Estimation of starvation and diel variation of the RNA/DNA ratios in field-caught Sardina pilchardus larvae off the north of Spain

Abstract

The aim of this study was to analyse the general larval condition, to determine the lncidence of starvation and to investigate the effect of time of day on RNA/DNA ratios among field-caught Sardina pilchardus (L.) larvae. The larvae were collected during 4 research cruises off northern Spain, during March, April, May and June 1992. A highly sensitive fluorometric method for nucleic acid quantification was applied to larvae of S. pilchardus. The means of the RNA/DNA ratio were relat~vely high, so the larvae collected off northern Spain were generally in good condition. Low percentages of starving larvae (RNA/DNA ratio less than 1.3), ranging from 0 to 3.23%, were found over the 4 mo. The RNA/DNA ratios were significantly correlated with zooplankton biomass. Larvae collected at night revealed higher RNA/DNA ratios compared to larvae caught during the day. This seems to indicate that there is some endogenous rhythm in the production of RNA. It would then follow that, if there are die1 changes in RNA concentrations, average RNA Indices can be unrepresentative if there IS any day/night bias in sampling.

Tissue effect on RNA:DNA ratios of marine fish larvae

“…It has also been pointed out that the RNA:DNA ratio may be correlated with age, size or developmental stage (Clemmesen, 1994;Suthers et al, 1996;Rooker and Holt, 1996;Bergeron, 1997), and that is influenced by temperature (Buckley et al, 2008) and diel cycle (Rooker and Holt, 1996;Chícharo et al, 1998). However, the effect of tissue on RNA:DNA ratios in larval fish has not been analysed.…”

Parental effects in the European sardine Sardina pilchardus

“…For the study of eggs and larvae these include amongst others: the ratio RNA/DNA (Buckley et al 1991, Bisbal & Bengtson 1995, Rooker & Holt 1996, Suthers et al 1996, Chícharo et al 1998, protein and amino acid content (Fyhn & Govoni 1995, Rønnestad et al 1998, 1999, Sivaloganathan et al 1998, enzymatic activity (Farris 1960, Takii et al 1997, content of lipids and fatty acids (Finn et al1995, Gunasekera et al 1999 and content of carbohydrates (Srivastava & Brown 1991).…”

Larval condition and growth of <i>Sardinella brasiliensis </i> (Steindachner, 1879): preliminary results from laboratory studies

“…The larvae were sampled for each kind of analysis every day at the same hour (10:00 h) to avoid the inclusion of diel variation in the rhythm of the RNA synthesis reported for other fish larvae of the same family (Chícharo et al, 1998). The biochemical measurements were not performed on the same individual larvae but on larvae from the same aquaria.…”

“…Biochemical indicators have also been used to demonstrate starvation mortality in the field and correlations between food availability or environmental characteristics and condition of the larvae (SetzlerHamilton et al, 1987;Canino et al, 1991;Clemmesen et al, 1997;Chícharo et al, 1998;Ramírez et al, 2001). A positive relationship of RNA/DNA ratio and prey abundance has been shown for stripped bass larvae (Martin et al, 1985), Atlantic cod and haddock larvae (Buckley and Lough, 1987) and Baltic cod (Grønkjaer et al, 1997).…”

“…The relationship between RNA and DNA is an index of the cell's metabolic intensity and has been used to measure recent growth in fish (Bulow, 1987;Buckley and Lough, 1987;Hovenkamp, 1990;Hovenkamp and Witte, 1991) and the nutritional condition in larval fish studies (Buckley, 1980(Buckley, , 1984Martin et al, 1985;Fukuda et al, 1986;Buckley and Lough, 1987;Raae et al, 1988;Robinson and Ware, 1988;Clemmesen, 1994;Chícharo, 1997Chícharo, , 1998Kimura et al, 2000).…”