Differences in Species Found using Different Examination Methods in a Large-scale Benthic Zone in the Banzu Tidalflat of Tokyo Bay (Adjacent to the Mouth of Obitsu River) and Comparative Community Analysis

Abstract

Many types of approaches may be used in surveys of species that inhabit intertidal zones (e.g. observational, qualitative, quantitative), and the degree of identification accuracy vary among methods. Thus, even when comparative studies of different surveys are conducted, their reliability often comes into question. In this study, we investigated the mudflat adjacent to the mouth of Obitsu River, which flows through Kisarazu City, Chiba Prefecture, before emptying into Tokyo Bay. Back marsh, foreshore mudflats, and many other types of wetlands intersect here. Two different methods with a similar level of identification accuracy--a qualitative core sampling method and a qualitative civil procedure--were used to identify species in an identical area. We compared the results of the two methods, as well as examined methods for comparing two different surveys, and evaluated the need to alter the classification system and be aware of easily misidentified species. Results of community structure analysis, such as cluster analysis and non-metric MDS, were extremely consistent, suggesting that comparisons of community structures may be sufficiently effective to compare surveys of species in this type of environment.