Gonadal Histopathological Disorders in Mytilus galloprovincialis Male Exposed to Tars Used in Mussel Farms

Abstract

Polycyclic aromatic hydrocarbons (PAHs) and trace metals are pollutants widely distributed in the marine environment with toxic effects on live organisms, but few laboratory studies have proved their causal relationship with histopathologic alterations from invertebrates. We analyse the histopathologic effects of a tar mixture used in mussel farms on the gonad of male mussels. Mussels were exposed to water-accommodated fractions from different sub-lethal concentrations of that tar mixture during different times. The accumulation of PAHs and metals in mussels was quantified in each one tar exposure condition, and a comparative histological and morphometric analysis of the male gonad was performed, as well as of the gametogenic disorders and the cellular pathologies induced. Spermatogenesis disruption and alterations of somatic and germinal cells were observed as a direct effect of treatment. The pathologies observed followed an increasing malignity sequence depending on dose and exposure time: spawning induction; arrest of spermatogenesis and spermiogenesis; suppression of immune response; dysplasia of Sertoli and connective cells and finally, severe disorders of germinal cells. We demonstrate for the first time that tar used in waterproofing of floating rafts from the mussel farms causes severe effects on male mussel gonad, constituting a direct risk to the health of these organisms, affecting gametogenesis, quality of gametes and, ultimately, the sustainability of this resource and their quality for human consumption. Moreover, we propose the pathologies described in mussel as biomarkers of marine pollution and the mussel gonad as study model of testicular toxicity mechanisms in male reproduction.

Morphological, Gene, and Hormonal Changes in Gonads and In-Creased Micrococcal Nuclease Accessibility of Sperm Chromatin Induced by Mercury

“…Both enzymes play an important role in hormone regulation, in particular for testosterone production and its involvement in spermatogenesis [ 22 ]. These results are in line with those observed in experiments previously conducted following exposure to sub-toxic copper concentrations [ 12 ] and those relating to the accumulation of Polycyclic Aromatic Hydrocarbons (PAH) and heavy metals in the male gonad of M. galloprovincialis showing that these pollutants disrupts spermatogenesis and produce alterations in somatic and germ cells [ 65 ]. The testicular toxicities of mercurials, including impaired spermatogenesis and/or steroidogenesis, have been demonstrated in a number of laboratory animal species: fish [ 50 , 66 , 67 , 68 , 69 ], fowls [ 67 ].…”

Histopathologic survey of free-living populations of 2 species of freshwater mussels in Indiana

“…In addition, certain pollutants could result in gonadal atrophy, as occurs with exposure to tar in the males of the marine mussel Mytilus galloprovincialis . 3 Further studies on normal seasonal gonadal histology in fatmuckets and plain pocketbooks would be needed to begin to elucidate whether the observed changes were pathological (atrophy) or physiological (atresia).…”

Impact of Pb Toxicity on the Freshwater Pearl Mussel, Lamellidens marginalis: Growth Metrics, Hemocyto-Immunology, and Histological Alterations in Gill, Kidney, and Muscle Tissue

“…Heavy metal toxicity causes notable histological changes in the vital organs of invertebrates [ 35 , 65 , 66 ]. Mussels’ gills are considered to be sensitive to toxicity because of their crucial role in respiration, food absorption, and extended surface area [ 67 , 68 ].…”