Sediment macrofaunal composition and sediment geochemistry of deep-sea coral habitats after the Deepwater Horizon oil spill in the Gulf of Mexico, 2010-2016

Deep-sea corals create complex habitats that support distinct sediment communities. Several deep-sea coral habitats were impacted by the 2010 Deepwater Horizon spill, and recovery of associated sediment communities may take several years. While spill-associated organic enrichment may lead to increased abundances of tolerant taxa, toxic effects of the spill may lead to declines in sensitive groups. However, temporal variability in coral-associated sediment macrofauna is unknown and represents an important consideration for post-spill community assessments. Here we examine how the macrofaunal communities change over time at impacted and reference sites. From 2010 to 2016, we examined macrofaunal communities at multiple impacted and reference deep-sea coral sites to quantify post-spill temporal changes in community metrics coupled with sediment characteristics (e.g., grain size, organic carbon, and stable carbon isotopes). Study areas were located in the northern Gulf of Mexico on the continental slope off Louisiana and Mississippi. Sediment push cores were collected to assess composition, numerical abundance, and diversity of macrofauna (greater than 300 μm) and sediment geochemistry adjacent to deep-sea coral habitats. These multi-year data provide an unprecedented 7-year post-spill baseline for assessing changes in coral-associated sediment communities in natural habitats than can help inform future monitoring and restoration activities.