Algae. 2007; 22(1): 37-44.
Ten Years’ Monitoring of Intertidal Macroalgal Vegetation of Hyogo Prefecture, Northwestern Coast of Honshu, Japan to Assess the Impact of the Nakhodka Oil Spill
Hiroshi Kawai1*, Mitsunobu Kamiya2, Teruhisa Komatsu3, Masahiro Nakaoka4, Tomoko Yamamoto5, and the Marine Life Research Group of Takeno6
1Kobe University Research Center for Inland Seas, Rokkodai, Nadaku, Kobe 657-8501, Japan 2Faculty of Biotechnology, Fukui Prefectural University, Obama, Fukui 917-0003, Japan 3Ocean Research Institute, The University of Tokyo, 1-15-1, Minamidai, Nakanoku, Tokyo 164-8639, Japan 4Graduate School of Science and Technology, Chiba University, Inage, Chiba 263-8522, Japan 5Faculty of Fisheries, Kagoshima University, 4-50-20, Shimoarata, Kagoshima 890-0056, Japan 6Takeno Snorkel Center, Takeno, Takeno-cho, Kinosaki, Hyogo 669-6201, Japan
ABSTRACT
In order to understand the impact of the heavy-oil pollution by the 1997 Nakhodka oil spill on the intertidal macroalgal vegetation, we have been monitoring succession in the intertidal flora since 1997 at Oh-ura, Takno, and Imago- Ura Cove, Kasumi in Hyogo Prefecture, northwestern coast of Honshu, Japan. We employed two different monitoring methods: 1) The percent cover of macro-algae (seaweeds) in 1 x 1 m quadrats along 450 m intertidal transects parallel to the shoreline were assessed and recorded by photographic imaging until 2002, and for 30-40 m transects of the most heavily polluted areas in 2004 and 2006; 2) The percent cover of macro-algae in 0.5 x 0.5 m quadrats along a transect line perpendicular to the shore were recorded and all macrophytes within the quadrat were completely removed to record the wet weight of each taxon (1997-2006). Based on the monitoring data, we conclude that the high intertidal zone at Imago-ura, where a large part of the stranded oil accumulated, suffered the heaviest damage and experienced the slowest recovery. In addition, although the original status of macroalgal vegetation before the impact was not well-documented, it appeared that recovery from the damage caused by the oil pollution required four to five years.
Keywords :
heavy-oil spill, impact on intertidal vegetation, line transect study, macroalgae
