Stroud, Gregory John (1982) The taxonomy and biology of fishes of the genus Parapercis (Teleostei: Mugiloididae) in Great Barrier Reef waters. PhD thesis, James Cook University.

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Abstract

This study was initiated as an investigation into the taxonomy and biology of fishes of the mugiloidid genus Parapercis from the Great Barrier Reef Province.

Nine species of Parapercis were found to inhabit Great Barrier Reef waters: Parapercis cylinrica, P. hexophtalma, P. cephalopunctata, P. clathrata, P. xanthozona, P. nebulosa, P. diplospilus, P. snyderi, plus one undescribed species. Detailed descriptions and a key to these species are presented.

The habitats in which Parapercis are most commonly encountered and the pattern of species occupancy within each of these habitats are described along with seasonal patterns of abundance.

The interrelationships between the morphology of the alimentary tract, the food taken, and feeding behaviour were investigated. A division was made into three groups, namely (1) small crustacean, algal, and polychaete feeders; (2) polychaete, large crustacean, and small crustacean feeders; and (3) large crustacean and fish feeders. All species are diurnal and utilize specialized feeding strategies in which vision plays a key role.

The social behaviour and organization of Parapercis cylindrica was investigated in detail. The basic social unit in this species is a harem consisting of a single male, two or three adult females, and a variable number of subadult females. Within each harem, individuals are arranged into a very stable, size-dependent, linear dominance hierarchy with the male always highest in status. Each female of the harem holds a relatively permanent territory which is defended against equivalent-sized or smaller females. The male maintains a permanent territory which encompasses all the territories of his females, and which he defends against other males. He also visits and aggressively interacts with each female of his harem at frequent, essentially regular intervals throughout the day. Motor patterns associated with male-male and male-female agonistic encounters are described. When the male dies, the dominant (largest) female of the harem changes sex and assumes control of the harem, provided she is large and aggressive enough to resist invasions of the harem by neighbouring males.

Parapercis cylindrica has a polygynous mating system and a male mates almost exclusively with the females of his harem. Motor patterns associated with courtship and spawning are described. Reproductive activity takes place every day and is restricted to the evening crepuscular period. It is suggested that the combination of strong site attachment, lack of mobility and clumped distributions of females, in creating a potential for mate monopolization by large males, has led to the development of the haremic social/mating system in this species.

Spawning activity in P. cylindrica is essentially restricted to between August and March each year although some harems spawn the year round. Settlement of juveniles of P. cylindrica and most other Parapercis species peaks in November each year. Evidence for the year round presence of juveniles was obtained for all species but P. hexophtalma.

Parapercis cylindrica, P. hexophtalma, P. clathrata, P. xanthozona, P. nebulosa and P. sp. 1 are monandric protogynous hermaphrodites. Each with the exception of P. nebulosa, is sexually dichroniatic. Sex reversal in P. cylindrica is under social control and is completed approximately 20 days after the time of its initiation. The adaptiveness of protogynous sex reversal and its relationship to the social system in P. cylindrica is discussed.

Item ID:	33041
Item Type:	Thesis (PhD)
Keywords:	distribution; feeding behavior; food preferences; GBR; Great Barrier Reef; Lizard Island; marine fishes; morphology; Mugiloididae; mullets; Parapercis; phylogeny; reproduction; social behaviour; taxonomy
Additional Information:	Thesis resubmitted in September 1984.
Date Deposited:	08 May 2014 01:23
FoR Codes:	06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060301 Animal Systematics and Taxonomy @ 60% 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060201 Behavioural Ecology @ 40%
SEO Codes:	96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 50% 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
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