Evaluation of lymphoid tissue structure in Sole (Euryglossa orientalis) and Yellowfin Seabream (Acanthopagus latus) affected by environmental contaminants in the Persian Gulf

This study sought to analyze structures of lymphatic tissues in two commercial fish species, e.g. Sole (Euryglossa orientalis) and Yellowfin Seabream (Acanthopagus latus), collected from five stations with varying levels of pollution in the Musa Creek near the Persian Gulf, e.g. Petro-chemical, Gaafari, Majidieh, Ghazaleh and Zangi Stations. Samples from Genaveh Station located outside Musa Creek were collected as controls. To correlate findings of changes in the studied tissues with local pollution status, levels of Hg, Pb, Zn, Cu and Cd were measured in sediments and water at each station. Fish were caught from the sampling stations; the spleen and head kidney were collected and sections prepared to permit histologic evaluation. The results indicated that, in both species, the most common changes were observed in fish collected near the Petrochemical station and included an increase in melano-macrophage aggregates, hemorrhage and damaged/dead red blood cells in the spleen; in the head kidney, the major findings were melano-macrophage aggregation, hemorrhage and lifting of the tubular basement membrane. No pathological alternations were noted in the spleen and head kidney of fish from the Zangi station. Samples of A. latus collected from Gaafari station and of E. orientalis from Majidieh station also had pathological changes. No significant differences were found in the tissue structures of fish recovered from the Zangi and Genaveh control stations. The concentrations for nearly all of the studied metals in sediment and water samples collected from the different stations followed the pattern: Petrochemical station approximate to Majidieh approximate to Gaafari>>Ghazaleh>Zangi Stations. From the data, it was concluded that changes in lymphoid tissues of the fish studied here correlated with geographical conditions and sources of pollution at the different test stations. What these changes mean to the long-term health of both species remains to be determined in ongoing studies.