments. The fluorosensors showed that the exchange of solutes between the sediment and overlying water was associated with burrowing activity. These results show that changes in environmental conditions affect infaunal burrowing activity, which in turn affects sediment characteristics. We discuss the need to consider infaunal responses to abiotic stress in order to understand community and ecosystem responses to environmental changes associated with climate change, pollution, and eutrophication.