Environmental heterogeneity and hydrocarbon-associated patterns in deep-sea meiofaunal communities following the Deepwater Horizon spill

Hydrocarbon contamination is associated with benthic ecosystem variation, yet biological responses are often heterogeneous and can be modified by organic enrichment and spatial environmental gradients. Hydrocarbon-associated patterns were evaluated for deep-sea meiofaunal communities at 109 stations sampled during September-October 2010. The sum of 44 polycyclic aromatic hydrocarbons (PAH44) was used as an aromatic-hydrocarbon exposure metric. At mean total organic carbon (TOC), a one-standard-deviation increase in ln-transformed PAH44 was associated with 39% higher nematode abundance and an approximately 75% higher modeled nematode:copepod response on the ln(1 + N:C) scale, whereas copepods, nauplii, kinorhynchs, and ostracods were approximately 21%, 33%, 49%, and 42% lower, respectively. After accounting for geographic structure, there was no robust PAH44 × depth interaction. These results refine, rather than overturn, earlier evidence of Deepwater Horizon (DWH)-related benthic change: within the established post-spill footprint, the magnitude of meiofaunal responses varied with environmental and spatial context.