Changes of Tissue N Content and Community Structure of Macroalgae on Intertidal Rocky Shores in Tongyeong Area due to Sewage Discharge

摘要

Enrichment in nutrients coming from urban sewage outfalls can lead to eutrophication in coastal areas, which can also change the species composition and community structure of macroalgal communities. We investigated the structure of the macroalgal community within three rocky shores in order to assess any possible differences in their characteristics. Site 1 was located near Tongyeong city's sewage outfall, Site 2 was located near a public beach area, and Site 3 faced open channel of the Ocean. All three sites were located within the same stretch of the coast, where Site 2 was located between sites 1 and 3. We measured the nutrient concentration in water and the tissue nitrogen content in macroalgae samples. Nutrients in the water column surroundingsite 1 were high in ammonium (30.2+- 1.8 mu M), nitrate (26.2+-0.1 mu M), and phosphate (2.7+-0.1 mu M) content, and were characterized by low numbers of macroalgal species and species and a low species diversity index. In contrast, site 3 exhibited relatively low nutrient concentration levels and a high number of macroalgal species and a high species diversity index. Comparative analysis showed that the tissue nitrogen content of macroalgae were significantly (P<0.05) affected by the nutrient concentration in the water column. The tissue nitrogen content of green algae within site 1 was higher than the others sites. However, the tissue nitrogen content of brown algae was similar at all three sites. Thus, the tissue nitrogen content of macroalgae andthe macroalgal community structure of intertidal rocky shores were dependent on location and the performance of macroalgal communities was dependent on water quality.