The effect of crude oil on the symbiotic association of the green alga Acrosiphonia arcta (Dillwyn) Gain and epiphytic bacteria

Abstract

It was experimentally shown that the green alga Acrosiphonia arcta, inhabiting the Barents Sea littoral zone, remains viable for 10 days in case of exposure to crude oil introduced into seawater at a concentration of 5 mg·L−1. This concentration corresponds to a weak oil spill in the marine environment. Morphological and functional changes in the symbiotic association of A. arcta and epiphytic bacteria on its surface were traced by the techniques of microbiology, light and electron microscopy, and physiology. During the experiment, most algal cells maintained a high level of photosynthesis, and their ultrastructure was preserved. Interestingly, by the end of the exposure, under the effect of crude oil, the proportion of chloroplasts decreased in algal cells, and the pyrenoid and starch granules disappeared. The dynamics of the number of epiphytic bacteria in the experiment and the proportion of hydrocarbon-oxidizing bacteria in the total number of cultivated heterotrophs were traced. The capability of A. arcta to absorb and transform oil products was shown. This algal species is capable of developing in oil-contaminated water areas on any substrate, preparing it for colonization by larger perennial macrophyte algae, and this determines the significant role of A. arcta in the restoration of coastal phytocoenoses.

Keywords

• Acrosiphonia arcta
• oil
• seawater bioremediation
• symbiotic association
• epiphytic bacteria
• photosynthesis