Dinoflagellate cyst assemblages in recent sediments of Iran's tropical mangrove forests

Abstract

We investigated the distribution and composition of dinoflagellate cysts, including potential harmful algal bloom (HAB) species, in Iranian mangroves bordering the Persian Gulf and Oman Sea. Sediment samples were collected from 62 stations across 10 locations in three provinces (Bushehr, Hormozgan, Sistan & Baluchestan) in autumn 2020. Analysis of dinoflagellate cysts revealed a diverse assemblage encompassing 56 species, including 10 known to be triggers of harmful algal blooms (HABs). Genus Protoperidinium was dominant, exhibiting a 21.4 % abundance and comprising 14 species across 60 sampling stations. In contrast, genus Margalefidinium was present in 34 stations with only a single species. Margalefidinium polykrikoides was the key species of dissimilarity between provinces, driving distinct compositions in all pairwise comparisons. Scrippsiella acuminata was a significant contributor to the dissimilarity observed between the Bu and S&B, as well as the Ho and S&B assemblages. DistLM, dbRDA, and marginal tests confirmed that environmental parameters significantly (P > 0.05) influenced cyst composition across the provinces. Regular monitoring of environmental parameters alongside analyses of dinoflagellate cyst assemblages is a potential use for predicting HABs and also provide valuable insights into the well-being of essential mangrove ecosystems.