Seasonal Variation of Cochlodinium polykrikoides in the North of Oman Sea (Iranian Waters)

Abstract

This study was carried out to investigate the Cochlodinium polykrikoides fluctuations in the north of Oman Sea during preand post-monsoon season in 2008. The study area was divided into 10 transects (T1-T10) from the Strait of Hormuz (T1) to Gwadar (T10) which cover the whole of the Iranian waters in the Oman Sea. The results showed that at first, Cochlodinium polykrikoides appeared in the northeast part (T10) in the pre-monsoon season, then it spread to other parts of the study area. Cochlodinium polykrikoides was observed in greater abundance in the Strait of Hormuz in the post-monsoon season. The results demonstrated that T10 (transect 10) had the highest abundance in the pre-monsoon season. The Kruskal-Wallis test showed a significant difference among transects (P < 0.05). The present study showed that the abundance of Cochlodinium polykrikoides increased from coastal to offshore waters in the pre-monsoon season; however, in the post-monsoon season, there was a higher abundance in coastal waters compared to the offshore zone. It could be seen that the abundance of Cochlodinium polykrikoides started in offshore waters, then increased in coastal waters. During the pre-monsoon season, water discoloration was not observed, however, the water changed to brown from T1 to T4 (northwest) and blooms of Cochlodinium polykrikoides was recorded in the post-monsoon season.