The effect of photoperiod on growth, survival, colour and activity of juvenile southern rock lobster, Jasus edwardsii

Abstract

Juvenile (1–10 g) southern rock lobsters, Jasus edwardsii, were subjected to five photoperiods [0L(light):24D(dark); 6L:18D; 12L:12D; 18L:6D; 24L:0D] during a 112‐day trial, and growth, survival, colour, food consumption and activity were examined. Lobsters grown under the 6L:18D and 24L:0D photoperiods had significantly lower (P < 0.05) final mean weight and specific growth rate than any other treatments. Photoperiod had no effect on survival or colour of lobsters. Food consumption differed significantly during the first week of the trial; after 5 weeks, food consumption was similar in all treatments. Major peaks in activity occurred during dark periods for lobsters exposed to photoperiods that had a light:dark regime. Activity of lobsters exposed to continuous light or dark regimes remained constant and at low levels during the 24‐h period. Food consumption or activity does not appear to determine the rate of growth of lobsters in the different photoregimes. One over‐riding outcome of this and other studies on photoperiod is that the growth and survival response of juvenile J. edwardsii was not significantly better than those of the standard 12L:12D cycle.

Effect of physical disturbance on reproductive performance in the spiny lobster,Jasus edwardsii

“…Spiny lobsters become more active at the onset of the dark phase of the photoperiod (Crear et al 2003), a phenomenon seen in this study in both treatments. However, activity was suppressed in animals from the disturbed treatment, which we suggest was a consequence of frequent disturbance.…”

“…Monitoring was conducted shortly after the start of the study (February) until before phyllosoma larval hatch (October). The monitoring times encompassed the peak lobster activity during light and dark hours, and at the presentation of feed (Westbury 1999;Crear et al 2003). Activity was noted and a score of 1 given when an animal was exposed on top of the shelter structure or on the tank floor; whereas a score of 0 was recorded for animals partially or fully located within shelters.…”

Crescimento de Aegla itacolomiensis (Crustacea, Decapoda) em um arroio da Mata Atlântica no sul do Brasil

“…A taxa de crescimento dos animais pode estar diretamente ligada a fatores abióticos que exercem influência sobre os indivíduos de uma população, podendo inclusive desencadear ou alterar processos fisiológicos relacionados entre outros, aos eventos da reprodução e ao crescimento (DÍAZ et al, 2003, CREAR et al, 2003. No presente trabalho, registrou-se que os machos de A. itacolomiensis possuem uma taxa de crescimento mais elevada do que as fêmeas.…”

“…Variações climáticas nos sistemas límnicos onde esses animais vivem podem influenciar nas suas atividades circadianas, incluindo aquelas dedicadas ao forrageamento, além de afetar a abundância de recursos alimentares nos cursos d´água, o que acaba por refletir no crescimento somático dos organismos (CHIPPS et al, 2000;KUMLU & EROLDOGAN, 2000;CREAR et al, 2003).…”

Bias in lobster tethering experiments conducted for selecting low-predation release sites

“…This involves on-growing harvested pueruli in tanks or seacages for1 yr, then releasing a proportion estimated to be equivalent to the number that would have survived naturally back to the area of capture. This system of management is underpinned for the year following settlement by a large discrepancy in field survival (3 to 5%; Herrnkind & Butler 1994, Edmunds 1995 and captive survival (85 to 95%; Phillips et al 1983, Kington 1999, Crear et al 2003) so that, following reseeding, a large proportion of juveniles are still available for on-growing in captivity to a marketable product. The success of management by reseeding is contingent on a high survival of released juveniles.…”