Biochemical and physiological effects of nickel in the euryhaline crab Neohelice granulata (Dana, 1851) acclimated to different salinities

Abstract

The estuarine crab Neohelice granulata was maintained under control condition or exposed to sublethal concentrations of dissolved Ni (measured: 128 and 1010μg/L) for 96h at different salinities (2 and 30ppt). After metal exposure, whole-body oxygen consumption was measured and tissue (hemolymph, gills, hepatopancreas and muscle) samples were collected. Control crabs acclimated to 2ppt salinity showed lower hemolymph concentrations of Na (33%), Mg (19%) and K (30%), as well as increased LPO levels in anterior gills (379%), posterior gills (457%) and hepatopancreas (35%) with respect to those acclimated to 30ppt salinity. In crabs acclimated to 2ppt salinity, Ni exposure increased whole-body oxygen consumption (75%), hemolymph K concentration (52%), hemolymph (135%) and hepatopancreas (62%) LDH activity. Also, it reduced hemolymph Cl concentration (16%) and muscle LDH activity (33%). In crabs acclimated to 30ppt salinity, Ni exposure increased LDH activity in hemolymph (195%), hepatopancreas (126%) and muscle (53%), as well as hemolymph osmolality (10%), Cl (26%) and Ca (20%) concentration. It also reduced hepatopancreas lipid peroxidation (20%) and hemolymph Mg (29%) and K (31%) concentration. These findings indicate that N. granulata is hyper-osmoregulating in 2ppt salinity and hypo-regulating in 30ppt salinity, showing adjustments of hemolymph ionic composition and metabolic rates, with consequent higher oxidative damage to lipids in low salinity (2ppt). Ni effects are associated with metabolic (aerobic and anaerobic) disturbances in crabs acclimated to 2ppt salinity, while osmotic and ionoregulatory disturbances were more evident in crabs acclimated to 30ppt salinity.

A Systematic Review on Metal Dynamics and Marine Toxicity Risk Assessment Using Crustaceans as Bioindicators

“…These emission sources, especially industrial sewage, transport Ni to the aquatic environment. In the aquatic environment, the predominant form is bivalent Ni, although free ions are approximately twice as toxic as their complex compounds [28,71]. In seawater, inorganic Ni may be present as free metal ions, carbonate, chloride, and organic matter complexed.…”

“…In invertebrates, acute exposure to Ni compromises the skeletal system, while also leading to impaired ionoregulation and/or respiratory gas exchange and oxidative stress, energy metabolism alterations, damage to lipid and DNA molecules and, disturbances in the regulation of divalent cations such as Ca 2+ [28]. Nagarjuna et al [120] verified the sublethal effect of Ni in shrimp (Penaeus monodon) post larvae (PL), identifying histological changes in vision, such as deformation, compression, fusion, and detachment of the corneal cells from the corneal facet of the ommatidia, indicating nickel toxicity.…”

“…The main metals, reported in several toxicity studies on animals, humans, and the environment, are Al, the metalloid As, Cd, Cr, Cu, Pb, Hg, Ni, and Ag [5,16,[23][24][25][26][27]. In the longterm, in animals, the accumulation of these metals whether essential in high concentrations or nonessential, can cause several types of damage, mainly to the respiratory [20,28] and gastrointestinal [29,30] systems, as well as affecting reproductive capacity [31,32] and interfering with animal metabolism [33,34]. In humans, these metals may lead to liver, kidney, central nervous system, mucus tissue, intestinal tract, and reproductive system damage, and are considered a severe public health issue [5].…”