The impact of weathered IXTOC I oil on experimental benthic communities colonized in the laboratory and in situ was observed. Text systems containing clean sand and receiving seawater from Aransas Pass Inlet were placed in the laboratory while similar systems were placed on the seafloor. All of these test systems were allowed to colonize for eight weeks by settlement of planktonic larvae. Weathered IXTOC I oil was added to randomly selected laboratory and in situ replicate compartments within the test systems and these were then exposed to flowing seawater in the laboratory for an additional four weeks.