Microbial deterioration of partially submerged service timbers in a tropical inter-tidal zone

The micromorphological features of decay in service timbers in a tropical inter-tidal zone were studied to ascertain the pattern of biodeterioration. Bacterial tunneling, soft-rot cavities and basidiomycete attack were evident in parts of the timbers between low and high tide water levels. Bacterial erosion was frequently encountered below the waterline at low tides while tunneling was rare and soft-rot or basidiomycete attack was not observed. However, only rare soft-rot and frequent basidiomycete degradation were observed above the waterline at high tide. A microchemical test indicated that lignin was attacked only in wood areas above the waterline at high tide while cellulose degradation occurred in all areas. The observation on the pattern of decay may be useful in predicting the service life of timbers in the tidal zone.