Abstract: In this study we selected five marine animal and plant macromolecular polymers or their natural tissues, including shrimp shells, fish scales, kelp blades, chitin and chitosan, which were enriched in the surface seawater and sediment environments and sampled regularly. The diversity of bacteria was analyzed with high-throughput sequencing. The results showed that significant differences were found in the diversity of bacteria in the In situ enrichment of organic compounds and in the degrading bacteria in the surface seawater and sediments of the same organic substrates. For species diversity, it is the most abundant on the fish scales enriched in the surface seawater environment in contrast to the lowest diversity of bacterial flora on the kelp blades enriched in the sediment environment. Besides thermophore, the dominant bacteria in all the other enrichments were Proteobacteria. Among them, Desulfobacteraceae, Flavobacteriaceae, Desulfovibrionaceae and Vibrioaceae accounted for a large proportion with dominant Desulfobacteraceae in all samples. Flavobacteriaceae dominated in bacterial flora in the samples in surface seawater environment. Vibrioaceae had a high abundance in chitin and chitosan samples in the sediments. With comparisons of the different enrichment samples in the same marine environment and the enriched bacteria on the same organic substrate in different environments, it shows the types of bacterium flora involved in the In situ degradation process of macromolecular polymers. However, it needs to be further verified with more marine enrichment samples.