TUBI (TUrkish Benthic Index): A new biotic index for assessing impacts of organic pollution on benthic communities

AbstractA new biotic index, TUBI (TUrkish Benthic Index) is proposed here to assess the impacts of organic enrichments on benthic community structures. This new index has two metrics; the Shannon-Weiver's diversity index (metric 1) and the relative abundance of ecological groups (metric 2). The ecological groups of species, which include five categories, were re-organized under three major categories here, namely, sensitive species (including GI and GII), tolerant species (GIII) and opportunistic species (GIV and GV). The metric 2 considers these groups with different weights and eliminates sensitive species in the calculation. Scores of TUBI vary between 0 and 5, and the benthic quality status increases with increasing TUBI scores. Benthic samples collected from Izmir Bay, and the Aegean and Levantine Seas were analyzed by using different biotic indices such as AMBI, M-AMBI, BENTIX, MEDOCC and TUBI, based on the national database for the ecological groups of benthic species. All biotic indices used, with some exceptions, discriminated poor and bad ecological status in the regions. The correlation analysis performed between the total organic carbon in sediment and total inorganic nitrogen in deep water, and biotic indices indicated that TUBI possessed the highest negative correlation values with these environmental variables, therefore better detecting the variability across a gradient of pollution-mediated impacts on benthic communities.