Polybridge Technical Report

This study examined the physical and chemical properties of a novel, fully-recirculated prawn and polychaete production system that incorporated polychaete-assisted sand filters (PASF). The aims were to assess and demonstrate the potential of this system for industrialisation, and to provide optimisations for wastewater treatment by PASF. Two successive seasons were studied at commercially-relevant scales in a prototype system constructed at the Bribie Island Research Centre in Southeast Queensland. The project produced over 5.4 tonnes of high quality black tiger prawns at rates up to 9.9 tonnes per hectare, with feed conversion of up to 1.1. Additionally, the project produced about 930 kg of high value polychaete biomass at rates up to 1.5 kg per square metre of PASF, with the worms feeding predominantly on waste nutrients. Importantly, this closed production system demonstrated rapid growth of healthy prawns at commercially relevant production levels, using methods that appear feasible for application at large scale. Deeper (23 cm) PASF beds provided similar but more reliable wastewater treatment efficacies compared with shallower (13 cm) beds, but did not demonstrate significantly greater polychaete productivity than (easier to harvest) shallow beds. The nutrient dynamics associated with seasonal and tidal operations of the system were studied in detail, providing technical and practical insights into how PASF could be optimised for the mitigation of nutrient discharge. The study also highlighted some of the other important advantages of this integrated system, including low sludge production, no water discharge during the culture phase, high ecosystem health, good prospects for biosecurity controls, and the sustainable production of a fishery-limited resource (polychaetes) that may be essential for the expansion of prawn farming industries throughout the world. Regarding nutrient discharge from this prototype mariculture system, when PASF was operating correctly it proved feasible to have no water (or nutrient) discharge during the entire prawn growing season. However, the final drain harvest and emptying of ponds that is necessary at the end of the prawn farming season released 58.4 kg ha-1 of nitrogen and 6 kg ha-1 of phosphorus (in Season 2). Whilst this is well below (i.e., one-third to one-half of) the current load-based licencing conditions for many prawn farms in Australia, the levels of nitrogen and chlorophyll a in the ponds remained higher than the more-stringent maximum limits at the Bribie Island study site. Zero-net-nutrient discharge was not achieved, but waste nutrients were low where 5.91 kg of nitrogen and 0.61 kg of phosphorus was discharged per tonne of prawns produced. This was from a system that deployed PASF at 14.4% of total ponded farm area which treated an average of 5.8% of pond water daily and did not use settlement ponds or other natural or artificial water remediation systems. Four supplemental appendices complement this research by studying several additional aspects that are central to the industrialisation of PASF. The first details an economic model and decision tool which allows potential users to interactively assess construction and operational variables of PASF at different scales. The second provides the qualitative results of a prawn maturation trial conducted collaboratively with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to assess dietary inclusions of PASF-produced worms. The third provides the reproductive results from industry-based assessments of prawn broodstock produced using PASF. And the fourth appendix provides detailed elemental and nutritional analyses of bacterial biofilm produced by PASF and assesses its potential to improve the growth of prawns in recirculated culture systems

Polybridge Season 3: Ecosystem effects of polychaete-assisted sand filters

This study is an extension of research undertaken in the first two seasons of the Polybridge Project (2013-2016: for results see Palmer et al., 2016), which sought to investigate operational aspects of polychaete-assisted sand filters (PASF) when deployed for scaled prawn farm recirculation at the Bribie Island Research Centre (BIRC). The aims of the present work were to assess its functionality with increased organic loading rates provided by higher prawn stocking densities than previously trialled, and to assess the ecological effects on this integrated farming system when using PASF to initially fill ponds for a range of biosecurity purposes. Using prawn postlarval stocking densities in excess of 44 m-2, prawn production of up to 12 tonnes ha-1 was achieved without discharge of any wastewater during the production season (2015-16). However, the average production for the two ponds was 9.4 tonnes ha-1, which was lower than in the previous season (9.9 tonnes ha-1 in 2014/15) which used a lower prawn stocking density (37.5 postlarvae m-2). The prawns and worms produced were again healthy and of high commercial quality and value, but slower prawn growth (particularly after 140 d) and lower worm survival limited overall production in the fully-recirculated system. There were also several concerning aspects to this closed-system approach that need to be highlighted. Firstly, nutrient levels in the pond waters rose to particularly high levels, and some of the more toxic parameters, such as ammonia, reached critical levels that could be considered dangerous for routine prawn culture operations. Worm production in the PASF beds also suffered from the very rich wastewaters in the integrated system, and the capacity of PASF to filter water via percolation was limited by excessive sand clogging and a build-up of organic matter on the upper surface of the sand beds. The resultant excessive anoxic conditions created in the sand beds appeared to reduce worm productivity which, in turn, reduced their sand cleansing actions, for an overall lower functionality in terms of nutrient (and particularly nitrogen) removal rates. Alternatively, within the confines of the overall study, there were no significant deleterious effects on worm production or nutrient removal efficacies from using the PASF beds to initially fill the prawn production pond. The apparent effect of this on pond plankton communities was: 1) to slow the development of copepod populations; and 2) change the assemblage of algal species in the first few weeks after filling. This slower development of natural feed organisms in the PASF-filled pond may have provided lower survival of the particularly-young (PL 13) prawn seedstock used to stock the pond. Importantly however, there may be several potential remedies to this issue. These include management for a longer period for bloom development after fill and before stocking, and assuming a greater reliance on artificial feeds more suited to small prawns. As expected, this pond-fill strategy appeared to beneficially help exclude some problematic algal species, and greatly reduced barnacle fouling, though tube worm fouling did not appear overly affected. The project successfully demonstrated a third successive season of zero-water discharge from an integrated prawn/ worm production system, though ultimately, the water in ponds with some residual nutrients were discharged. The expansion of prawn farming in Australia is limited by nutrient discharge issues, and biosecurity measures are also of increasing interest to this industry. In this legacy project, polychaete-assisted sand filters are further demonstrated to hold potential for biosecurity controls whilst minimising nutrient discharge

Developing Jungle Perch Fingerling Production to Improve Fishing Opportunities

This project has for the first time demonstrated the feasibility of hatchery production of jungle perch fingerlings. The research on jungle perch production has enabled a hatchery production manual with accompanying videos to be produced. This has given private commercial hatcheries the information needed to produce jungle perch fingerlings. Several hatcheries have already indicated an interest in producing jungle perch and will be assisted to do so in 2016. Currently jungle perch are not a permitted stocking species, so cannot be sold to fish stocking groups. However, hatcheries will be able to sell fingerlings to the aquarium trade or supply grow out facilities that could produce jungle perch for human consumption. Should jungle perch become a permitted species for stocking, this will provide hatcheries with a major new product option to sell to fish stocking groups. It would also benefit anglers by providing another iconic species for impoundment stocking programs. This could have flow-on benefits to regional economies through angler tourism. Should the pilot reintroductions of jungle perch into streams result in self-sustaining jungle perch populations, then there will be three restored jungle perch populations close to major population centres. This will create a new opportunity for anglers not normally able to target jungle perch. Since the majority of anglers who target jungle perch are catch and release fishers, angling is expected to have minimal impact on recovery of the populations. This project led to the development of a hatchery manual for jungle perch production and to a summary brochure. In late 2014 and in 2015 researchers were able to make the first ever releases of jungle perch fingerlings back into rivers and streams within their historical range

Developing Jungle Perch Fingerling Production to Improve Fishing Opportunities

This project has for the first time demonstrated the feasibility of hatchery production of jungle perch fingerlings. The research on jungle perch production has enabled a hatchery production manual with accompanying videos to be produced. This has given private commercial hatcheries the information needed to produce jungle perch fingerlings. Several hatcheries have already indicated an interest in producing jungle perch and will be assisted to do so in 2016. Currently jungle perch are not a permitted stocking species, so cannot be sold to fish stocking groups. However, hatcheries will be able to sell fingerlings to the aquarium trade or supply grow out facilities that could produce jungle perch for human consumption. Should jungle perch become a permitted species for stocking, this will provide hatcheries with a major new product option to sell to fish stocking groups. It would also benefit anglers by providing another iconic species for impoundment stocking programs. This could have flow-on benefits to regional economies through angler tourism. Should the pilot reintroductions of jungle perch into streams result in self-sustaining jungle perch populations, then there will be three restored jungle perch populations close to major population centres. This will create a new opportunity for anglers not normally able to target jungle perch. Since the majority of anglers who target jungle perch are catch and release fishers, angling is expected to have minimal impact on recovery of the populations. This project led to the development of a hatchery manual for jungle perch production and to a summary brochure. In late 2014 and in 2015 researchers were able to make the first ever releases of jungle perch fingerlings back into rivers and streams within their historical range

Sensor-Based Gait Retraining Lowers Knee Adduction Moment and Improves Symptoms in Patients with Knee Osteoarthritis: A Randomized Controlled Trial

The present study compared the effect between walking exercise and a newly developed sensor-based gait retraining on the peaks of knee adduction moment (KAM), knee adduction angular impulse (KAAI), knee flexion moment (KFM) and symptoms and functions in patients with early medial knee osteoarthritis (OA). Eligible participants (n = 71) with early medial knee OA (Kellgren-Lawrence grade I or II) were randomized to either walking exercise or gait retraining group. Knee loading-related parameters including KAM, KAAI and KFM were measured before and after 6-week gait retraining. We also examined clinical outcomes including visual analog pain scale (VASP) and Knee Injury and Osteoarthritis Outcome Score (KOOS) at each time point. After gait retraining, KAM1 and VASP were significantly reduced (both Ps < 0.001) and KOOS significantly improved (p = 0.004) in the gait retraining group, while these parameters remained similar in the walking exercise group (Ps ≥ 0.448). However, KAM2, KAAI and KFM did not change in both groups across time (Ps ≥ 0.120). A six-week sensor-based gait retraining, compared with walking exercise, was an effective intervention to lower medial knee loading, relieve knee pain and improve symptoms for patients with early medial knee OA

Transportation infrastructure and rural development in China

Purpose: The infrastructure investment is one important source of economic growth in China in the past three decades. However it is not clear to what extent such investment affects development in rural area. The purpose of this paper is to explore this impact both conceptually and quantitatively, and draw policy implications from the empirical exercise. Design/methodology/approach: The authors first describe the conceptual link between the transportation infrastructure and rural development, which motivates the empirical model. Then by utilizing an autoregressive distributed lag model, the authors estimate both the short- and long-run impacts of the transportation infrastructure on rural development, in terms of cereal yield and per capita net income of rural households. Findings: The authors find that investment in transportation infrastructure positively affects rural development in China. In terms of cereal yield, a 1 percent increase in the road infrastructure (road length) leads to around 0.05 percent increase in cereal yield in the short- ,and around 0.19 percent increase in the long-run. In terms of the per capita net income of rural households, a 1 percent increase in the road infrastructure results in around 0.14 percent increase in the short-, and its long-run impact is not statistically significant. The positive impacts lend supports to promote investment in the transportation infrastructure. To this end, in addition to the government funding, the participation of private capital can also be promoted through a number of channels, such as the build-operate-transfer, public-private partnership, and establishment of infrastructure investment bank. Originality/value: This study evaluates the impacts of transportation infrastructure on rural development in China. Despite of the importance of infrastructure and rural development, there is a lack of study on the interaction between them. This paper intends to fill in this gap. In addition, implications drawn in this exercise can benefit policy makers not only in China, but also in other developing countries

Polybridge Technical Report

This study examined the physical and chemical properties of a novel, fully-recirculated prawn and polychaete production system that incorporated polychaete-assisted sand filters (PASF). The aims were to assess and demonstrate the potential of this system for industrialisation, and to provide optimisations for wastewater treatment by PASF. Two successive seasons were studied at commercially-relevant scales in a prototype system constructed at the Bribie Island Research Centre in Southeast Queensland. The project produced over 5.4 tonnes of high quality black tiger prawns at rates up to 9.9 tonnes per hectare, with feed conversion of up to 1.1. Additionally, the project produced about 930 kg of high value polychaete biomass at rates up to 1.5 kg per square metre of PASF, with the worms feeding predominantly on waste nutrients. Importantly, this closed production system demonstrated rapid growth of healthy prawns at commercially relevant production levels, using methods that appear feasible for application at large scale. Deeper (23 cm) PASF beds provided similar but more reliable wastewater treatment efficacies compared with shallower (13 cm) beds, but did not demonstrate significantly greater polychaete productivity than (easier to harvest) shallow beds. The nutrient dynamics associated with seasonal and tidal operations of the system were studied in detail, providing technical and practical insights into how PASF could be optimised for the mitigation of nutrient discharge. The study also highlighted some of the other important advantages of this integrated system, including low sludge production, no water discharge during the culture phase, high ecosystem health, good prospects for biosecurity controls, and the sustainable production of a fishery-limited resource (polychaetes) that may be essential for the expansion of prawn farming industries throughout the world. Regarding nutrient discharge from this prototype mariculture system, when PASF was operating correctly it proved feasible to have no water (or nutrient) discharge during the entire prawn growing season. However, the final drain harvest and emptying of ponds that is necessary at the end of the prawn farming season released 58.4 kg ha-1 of nitrogen and 6 kg ha-1 of phosphorus (in Season 2). Whilst this is well below (i.e., one-third to one-half of) the current load-based licencing conditions for many prawn farms in Australia, the levels of nitrogen and chlorophyll a in the ponds remained higher than the more-stringent maximum limits at the Bribie Island study site. Zero-net-nutrient discharge was not achieved, but waste nutrients were low where 5.91 kg of nitrogen and 0.61 kg of phosphorus was discharged per tonne of prawns produced. This was from a system that deployed PASF at 14.4% of total ponded farm area which treated an average of 5.8% of pond water daily and did not use settlement ponds or other natural or artificial water remediation systems. Four supplemental appendices complement this research by studying several additional aspects that are central to the industrialisation of PASF. The first details an economic model and decision tool which allows potential users to interactively assess construction and operational variables of PASF at different scales. The second provides the qualitative results of a prawn maturation trial conducted collaboratively with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to assess dietary inclusions of PASF-produced worms. The third provides the reproductive results from industry-based assessments of prawn broodstock produced using PASF. And the fourth appendix provides detailed elemental and nutritional analyses of bacterial biofilm produced by PASF and assesses its potential to improve the growth of prawns in recirculated culture systems

Byssal attachment of Amusium balloti (Bernardi, 1861) (Bivalvia: Pectinidae) spat

It has been previously reported that the saucer scallop, Amusium balloti, either lacked the ability to produce byssal threads or could do so only briefly. This present study reports our main conclusion that in the early spat stages, A. balloti does indeed secrete byssus, albeit at a time different from most scallops. We found that A. balloti first attaches by a byssus only after metamorphosis (indicated by the presence of dissoconch shell), and we found no evidence of the byssal attachment before or during early metamorphosis. By the time spat reach a shell height of 1-2 mm they secrete two or three fine byssal filaments. Byssal attachment is maintained until the spat reaches 4-5 mm, around the stage where they develop the ability to swim. This pattern is unlike that found in most other scallops that initiate byssal production and attachment before metamorphosis. We also describe post-settlement behavior of A. balloti. The newly settled postlarvae (∼200 μm shell height) crawl along the substratum by using their foot. During attachment, spat change their positions daily, moving an average of 17 mm per day. In culture, a gentle water jet and hypersaline bath (40‰) effectively detached spat, with the majority rapidly reattaching