Long-term Assessment of the Environmental Conditions of Lake Nakaumi (Japan) Using Multivariate AZTI Marine Biotic Index (M-AMBI)

This study aimed to identify and understand the temporal changes in the benthic ecosystem of Lake Nakaumi, which is an enclosed brackish water body, using the multivariate AZTI marine biotic index (M-AMBI) as biotic indicators and to evaluate the benthos response to the reclamation project for the lake. The monitoring data collected during 1994–2012 were used. Paraprionospio patiens, classified as second-order opportunistic species, appeared with high frequency in all the survey sites throughout the investigation period and was mostly dominant. Therefore, the variation of AMBI was small during the survey period. However, the species richness and Shannon diversity significantly increased from 1994 at the center of the lake. The benthic community of Lake Nakaumi was characterized by a coexistence of marine and brackish benthos and controlled by the Cl− concentration through the change in their proportions.