Seasonal Changes in the Intertidal and Subtidal Algal Communities of Extremely and Moderately Polluted Coastal Regions of Sanya Bay (Hainan Island, China)

Eduard A Titlyanov,Huili Xu,Hui Huang,Xiubao Li,Tamara V Titlyanova,Anna V Scriptsova

doi:10.3390/jmse7040093

Abstract

At the end of the rainy season in 2016 and at the end of the dry season in 2017, we conducted a floristic study of marine macrophytic algae in the intertidal and subtidal zones in moderately and heavily polluted areas at Luhuitou reef, Sanya Bay, Hainan Island, China. A total of 109 species of marine macrophytes were found during these samplings. At the end of the rainy season, 72 species of macrophytes (50% reds, 19% browns, and 31% greens) were found. At the end of the dry season, we found and identified 92 species of macrophytes (46% reds, 20% browns, and 34% greens). Seasonal changes in species diversity, species composition, and the structure of algal communities at differently polluted sites exhibited common features as well as specific characteristics. By the end of the dry season, the diversity of macroalgal species was increased, and the composition of dominant and accompanying species of macrophytes in polydominant communities was changed in moderately and heavily polluted areas. Seasonal changes in the marine flora of differently polluted areas were characterized by specific features as follows: Less changes in species diversity of heavily polluted area compared with moderately polluted area during the change from the rainy season to the dry season; significant increase in the biomass of green algae and their projective coverage in the middle and low intertidal zones of heavily polluted sites in the dry season; and the increase in the numbers of mono- and bidominant communities in the middle and low intertidal zones of heavily polluted sites by the end of the dry season.

Highlights

Recent studies have shown that a number of natural and anthropogenic factors can cause long-term changes in the subtropical-tropical marine flora, and those annual and seasonal changes may be attributed to both abiotic and biotic environmental factors [1,2,3,4]
Previous studies [14,15,16,17,18] have shown that Sanya Bay is heavily polluted by dissolved inorganic nitrogen (DIN), phosphates, and dissolved organic compounds due to the intensive discharge of industrial wastewater from Sanya City into the bay as well as the wastes discharged from mariculture farms into the coastal waters
We have shown that heavily polluted areas are significantly different from moderately polluted areas in terms of the diversity of the flora, species composition, taxonomic composition, and the structure of algal communities, suggesting that extremely high concentrations of nutrients in seawater affect the succession of algal communities and seasonal changes related with their formation

Summary

Introduction

Recent studies have shown that a number of natural and anthropogenic factors can cause long-term changes in the subtropical-tropical marine flora, and those annual and seasonal changes may be attributed to both abiotic and biotic environmental factors [1,2,3,4]. Previous studies [14,15,16,17,18] have shown that Sanya Bay is heavily polluted by dissolved inorganic nitrogen (DIN), phosphates, and dissolved organic compounds due to the intensive discharge of industrial wastewater from Sanya City into the bay as well as the wastes discharged from mariculture farms into the coastal waters. Some coastal waters are catastrophically polluted by organic wastes discharged from marine farms producing fish and invertebrate animals, where the nutrient concentration exceeds on average 10 times or even hundreds the recommended levels [18]

Methods

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Discussion

Conclusion