The effects of salinity on growth, gill tissue and muscle cellularity in Lophiosilurus alexandri juvenile, a Neotropical freshwater catfish

Abstract

The present study investigated the effects of salinity on growth, mortality, gill morphology and muscle cellularity in Lophiosilurus alexandri. Fish were submitted to the following salinity for 28 days: 0 (S0), 2.5 (S2.5), 5.0 (S5), 7.5 (S7.7) and 10 (S10) ppt. Growth and protein efficiency ratio (PER) decreased with the increase of salinity. All fish from S10 died between the 16th and 21st day of the experiment. Mortality in S7.5 was 78% at the end of 28 days of salinity exposure. Increased salinity was accompanied by increased vascular congestion, hyperplasia of gill filament epithelium, lamellar fusion and loss of structural integrity of pillar cells. Fish at S2.5 and S5 had higher mucosal cell hyperplasia. Chloride cell quantity was higher in fish in the S2.5 to S7.5. In general, L. alexandri juvenile exposed to treatments of freshwater and S2.5 had similar patterns of muscle cellularity, with high averages for the most of the variables of muscle cellularity evaluated. The large fibre size classes tended to decrease with increasing salinity. L. alexandri juveniles may be cultivated up to 2.5 g of salt/L, and superior concentrations change growth, induce damage to gills and modify muscle cellularity.

Correlation between Metabolic Rate and Salinity Tolerance and Metabolic Response to Salinity in Grass Carp (Ctenopharyngodon idella)

“…This phenomenon could be due to morphological and physiological restructuring in response to increasing salinity because these processes are energy expensive [ 64 ]. As a form of regulation of ion flux and oxygen uptake, the size of the interlamellar cell mass in the gills of some fish changes under varying salinities, which has been observed in several freshwater and seawater fish species, e.g., Atlantic killifish ( Fundulus heteroclitus ), pacamã ( Lophiosilurus alexandri ), Nile tilapia ( Oreochromis niloticus ), mangrove killifish ( Kryptolebias marmoratus ), Arctic grayling ( Thymallus arcticus ), rainbow trout ( Oncorhynchus mykiss ), and threespine stickleback ( Gasterosteus aculeatus ) [ 19 , 32 , 33 , 65 , 66 , 67 ]. In our results, the structure of filaments of the gills changed under slightly increased salinity.…”

“…However, the response of the resting metabolic rate to salinity varies depending on fish species, life habitats, and salinity levels [ 9 , 25 , 26 ]. Although the resting metabolic rate of some fish species was lower under near-isosmotic salinity than under hypo-osmotic salinity [ 24 , 27 , 28 , 29 , 30 ], the resting metabolic rate of other fish species showed no changes, linear increases, and bell-shaped changes with increasing salinity [ 9 , 14 , 19 , 25 , 31 , 32 , 33 ]. In addition, the lamellar morphology of the fish gills may change under varying salinity to regulate osmotic water movement and ion diffusion [ 14 , 24 , 32 , 33 ], which could be hypothesized to affect the respiratory gas exchange capacity of fish.…”

“…Although the resting metabolic rate of some fish species was lower under near-isosmotic salinity than under hypo-osmotic salinity [ 24 , 27 , 28 , 29 , 30 ], the resting metabolic rate of other fish species showed no changes, linear increases, and bell-shaped changes with increasing salinity [ 9 , 14 , 19 , 25 , 31 , 32 , 33 ]. In addition, the lamellar morphology of the fish gills may change under varying salinity to regulate osmotic water movement and ion diffusion [ 14 , 24 , 32 , 33 ], which could be hypothesized to affect the respiratory gas exchange capacity of fish. Since the maximum metabolic rate is limited by the respiratory gas exchange capacity of fish [ 23 ], an increase in salinity would affect the maximum metabolic rate of fish.…”

Toxicity, physiological, histopathological, handling, growth and antiparasitic effects of the sodium chloride (salt) in the freshwater fish aquaculture

“…Salinity is an abiotic factor that influences water quality, fish development and physiological status (Takata et al, 2021). Freshwater fish maintain their body fluids hyperosmotic in relation to the external environment.…”

“…Exposure to 3.0 and 5.0 g L −1 of NaCl for 5 and 1 min, respectively, caused 5% mortality in Silurus glanis (Krasteva et al, 2020). Lophiosilurus alexandri exposed to 7.5 and 10.0 mg L −1 of NaCl for 28 days showed 78.0 and 100% mortality respectively (Takata et al, 2021).…”