Dr. Fereydoun Ghazban is an environmental geochemist from the University of Tehran who studies the interactions between geological and biological systems. Dr. Ghazban will be telling us about the influence of geological and anthropogenic input of nutrients on photosynthetic activity of phytoplankton communities in the Persian Gulf and how this can be related to climate-related carbon exchange.

Dr. Fereydoun Ghazban
Emeritus Professor of Environmental Geochemistry
University of Tehran

Potential Climatic and Ecological Impacts of Hormuz Salt Diapirs and associated minerals on Phytoplankton Communities in the Persian Gulf

Hormuz Island, located at the Strait of Hormuz in the Persian Gulf, is surrounded by a complex marine environment influenced by unique geological features, particularly submarine salt diapirs. Elevated chlorophyll-a concentrations were consistently observed along the southern and western coasts of the island during spring and autumn. The ascent of salt diapirs has exposed iron-rich sediments at the surface, while episodic rainfall and flash flooding facilitate the transport of iron-rich runoff from mining areas into adjacent coastal waters. Iron, a critical micronutrient that frequently limits phytoplankton growth in oligotrophic marine systems, appears to play a key role in stimulating localized phytoplankton blooms in the waters surrounding Hormuz Island. Enhanced iron availability promotes photosynthetic activity, increasing primary productivity and dissolved oxygen concentrations, while simultaneously facilitating the uptake of atmospheric carbon dioxide through the biological carbon pump. The combined influence of geological processes, particularly salt diapirs, and terrestrial iron input from mining runoff creates unique ecological niches that support diverse and spatially variable phytoplankton communities. This highlights the importance of geological-biogeochemical interactions in regulating coastal productivity and suggests that localized biological enhancement around Hormuz Island may contribute, at small scales, to regional ecosystem functioning and climate-related carbon cycling in the Persian Gulf.