Low salinity negatively affects early larval development of Nile tilapia, Oreochromis niloticus: insights from skeletal muscle and molecular biomarkers

Abstract

SummaryThe present study evaluated the effects of low salinity on the early larval development of Oreochromis niloticus, specifically histological damage to white muscle, morphology of the yolk-sac surface and trunk area, and molecular expression of apoptosis and cell proliferation biomarkers. Newly hatched larvae were submitted to four salinity treatments for a period of 48 or 72 h, in duplicate: (S0) freshwater, (S2) 2 g l−1, (S4) 4 g l−1, and (S6) 6 g l−1NaCl. Larval development was examined using histology, electron microscopy, enzyme-linked immunosorbent assay (ELISA), and morphometry. At the yolk-sac surface, larvae of S4 and S6 displayed alterations to the apical opening of chloride cells that may be related to osmotic expenditure caused by the increased salinity. Caspase-3 expression did not differ significantly among treatments, however significantly lower proliferating cell nuclear antigen (PCNA) expression (P < 0.05) suggested minor cell proliferation in larvae of S4 and S6 compared with S0 and S2. Furthermore, there was a significant reduction in both trunk area and percentage of normal white muscle fibres (WF) in larvae of S4 and S6. Vacuolated areas and myofibrils concentrated at the cell periphery and found in the white muscle from larvae exposed to saline environments suggested disturbance to muscle development. Oedema and mononuclear infiltrate were also observed in the white muscle of S4 and S6 larvae. Together these results indicated that treatments with 4 and 6 g l−1 NaCl may cause osmoregulation expenditure, morphological alterations to the yolk-sac surface and histological damage to skeletal muscle that negatively affected the early larval development of O. niloticus.

Survival, Growth, and Development in the Early Stages of the Tropical Gar Atractosteus tropicus: Developmental Critical Windows and the Influence of Temperature, Salinity, and Oxygen Availability

“…However, there is little information regarding salinity and their early life stages and available information exists only for juveniles and adults [59][60][61][62][63][64]. Lack of maturity of their ionoregulatory and osmoregulatory organs likely explains why newly hatched larvae in the present study could not cope with environmental salinities that could be easily tolerated by adults, since gills are the principal organ for iono/osmoregulation in larval fishes [65][66][67][68]. Atractosteus tropicus has visible gills at hatch, but regular gill ventilation did not start until~5 dph [37].…”

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

“…Individually, and in combination with another factors such as feeding and nutrition, the environment affects all physiological systems including skeletal musculature (Alami‐Durante, Médale, et al, 2010; Alami‐Durante, Wrutniak‐Cabello, et al, 2010; Johnston, 2006). Among environmental conditions, salinity and temperature are one the most important factors for fish growth mainly because of its influence on physiology, with direct consequences for muscle development (Johnston, 2006; Melo et al, 2019). As observed for salinity in the present study, the temperature also affected the muscle cellularity in L. alexandri larvae and juveniles (Takata et al, 2018).…”

“…Changes in water parameters may induce to an stress condition and increasing in energy expenditure for the maintenance of homeostasis, thus decreasing the capacity for growth and increasing the efficiency of transforming food energy to net energy (Bermudes et al, 2010; Melo et al, 2019; Van Ham et al, 2003). In such a context, L. alexandri juvenile exposed to salinity ranging from 0 to 10 ppt experienced increased energy expenditure to maintain homeostasis, or at least attempt to because fish did not survive until the end of the experiment in 10 ppt.…”

“…For juveniles that tolerated salinity until the end of the experiment, the higher salinity (7.5 ppt) produced the lowest values for fibre diameter. For larval L. alexandri (Martins et al, 2014) and Nile tilapia, O. niloticus (Melo et al, 2019), water salinity was found to affect muscle development with evident problems in muscle growth at salinity of 4 and 6 ppt. Moreover, these salt concentrations can cause osmoregulation expenditure with severe consequences to skeletal muscle.…”

Morphological and Molecular Responses of Lateolabrax maculatus Skeletal Muscle Cells to Different Temperatures

“…The indeterminate growth observed in most fishes is influenced by environmental factors such as temperature [ 10 ], nutrition [ 11 ], salinity [ 12 ] and oxygen concentrations [ 13 ]. Among them, temperature strongly modulates muscle development in ectothermic teleosts [ 10 ].…”