Jasus Edwardsii Research Articles

Spiny lobsters prefer native prey over range-extending invasive urchins

Abstract Climate change increases the need to control range-extending species, which adversely impact their recipient ecosystem. Increasing populations of resident predators may be effective to counter such range-extension, but only if they consume the novel invaders at sufficient rates. In South-East Australia, poleward range-extending Longspined Sea Urchins (Centrostephanus rodgersii) are causing catastrophic ecological habitat transition to extensive urchin barrens. Tasmanian native Southern Rock Lobster (Jasus edwardsii) is a potential predator that could control further urchin expansion. Experimental feeding trials showed that range-extending Longspined Sea Urchins are the least preferred prey choice for Southern Rock Lobsters (3.8% predation events), when compared to three local species: abalone, urchins, and snails (36.6, 32.6, and 27%). Interestingly, habitat origin and naivete of lobsters to urchins affected urchin consumption with 85% being consumed by lobsters originating from urchin barrens. Low predation rates on Longspined Sea Urchin suggest that resident lobsters are unlikely to control further barren expansion unless a behavioural shift occurs. Results imply that potential control of Longspined Sea Urchins by Southern Rock Lobsters has previously been overestimated. Additional control methods are needed to safeguard ecological communities and important commercial stocks from this climate change-induced, range-extending pest species.

Metabolic plasticity improves lobster\u2019s resilience to ocean warming but not to climate-driven novel species interactions

Marine species not only suffer from direct effects of warming oceans but also indirectly via the emergence of novel species interactions. While metabolic adjustments can be crucial to improve resilience to warming, it is largely unknown if this improves performance relative to novel competitors. We aimed to identify if spiny lobsters—inhabiting a global warming and species re-distribution hotspot—align their metabolic performance to improve resilience to both warming and novel species interactions. We measured metabolic and escape capacity of two Australian spiny lobsters, resident Jasus edwardsii and the range-shifting Sagmariasus verreauxi, acclimated to current average—(14.0 °C), current summer—(17.5 °C) and projected future summer—(21.5 °C) habitat temperatures. We found that both species decreased their standard metabolic rate with increased acclimation temperature, while sustaining their scope for aerobic metabolism. However, the resident lobster showed reduced anaerobic escape performance at warmer temperatures and failed to match the metabolic capacity of the range-shifting lobster. We conclude that although resident spiny lobsters optimise metabolism in response to seasonal and future temperature changes, they may be unable to physiologically outperform their range-shifting competitors. This highlights the critical importance of exploring direct as well as indirect effects of temperature changes to understand climate change impacts.

Resident lobsters dominate food competition with range-shifting lobsters in an ocean warming hotspot

Species redistributions are one of the most prevalent changes observed in oceans worldwide due to climate change. One of the major challenges is being able to predict temperature-driven changes to species interactions and the outcome of these changes for marine communities due to the complex nature of indirect effects. In the ocean-warming hotspot of south-east Australia, the ranges of many species have shifted poleward. The range of the eastern rock lobster Sagmariasus verreauxi has extended into warming Tasmanian waters inhabited by the resident southern rock lobster Jasus edwardsii, which may lead to increased competitive interactions between the species. Using video monitoring, we investigated how the 2 species compete for food at current (18°C), future (21°C) and future heatwave (24°C) summer temperatures. Behavioural competition occurred in 80% of experiments, during which J. edwardsii won 84% of competitive interactions and showed more aggressive behaviour at all temperatures. This indicates that resident J. edwardsii is not only more dominant in direct food competition than the range-shifting S. verreauxi but, surprisingly, also sustains competitive dominance beyond its physiological thermal optimum under predicted future ocean warming and heatwave scenarios.

Rare report of bryozoan fouling of rock lobsters (Jasus edwardsii: Decapoda: Palinuridae) from the North Island of New Zealand

ABSTRACT Bryozoan epibiosis on lobster hosts is rarely reported. Here we document bryozoan fouling of the spiny rock lobster Jasus edwardsii from the Hauraki Gulf, North Island of New Zealand. The 92 lobsters in this study came from the Cape Rodney-Okakari Point Marine Reserve. The lobsters were measured for size and weight, sexed, scanned for epibionts, and photographed. Forty-two per cent of the lobsters were fouled by epibionts, but only 9% by bryozoans, and they were all males. The bryozoans were all cheilostome gymnolaemates. Only erect colonies were found on the dorsal carapace, and only encrusting colonies were found on the ventral surface. Two of the erect colonies were found in gaping exposed wounds through the exterior wall into the branchial chamber. In addition to host wounds, differences in frequency and location of fouling bryozoan colonies were also attributed to time since last moult and grooming. This epibiosis is interpreted as more of a one-sided commensal symbiotic relationship, perhaps best described as phoretic (i.e. hitchhiking relationship).

Field Validation of the Southern Rock Lobster Paralytic Shellfish Toxin Monitoring Program in Tasmania, Australia.

Paralytic shellfish toxins (PST) are found in the hepatopancreas of Southern Rock Lobster Jasus edwardsii from the east coast of Tasmania in association with blooms of the toxic dinoflagellate Alexandrium catenella. Tasmania’s rock lobster fishery is one of the state’s most important wild capture fisheries, supporting a significant commercial industry (AUD 97M) and recreational fishing sector. A comprehensive 8 years of field data collected across multiple sites has allowed continued improvements to the risk management program protecting public health and market access for the Tasmanian lobster fishery. High variability was seen in toxin levels between individuals, sites, months, and years. The highest risk sites were those on the central east coast, with July to January identified as the most at-risk months. Relatively high uptake rates were observed (exponential rate of 2% per day), similar to filter-feeding mussels, and meant that lobster accumulated toxins quickly. Similarly, lobsters were relatively fast detoxifiers, losing up to 3% PST per day, following bloom demise. Mussel sentinel lines were effective in indicating a risk of elevated PST in lobster hepatopancreas, with annual baseline monitoring costing approximately 0.06% of the industry value. In addition, it was determined that if the mean hepatopancreas PST levels in five individual lobsters from a site were <0.22 mg STX equiv. kg−1, there is a 97.5% probability that any lobster from that site would be below the bivalve maximum level of 0.8 mg STX equiv. kg−1. The combination of using a sentinel species to identify risk areas and sampling five individual lobsters at a particular site, provides a cost-effective strategy for managing PST risk in the Tasmanian commercial lobster fishery.

Investigating public preferences for the management of native and invasive species in the context of kelp restoration

The Southern Rock Lobster (Jasus edwardsii) is key to management of the Long Spined Sea Urchin (Centrotephanus rodgersii). The southern shift of the urchin has created ‘urchin barrens’ of the kelp forests (Ecklonia radiata and Macrocystis pyrifera) in coastal waters off the East Coast of Tasmania. Consistently high fishing efforts of large Southern Rock Lobster in the region has reduced natural predation of the urchin. A number of restoration options exist but these options have not been tested for acceptability with the public to date. In this study we estimate the willingness to pay by households in Tasmania for Southern Rock Lobster habitat and management. The willingness to pay estimates can be used in benefit-cost analysis of the various combinations of restoration options supporting decision-making in this Australian marine planning context. Results indicate that direct replanting of kelp is worth $37 per household per year for five years and a 1% increase in the area of marine reserves is worth $2 per household per year for five years. Direct intervention to control sea urchin populations by reintroducing Rock Lobsters or capturing and crushing urchins is worth $33 and $31 respectively per household per year for five years. Households did not support artificial kelp beds installations or subsidising urchin farming operations.

Lobster Supply Chains Are Not at Risk from Paralytic Shellfish Toxin Accumulation during Wet Storage.

Lobster species can accumulate paralytic shellfish toxins (PST) in their hepatopancreas following the consumption of toxic prey. The Southern Rock Lobster (SRL), Jasus edwardsii, industry in Tasmania, Australia, and New Zealand, collectively valued at AUD 365 M, actively manages PST risk based on toxin monitoring of lobsters in coastal waters. The SRL supply chain predominantly provides live lobsters, which includes wet holding in fishing vessels, sea-cages, or processing facilities for periods of up to several months. Survival, quality, and safety of this largely exported high-value product is a major consideration for the industry. In a controlled experiment, SRL were exposed to highly toxic cultures of Alexandrium catenella at field relevant concentrations (2 × 105 cells L−1) in an experimental aquaculture facility over a period of 21 days. While significant PST accumulation in the lobster hepatopancreas has been reported in parallel experiments feeding lobsters with toxic mussels, no PST toxin accumulated in this experiment from exposure to toxic algal cells, and no negative impact on lobster health was observed as assessed via a wide range of behavioural, immunological, and physiological measures. We conclude that there is no risk of PST accumulation, nor risk to survival or quality at the point of consumption through exposure to toxic algal cells.

Small marine reserves do not provide a safeguard against overfishing

AbstractMarine reserves aim to protect harvested species within their boundaries and can therefore provide insurance against the effects of overfishing. To evaluate whether marine reserves are meeting this expectation, we compiled over 40 years of rock lobster (Jasus edwardsii) monitoring data and examined long‐term trends in three relatively small marine reserves (c.4–8 km2) in northern New Zealand, a region that has experienced large‐scale declines in the fishery over the last decade. In all three reserves, lobster density initially increased by at least a factor of three following protection. However, over the last 10 years, lobster populations have experienced large declines in all three reserves with densities now 59–80%, and spawning stock biomass (SSB) now 51–86%, below historic levels. Using peak lobster density in each reserve as an unfished reference point, current densities on fished reefs are &lt;15% of unfished levels and SSB is currently only 3–12% of peak population biomass in reserves. These results highlight the poor state of the wider stock and declines in the reserves follow regional declines in catch‐per‐unit‐effort in the fishery, suggesting that lobster populations within these reserves are not fully protected from fishing. Adult J. edwardsii are known to undertake seasonal foraging excursions that carry them beyond the offshore boundaries of these reserves where they are susceptible to fishing‐related mortality. We propose that the observed declines are likely a result of direct harvest of individuals beyond reserve boundaries and that larger reserves which encompass both a species' longshore and offshore movements are needed.

Response of a southern rock lobster (Jasus edwardsii) population to three years of Marine Protected Area implementation within South Australia

AbstractThe Western Kangaroo Island Marine Park (WKIMP) was declared as part of South Australia's representative system of Marine Protected Areas in 2009. Sanctuary Zone 3 (SZ-3) of the WKIMP is a no-take area protected from fishing since 1 October 2014 and is located within the Northern Zone Rock Lobster Fishery (NZRLF). In February 2017, a dedicated survey was undertaken to estimate the relative abundance (catch per unit effort (CPUE), kg/potlift) and size of southern rock lobster (Jasus edwardsii) inside and outside SZ-3. Survey results were then compared with historical estimates of abundance and size obtained from commercial fishery-dependent data. Survey estimates of relative abundance of legal-size lobsters were 4.4 times greater inside SZ-3 compared with outside in 2017. Since 2014, when fishing was last permitted inside SZ-3, the relative abundance of lobsters increased by 75%. The mean size of legal-size female and male lobsters also increased by 4.1% and 12.5%, respectively. The population responses recorded are consistent with the results recorded for southern rock lobster stocks in marine parks in other jurisdictions.

Accumulation of paralytic shellfish toxins by Southern Rock lobster Jasus edwardsii causes minimal impact on lobster health

Recurrent dinoflagellate blooms of Alexandrium catenella expose the economically and ecologically important Southern Rock Lobster in Tasmania to paralytic shellfish toxins (PST), and it is unknown if PST accumulation adversely affects lobster performance, health and catchability. In a controlled aquaculture setting, lobsters were fed highly contaminated mussels to accumulate toxin levels in the hepatopancreas (mean of 6.65 mg STX.2HCl equiv. kg−1), comparable to those observed in nature. Physiological impact of PST accumulation was comprehensively assessed by a range of behavioural (vitality score, righting ability and reflex impairment score), health (haemocyte count, bacteriology, gill necrosis and parasite load), nutritional (hepatopancreas index and haemolymph refractive index) and haemolymph biochemical (21 parameters including electrolytes, metabolites, and enzymes) parameters during a 63 day period of uptake and depuration of toxins. Exposure to PST did not result in mortality nor significant changes in the behavioural, health, or nutritional measures suggesting limited gross impact on lobster performance. Furthermore, most haemolymph biochemical parameters measured exhibited no significant difference between control and exposed animals. However, the concentration of potassium in the haemolymph increased with PST, whilst the concentration of lactate and the sodium:potassium ratio decreased with PST. In addition, exposed lobsters showed a hyperglycaemic response to PST exposure, indicative of stress. These findings suggest that PST accumulation results in some measurable indicators of stress for lobsters. However, these changes are likely within the adaptive range for Jasus edwardsii and do not result in a significant impairment of gross performance. Our findings support previous conclusions that crustaceans are relatively tolerant to PST and the implications for the lobster fishery are discussed.

Mismatch of thermal optima between performance measures, life stages and species of spiny lobster

In an ocean warming hotspot off south-east Australia, many species have expanded their ranges polewards, including the eastern rock lobster, Sagmariasus verreauxi. This species is likely extending its range via larval advection into Tasmanian coastal waters, which are occupied by the more commercially important southern rock lobster, Jasus edwardsii. Here, thermal tolerances of these lobster species at two life stages were investigated to assess how they may respond to warming ocean temperatures. We found that the pattern, optimum and magnitude of thermal responses differed between performance measures, life stages and species. Sagmariasus verreauxi had a warmer optimal temperature for aerobic scope and escape speed than J. edwardsii. However, J. edwardsii had a higher magnitude of escape speed, indicating higher capacity for escape performance. There were also differences between life stages within species, with the larval stage having higher variation in optimal temperatures between measures than juveniles. This inconsistency in performance optima and magnitude indicates that single performance measures at single life stages are unlikely to accurately predict whole animal performance in terms of life-time survival and fitness. However, combined results of this study suggest that with continued ocean warming, S. verreauxi is likely to continue to extend its distribution polewards and increase in abundance in Tasmania.

Lobsters with pre-existing damage to their mechanosensory statocyst organs do not incur further damage from exposure to seismic air gun signals

Staotcysts, the mechanosensory organs common to many marine invertebrates, have shown sensitivity to aquatic noise. Previously, rock lobsters (Jasus edwardsii) from a remote site with little exposure to anthropogenic noise incurred persistent damage to the statocyst and righting reflex following exposure to seismic air gun signals. Here, J. edwardsii collected from a site subject to high levels of anthropogenic noise were exposed to an equivalent seismic air gun signal regime as the previous study of noise-naïve lobsters. Following exposure, both control and exposed treatments were found to have damage to the statocyst equivalent to that of noise-naïve lobsters following seismic exposure, which led to the conclusion that the damage was pre-existing and not exacerbated by seismic exposure. The source of the damage in the lobsters in this study could not be ascertained, but the soundscape comparisons of the collection sites showed that the noisy site had a 5–10 dB greater level of noise, equivalent to a 3–10 times greater intensity, in the 10–700 Hz range than was found at the remote collection site. In addition to the lack of further damage following seismic exposure, no disruption to the righting reflex was observed. Indeed, compared to the noise naïve lobsters, the lobsters here demonstrated an ability to cope with or adapt to the mechanosensory damage, indicating a need for better understanding of the ecological impacts of the damage caused by low frequency noise on marine organisms. More broadly, this study raises historical exposure to noise as a previously unrecognised but vitally important consideration for studies of aquatic noise.

Investigation of risk factors associated with sub-optimal holding survival in southern rock lobster (Jasus edwardsii) in Australia

Southern rock lobster (SRL11SRL – Southern rock lobster., Jasus edwardsii) are caught from the wild waters of southern Australia and form an important commodity economically for the fisheries industry in Australia. Between landing and export, SRL are held in specialised tanks within holding facilities for varying time periods before being exported to China. During the 2015−16 fishing season a lower stock survival rate was reported by some holding facilities when compared to previous fishing seasons. An investigation was undertaken to identify possible causes and favouring factors using a retrospective, single cohort, observational study.A custom questionnaire was built and trialled to collect qualitative and quantitative information on facilities infrastructure and capacity (10 questions), water systems (16 questions), SRL stock and health management (12 questions). Onsite visits and interviews of consenting holding facilities, with active holding operations, were conducted. Facilities were categorised into different capacity and management profiles based on a multivariate factor analysis. The association between facility profiles and perceived sub-optimal survival was then explored using simple logistic regression models.Out of the 83 license holders on record, 63 were in operation at the time of survey and 52 (83%) consented to participate. Perceived sub-optimal survival was reported in 22 (42%) facilities. The capacity, bio-filtration and water management practices across the surveyed facilities was highly variable but did not appear to be associated with survival. However, ‘Intensive holding’ facilities compared to the ‘Extensive holding’ facilities were significantly associated with an increased risk of sub-optimal survival (OR = 7.0, 95% CI: 2.1–26.13, P = 0.002). ‘Intensive holding’ facilities were more likely to hold higher annual tonnage sourced from distant, diverse and higher number of sources, to multiple handle and stock SRL in crates (as opposed to free swimming in tanks), and hold them for longer time periods.Holding practices are highly diverse across the SRL industry with little evidence of impact on survival, however, intensive and large scale holding practices appeared to be at higher risk of sub-optimal survival. A longitudinal and finer scale study is warranted to identify which one(s) of the stock management practices directly impact SRL survival during holding.

Convolutional Neural Networks for individual identification in the Southern Rock Lobster supply chain

In most traceability system, product identification is the key to enable the tracking activities along the supply chain to be carried out. Product tagging using barcode and RFID is the most common method for this purpose. However, these practices can be challenging for small businesses due to the cost and time burdens. In addition to this, concern of fraudulent activities such as cloning, substitution and reuse becomes a tangible risk in complicated and poor controlled markets. In approaching Southern Rock Lobster (SRL), this paper proposes an image-based identification solution for individuals using Convolutional Neural Networks (CNNs). This work is built on the prior research of automated lobster grading by the authors, with this next step working towards a low-cost biometric recognition solution for lobster tracking from catch to consumers. In this approach, a Siamese model combined with a contrastive loss function was adopted to distinguish between individual lobsters based on carapace images. These areas are believed to contain individually recognisable features formed by colours and spiny patterns. Preliminary experiments on an image dataset of 200 individual lobsters collected at a lobster processor show the feasibility of using lobster images as an additional factor to provide increased security to the current tag-based tracking systems in use within the SRL supply chain.

Detection of Paralytic Shellfish Toxins in Southern Rock Lobster Jasus edwardsii Using the Qualitative Neogen™ Lateral Flow Immunoassay: Single-Laboratory Validation.

Paralytic shellfish toxins (PST) are a significant problem for the Tasmanian shellfish and Southern Rock Lobster (Jasus edwardsii) industries, and the introduction of a rapid screening test in the monitoring program could save time and money. The aim was to perform a single-laboratory validation of the Neogen rapid test for PST in the hepatopancreas of Southern Rock Lobster. The AOAC INTERNATIONAL guidelines for the validation of qualitative binary chemistry methods were followed. Three different PST profiles (mixtures) were used, of which two were commonly found in naturally contaminated lobster hepatopancreas (high in gonyautoxin 2&3 and saxitoxin), and the third toxin profile was observed in a few select animals (high in gonyautoxin 1&4). The Neogen test consistently returned negative results for non-target toxins (selectivity). The probability of detection (POD) of PST in the lobster hepatopancreas using the Neogen test increased with increasing PST concentrations. POD values of 1.0 were obtained at ≥0.57 mg STX-diHCl eq/kg in mixtures 1 and 2, and 0.95 and 1.0 for mixture 3 at 0.79 and 1.21 mg STX-diHCl eq/kg, respectively, with a fitted POD of 0.98 for 0.80 mg STX-diHCl eq/kg. The performance of the Neogen test when using four different production lots (ruggedness) showed no significant differences. The results of the validation study were satisfactory and the Neogen test is being trialed within the Tasmanian PST monitoring program of Southern Rock Lobster. The Neogen rapid kit was successfully validated for the detection of PST in Southern Rock Lobster hepatopancreas.

Paralytic shellfish toxin uptake, tissue distribution, and depuration in the Southern Rock Lobster Jasus edwardsii Hutton

Up to 13.6 mg STX.2HCl equiv. kg−1 of paralytic shellfish toxins (PST) have been found in the hepatopancreas of Southern Rock Lobster, Jasus edwardsii, on the east coast of Tasmania. Blooms of the toxic dinoflagellate Alexandrium catenella have been reported in this region since 2012. Experimental work was undertaken to improve the understanding of the uptake and depuration mechanisms involved. Adult male lobsters were fed highly toxic mussels (6 mg STX.2HCl equiv. kg−1) sourced from the impacted area. The apparent feed intake of the lobster was positively correlated to increasing PST levels in the hepatopancreas. Toxins accumulated rapidly in the hepatopancreas reaching a maximum of 9.0 mg STX.2HCl equiv. kg−1, then depurated at a rate of 7% per day once toxic fed was removed. However, PST were not detected at significant levels in the haemolymph of these animals. Notable increases occurred in the relative amount of several PST analogues in the hepatopancreas, including GTX2&3, C1&2 and several decarbomoyl toxins in comparison to the profile observed in contaminated mussel feed. The concentration of PST in lobster antennal glands was two orders of magnitude lower than concentrations found in the hepatopancreas. This is the first report of PST in lobster antennal glands which, along with the gills, represent possible excretion routes for PST. Implications for biotoxin risk monitoring are: lobsters will continue to feed during bloom periods and high concentrations of PST can occur; animal collection should be frequent at the start of a bloom in case of a rapid accumulation of PST; and non-lethal sampling is not possible as haemolymph PST levels do not reflect what is in the hepatopancreas.

Responding to Climate Change: Participatory Evaluation of Adaptation Options for Key Marine Fisheries in Australia’s South East

Planned adaptation to climate impacts and subsequent vulnerabilities will necessarily interact with autonomous responses enabled within existing fisheries management processes and initiated by the harvest and post-harvest components of fishing industries. Optimal adaptation options are those which enable negative effects to be mitigated and opportunities that arise to be maximised, both in relation to specific climate-driven changes and the broader fisheries system. We developed a two-step participatory approach to evaluating adaption options for key fisheries in the fast-warming hotspot of south-eastern Australia. Four fisheries (southern rock lobster, abalone, snapper and blue grenadier) were selected as case studies on the basis of their high to moderate vulnerability to climatic effects on species distribution and abundance. Involved stakeholders undertook a “first pass” screening assessment of options, by characterising and then evaluating options. In the characterisation step potential adaptation options for each fishery, contextualised by prior knowledge of each species’ climate change exposure and sensitivity, were described using a characterisation matrix. This matrix included: the specific climate vulnerability/challenges, the implications of each option on the fishery system as a whole, the temporal and spatial scales of implementation processes, and realised benefits and costs. In the evaluation step, semi-quantitative evaluation of options was undertaken by stakeholders scoring the anticipated performance of an option against a pre-determined set of criteria relating to perceived feasibility, risk (inclusive of potential costs) and benefit. Our screening assessment represents a pragmatic approach to evaluate and compare support for and the effects of alternative adaptation options prior to committing to more detailed formal and resource intensive evaluation or implementation.

An application of Convolutional Neural Network to lobster grading in the Southern Rock Lobster supply chain

Southern Rock Lobster (SRL) is an important commercial export fishery of the Australian economy with a contribution of $250 million annually. However, a range of risks relating to food safety and product fraud requires this industry to develop an effective traceability solution. In response to this biometric identification techniques are seen as a possible solution to provide greater security compared to the current tag-based tracking systems. This paper describes how a Convolutional Neural Network (CNN) can be used in conjunction with image processing techniques to enable an autonomic grading solution in the SRL supply chain. The research is an essential part of an overall investigation into designing a low-cost biometric identification solution for tracking lobsters along their supply chain from catch to table. By using a CNN, the research aims to improve the previous research on lobster grading in establishing a reliable and flexible traceability method to meet different supply chain contexts. In this approach, a pre-trained Mask-RCNN model was adopted to extract regions of interest from lobster images. The deep learning ability of this model allows the carapace areas to be segmented from lobster images automatically for calculating grading attributes including size, weight and colour. This outcome then also generates a high-quality input dataset for the follow-up research on identifying individual lobsters. To prove the effectiveness, the proposed method was validated on a large image dataset collected at a lobster processor and tested on mobile application environment. The findings establish a critical contribution to the complete biometric solution developed for SRL products traceability.

Identification of the molecular components of a putative Jasus edwardsii (Crustacea; Decapoda; Achelata) circadian signaling system.

Like all organisms, members of the crustacean order Decapoda must coordinate their physiology and behavior to accommodate recurring patterns of environmental change. Genetically encoded biological clocks are responsible, at least in part, for the proper timing of these organism-environment patternings. While biological clocks cycling on a wide range of timescales have been identified, the circadian signaling system, which serves to coordinate physiological/behavioral events to the solar day, is perhaps the best known and most thoroughly investigated. While many circadian patterns of physiology/behavior have been documented in decapods, few data exist concerning the identity of circadian genes/proteins in members of this taxon. In fact, large collections of circadian genes/proteins have been described from just a handful of decapod species. Here, a publicly accessible transcriptome, produced from tissues that included the nervous system (brain and eyestalk ganglia), was used to identify the molecular components of a circadian signaling system for rock lobster, Jasus edwardsii, a member of the decapod infraorder Achelata. Complete sets of core clock (those involved in the establishment of the molecular feedback loop that allows for ~ 24-h cyclical timing), clock-associated (those involved in modulation of core clock output), and clock input pathway (those that allow for synchronization of the core clock to the solar day) genes/proteins are reported. This is the first description of a putative circadian signaling system from any member of the infraorder Achelata, and as such, expands the decapod taxa for which complete complements of putative circadian genes/proteins have been identified.

Highly efficient recovery of nutritional proteins from Australian Rock Lobster heads (Jasus edwardsii) by integrating ultrasonic extraction and chitosan co-precipitation

Australian Rock lobster head by-products (LHBs) are underutilised, but they contain about 43.5% protein. An integrated process of ultrasonic intensification and chitosan co-precipitation was developed for the efficient protein recovery. This process efficiency is influenced by pH, the ratio of water/LHBs and chitosan concentration. Up to 99% lobster head proteins (LHPs) could be ultrasonically extracted within 5 min at a pH of 13 and water to LHBs ratio of 8 mL/g, of which 86.6% LHPs could be recovered by 250 mg/L chitosan co-precipitation. Nutritionally, 83.2% of LHPs are relatively intact proteins (molecular weights 50–150 kDa) enriched with umami, aromas and essential amino acids (EAAs – up to 38.9% - double the amount of adult requirements that is suggested by WHO/FAO), and low lysine/arginine ratio (1.0). The LHPs recovered have digestibility comparable to that of the egg protein and contain significantly lower toxic metals satisfying food safety standards, that makes this novel process and the extracted proteins very attractive for industrial applications.