Fred E. Wells

Population characteristics of the abalone Haliotis roei on intertidal platforms in the Perth metropolitan area

Abstract Basic population characteristics of the commercial abalone species Haliotis roei are compared on a heavily fished intertidal platform and a platform with no fishing pressure. Seasonal and annual variations in population density were large on both platforms, though densities were lower on the fished platform (Trigg) than the unfished area (Waterman). Most abalone at Waterman were adults of 2+ years (>60 mm), while few animals of this size occurred at Trigg. There were not sufficient adults at Trigg for reproduction on the platform to replenish the population, and it is postulated that replenishment comes from larvae originating from adjacent platforms. A subtidal rock with an unfished population of H. roei recovered at a rate of only about 10% per year, suggesting that heavily overfished populations would recover slowly, if at all.

Reproductive strategies of Hydrococcus brazieri (Tenison Woods, 1876) and Arthritica semen (Menke, 1843) in Peel Inlet, Western Australia

Abstract Females of Hydrococcus brazieri deposit egg capsules on any suitable hard substrate within which a single embryo develops. Young of Arthritica semen develop in a brood pouch in the female. In both species the young emerge at a crawling juvenile stage. Adaptations of H. brazieri and A. semen for estuarine life include: continuous reproduction, lack of a planktonic stage, rapid growth rates and short maturation times. In these characteristics H. brazieri and A. semen are relatively r selected in comparison with the other group of dominant estuarine molluscs, the mussels.

The apparent demise of the Asian date mussel Musculista senhousia in Western Australia: or using acts of god as an eradication tool

Musculista senhousia (Benson in Cantor, 1842) is a small thin-shelled mytilid inhabiting intertidal and shallow subtidal sediments. Prior to 2000, M. senhousia was widespread in the Swan River estuary, Perth, Western Australia. In 2000 the Perth region experienced its largest recorded summer rainfall event, with over 270 GL entering the estuary. The rainfall formed a freshwater lens over much of the river and a subsequent toxic algal bloom of the cyanobacterium Microcystis aeruginosa. M. aeruginosa produces a toxin microcystin, known to have adverse effects upon molluscs. Surveys to assess the status of M. senhousia in the estuary in 2007 failed to find any individuals. We suggest the apparent death of M. senhousia from the estuary may be attributable to a combination of high seasonal variability in the mussel’s populations, high summer rainfall reducing salinity, and a toxic algal bloom that eliminated any remaining M. senhousia individuals.

Molluscs of the Peel-Harvey estuarine system, with a comparison with other south-western Australian estuaries

Abstract Thirty-four mollusc species are recorded from the Peel-Harvey estuarine system; 13 are marine, 9 of marine affinity, 9 estuarine, and 1 freshwater (2 were undetermined). The number of marine and marine affinity species in the system is low compared to some of the other areas of southwestern Australia. Factors limiting the numbers of these species were considered to be the lack of varied habitat types, geographical location and the rigorous temperature and salinity regime. Eleven estuarine mollusc species are widespread in southwestern Australia; nine were recorded in Peel-Harvey. Two of these, Hydrococcus brazieri and Arthritica semen are numerically dominant in the system.

How many juvenile abalone are there? The example of Haliotis roei

Abstract We use population surveys of Haliotis roei on intertidal rock platforms at Perth, Western Australia to examine recruitment of juvenile individuals into the adult, fishable population. Despite intensive surveys conducted seasonally and over several years very few small H. roei were found. We propose the following life cycle for Haliotis roei: juveniles grow fast, reach adult size quickly, and survive for a number of years as adults. Recruitment of juveniles to the adult population is low, either through a steady annual maturation of juveniles or by substantial recruitment during an occasional good year.

A revision of the Recent Australian species of the turrid genera Clavus, Plagiostropha, and Tylotiella (Mollusca: Gastropoda)

Abstract Species of the drilliine genera Clavus (16 species), Plagiostropha (2 species), and Tylotiella (1 species) from Australian waters are revised. Four new species of Clavus are described from off Western Australia. Clavus viduus (Reeve, 1845) is regarded as a synonym of C. unizonalis (Lamarck, 1822). Clavus lamberti (Montrouzier, 1860), C. laetus (Hinds, 1843) and C. obliquatus (Reeve, 1845) and tentatively C. flammulatus Montfort, 1810 are recorded from Australia for the first time. Clavus undatus (Hedley, 1907) from New South Wales is recorded for the first time from Western Australia. The genus Plagiostropha Melvill, 1927 is separated from Clavus. Two species are recorded from Australia, one of which is described as new. Tylotiella pica (Reeve, 1843) is recorded from the Australian Indian Ocean territory of Christmas Island, but not continental Australia.

Revision of the recent Australian Turridae referred to the Genera Splendrillia and Austrodrillia

Abstract Turrids previously referred to the genera Splendrillia and Austrodrillia from southern Australian waters are revised; two tropical representatives are included. Sixteen species are recognized in Splendrillia and five in Austrodrillia. Clavus candidulus Hedley, 1922 is transferred to Splendrillia. Five new species of Splendrillia are described, three from southern Western Australia and two from Queensland. In Splendrillia, S. molleri Laseron, 1954 is synonymized with S. woodsi (Beddome, 1883) and S. harpularia (Desmoulins, 1842) and S. duplaris Hedley, 1922 are provisionally transferred to the genus Crassispira in the subfamily Crassispirinae, and a new species is described in this genus. Based on an examination of the radula of the type species, Austrodrillia angasi (Crosse, 1863), the genus Austrodrillia is also transferred to the Crassispirinae. In Austrodrillia, A. achatina (Verco, 1909) is synonymized with A. dimidiata (Sowerby, 1896).

Reproductive periodicity of the Chiton Acanthopleura hirtosa on intertidal platforms in the Perth area of Western Australia

Abstract The reproductive periodicity of populations of Acanthopleura hirtosa on three intertidal platforms in the Perth metropolitan area was studied using both gonad indices and histological analysis of gonad tissue. Both methods showed that the animals spawned in a single discrete period from April to June. The largest influx of juveniles into the population occurred from June to August, but recruitment was at a low level, suggesting that the animals survive for at least two years. Reproductive periodicity of A. hirtosa is compared with that known for other chitons.

The taxonomic status of the opisthobranch mollusc Bulla tenuissima Sowerby 1868

Based on an examination of type material, Bulla tenuissima Sowerby, 1868, described from Western Australia, is shown to be a synonym of B. quoyii Gray, 1843 of southern Australia and New Zealand. T...

A revision of the Recent Australian species of the turrid genera Inquisitor and Ptychobela

Recent Australian species of the genera Inquisitor and Ptychobela are revised, and many species previously included in Inquisitor are excluded. A total of 13 species are recognized in Inquisitor, including two described as new from Western Australia, and two species are recognized in Ptychobela. Pleurotoma torresiana Smith, 1884 is considered to be a synonym of I. sterrha (Watson, 1881); Brachytoma alma Thiele, 1930 is synonymized with I. lassulus Hedley, 1922; and I. fibratus Hedley, 1922, Drillia hololeuca Odhner, 1917 and Drillia spaldingi Brazier, 1876 with I. spicata Hinds, 1843. Inquisitor sterrha is recorded for the first time from southern Indonesia and southern Papua New Guinea.