Effects of elevated CO2 on the ecological status of benthic harpacticoid copepods

Abstract

In order to understand the effects of ocean acidification on coastal benthic organisms, research needs to address the species-specific changes in relation to the ecological status of the species. We investigated the changes in community characteristics and survival rates of harpacticoid copepods in non-classified assemblages and in a single-species community when exposed to increased CO2 levels indirectly in the sediment or directly in the seawater. The level of CO2 in the seawater was elevated artificially to concentrations of 1000 ppm in the laboratory setting to emulate the conditions of ocean acidification. The abundance and biomass of harpacticoid copepods in the sediment did not differ significantly between the control (400ppm) and the test (1000ppm) groups when exposed to increased CO2 levels in the seawater. The experiments with harpacticoid copepod assemblages and harpacticoid adult copepods of one species, Tigriopus japonicus, cultured in the laboratory, revealed no significant difference in the changes of survival rates between the control and the test groups when exposed directly to increased CO2 levels in the seawater. However, the changes of survival rates of T. japonicus adults collected from the coastal areas and nauplii originating from the cultivated T. japonicus were significantly different between the control and the test groups. This means that survival rates of T. japonicus adult in situ and nauracteristics and survival rates of harpacticoid copepods in non-classified assemblages and in a single-species community when exposed to increased CO2 levels indirectly in the sediment or directly in the seawater. The level of CO2 in the seawater was elevated artificially to concentrations of 1000 ppm in the laboratory setting to emulate the conditions of ocean acidification. The abundance and biomass of harpacticoid copepods in the sediment did not differ significantly between the control (400ppm) and the test (1000ppm) groups when exposed to increased CO2 levels in the seawater. The experiments with harpacticoid copepod assemblages and harpacticoid adult copepods of one species, Tigriopus japonicus, cultured in the laboratory, revealed no significant difference in the changes of survival rates between the control and the test groups when exposed directly to increased CO2 levels in the seawater. However, the changes of survival rates of T. japonicus adults collected from the coastal areas and nauplii originating from the cultivated T. japonicus were significantly different between the control and the test groups. This means that survival rates of T. japonicus adult in situ and nau