Variation in the diversity and abundance of benthic foraminifera on the Bandar Abbas coasts; an indicator for influence of wastewater effluent to the coastal ecosystem during the last century.

In this study, frequency and diversity of benthic foraminifera of 44 samples from a 14C dated sediment core were used to assess the effects of human activities on pollution and creating hypoxic conditions in coastal sediments of Bandar Abbas. The results showed that during the last century, the construction of coastal infrastructures and expansion of the city caused 5% elevation of  sand input to the area. Variations of frequency and diversity of benthic foraminifera during the last decades also follows the above-mentioned changes. During the recent decades, the relative abundance of opportunistic hyaline taxa such as Cribroelphidium, Asterorotalia and Ammonia, and also conical species such as Bolivina and Bulimina which show higher ability to survive in polluted environments with lower oxygen content increased 100 to 200%. On the other hand, more than 150% reduction of species with thicker walls (Milliolids such as Massilina and Quinqueloculina) in this time show the intense environmental changes caused by human activities in coastal areas of Bandar Abbas. Altogether, significant increase in sewage runoff due to urban and industrial development of Bandar Abbas has had a great impact on the coastal ecosystem of the city, which should be mitigated by taking the right management decisions