In pelagic plankton ecosystems, the number of zooplankton species in a certain taxon (e.g., copepods) can be used, because there are a sufficient number of samples to provide accurate estimates. The number of benthic species can also be used for deep-sea ecosystems. Thus, simple and common indices such as species richness

(i.e., the number of species) can be used for different ecosystem types. The next step is to develop better indices considering the evenness of species distribution as well as phylogenetic relatedness. This is especially important for comparisons among different ecosystems because of large differences in lifetimes and speed of evolution [42]. More importantly, problems associated with the effects of research efforts on the estimation of species diversity should be

considered as in the case of criterion 1 (Nakajima et al. 2015). This criteria is defined as an “area with a comparatively higher VE-821 cell line degree of naturalness as a result of the lack of or low level of human-induced disturbance or degradation,” [5]. This criterion is a relative measure in that “pristine conditions” are most important and should be preserved as best as possible. In Selleckchem BGB324 this research program, data such as the area of natural reserves, ratio of natural to artificial coastline, and human population size per catchment area are available and can be used for coastal ecosystems like kelp forests, seagrass beds, and coral reefs. On the other hand, offshore pelagic plankton and deep-sea benthic ecosystems, of which we are not yet able to determine the direct effect on fisheries, are mostly regarded as relatively natural; therefore, it is difficult to find relevant data showing variations in “naturalness.” For offshore pelagic ecosystems, data recorded from fisheries can be used, although the available species are limited. Distance from the coast can also be used as a rough approximation of fishing intensity. For deep-sea ecosystems, depth can be used as an approximation of fishing effort. The possible exploitation of deep-sea

energy and mineral resources must also be Dimethyl sulfoxide considered, because deep-sea research that is based on long-term observations is insufficient to analyze the dynamics of unique ecosystems such as hydrothermal vents [43]. In theory, criterion 7 must be identified by quantifying human activity and its impacts on ecosystems. Available quantitative indices are mostly from the statistics of the Japanese government. In order to apply these indices to other countries in Asia, satellite images such as nighttime images of artificial light density and changes in coastline structures can be used to measure spatial and temporal variations in human impacts. Globally, the human impact model [44] can be used as an index of naturalness. For the open ocean, the use of fisheries statistics should be considered.