Zooplankton abundance and diversity in the ballast water of ships, Shahid Rajaee Port, Persian Gulf, Hormozgan, Iran

In the present study, the ballast waters from 24 ships arriving at Shahid Rajaee Port in Bandar Abbas, Hormozgan Province, Iran, were studied in two warm and cold seasons (summer 2017 and winter 2018). The zooplankton sampling was conducted under the MEPC 173(58) method, by bucket and using a 50-micron mesh to filter 300 liters of ballast water. In total, 57 zooplankton species, belonging to 8 phyla, 11 classes, 15 orders, and 35 families were identified in the sampled ballast water, among which the Arthropoda phylum with 16 families and 23 species recorded the highest number of species  The highest and lowest density among the studied samples belonged to the Tintinnopsis gracilis species from the Codonellidae family (11.4%) and Calanopia elliptic species from the Pontellida family (0.04%), respectively. The results of the Pearson correlation test showed that there was a negative correlation between the measured pH parameter and the frequency of zooplankton (p<0.01). There was also a positive correlation between EC and Shannon diversity index (p<0.05). PCA test results showed that EC, temperature, salinity, and TDS factors had the most impact in stations with the highest number of species and abundance of zooplankton. The results of the cluster diagram showed the highest similarity between winter at the Western Indian Ocean (WW) and summer at the Western Indian Ocean (WS) at the level of 54%, and the lowest similarity between the winters at the Northwestern Indian Ocean (NW) at the level of 24% with other regions. All the studies species in the ballast waters of the Persian Gulf had been identified and reported by previous studies but certainly requires continuous monitoring management of the ballast water, and supervising their discharge into the marine environment.