The effects of gradual or abrupt changes in salinity on digestive enzymes activity of Caspian kutum,Rutilus kutum(Kamensky, 1901) larvae

Abstract

This study investigates the effects of gradual or abrupt changes in rearing salinity on food transit time and digestive enzymes activity of Caspian kutum (Rutilus kutum) larvae. The larvae (532 AE 0.05 mg) were supplied and randomly allocated into 12 tanks at a density of 45 fish per tank. Experimental treatments were fresh water (salinity 0) [FW] as control, exposure to salinity 5 [T 1 ], and gradual transfer to salinity 10 in two steps of first to 5 h, then and after 12 h to a salinity of 10 [T 2 ], and abrupt change (direct transfer to a salinity of 10 [T 3 ]). Results showed at 8 h after start of feeding that the larvae intestine was filled with food pellets except in treatment T 1 . Enzyme activity responded to salinity change as follows: the highest trypsin, amylase, and chymotrypsin activities were observed in T 1 ; however, these were not significantly different to treatment T 3 (P > 0.05). Trypsin activity peaks in the FW and T 2 groups occurred 8 h after feeding, and in T 3 and T 1 groups 5 h after feeding. Peak chymotrypsin and alkaline phosphatase activity was observed 5 and 8 h after feeding in all experiments, respectively. The highest a amylase activity in FW and T 2 groups occurred 5 h after feeding, while in T 3 and T 1 these peaks were observed 8 h after feeding. These results indicate that salinity had some noticeable effects on the activities of digestive enzymes after feeding.

iTRAQ‐based quantitative proteomic analysis reveals metabolic changes in overwintering Scylla paramamosain at two different salinities

“…In this study, TRYP in the LS group was significantly up-regulated compared with the HS group after overwintering. A similar report has found that low salinity has a positive effect on TRYP in Rutilus kutum (Gheisvandi et al, 2015).…”

“…In this study, TRYP in the LS group was significantly up‐regulated compared with the HS group after overwintering. A similar report has found that low salinity has a positive effect on TRYP in Rutilus kutum (Gheisvandi et al, 2015). It has also been found that TRYP mRNA expression in Litopenaeus vannamei was highest at low‐salinity levels (Gao et al, 2016).…”

Effect of salinity on growth, survival, haemato‐biochemical and antioxidative status ofAnabas testudineus(Bloch, 1792) juveniles reared in inland saline water

“…Digestive enzymes depict the overall digestion process and nutritional status of fish (Bolasina et al, 2006; Haque et al, 2021). In teleosts, several studies demonstrated that intestinal enzyme activity changes with salinity (Bolasina et al, 2007; Gheisvandi et al, 2015). In the present study, high digestive enzyme activity observed at higher salinities (9 and 12 ppt) compared with lower ones (T2 and T3) and freshwater T1 (0 ppt) group.…”

Influence of salinity and linoleic or α-linolenic acid based diets on ontogenetic development and metabolism of unsaturated fatty acids in pike perch larvae (Sander lucioperca)

“…Limited knowledge exist about influence of hyperosmotic or isosmotic salinity on early pike perch larval ontogeny or physiology. Environmental changes in salinity have shown to result in modification of physicochemical conditions of the gut lumen in other fish larvae and may exert a direct action on digestive enzyme performance (Boef and Payan, 2001) as well as food transition time (Gheisvandi et al, 2015), that may have implications on growth performance.…”