Female Reproductive Biology and Spawning Periodicity of Two Species of King Prawns, Penaeus longistylus Kubo and Penaeus latisulcatus Kishinouye, from Queensland's East Coast Fishery

In the coastal region of central Queensland female red-spot king prawns, P. longistylus, and the western or blue-leg king prawns, P. latisulcatus, had high mean ovary weights and high proportions of advanced ovary development during the winter months of July and August of 1985 and 1986. On the basis of insemination, both species began copulating at the size of 26-27 mm CL, but P. longistylus matured and spawned at a smaller size than P. latisulcatus. Abundance of P. longistylus was generally three to four times greater than that of P. latisulcatus but the latter was subject to greater variation in abundance. Low mean ovary weight and low proportions of females with advanced ovaries were associated with the maximum mean bottom sea-water temperature (28.5ºC) for both species. Population fecundity indices indicated that peaks in yolk or egg production (a) displayed a similar pattern for both species, (b) varied in timing from year to year for both species and (c) were strongly influenced by abundance. Generally, sample estimates of abundance and commercial catch rates (CPUE) showed similar trends. Differences between the two may have been due to changes in targeted commercial effort in this multi-species fishery.

Reproductive Biology and Spawning Periodicity of Endeavour Shrimps Metapenaeus endeavouri (Schmitt, 1926) and Metapenaeus ensis (de Haan, 1850) from a Central Queensland (Australia) Fishery

Metapenaeus endeavouri and M. ensis from coastal trawl fishing grounds off central Queensland, Australia, have marked seasonal reproductive cycles. Female M. endeavouri grew to a larger size than female M. ensis and occurred over a wider range of sites and depths. Although M. ensis was geographically restricted in distribution to only the shallowest sites it was highly abundant. Mating activity in these open thelycum species, indicated by the presence or absence of a spermatophore, was relatively low and highly seasonal compared with closed thelyeum shrimps. Seasonal variation in spermatophore insemination can be used as an independent technique to study spawning periodicity in open thelycum shrimps. Data strongly suggest an inshore movement of M. endeavouri to mature and spawn. This differs from most concepts of Penaeus species life cycles, but is consistent with the estuarine significance in the life cycle of Metapenaeus species. Monthly population fecundity indices suggest summer spawning for both species, which contrasts with the winter spawning of other shrimps from the same multispecies fishery.

The fishery and reproductive biology of Barking crayfish, Linuparus trigonus (Von Siebold, 1824) along Queenslands east coast

This paper describes the fishery and reproductive biology for Linuparus trigonus obtained from trawl fishermen operating off Queensland’s east coast, Australia. The smallest mature female lobster measured 59.8 mm CL, however, 50% maturity was reached between 80 and 85 mm CL. Brood fecundity (BF) was size dependent and ranged between 19,287 and 100,671 eggs in 32 females from 59.8 to 104.3 mm CL. The relationship was best described by the power equation BF = 0.1107*CL to the power of 2.9241 (r to the power of 2 = 0:74). Egg size ranged from 0.96 to 1.12 mm in diameter (mean = 1:02 (+or-) 0:01 mm). Egg weight and size were independent of lobster size. Length frequencies displayed multi-modal distributions.The percentage of female to male lobsters was relatively stable for small size classes (30 to 70 mm CL; 50.0 to 63.6% females), but female proportions rose markedly between 75 and 90 mm (72.2 to 85.4%) suggesting that at the onset of sexual maturity female growth rates are reduced. In size classes greater than 95 mm, males were numerically dominant. A description of the L. trigonus fishery in Queensland is also detailed.

On Systems Thinking, Systems Biology, and the in Silico Plant

The recent summary report of a Department of Energy Workshop on Plant Systems Biology (P.V. Minorsky [2003] Plant Physiol 132: 404-409) offered a welcomed advocacy for systems analysis as essential in understanding plant development, growth, and production. The goal of the Workshop was to consider methods for relating the results of molecular research to real-world challenges in plant production for increased food supplies, alternative energy sources, and environmental improvement. The rather surprising feature of this report, however, was that the Workshop largely overlooked the rich history of plant systems analysis extending over nearly 40 years (Sinclair and Seligman, 1996) that has considered exactly those challenges targeted by the Workshop. Past systems research has explored and incorporated biochemical and physiological knowledge into plant simulation models from a number of perspectives. The research has resulted in considerable understanding and insight about how to simulate plant systems and the relative contribution of various factors in influencing plant production. These past activities have contributed directly to research focused on solving the problems of increasing biomass production and crop yields. These modeling approaches are also now providing an avenue to enhance integration of molecular genetic technologies in plant improvement (Hammer et al., 2002).

Reproductive biology of the red throat emperor Lethrinus miniatus (Pisces : Lethrinidae) from the southern Great Barrier Reef, Australia

The reproductive biology of the red throat emperor, Lethrinus miniatus (Schneider, 1801) was examined in the southern Great Barrier Reef (GBR), Australia. The species was found to display the characteristics of an incomplete metagynous hermaphrodite based on histological evidence and size frequency information. Over 95% of functional males possessed a remnant lumen, but there was no evidence of oocytes in the testes of males. A single transitional fish was sampled which had both ovarian and testicular tissue present in its gonad. Size frequency data showed that females dominated the smaller size classes with the majority of fish < 40 cm being females. Lethrinus miniatus had an extended spawning season from July-November, although spawning was more pronounced during the spring. Spawning was initiated earlier at lower latitudes. There was no particular size or age when sex change occurred since females older than 20 and males as young as 2-yrs old were sampled.

Biology of Plant Rhabdoviruses

The Rhabdoviridae, whose members collectively infect invertebrates, animals, and plants, form a large family that has important consequences for human health, agriculture, and wildlife ecology. Plant rhabdoviruses can be separated into the genera Cytorhabdovirus and Nucleorhabdovirus, based on their sites of replication and morphogenesis. This review presents a general overviewof classical and contemporary findings about rhabdovirus ecology, pathology, vector relations, and taxonomy. The genome organization and structure of several recently sequenced nucleorhabdoviruses and cytorhabdoviruses is integrated with new cell biology findings to provide a model for the replication of the two genera. A prospectus outlines the exciting opportunities for future research that will contribute to a more detailed understanding of the biology, biochemistry, replication and host interactions of the plant rhabdoviruses.

Recent advances in the molecular biology of Leifsonia xyli subsp. xyli, causal organism of ratoon stunting disease

Twelve years ago our understanding of ratoon stunting disease (RSD) was confined almost exclusively to diagnosis of the disease and control via farm hygiene, with little understanding of the biology of the interaction between the causal agent (Leifsonia xyli subsp. xyli) and the host plant sugarcane (Saccharum spp. hybrids). Since then, research has focused on developing the molecular tools to dissect L. xyli subsp. xyli, so that better control strategies can be developed to prevent losses from RSD. Within this review, we give a brief overview of the progression in research on L. xyli subsp. xyli and highlight future challenges. After a brief historical background on RSD, we discuss the development of molecular tools such as transformation and transposon mutagenesis and discuss the apparent lack of genetic diversity within the L. xyli subsp. xyli world population. We go on to discuss the sequencing of the genome of L. xyli subsp. xyli, describe the key findings and suggest some future research based on known deficiencies that will capitalise on this tremendous knowledge base to which we now have access.

The effects of holding space on growth and survival of individually reared three-spot crab (Portunus sanguinolentus).

The problem of cannibalism in communally reared crabs can be eliminated by separating the growing crabs into holding compartments. There is currently no information on optimal compartment size for growing crabs individually. 136 second instar crablets (Portunus sanguinolentus) (C2 ca. 7-10 mm carapace width (CW)) were grown for 90 days in 10 different-sized opaque and transparent walled acrylic compartments. The base area for each compartment ranged from small (32 mm × 32 mm) to large (176 mm × 176 mm). Effects of holding space and wall transparency on survival, CW, moult increment, intermoult period and average weekly gain (AWG) were examined. Most crabs reached instars C9-C10 (50-70 mm CW) by the end of experiment. The final survival rate in the smallest compartment was 25% mainly due to moult-related mortality predominantly occurring at the C9 instar. However, crabs in these smaller compartments had earlier produced significantly larger moult increments from instar to instar than those in the larger compartments (P < 0.05). Crabs in the smaller compartments (<65 mm × 65 mm) also showed significantly longer moult periods (P < 0.05). The net result was that AWG in CW was 5.22 mm week-1 for the largest compartment and 5.15 mm week-1 in smallest and did not differ significantly between compartment size groups (P = 0.916). Wall transparency had no impact on survival (P = 0.530) but a slight impact on AWG (P = 0.014). Survival rate was the best indicator of minimum acceptable compartment size (?43 mm × 43 mm) for C10 crablets because below this size death occurred before growth rate was significantly affected. For further growth, it would be necessary to transfer the crablets to larger compartments.

Spatial patterns in the biology of the chokka squid, Loligo reynaudii on the Agulhas Bank, South Africa

Although migration patterns for various life history stages of the chokka squid (Loligo reynaudii) have been previously presented, there has been limited comparison of spatial variation in biological parameters. Based on data from research surveys; size ranges of juveniles, subadults and adults on the Agulhas Bank were estimated and presented spatially. The bulk of the results appear to largely support the current acceptance of the life cycle with an annual pattern of squid hatching in the east, migrating westwards to offshore feeding grounds on the Central and Western Agulhas Bank and the west coast and subsequent return migration to the eastern inshore areas to spawn. The number of adult animals in deeper water, particularly in autumn in the central study area probably represents squid spawning in deeper waters and over a greater area than is currently targeted by the fishery. The distribution of life history stages and different feeding areas does not rule out the possibility that discrete populations of L. reynaudii with different biological characteristics inhabit the western and eastern regions of the Agulhas Bank. In this hypothesis, some mixing of the populations does occur but generally squid from the western Agulhas Bank may occur in smaller numbers, grow more slowly and mature at a larger size. Spawning occurs on the western portion of the Agulhas Bank, and juveniles grow and mature on the west coast and the central Agulhas Bank. Future research requirements include the elucidation of the age structure of chokka squid both spatially and temporally, and a comparison of the statolith chemistry and genetic characterisation between adults from different spawning areas across the Agulhas Bank.

Fishery biology and management of Protonibea diacanthus (Sciaenidae) aggregations in far Northern Cape York Peninsula waters

The sciaenid Protonibea diacanthus is a large, long-lived predatory fish of inshore northern Australian waters, which forms annual aggregations that are fished extensively by traditional (subsistence) and recreational fishers. There are now widespread concerns that the resource is being overexploited. Indigenous fishers of the Cape York Northern Peninsula Area (NPA) relate that large adult fish (up to 1500 mm total length (TL)) made up the bulk of the catch from the sciaenid aggregations until about 1994. In contrast, sexually mature P. diacanthus comprised only a small component (12 fish out of 270=4.4%) examined in a 1999–2000 sampling programme that was biased towards the largest individuals available. At 790 mm TL, the minimum size at first maturity for female P. diacanthus in this study is much smaller than the 920 mm TL reported previously in Queensland waters. Developing ovaries were observed in specimens sampled from sciaenid aggregations which formed in NPA waters between May and September 2000. However, no fish with ripe or spent gonads were found in the study, so the current timing and location of the spawning season for P. diacanthus in the region remain unknown. Food items observed in the analysis of the diet of P. diacanthus from the NPA included a variety of teleosts and invertebrates. The range of animal taxa represented in the prey items support the description of an ‘opportunistic predator’ attributed to the species. In our sampling, the stomach contents of fish caught during the time of the aggregation events did not differ from those observed at other times of the year. A total of 114 P. diacanthus were tagged and released at aggregation sites during the study period, and 3 fish (2.6%) were subsequently recaptured. The low rate of tag returns from the wild stock tagging programme, both in this study (2.6%) and from recreational fisher tag/release programmes for the sciaenid elsewhere in Queensland (6.5%), were not explained by tag loss nor mortality, given the high retention rate of tags and the zero mortality seen in tank trials. In response to the biological findings from this study, indigenous community councils of the NPA imposed a 2-year fishing moratorium for P. diacanthus. Surveys at aggregation sites in 2002 and 2003 established that much larger fish (mean size 103.5 cm TL) were again present on the grounds, albeit in very low numbers. These recent preliminary results highlight the critical need for continued monitoring and management of the P. diacanthus fishery in the NPA, if prospects for resource recovery are to be realised. The NPA initiative has provided a rare opportunity to negotiate a co-management strategy, based on scientific data and traditional knowledge, for the recovery of a cultural and economically significant fished resource.

Reproductive biology of mangrove jack (Lutjanus argentimaculatus) in northeastern Queensland, Australia

Lutjanus argentimaculatus is an Indo-Pacific species that inhabits riverine, coastal and offshore reef habitats. An investigation of the reproductive biology of Lutjanus argentimaculatus in northeastern Queensland waters (Australia) was undertaken between 1999 and 2002. Individuals in inshore estuarine and freshwater riverine habitats were mostly immature whereas those captured in offshore reef waters were predominantly mature. Males matured at a smaller size than females, with the length-at-50%-maturity (Lm50) for males estimated to be 470.7 mm fork length (FL) and 531.4 mm FL for females. The spawning season in northeastern Queensland was mostly during the austral spring-summer and peaked in December. The presence of ripe female fish and occurrence of postovulatory follicles in histological sections provided evidence that spawning activity was more pronounced during the full and third quarter moon phases. Lutjanus argentimaculatus were highly fecund with estimates of up to 4 x 106 ova per spawning event. Immature fish concentrated in inshore areas where they were targeted by recreational fishers whereas, in offshore areas, commercial fishers caught predominantly larger, mature fish.

Space allowances for confined livestock and their determination from allometric principles

The amount of space provided to animals governs important elements of their behaviour and, hence, is critical for their health and welfare. We review the use of allometric principles and equations to estimate the static space requirements of animals when standing and lying, and the space required for animals to feed, drink, stand-up and lie-down. We use the research literature relating to transportation and intensive housing of sheep and cattle to assess the validity of allometric equations for estimating space allowances. We investigated these areas because transportation and intensive housing provide points along a continuum in terms of the duration of confinement, (from hours to months) and spatial requirements are likely to increase with increasing duration of confinement, as animals will need to perform a greater behavioural repertoire for long-term survival, health and welfare. We find that, although there are theoretical reasons why allometric relationships to space allowances may vary slightly for different classes of stock, space allowances that have been demonstrated to have adverse effects on animal welfare during transportation correlated well with an inability to accommodate standing animals, as estimated from allometry. For intensive housing, we were able to detect a space allowance below which there were adverse effects on welfare. For short duration transportation during which animals remain standing, a space allowance per animal described by the allometric equation: area (m^2) = 0.020W^0.66, where W = liveweight (kg), would appear to be appropriate. Where it is desirable for all animals to lie simultaneously, then a minimum space allowance per animal described by the allometric equation: area (m^2) = 0.027W^0.66 appears to permit this, given that animals in a group time-share space. However, there are insufficient data to determine whether this allowance onboard a vehicle/vessel would enable animals to move and access food and water with ease. In intensive housing systems, a minimum space allowance per animal described by the allometric equation: area (m^2) = 0.033W^0.66 appears to be the threshold below which there are adverse effects on welfare. These suggested space allowances require verification with a range of species under different thermal conditions and, for transportation, under different conditions of vehicular/vessel stability. The minimum length of trough per animal (L in m) required for feeding and drinking can be determined from L = 0.064W^0.33, with the number of animals required to feed/drink simultaneously taken into account, together with any requirement to minimise competition. This also requires verification with a range of species. We conclude that allometric relationships are an appropriate basis for the formulation of space allowances for livestock.

The biology of Australian weeds: Volume 3

Over the past decade, The biology of Australian weeds series has presented summary chapters about the biology, taxonomy, significance and control of most of Australia's most problematic weeds. Many of these chapters first appear in Plant Protection Quarterly and are then updated and revised for the book. Dane Panetta was also an editor of the second volume. This volume contains chapters of a further sixteen weed species including several of interest to Queensland.

Biology and host range of Ophiomyia camarae Spencer (Diptera: Agromyzidae), a potential biocontrol agent for Lantana spp. (Verbenaceae) in Australia

The life history and host range of the herringbone leaf-mining fly Ophiomyia camarae, a potential biological control agent for Lantana spp., were investigated. Eggs were deposited singly on the underside of leaves. Although several eggs can be laid on a single leaf and a maximum of three individual mines were seen on a single leaf, only one pupa per leaf ever developed. The generation time (egg to adult) was about 38 days. Females (mean 14 days) lived longer than males (mean 9 days) and produced about 61 mines. Oviposition and larval development occurred on all five lantana phenotypes tested. Eleven plant species representing six families were tested to determine the host range. Oviposition and larval development occurred on only lantana and another nonnative plant Lippia alba (Verbenaceae), with both species supporting populations over several generations. A CLIMEX model showed that most of the coastal areas of eastern Australia south to 30°16' S (Coffs Harbour) would be suitable for O. camarae. O. camarae was approved for release in Australia in October 2007 and mines have been observed on plants at numerous field sites along the coast following releases.

The host range and biology of Cometaster pyrula; a biocontrol agent for Acacia nilotica subsp. indica in Australia

Prickly acacia, Acacia nilotica subsp. indica (Benth.) Brenan, a major weed of the Mitchell Grass Downs of northern Queensland, Australia, has been the target of biological control projects since the 1980s. The leaf-feeding caterpillar Cometaster pyrula (Hopffer) was collected from Acacia nilotica subsp. kraussiana (Benth.) Brenan during surveys in South Africa to find suitable biological control agents, recognised as a potential agent, and shipped into a quarantine facility in Australia. Cometaster pyrula has a life cycle of approximately 2 months during which time the larvae feed voraciously and reach 6 cm in length. Female moths oviposit a mean of 339 eggs. When presented with cut foliage of 77 plant species, unfed neonates survived for 7 days on only Acacia nilotica subsp. indica and Acacia nilotica subsp. kraussiana. When unfed neonates were placed on potted plants of 14 plant species, all larvae except those on Acacia nilotica subsp. indica and Acacia nilotica subsp. kraussiana died within 10 days of placement. Cometaster pyrula was considered to be highly host specific and safe to release in Australia. Permission to release C. pyrula in Australia was obtained and the insect was first released in north Queensland in October 2004. The ecoclimatic model CLIMEX indicated that coastal Queensland was climatically suitable for this insect but that inland areas were only marginally suitable.