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Green-lipped mussel (Perna canaliculus) aquaculture is vulnerable to environmental changes, which are increasingly being studied to pinpoint physiological, economic and ecological threats. This study utilised a targeted liquid chromatography-mass spectrometry metabolomics approach, focusing on the central carbon metabolism, to examine the metabolic response of P. canaliculus haemolymph to heat stress (30 degrees C) and multi-point recovery (up to 47 h). Heat stress disturbed sugar-based-, amino acid- and purine-derived metabolites, implementing anaerobic pathways and phosphagen breakdown, following initial thermal exposure, to support energy production. Time course recovery revealed varying metabolic adjustments in P. canaliculus, resulting in new metabolic setpoints in the heat-stressed mussel group, which overlapped with the responses of the control group. Metabolic recovery in metabolites, such as pyruvate and malate, suggests the gradual return to aerobic energy generation, while amino acids, such citrulline, methionine and tyrosine, supported protein regulation and nitrogen homeostasis. In addition, purine-derived metabolites (guanosine diphosphate, guanosine and guanine) linked to guanine-based nucleotides support the use thereof towards energy production in heat-stressed mussels, after which their levels stabilised, to control levels. Overall, the results show that P. canaliculus implements specific metabolic adjustments, as shifts in energy-related and stress-associated metabolites, to cope with short-term high-temperature exposure. After around two days of recovery at ambient temperatures, these metabolites do not simply return to baseline but instead stabilise at a new metabolic setpoint, suggesting a reprogramming of physiological homeostasis. These changes reflect an adaptive response in mussels that provides valuable insight for climate change adaptation and breeding resilient stocks.
Over the last 150 years, most large, easily accessible lakes and tarns in Aotearoa (New Zealand) have experienced trout introductions or incursions, leaving few salmonid-free reference lakes. Using database information and field surveys, we characterized lake, pond/tarn, and wetland systems found throughout Aotearoa that support populations of k & omacr;aro (Galaxias brevipinnis) known or putatively believed to be trout-free. These systems require more research because our existing knowledge is outdated, patchy, and largely unacknowledged, while their k & omacr;aro populations may be increasingly vulnerable. Although persisting trout-free k & omacr;aro populations tend to be found in small, isolated, and difficult to access lakes, at least 10% and potentially up to 22% of known trout-free k & omacr;aro populations may have already been lost in the last 20 years. The causes of these losses are varied and highlight the sensitivity of the remaining populations, which are likely genetically isolated and evolutionarily significant. Historic and modern threats to these remaining k & omacr;aro populations include incursions of introduced fishes and worsening climate impacts. Lakes supporting isolated k & omacr;aro populations hold substantial conservation value, require more consistent monitoring to prevent additional losses of irreplaceable populations, and need targeted conservation of this important taonga (treasured species) consistent with the diversity they contribute to Aotearoa's broader freshwater biodiversity.
Customary harvest plays a vital role in expressing M & amacr;ori identity, maintaining relationships with place and whakapapa, and transmitting m & amacr;tauranga across generations. However, re-engaging with traditional practices can be constrained by ecological risks and regulatory frameworks, particularly in protected areas. This study presents an integrated ecological and toxicological assessment of the customary longfin tuna (Anguilla dieffenbachii) harvest by Ng & amacr;ti Apa ki te R & amacr; T & omacr; at Rotoroa, Nelson Lakes National Park. A dual knowledge approach combining m & amacr;tauranga M & amacr;ori and biophysical science was used to evaluate sustainability and food safety. From 2022 to 2024, annual harvests were paired with tuna monitoring and biological sampling. Otolith analysis revealed a mature slow-growing population, and production modelling indicated that harvest levels (similar to 2-3% of annual cohort biomass production) were within conservative ecological limits. Mercury concentrations in muscle tissue averaged 0.31 mg & centerdot;kg-1 (wet weight), with estimated dietary exposure from a single meal approaching short-term health guidelines. Mercury levels were inversely correlated with condition factor, suggesting that the selective harvest of healthier individuals may reduce contaminant risk. These findings demonstrate that tikanga-aligned harvest, supported by scientific assessment, can enable safe, sustainable customary use within conservation settings and offer a transferable model for iwi-led freshwater management.
Many shellfish species are intentionally taken out of water at different times throughout their farming cycle; especially those sold to live markets. For example, mussels can spend days out of the water after harvest during transport. In this study, we evaluated the potential to enhance recovery in seawater after aerial exposure in the green-lipped mussel, Perna canaliculus. Survival and oxidative stress kinetics were assessed in mussels with no gaping restriction (NGR) versus mussels in which gaping was moderately (MGR) or fully restricted (FGR) during different emersion periods (3, 5 or 7 days (d) after harvest) and their ability to recover in seawater. Results suggested that gaping restriction had a positive effect on re-immersion recovery survival after 3 d of emersion (43 % higher in FGR and 78 % higher in MGR mussels); however, the benefits were time-dependent, as survival decreased after 5 and 7 d of emersion, regardless of gaping restriction treatment. This was reflected in the changes observed in the oxidative stress biomarkers of mussels emersed for 7 d before re-immersion. These mussels appeared unable to compensate for the accumulated damage during emersion and subsequent reoxygenation stress. Damage was apparent as accumulation of protein carbonyls, lipid hydroperoxide and 8-hydrox-ydeoxyguanosine within one hour of re-immersion in seawater, with all mussels dying within the following ten days. In mussels that recovered after 3 or 5 d of emersion, levels of oxidative damage decreased within 8 h of re-immersion for the NGR and FGR mussels, while the MGR mussels showed no significant reoxygenation damage after 3 d of emersion and recovered faster (i.e., within 4 h) after 5 d of emersion. The antioxidant enzymes showed similar trends in all gaping restriction treatments, and only catalase and glutathione peroxidase activities decreased within ten days after re-immersion. Understanding the changes over time of the mussels' antioxidant capacity and oxidative damage helps explain emersion thresholds for recovery survival. This study presents a promising tool (i.e., gaping restriction) for consideration to enhance the mussels' ability to cope with live transport, and the subsequent reoxygenation stress when mussels are placed back in seawater in live shellfish markets.
The New Zealand green-lipped mussel, Perna canaliculus, is a key aquaculture species, and improving live transport performance is vital for quality and supply. Mussels pre-treated with magnesium chloride (MgCl2), ambient 14 degrees C, or chilled 4 degrees C seawater were assessed after a 3-day simulated out-of-water live transport at 8 degrees C and recovery in seawater (+1 h, 1 day, 14 days) for gill and adductor metabolomics, haemolymph biochemistry (pH, antioxidant capacity and osmolality), heart rate (HR) and relative gaping magnitude (RGM), allowing comparison of treatment-specific responses. During the live transport simulation, mussels pre-treated at 14 degrees C showed elevated HR, whereas 4 degrees C- and MgCl2-treated mussels had lower HR on Day 1. By Day 3, HR was low (similar to 1 bpm) and did not differ among treatments. Compared to 14 degrees C- and 4 degrees C-pre-treated mussels, MgCl2-pre-treated mussels showed higher RGM and 1.6-2.3-fold lower anaerobic biomarkers (e.g., succinate, alanine and strombine), indicating reduced metabolic stress and minimal anaerobic activation. After 1-h recovery, there was a significant difference between metabolic profiles of mussels from different pre-treatment groups, which was largely driven by varying levels of metabolites for anaerobic energy metabolism (e.g., succinate and strombine) for cellular stress responses and during early stages of recovery. MgCl2-treated mussels showed increased anaerobic markers, but lower than the other groups, suggesting less energy was needed to recover from transport-induced stress. After 1-day recovery, metabolic profiles of all groups resembled control mussels, indicating successful recovery. Overall, MgCl2 pre-treatment of mussels provided the most effective mitigation of transport stress and supported faster recovery, highlighting its potential for improving long-distance live mussel transport.
