| INFLUENCE OF NUTRITIONAL CONDITION (RNA:DNA RATIOS) OF TEMPERATE MARINE FISH LARVAE ON THEIR SWIMMING ABILITIES |
| CHÍCHARO, MARIA ALEXANDRA, Centre of Marine Sciences, CCMAR, University of Algarve, Campus de Gambelas, 8005-117 Faro, Portugal, mchichar@ualg.pt; Faria, Ana M., Eco-Ethology Research Unit, ISPA Instituto Universitrio, R. Jardim do Tabaco 34, 1149-041 Lisboa, Portugal, afaria@ispa; Garrido, Susana, Lisbon Oceanarium, University of Lisbon, Campo Grande, Faculdade de Cincias, Portugal, garridous@gamil.com; Silva, Luis, Centre of Marine Sciences, CCMAR, University of Algarve, Campus de Gambelas, 8005-117 Faro, Portugal; Gonalves, Emanuel J. Eco-Ethology Research Unit, ISPA Instituto Universitrio, R. Jardim do Tabaco 34, 1149-041 Lisboa, Portugal, emanuel@ispa.pt |
| Several studies indicate that condition in larval fish can influence survival and recruitment in the natural environment, but few studies correlate condition with any behavioral trait critical for survival, such as swimming. In the present study we evaluate the effects of starvation on growth, nutritional condition and swimming abilities of Senegalese sole (Solea senegalensis, Kaup, 1858), gilthead seabream (Sparus aurata, Linnaeus 1758) and pilchard sardine (Sardina pilchardus Walbaum, 1792) throughout larval phase. Biochemical analysis (RNA/DNA ratios) and behavioural experiments (critical swimming speed, Ucrit) were conducted on larvae reared under different feeding treatments from fed (ad libitum) to starvation (starved for 96 h). Growth was significantly affected by feeding treatment, while only slight decreases on RNA:DNA ratio and swimming performance were registered. The behavioural and physiological changes are in accordance with previous results, which show that flatfish larvae are less active and are more resistant to starvation when compared to pelagic species, such as sparid or clupeid. However, in the endurance experiment, higher condition individuals swum twice as long far as the lower condition of sparid larvae (19.7 km for fed larvae and 9.5 km for unfed larvae). These results suggest that even in poor condition, larvae may be able of to performing escaping, foraging and orientation behaviours (activities in which critical and routine speeds might be involved), but sub-lethal effects of starvation may affect dispersal potential (for which endurance swimming is critical), and therefore may compromise subsequent survival, and modelling studies that quantify survival should take this in consideration in order to produce reliable estimation of recruitment |
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