The deleterious effects of oil and dispersants on marine sponges and their microbial symbionts have yet to be examined for ecotoxicological purposes. In this study, we will examine the impacts of the Deepwater Horizon ("Macondo") crude oil and the dispersant, Corexit 9500, used in the BP oil spill, on the marine sponge, Cinachyrella alloclada by analyzing the expression of a panel of stress-related genes using real-time quantitative PCR, fluorescence in-situ hybridization (FISH), transmission electron microscopy (TEM) and measuring hydrocarbon compound load. Gene expression profiles of nuclear factor kappa beta (nf-?ß); thioredoxin (txn); dnaJ; heat shock protein 70 (hsp70); multidrug resistance-1 (mdr-1); glutathione peroxidase (gpx); ribosomal L12 (ribL12); elongation factor 1-alpha (ef-1a); ubiquitin; a-tubulin, and silicatein beta (silicb) will be examined following 1, 8, 24, and 48 h exposures to 0.5 ppm oil and dispersant fractions to test for a pollutant-related stress response. Additionally, FISH probes will be designed and hybridized to each time point/treatment sample and analyzed microscopically for probe signal intensity as it relates to strain specific bacterial load. TEM will be utilized to support identification of bacterial species found in FISH samples and validation by 454 sequencing results. Chemical analysis will report the hydrocarbon amounts for initial and end time point samples to infer their relations to sponge physiology. These findings will provide important insight into marine sponges as bioindicators of water and reef quality and their role in mitigating future oil spills.