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Comparative reproductive biology of the Tasmanian freshwater crayfishes Astacopsis gouldi Clark, Astacopsis franklinii, Gray and Parastacoides tasmanicus Clark (Decapoda: parastacidae)

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Hamr, P (1990) Comparative reproductive biology of the Tasmanian freshwater crayfishes Astacopsis gouldi Clark, Astacopsis franklinii, Gray and Parastacoides tasmanicus Clark (Decapoda: parastacidae). PhD thesis, University of Tasmania.

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Abstract

The reproductive biology and life history of the Tasmanian freshwater
crayfishes in the endemic genera Astacopsis and Parastacoides were studied in the
field and laboratory from April 1985 to May 1987.
A. gouldi and A. franklinii are open water species associated with riverine
and lacustrine habitats from highlands to coastal plains. The burrowing, semiterrestrial
P. tasmanicus occurs in wet heathlands, water courses and highland
lakes in the wetter cooler, western half of the state.
The three species were studied in representative, relatively undisturbed
habitats. The habitats of all three species were typified by low water temperatures,
high rainfall and fluctuating water levels.
Reproductive morphology and anatomy of Astacopsis and Parastacoides
was described in detail. Male and female gonads differ from those of northern
hemisphere crayfishes, resembling anatomically the gonads of the Palinuridae. The
male gonopores show considerable complexity and variation among genera.
Female genitalia undergo significant changes in morphology at the onset of sexual
maturity.
Sexual dimorphism is developed to a greater degree in Astacopsis than in
Parastacoides. Secondary sexual characters are more numerous in females of both
genera and perform important functions in spawning and incubation of eggs.
Data on seasonal reproduction, growth, population structure and density were
obtained from regular sampling and mark recapture programs. Size at maturity and
reproductive condition were determined by changes in reproductive morphology
and gonad condition.
In both genera males reach sexual maturity at a smaller size than females.
Females, upon reaching maturity, exhibit a biennial breeding and molting cycle
which is a unique strategy, apparently a result of the cooler climate conditions in
Tasmania. In Astacopsis, mating and spawning take place in autumn, eggs are
carried over winter, hatch mid to late the following summer and young remain
attached until late summer to early autumn. Parastacoides mates and spawns in
autumn, eggs are carried over winter, hatch early the following summer and
postlarvae remain attached until mid summer.
The larval development and morphology of Astacopsis and Parastacoides
was described. Marked differences between the two genera were found and the
"primitive" larval development of Astacopsis differed significantly from that
described for other freshwater crayfishes. Growth rates, although faster in juveniles, are relatively slow in adults of
both genera. In reproductive adults of both sexes, molting frequency is low
(apparently biennial). This results in maturity being reached late and at a relatively
large size as well as in overall longer life spans as compared to most other
freshwater crayfishes.

Item Type: Thesis (PhD)
Keywords: Crayfish
Copyright Holders: The Author
Copyright Information:

Copyright 1990 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Journal article included in main PDF. Includes bibliographical references (leaves 136-153). Thesis (Ph.D.)--University of Tasmania, 1991

Date Deposited: 09 Dec 2014 00:00
Last Modified: 11 Mar 2016 05:55
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