Effects of short-term salinity exposure on haemolymph osmolality, gill morphology and Na+/K+ - ATPase activity in Solenaia oleivora

In order to explore the physiological reaction to hyperosmotic environment, Solenaia oleivora were exposed to 2.23‰ salinity. In 48h, the hemolymph osmolality kept increasing, and the hemolymph protein concentration increased in the first 6h and then decreased significantly, while the free amino acid content increased in the first 24h and then kept stable (P < 0.05). The activity of Na+/K+-ATPase at 0h was significantly higher than other times in most organs except intestine, which was highest at 3h (P < 0.05). The ions concentration were also influenced. The concentration of Na+ rose in haemolymph, axe foot and intestine, but decreased in gill and hepatopancreas. In hemolymph, gill, hepatopancreases and adductor muscle, the K+ concentration was the highest at 0h, while in axe foot and intestine, it showed a positive tendency. The concentration of Cl- in haemolymph, adductor muscle, intestine and axe foot were positively correlated with treatment time, while hepatopancreas showed opposite tendency. High salinity stress caused a difference in the gill histological structure, the gill structure shrunk, the gill lamellas space and shrinking degree showed an enlarging trend with salinity treatment time.

Respiratory profile and gill histopathology of Carassius auratus exposed to different salinity concentrations

The aim of this study was to evaluate the chronic salinity tolerance of Carassius auratus and the effects on blood parameters, gill morphology, and survival. In the first test, nine different concentrations (0.0, 0.5, 1.0, 2.5, 5.0, 10, 15, 20, and 25 g L-1) of NaCl were used with nine repetitions for 96 h. The survival of fish subjected to 15 g L-1 NaCl was 4 h, and 5 min at a concentration of 25 g L-1. The mortality of fish with 15 g L-1 NaCl was 100%. Morphological analyses of the gills showed hyperplasia of the coated cells in the interlamellar space and hypersecretion of mucus in fish exposed to 10 g L-1 of NaCl. At concentrations of 20 and 25 g L-1, necrosis of the support collagen caused the cells to detach from the lamellar structure mucosa. In the chronic test, two concentrations were used, with four replications containing nine fish in each aquarium for a period of 21 days. Blood samples and gills from the fish were collected, and it was observed that the fish showed a decrease in the concentration of bicarbonate (NaHCO3) in the blood, indicating hypernatremia. Acute exposure of C. auratus to sodium chloride (NaCl) should be at a maximum of 10 g L-1 of NaCl, after which level there would be a loss in animal performance and/or mortality. Chronic exposure to 5 g L-1 of NaCl promotes acidemia, ionic imbalance, and pathological changes in the gills; therefore, it is not recommended.

Gill morphology and formulae of crayfishes (Decapoda: Astacidea: Parastacidae) from New Guinea and New Zealand and a comparison with other selected species of crayfishes

The Infraorder Astacidea comprises four superfamilies of decapod crustaceans: the freshwater Astacoidea and Parastacoidea and the marine Enoplometopoidea and Nephropoidea. The gill morphology of four species of crayfishes belonging to Astacoidea and Parastacoidea, two coral reef species of Enoplometopoidea, and 2 deep-water species of Nephropoidea are described and illustrated for comparisons and to determine characters characteristic to members of the family Parastacidae (Parastacoidea) from New Guinea. Morphology of the arthrobranchs and pleurobranchs were similar among all species, having a single stem with filament, but podobranchs of the parastacoideans differed from those of Astacoidea, being corrugated and tubular and having filaments. The astacoidean P. virginalis had a plate-like lamella with filament. The two nephropoid and two enoplometopoid species were similar to each other; their podobranch had a flat blade-like lamella without a filament and a shaft with a filament. The gill formulae of the New Guinea species of Cherax were the same as those of the Australian congeners, but the formula of the New Zealand Paranephrops planifronsWhite, 1842 was the same as those of the South American parastacids.

Road salt compromises functional morphology of larval gills in populations of an amphibian

Throughout much of the world, winter deicing practices have led to secondary salinization of freshwater habitats, where numerous taxa are vulnerable to elevated salinity. Many amphibians are of particular concern because of their permeable skin and reliance on small ponds and pools, where salinity levels can be high. The early life-history stages of amphibians that develop in these habitats are especially sensitive to salt exposure. Larvae developing in salt-polluted environments must osmoregulate through ion exchange in gills. While salt-induced changes to the physiology of ion exchange in amphibian gills is generally understood, functionally relevant changes in gill morphology remain poorly described. Yet the structure of gills should be an important component affecting their ionoregulatory capacity, for instance in terms available surface area. Larval amphibian gills also play critical roles in gas exchange and foraging. Thus, changes in gill morphology due to salt pollution potentially affect not only osmoregulation, but also respiration and feeding. Here, we used a chronic exposure experiment to quantify the effect of salinity on larval gill morphology in populations of the wood frog (Rana sylvatica). We measured a suite of morphological traits on gill tufts, where ionoregulation and gas exchange occur, and on gill filters, which are used in feeding. Larvae raised in high salinity conditions had gill tufts with lower surface area to volume ratio, while epithelial cells on these tufts were less circular but occurred at higher densities. Gill filters showed increased spacing, which can potentially reduce their efficiency in filtering food particles. Together, these changes seem likely to diminish the ionoregulatory and respiratory capacity of gill tufts, and compromise feeding functionality of gill filters. Thus, a singular change in the aquatic environment from a widespread pollutant has the potential to generate a suite of consequences via changes in gill morphology. Critically, this suite of negative effects is likely most detrimental in salinized environments, where ionoregulatory demands are higher, which in turn should increase respiratory demands along with energy acquisition demands through foraging.