Spatial variation of metal bioaccumulation in the hydrothermal vent mussel Bathymodiolus azoricus

Abstract

The variability of the bioaccumulation of metals (Ag, Cd, Cu, Fe, Mn and Zn) was extensively studied in the mussel Bathymodiolus azoricus from five hydrothermal vent sites inside three main vent fields of increasing depth along the Mid-Atlantic Ridge: Menez Gwen, Lucky Strike and Rainbow. Metal bioaccumulation varied greatly between vent fields and even between sites inside a vent field with B. azoricus showing a great capacity to accumulate metals. The bioaccumulation of these metals also varied significantly among tissues. The main target was the gills where metals were mainly associated with soluble compounds whereas in the digestive gland they were mainly associated with insoluble compounds. Storage of metals under insoluble forms in B. azoricus seems to be a major pathway for the detoxification of both essential and non-essential metals. Mussels from the studied fields can be discriminated following their metallic load but the segregation relies partially on the composition of the metal-enriched fluids.

Mercury accumulation in hydrothermal vent mollusks from the southern Tonga Arc, southwestern Pacific Ocean

“…Studies have shown that metal accumulation in hydrothermal organisms is influenced not only by environmental factors (e.g., depth, temperature, fluid chemical composition, and geological features) but also by biological factors (e.g., species, ontogenesis stage, metabolism, feeding type, and trophic level) (Colaço et al, 2006;Kádár and Pawell, 2006;Kádár et al, 2006aKádár et al, ,b, 2007Demina and Galkin, 2008;Demina et al, 2013). Previous studies with mollusks from hydrothermal vents have shown high levels of metal accumulation, mainly in the gills and digestive glands as the major target organs (Ruelas-Inzunza et al, 2003;Colaço et al, 2006;Kádár et al, 2007;Cosson et al, 2008;Demina et al, 2013;Koschinsky et al, 2014). At the Guaymas vent site, the gills and digestive glands of vent clams, Vesicomya gigas, accumulate high concentrations of Cd, Fe, Hg, Mn, and Zn, while the gonads or mantles contained relatively low concentrations of those metals (Ruelas-Inzunza et al, 2003).…”

DNA Damage and Transcriptional Changes in the Gills of Mytilus galloprovincialis Exposed to Nanomolar Doses of Combined Metal Salts (Cd, Cu, Hg)

“…The efficient metal absorption observed in bivalves is largely determined by species-specific and temperature-dependent filtration rates: according to the dissolved and particulate metal amounts, the uptake mainly occurs through the gills and digestive tube, and is also influenced by selective regulatory mechanisms for essential redox elements such as copper, involved in the hemocyanin-mediated oxygen transport [22], [23]. Passive diffusion of lipophilic metal compounds/complexes, transfer through membrane ion channels and transporters as well as the formation of endocytic vesicles have a role in the metal influx.…”

“…Bivalve plasma components and haemocytes can drive metal ions into the soft tissues and mediate their accumulation in diverse cell types, cytoplasmic organelles and granules, and even in the bissal threads and shells wherein metal ions can replace calcium in the carbonate complex [15], [22], [24]. As regards the soft mussel tissues, gills have been reported to accumulate the highest or comparable metal levels than digestive gland [18], [23]. In filibranch bivalves, two gill lamellae per demibranch divide the pallial cavity into inhalant and exhalant chambers; each one is arranged in rows of ciliated filaments enclosing haemolymph sinuses and consisting of ciliated/non-ciliated epithelial cells, endothelial-like and mucous cells [25].…”

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

“…In this environment, the dominant primary production is autochthonous and chemosynthetic by bacteria [9] and symbiotrophy with these bacteria is also a major source of energy for benthic fauna inhabiting the vents. [10] Vent organisms can be exposed to high metal concentrations from the vent fluid waters, [11, 12] although mixing can be rapid, causing high spatial and temporal variation in metal concentrations. [12] In the high pressure and temperature conditions of the Mid-Atlantic Ridge, the composition of vent fluids are controlled by phase separation processes, where shallower sites are more gas-enriched than deeper sites, which are metal-enriched.…”