Experimental result of a shipwreck influence on the surrounding soft sediment communities in the vicinity of Bushehr port, Persian Gulf

Abstract

Unplanned artificial reefs like old shipwrecks provide a hard substratum for the colonization of organisms, contributing to increasing local productivity and environmental carrying capacity especially when they are lies in soft sediment-dominated areas. Also, these structures can change the local current regime, sedimentation processes and composition of benthic species in the adjacent sediment. The present study aimed to evaluate the spatial effect of a shipwreck on its surroundings. Experimentally have been examined the relationship between sediment characteristics, abundance and macroinvertebrates richness in distance gradient (20, 50, 100 and 400 m) from a shipwreck that sank in 1983 on a soft bottom floor in the north of the Persian Gulf. Around the shipwreck, a total of 74 taxa were identified. The result indicated that macrobenthic density and richness varied significantly between distances with higher values at 20 and 50 m away from the wreck. Likewise, spatial variations in grain size were observed. A high concentration of gravel (63%) was recorded at about 20 m away from the wreck. Although, the amount of total organic carbon did not differ significantly among distances and does not explain the observed variations in density, richness and diversity of macrobenthos. In consequence, it is suggested that the proximity of the wreck modified the community structure of macrobenthos and sediment characteristics up to a distance of 50 m.