Salinity tolerance and osmoregulation in the silver perch, Bidyanus bidyanus Mitchell (Teraponidae), an endemic Australian freshwater teleost

Abstract

Juvenile silver perch, Bidyanus bidyanus, were subjected to direct transfer from fresh water to various test salinities. No mortality was observed when the fish were transferred from fresh water to a salinity of 12, but 40% mortality was observed at a salinity of 15 after seven days. Pre-acclimation of silver perch to a salinity of 12 for seven days resulted in only marginally better survival at higher salinities. Plasma osmotic concentrations of silver perch rose slightly in salinities below 9 but rapidly at higher salinities, following the same track as the iso-osmotic line. Minimum body water content was observed in individuals subjected to a salinity of 15 for 24 h. As found in other freshwater teleosts, chloride cells were found in the branchial epithelium of silver perch. Accessory cells were observed beside the chloride cells in both freshwater and salt-water conditions. Fish subjected to a salinity of 12 for seven days showed chloride cells with a more developed tubular system than controls. The length of the junctions between chloride cells and accessory cells was significantly shorter in fish adapted to a salinity of 12 than in controls. The ultrastructural feature of 'interdigitations' of accessory cells was not observed during salt-water adaptation. These data indicate that silver perch is the least tolerant of high salinities and the most truly freshwater Australian teleost species examined to date.

Responses of freshwater biota to rising salinity levels and implications for saline water management: a review

“…LD50 is the concentration of salts at which 50% of the sample population dies. For references, see the following: (1) Chessman and Williams (1975), (2) Jackson and Pierce (1992), (3) O'Brien and Ryan (1999), (4) Guo et al (1995), (5) , (6) Bacher and Garnham (1992), (7) Williams (1987), (8) Hart et al (1991), (9) Hogan and Nicholson (1987), (10) Merrick and Schimda (1984), (11) Guo et al (1993), (12) Beumer (1979) in Hart et al (1991), (13) Bacher and O'Brien (1989), (14) Alderman et al (1976, (15) Geddes (1979), (16) Chessman and Williams (1974), (17) Karimov and Keyser (1998), (18) Jasim (1988), (19) Cadwallader and Backhouse (1983), (20) Nordlie and Mirandi (1996) Species that groups such as Atherinids (hardyheads), Eleotids (gudgeons), Gobiids (gobies) and Ariids and Plotosis (catfishes), which may have more recent marine divergence, are more tolerant to saline conditions (Hart et al 1991). For example, unspecked hardyhead (Craterocephalus stercusmuscarum fulvus) and smelt (Retropinna semoni), within the Hardyhead family, have tested salinity tolerances (LD 50, the concentration of salts at which 50% of the sample population dies) of 43700 and 59000 mg L -1 , respectively (Table 1) .…”

“…Although most adult fish appear to be tolerant to salinity levels of at least between 7000 and 13000 mg L -1 , during early life stages they are particularly vulnerable (Hogan and Nicholson 1987;Williams 1987;Hart et al 1991;Bacher and Garnham 1992;Guo et al 1993Guo et al , 1995O'Brien and Ryan 1999). Juvenile growth rate and survivorship, and sperm motility were optimal between 3000 and 5000 mg L -1 but deteriorated rapidly above this level (Tables 1, 2).…”

Effects of salinity on the growth and nutrient retention in silver perch, Bidyanus bidyanus (Mitchell 1838) (Teraponidae)

“…The silver perch, Bidyanus bidyanus, is native to the Australian Murray‐Darling River system ( Merrick 1984) and migrates wholly within freshwater ( Guo 1995) . The freshwater fish and crayfish of the Murray‐Darling River system are also known to tolerate considerably high salinities ( Guo 1993) .…”

“…The freshwater fish and crayfish of the Murray‐Darling River system are also known to tolerate considerably high salinities ( Guo 1993) . Although a freshwater species, silver perch have a toleration up to a salinity of 15 ( Guo et al . 1995 ); improved survival and growth rates were reported when both larvae and juveniles were reared in slightly saline waters ( Guo et al .…”

“…Although a freshwater species, silver perch have a toleration up to a salinity of 15 ( Guo et al . 1995 ); improved survival and growth rates were reported when both larvae and juveniles were reared in slightly saline waters ( Guo et al . 1995 ; Ingram 1996) .…”