Abstract
The survival and the growth of Pseudoplatystoma corruscans larvae exposed to four photoperiods: light:dark (LD) 0:24, LD 10:14, LD 14:10, and LD 24:0, in a brackish water (5‰) culture were analyzed. Larvae were fed with Artemia sp. nauplii at a 500 nauplii/larvae/day ratio. Survival on day 5 was inversely related to the length of photoperiod. From days 5 to 10, intermediate photoperiods resulted in a better survival, although LD 0:24 and LD 14:10 resulted in similar survival on day 10. Larvae presented higher weight at intermediate photoperiods. The results suggested that photoperiod requirements shifted during early development of P. corruscans larvae.
Highlights
Fundamental biological rhythms in nature are frequently related to the periodicity of light and many animals, including fish, exhibit a 24-hour cycle in their activities (Boeuf and Le Bail, 1999)
The mechanism which regulates that rhythm and produces effects on growth are not completely clear, but photoperiod can influence the release of several hormones that affect fish larvae development and performance (Hart et al, 1996; Boeuf and Le Bail, 1999)
Photoperiod requirements are specific for each species, and the positive effects on the growth and/or survival can occur under continuous light
Summary
Fundamental biological rhythms in nature are frequently related to the periodicity of light and many animals, including fish, exhibit a 24-hour cycle in their activities (Boeuf and Le Bail, 1999). This cycle dictates the feeding rhythm and is specific for each species, being classified as diurnal, nocturnal, or diurnal-nocturnal (ZavalaCamin, 1996). Photoperiod requirements are specific for each species, and the positive effects on the growth and/or survival can occur under continuous light Photoperiod requirements vary according to the ontogenetic developmental stage (Puvanendran and Brown, 2002; Kestemont et al, 2003)
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