A method for identifying in situ presence of a hydrocarbon reservoir or of a pipeline leakage is disclosed. The method can include obtaining a sample from an area of interest, such as a sediment sample or water column sample near a hydrocarbon seep or near an offshore pipeline; analyzing the sample to detect nucleic acid, protein or metabolite signatures that are indicative of cold-shock response; identifying the relative abundance of the cold-shock signatures present in the sample in comparison to the surrounding environment.