Distribution and seasonal variations of hydrocarbons in the molluscs of Shatt al-Arab River

الملخص EN

The seasonal variations of hydrocarbons in molluscs of Shatt Al- Arab river have been studied.

These species of molluscs were the snails, Lymnaea auricularia, Theodoxus jordani, Physa acuta, Melanopsis nodosa and Melanoides tuberculata while the bivalves were Corbicula fluminea and Corbicula fluminalis.

The molluscs were collected from different locations of Shatt Al-Arab river (along the region extended from Abu Al-Khasib to Garmat-Ali) during 2004 and 2005.

Each species consisted of at least 3500 adults and uniform size of individuals.

The hydrocarbons were extracted and analyzed by spectroflurometer.

The concentrations of total hydrocarbons referred to (Basrah regular crude oil equivalents) in different molluscs species varied from 1.93 μg / g dry weight in the T.

jordani to 9.83 μg / g dry weight in the C.

fluminea during Summer and from 2.90 μg / g dry weight to 22.37 μg / g dry weight during Autumn.

While ranges from 3.58 μg / g dry weight to 26.56 μg / g dry weight and from 2.60 μg / g dry weight to 14.13 μg / g dry weight during winter and spring.

This study confirmed higher concentrations of hydrocarbons in the mollusc’s species during winter and autumn while lower concentrations were measured during summer and spring.

This is due to several factors which could act to produce such seasonal variations.