Copepod abundance and species composition in the ballast water of ships entering the port of Majidiyeh-Mahshahr (northwest of the Persian Gulf)

The transfer of alien and invasive species through the ballast water of vessels is one of the most important threats to aquatic ecosystems.  This study aimed to investigate the ballast water of 10 vessels entering the export port of Majidiyeh Mahshahr in 2018. A sampling of zooplankton from each vessel was performed by filtering 100 litres of ballast water of each vessel using a plankton sampling net with 50 μm mesh with three replications. Simultaneously, environmental factors including dissolved oxygen, acidity, temperature, and salinity were measured with 3 replications in the ballast water of the vessels. The results of a one-way analysis of variance showed that there is a significant difference between the vessels entering the export port of Majidiyeh in terms of the average density of Copepods. The highest average density 3.2×104 ind/m-3 and the number of species (36 species) related to ARGO1 ship from Bandar Abbas and the lowest average density 1×104 and the lowest number of species (24 species) belonged to PRECIGIOUS and GUNISHLI from Fujairah, UAE, respectively. There was a significant positive correlation between the average density of Copepods with temperature and dissolved oxygen. In total, 3 orders, 20 families, 28 genera, and 56 species were identified. All identified species except Oithona davisae have been previously reported from the Persian Gulf. O. davisae species was found only on the CONSTANTINOS ship from the port of Fujairah, UAE. It is native to the coastal waters of East Asia, especially around Japan and China, and has been reported in the Black Sea, the central Mediterranean, and more recently in the Aegean Sea. This research can be important for assessing the potential risk of new invasive species as well as for improving the quantitative and quality management practices of ships' ballast water.