Hemolymph Parameters Are a Useful Tool for Assessing Bivalve Health and Water Quality

Abstract

Bivalves play a key role in aquatic ecosystems and are a valuable commercial resource. The prosperity of these aquatic organisms depends mainly on the effectiveness of their immune defense, in which the hemolymph plays a central role. Hemolymph may be used as an effective non-lethal criterion of health. However, the predictive value of hemolymph analysis depends on the comparison between the obtained results and reference data from healthy individuals living in natural aquatic environments. We collected hemolymph from 15 commercially important species from wild populations at stations located in non-impacted and impacted water areas of the Sea of Japan. Of the 11 hemolymph parameters we analyzed, the total hemocyte count, percentage of hemocyte types, phagocytic activity, presence of reactive oxygen species, and protein concentration differed significantly between populations from non-impacted and impacted water areas. The most responsive species to pollution were Magallana gigas, Crenomytilus grayanus, Mizuhopecten yessoensis, and Mactra chinensis. This work is the first to examine a large number of commercially important species simultaneously. The results of this study are the basis for establishing the health status criteria of commercial bivalves for veterinary control in aquaculture and biomonitoring.