Long-term changes in rocky intertidal macrobenthos during the five years after the Hebei Spirit oil spill, Taean, Korea

ABSTRACT An appropriate oil spill response involves evaluation of the likely consequences of treatment or cleanup on ecological and human resources. Two cases are examined: the first is the Metula spill in the Straits of Magellan, Chile, where surveys over a 24-year period provide data on long-term changes on oiled shorelines that were not cleaned or treated. The consequences of the decision not to clean or treat are minimal as the only remaining oil today is restricted to an asphalt pavement and two marshes. In the second case, the 1995–1996 cleanup that followed the Komi pipeline spills in Russia, the operational objective was to prevent oil from affecting downstream resources and populations. This objective was achieved by containment of the oil near the source but the success of the project must be weighed against the consequential additional oiling and construction damage that resulted from the operations to more than 20 hectares of pristine terrain. These two spills in remote locations provide valuable lessons on some aspects of decision trade-offs and on the consequences of the cleanup decision in the context of the concept of net environmental benefit.

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Long-Term Changes in Thecomposition, Abundance and Diversity of Phytoplankton Community of Oshika Rivers State

Asian Journal of Environment & Ecology ◽

10.9734/ajee/2021/v16i430262 ◽

2021 ◽

pp. 92-116

Author(s):

Nkechinyere Gladys Nwambara ◽

John Onwuteaka ◽

Onyinye Prince Choko

Keyword(s):

Community Structure ◽

Oil Spill ◽

Phytoplankton Community ◽

Species Turnover ◽

Diversity Indices ◽

Dry Season ◽

Wet Season ◽

Long Term Changes ◽

Abundance And Diversity

This study was aimed at determining the long-term changes in composition, abundance, and diversity of the phytoplankton community of the Oshika freshwater biota. Phytoplankton samples at Oshika lake were collected from the same stations and similar months as in the year 1983 study of the 5000 barrels of oil spill. The samples were handled with optimum care and treated according to standard practices in order to preserve the plankton for further analysis and identification. The results of the analysis showed that the phytoplankton yielded a total of 40 species belonging to three groups in 1983 and 36 species belonging to four groups in 2019. Xanthophyceae was the group absent in 1983 but present in 2019, while Chlorophyceae, Cyanophyceae and Bacilariophyceae were common to both 1983 and 2019. Generally, the abundance of phytoplankton in each group in 1983 was significantly different from those of 2019. The Chlorophyceae was the most abundant in both 1983(12.31-186.5) and 2019 (1.27-6.58). The diversity indices result showed that the phytoplankton in 1983 (2.123- 2.563) had lower diversity compared to 2019 (2.381- 2.815). The cluster analysis revealed two groups in 1983 viz the generalist and the dry season specialist, while three groups viz the dry season specialist, wet season specialist and the generalist were observed in 2019. More so, greater data variations were observed in 1983 than 2019. Hence, we infer that there were changes in the phytoplankton community structure between 1983 and 2019. There were changes in the biological community structure between 1983 and 2019. These changes cannot be linked to the oil spill but seems more likely a result of natural variation since results of studies on the hydrocarbon values in water were very insignificant. Since the lake-riverine system is subject to flooding it can be concluded that new plankton from unaffected areas are transported into this area during the flood. The mixing of the water over the years leads to the high variable change. The high variable change brings about high species turnover given the unrestricted hydrodynamics of the River Niger flooding system and its influence on the floodplain Oshika lake.

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