Seaweeds and Decapod Crustaceans on Gulf Deep Banks after the Macondo Oil Spill

The diversity of seaweeds and decapod crustaceans associated with rhodoliths on deep offshore banks in the northwestern Gulf of Mexico decreased dramatically after the Macondo blowout. Decapod crustacean communities declined in both abundance and diversity and exhibited major shifts in species dominance. Rhodoliths appear to serve as seedbanks for biological diversity because dead rhodolith rubble became covered by epi- and endolithic algae and microbes in laboratory microcosms. Decreased seaweed abundance in the field may relate to nutrient availability and microbial interactions. We hypothesize that declines of deep bank decapods largely reflect the loss of seaweed cover, which may have led to cascading effects on direct consumers and higher trophic levels. However, negative impacts of postspill increases in lipoclastic and chitinoclastic bacteria cannot be ruled out as possible contributors to overall decapod declines, although the evidence implicating these factors was limited only to decapod samples from nearby deeper soft substrates.