Ecology of Pinna bicolor gmelin (Mollusca : Bivalvia) in Gulf St Vincent, South Australia: density, reproductive cycle, recruitment, growth and mortality at three sites

1987 ◽  
Vol 38 (6) ◽  
pp. 743 ◽  
Author(s):  
AJ Butler
Keyword(s):  
Mortality Rate ◽  
Reproductive Cycle ◽  
Shell Length ◽  
South Australia ◽  
Maximum Size ◽  
Adult Mortality ◽  
Early Summer ◽  
Random Samples ◽  
Intertidal Site

Random samples of P. bicolor were taken from one intertidal and two subtidal sites over 3 years and tagged individuals of P. bicolor were followed for up to 6 years at two other sites. P. bicolor is dioecious. Mature gonads were observed in early summer (November-January) with a peak in December each year. The pattern appeared to differ little between years or sites but the period of maximum gonad activity was shorter at the intertidal site. Growth was slower at the intertidal site and animals reached a smaller maximum size there than at the subtidal sites, which differed slightly. It is concluded that P. bicolor can reach reproductive size (15 cm shell length) in little more than a year but, at least subtidally, have a low mortality rate (less than 0.1 year-1) thereafter. Recruitment is variable and it is argued that at some sites superficially 'stable' densities of P. bicolor are maintained by occasional strong recruitments, which are 'stored' in the population because of low adult mortality. The implications of this for management and for the use of P. bicolor as a biological monitor are discussed.

Size Distributions and Growth of the Fan-shell Pinna bicolor Gmelin (Mollusca : Eulamellibranchia) in South Australia

1979 ◽  
Vol 30 (1) ◽  
pp. 25 ◽  
Author(s):  
AJ Butler ◽  
FJ Brewster
Keyword(s):  
South Australia ◽  
Adductor Muscle ◽  
Size Distributions ◽  
Limited Data ◽  
Length Frequency ◽  
Age Classes ◽  
Frequency Distributions ◽  
Growth And Survival ◽  
Random Samples ◽  
Variable Success

Fourteen random samples of Pinna bicolor were collected over a period of 31 months from 6 m depth in Gulf St Vincent off Edithburgh, South Australia. The length-frequency distributions suggest that: P. bicolor larvae settle in spring but with variable success; growth of newly settled young is rapid over summer; by age 1 year their modal shell length is about 20 cm; by age 2 it is about 26 cm; they may survive substantially longer than 3 years so that a length-class of mode c. 35 cm is always present and is composed of several age-classes not necessarily equally represented. These suggestions are corroborated by limited data on adductor muscle scars, the development of epibiota on the shells, and the growth and survival of tagged animals over 9 months.

scholarly journals Reproductive cycle of male wall lizard, Podarcis vaucheri (Reptilia: Sauria: Lacertidae), in Djurdjura, Northern Algeria

2017 ◽  
Author(s):  
Rabah Mamou ◽  
Elara Moudilou ◽  
Jean-Marie Exbrayat ◽  
Mansour Amroun
Keyword(s):  
Sexual Activity ◽  
Reproductive Cycle ◽  
Mixed Type ◽  
Progressive Increase ◽  
Early Summer ◽  
Seminiferous Tubules ◽  
Testis Weight ◽  
Field Observations ◽  
Testicular Weight ◽  
Resting Period

The reproductive cycle of male wall lizard Podarcis vaucheri (Boulenger, 1905) living in Djurdjura mountain, was analyzed from April till October 2014. Its seasonal mixed-type cycle was characterized by three phases: sexual activity, quiescence and recrudescence. After the emergence of lizard from hibernation an intense sexual activity was observed in spring (April, May, and June) at which the testicular weight and seminiferous tubules diameter reached their maximal values. At this period, spermiogenesis was also maximal and the spermiation allowed the release of a large quantity of spermatozoa in both the seminiferous tubules and epididymis lumen. In July, a short sexual resting period followed, during which the testes mass and seminiferous tubules diameter decreased. Spermatogonia and some primary spermatocytes were observed against the wall of seminiferous tubules. The recrudescence period (August, September and October) was characterized by a progressive increase of the testis weight and seminiferous tubules diameter. Spermatocytogenesis began in August, and spermiogenesis occurred in September and October, before the diapause period. But the presence of spermatozoids was not signaled in the epididymis lumen. Field observations and microscopic evidence of testis showed that both sexes reproduced synchronously during spring and early summer.

The ecology of sympatric scincid lizards (Ctenotus) in arid South Australia

1998 ◽  
Vol 46 (6) ◽  
pp. 617 ◽  
Author(s):  
J. L. Read
Keyword(s):  
Home Range ◽  
Environmental Conditions ◽  
Plant Material ◽  
Reproductive Effort ◽  
Arid Zone ◽  
South Australia ◽  
Early Summer ◽  
Home Ranges ◽  
Local Species ◽  
Olympic Dam

Ctenotus skinks are the most diverse and abundant diurnal reptile genus at Olympic Dam, in the South Australian arid zone. The home range, demography, reproduction and diet of five syntopic Ctenotus species was studied over a 6-year period in chenopod shrubland. Longevity frequently exceeded three years in C. regius, four years in C. schomburgkii and five years in C. leonhardii, with a 7-year-old specimen of C. leonhardii being recorded. Females of most species tended to be larger and lived longer than males. Two eggs were typically laid by each species in early summer. Annual reproductive effort, particularly in C. leonhardii, varied considerably depending upon the prevailing environmental conditions. All local species apparently occupied home ranges, with maximum recapture radii in different species of 40–60 m. Ctenotus appear to be unspecialised insectivores, although plant material and lizards are sometimes eaten by the larger species.

Reproductive cycle of purple clam, Amiantis purpurata (Bivalvia: Veneridae) in northern Patagonia (Argentina)

2005 ◽  
Vol 85 (2) ◽  
pp. 367-373 ◽  
Author(s):  
Enrique M. Morsan ◽  
Marina A. Kroeck
Keyword(s):  
Reproductive Cycle ◽  
Continuous Process ◽  
Early Summer ◽  
Maturation Stage ◽  
Reproductive Pattern ◽  
Oocyte Diameter ◽  
Histological Techniques ◽  
Northern Patagonia ◽  
History Of ◽  
Quantitative Indicators

The reproductive cycle of the purple clam (Amiantis purpurata) northern Patagonian population was studied throughout a 19-month period (September 1993–March 1995) using standard histological techniques and quantitative indicators (oocyte diameter distributions, oocytes per ocular field and relative oocyte area). In this species gametogenesis is a continuous process involving a complete gonadal restitution after the end of the reproductive season (no resting period). The proliferation phase occurs during the coldest half of the year (April to September) and maturation takes place during spring (September to December). Several partial emissions of gametes, with subsequent restitution of the gametogenic series, occur during the summer months. During the total maturation stage, oocytes never filled the whole alveolar area: maximum per cent of alveolar sections occupied by oocytes (46%) was observed in late spring–early summer. Implications of the reproductive pattern in the context of palaeogeographic history of northern Patagonia, and the isolation of this population are discussed.

The effect of temperature and moisture on the Immature Stages of Aphodius tasmaniae Hope (Scarabaeidae) in the lower South-east of South Australia.

1961 ◽  
Vol 9 (2) ◽  
pp. 173 ◽  
Author(s):  
DA Maelzer
Keyword(s):  
Mortality Rate ◽  
Water Content ◽  
South Australia ◽  
Effect Of Temperature ◽  
Annual Rainfall ◽  
Field Observations ◽  
Immature Stages ◽  
Rate Of Increase ◽  
Lower South ◽  
Third Instar Larvae

The distribution and abundance of the univoltine species A. tasmaniae in the lower south-east of South Australia appears to be related to annual rainfall. The effects of moisture on the mortality rates of the immature stages were consequently studied and observations were made of the effects of variations in moisture in the field. Laboratory experiments and field observations suggested that variations in soil moisture have little effect on the eggs and the diapausing prepupae in the field. Eggs absorbed water and hatched normally within a pF range of 2.50-3.75 in a sand and in a clay loam. At pF 4.0 in both soils, eggs lost weight and did not hatch. The adults, however, tend to lay the eggs well within the pF range in which the eggs can develop, and soil samples suggested that eggs would develop with little mortality in the kinds of places in which they are usually laid. When prepupae enter diapause they have a water content of c. 77%. When desiccated in the laboratory, few prepupae died until their water content fell below 62%. The mortality rate then increased sharply, and it was estimated that 50% of the prepupae died when their water content dropped to 57%. Droughts of sufficient duration and intensity to kill 50% of the prepupae have never been recorded from the study area, and field observations suggested that few prepupae died of desiccation in summer. Unlike the two stages above, the first and third instar larvae may be markedly affected by variations in moisture in the field. The first instar larvae, after hatching, do not move to the surface of the soil and do not feed much until the soil is saturated with rain. As rainfall is variable at this time of the year, the larvae may be in dry soil for many weeks before they are stimulated to extend their burrows to the surface and search for food. Many larvae may die of starvation during this time, and the mortality rate of the larvae was related empirically to the length of the autumn "drought". Third instar larvae may be affected, on the other hand, by excessive water. In wet winters, vast numbers of larvae are drowned when extensive flooding occurs on the poorly-drained soils, and on well-drained soils a large proportion of larvae are killed by the entomophagous fungus Cordyceps aphodii. The above data have suggested that moisture is one of the major factors affecting the distribution and abundance of the species. Temperature has little effect on the rate of increase of the species.

Population Dynamics and Movement Patterns of Bolam's Mouse, Pseudomys bolami, at Roxby Downs, South Australia.

1998 ◽  
Vol 20 (3) ◽  
pp. 353
Author(s):  
K.E. Moseby ◽  
J.L. Read
Keyword(s):  
Arid Zone ◽  
Sand Dunes ◽  
South Australia ◽  
Breeding Strategy ◽  
Early Summer ◽  
Ecological Data ◽  
Winter Rainfall ◽  
Land Systems ◽  
Single Night ◽  
Time Of Year

Basic ecological data were collected on Bolam's mouse, Pseudomys bolami, during a six year trapping study at Roxby Downs in northern South Australia. Pseudomys bolami inhabited mixed arid land systems in the Roxby Downs area, sheltering in the longitudinal orange sand dunes but foraging at night principally on the adjacent chenopod swales. Distances of up to 334m were traversed in a single night and recapture rates were high within trapping sessions but low between sessions suggesting wide-ranging movements and short-term residency. Dietary observations imply an omnivorous diet. Whilst the closely related P. hermannsburgensis is regarded as having an opportunistic breeding strategy, P. bolami reproduced opportunistically but also regularly in spring and early summer. Different reproductive strategies may be influenced by the latitudinal distribution of P. bolami near the southern margin of the arid-zone, where rainfall can occur at any time of year but winter rainfall is more predictable. This contrasts with P. hermannsburgensis, which inhabits more northerly arid areas where rainfall is erratic and unpredictable. There was a 10 fold fluctuation in P. bolami captures over the trapping period with numbers of P. bolami and house mice, Mus domesticus peaking 12 months after above average rains during 1992. Rodent captures remained high for two years afterwards. Although P. bolami persisted throughout the study period, M. domesticus was only present when conditions were above average. Trap success of P. bolami or M. domesticus did not vary between the five sub habitats at the 1 ha study site. However, trap success of P. bolami was positively related to vegetation cover, particularly cover of low bluebush, Maireana astrotricha. Maireana astrotricha may be important in providing both food and cover for P. bolami, a scenario consistent with the utilisation of spinifex, Triodia spp. by P. hermannsburgensis in the northern arid-zone. Past over- grazing of chenopod shrublands may have reduced cover and contributed to the suggested decline in the distribution of P. bolami.

scholarly journals Meningococcal disease in South Australia: incidence and serogroup distribution 1971–1980

1983 ◽  
Vol 90 (1) ◽  
pp. 49-54 ◽  
Author(s):  
D. Hansman
Keyword(s):  
Mortality Rate ◽  
Meningococcal Disease ◽  
Single Case ◽  
South Australia ◽  
Neisseria Lactamica ◽  
Annual Prevalence ◽  
Group A ◽  
Overall Mortality

SUMMARYDuring the ten-year period 1971–80 isolates of meningococci from 85 cases of meningococcal disease (MD) in South Australia, from 66 children, 6 adolescents and 13 adults, were examined. These comprised 69 cases of meningitis and 16 cases of bacteraemia without meningitis. Thirty-three (39%) of all cases of MD occurred in children less than 1 year of age, the median age was 19 months. Serogroup B accounted for 61 (72%) cases of MD, group A seven (8%), group C seven (8%), group W135 five (6%), group Y three (4%) and group X one (1%); in addition there was a single case of Neisseria lactamica infection.The annual prevalence of MD in South Australia for the period was 11 cases per 100000 for children under the age of 2 years and 0·7 cases per 100000 overall. The prevalence was highest in winter (45% cases) and spring (26%) and lowest in summer (13%). The overall mortality rate was 8%. Four of the 21 infants under the age of 6 months died (mortality rate 19 %) whereas none of the 32 children aged from 6 months to 14 years died (P = 0·02). Amongst the survivors, three children had deafness, which was bilateral and severe in two.

Incidence of Marvinmeyeria lucida (Hirudinea: Glossiphoniidae) in the fingernail clam, Sphaerium occidentale

1979 ◽  
Vol 57 (3) ◽  
pp. 499-503 ◽  
Author(s):  
P. M. McKee ◽  
G. L. Mackie
Keyword(s):  
Dissolved Oxygen ◽  
Shell Length ◽  
Early Summer ◽  
Freshwater Gastropods ◽  
Oxygen Levels ◽  
Marked Preference

Marvinmeyeria lucida (Moore, 1954) is noted for the first lime in Ontario. It has been reported to feed exclusively on freshwater gastropods but the present study shows that it also occurs in natural association with the fingernail clam. Sphaerium occidentale (Prime). This small leech is found in the pericardium of its sphaeriid host and shows a marked preference for larger clams (> 5.0 mm shell length). Infestation rates are highest in winter (11.1–15.5%), lowest in spring and fall (1.1–3.6%), and intermediate (4.1–5.4%) in estivating clams. Rates of infestation are inversely related to dissolved oxygen levels in spring, fall, and early summer and to temperature in the fall. Possible commensal, parasitic, and (or} predatory relationships of M. lucida with S. occidentale are discussed.

The annual reproductive cycle and sperm storage in the bearded dragon, Pogona barbata

2000 ◽  
Vol 48 (4) ◽  
pp. 411 ◽  
Author(s):  
Andrew P. Amey ◽  
Joan M. Whittier
Keyword(s):  
Reproductive Cycle ◽  
Reproductive Output ◽  
Late Summer ◽  
Sperm Storage ◽  
Early Summer ◽  
Breeding Period ◽  
Eastern Australia ◽  
Bearded Dragon ◽  
Reproductive Females ◽  
Term Storage

Pogona barbata, a large lizard that inhabits the open woodlands of eastern Australia, has been reported to have a high annual reproductive output, which is contrary to expectations for a large lizard. To better understand this anomaly, its reproductive cycle and morphology were investigated. Males were spermatogenic year round, with only a brief period of regression in January (late summer). Females were vitellogenic and gravid through August–December (spring to early summer). Two or three large clutches (14–26 eggs per clutch) were produced each breeding period. Females had two germinal beds in each ovary, and all four actively produced eggs simultaneously. Clutches overlapped such that the next clutch began vitellogenesis before the first was laid. These characteristics make this species’ reproductive output one of the largest known among lizards. Reproductive females had sperm stored in oviductal crypts, but there was no evidence of sperm storage outside the breeding period. The short-term storage of sperm by breeding females may promote sperm competition between males.

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