New Zealand Journal of Marine and Freshwater Research abstracts
Reproductive cues in Panulirus ornatus
N. G. Sachlikidis
C. M. Jones
Department of Primary Industries
Northern Fisheries Centre
P.O. Box 5396
Cairns, Q 4870
Australia
email: Nikolas.Sachlikidis@ dpi.qld.gov.au
J. E. Seymour
School of Tropical Biology
James Cook University
Cairns, Q 4870
Australia
Abstract Two experiments were performed to assess the
effect of photoperiod and temperature on spawning of Panulirus ornatus.
In experiment 1, sexually mature lobsters taken from the wild during summer
were held at one of two photoperiods, winter (13 Light:11 Dark) and summer
(14.5 Light:9.5 Dark). Additionally, lobsters were also exposed to either
summer (29°C) or winter (24°C) average water temperatures. Spawning
was significantly greater when animals were exposed to summer photoperiod
than to winter photoperiod, irrespective of temperature. Although a higher
percentage of lobsters spawned when placed under a higher temperature, this
trend was not statistically significant. In experiment 2, sexually mature
lobsters were taken from the wild during winter and exposed to the same two
photoperiods as in experiment 1, at a summer equivalent temperature of 29°C.
Breeding started earlier and was more successful at the summer photoperiod.
Time to first breeding was 17 weeks after exposure to summer photoperiod,
compared with less than 1 week in experiment 1, and did not occur until individuals
had moulted. Moulting occurred in 81% of lobsters, primarily after an increase
in temperature to 29°C. The time between moulting and mating was varied
and there was no significant difference in moult frequency between the two
experimental photoperiods. After the lobsters had moulted, breeding success
was reached earlier if photoperiod was lengthened. Results suggest photoperiod
is the primary cue for the onset of gonad maturity and mating activity, with
temperature playing a less important role. Physiological rest and possibly
a moult may be required between breeding seasons before spawning can occur.
Furthermore, temperature may be an important cue for pre-reproduction moulting.
Keywords Panulirus ornatus; photoperiod; temperature;
breeding; moulting
M04072; Online publication date 31 May 2005 Received 31 March 2004; accepted
5 March 2005
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
305-310
0028-8330/05/3902-0305 © The Royal Society of New Zealand 2005
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