Jessica. A. Ericson

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°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.

The green‐lipped mussel, Perna canaliculus , is an important aquaculture species in New Zealand. Recently, the industry has been increasingly challenged by stressors associated with climate change. Predicting its response to climate change requires more than single‐parameter measurements, as mussels show various physiological and behavioural adaptations. In this study, heart rate (HR), respiration rate (), and relative gaping magnitude (RGM) of P. canaliculus were measured simultaneously under increasing temperature from 17°C to 30°C at a rate of 1°C every 20 min over seven hours. HR, and RGM responded differently to acute temperature increase. HR peaked at 26°C, while continued to rise until 30°C, and RGM spiked beyond 28°C. These integrated responses suggest the mussels’ upper thermal limit is around 26°C, higher than typical seawater temperatures of 20°C seen during summer heatwaves, indicating a significant thermal safety margin. Only HR and were positively correlated, but this relationship was disrupted at higher temperatures due to higher inter‐individual variabilities of those physio‐behavioural responses. Variations in such responses have potential in identifying more thermally tolerant mussel lines within selective breeding programmes that ultimately may help produce mussels tolerant of a warming future.

New Zealand’s green-lipped mussel (Perna canaliculus) is an ecologically and economically important species. Marine heatwaves are increasing in frequency around NZ’s coastline, and these events are correlated with increased stress and mortality of some aquaculture species. This study aimed to identify general biomarkers of heat stress in P. canaliculus and to assess whether responses differed between genetically distinct selectively bred mussels. We exposed three families of selectively bred mussels (families A, B and C) to three seawater temperature regimes in the laboratory: 1) a “control” treatment (ambient 12°C), 2) a 26°C heat challenge with a subsequent recovery period, and 3) a sustained 26°C heat challenge with no recovery. We investigated whether the survival, immune response (hemocyte concentration and viability, oxidative stress and total antioxidant capacity), hemocyte gene expression and gill microbiome differed between the families during the temperature challenges. In the sustained heat-stress treatment, family A had the highest survival rate (42% compared with 25% and 5% for families C and B, respectively). Gene expression levels significantly shifted during thermal stress and differed between families, with family A more dissimilar than families B and C. Family C had substantially more genes impacted by temperature treatment and timepoint than the other families, while family B had very little genes/pathways that responded to thermal stress. Genes related to heat shock proteins and immune responses (e.g., AIF1, CTSC, TOLL8, CASP9, FNTA, AHCY, CRYAB, PPIF) were upregulated in all families during heat stress. Microbiome species-richness differed between families before and during heat-stress, with family A having a distinctly different microbiome flora than the other families. Microbial diversity changed similarly in all families exposed to prolonged heat-stress, with species of Vibrio and Campylobacter increasing in these mussels. Our study highlights the use of non-lethal sampling of hemocytes as a diagnostic tool to explore the immune response and gene expression of selectively bred mussels, to predict their response to ocean warming. This approach can identify potential thermotolerant candidates for further selective breeding, which may increase the resilience of the mussel aquaculture industry in a warming ocean.

Temperature is considered to be a major abiotic factor influencing aquatic life. Marine heatwaves are emerging as threats to sustainable shellfish aquaculture, affecting the farming of New Zealand’s green-lipped mussel [Perna canaliculus (Gmelin, 1791)]. In this study, P. canaliculus were gradually exposed to high-temperature stress, mimicking a five-day marine heatwave event, to better understand the effects of heat stress on the metabolome of mussels. Following liquid chromatography-tandem mass spectrometry analyses of haemolymph samples, key sugar-based metabolites supported energy production via the glycolysis pathway and TCA cycle by 24 h and 48 h of heat stress. Anaerobic metabolism also fulfilled the role of energy production. Antioxidant molecules acted within thermally stressed mussels to mitigate oxidative stress. Purine metabolism supported tissue protection and energy replenishment. Pyrimidine metabolism supported the protection of nucleic acids and protein synthesis. Amino acids ensured balanced intracellular osmolality at 24 h and ammonia detoxification at 48 h. Altogether, this work provides evidence that P. canaliculus has the potential to adapt to heat stress up to 24 °C by regulating its energy metabolism, balancing nucleotide production, and implementing oxidative stress mechanisms over time. The data reported herein can also be used to evaluate the risks of heatwaves and improve mitigation strategies for aquaculture.

The New Zealand abalone industry relies mostly on the export of processed products to distant Asian markets, notably China. Over the past five years, live export of high quality abalone from New Zealand has proven successful. However, transport of live animals is associated with multiple stressors that affect survival and meat quality at the end of the transport phase. Better understanding of transport-derived stress is needed to improve transport conditions and recovery at destination to ensure high product quality and safety throughout the supply chain. To this end, we applied an untargeted GC–MS-based metabolomics approach to examine the changes in metabolite profiles of abalone after a 2-day transport event and subsequent water re-immersion for 2 days. The results revealed alterations of many metabolites in the haemolymph and muscle of post-transported abalone. Decreased concentrations of many amino acids suggest high energy demands for metabolism and stress responses of transported abalone, while increases of other amino acids may indicate active osmoregulation and/or protein degradation due to oxidative stress and apoptosis. The accumulation of citric acid cycle intermediates and anaerobic end-products are suggestive of hypoxia stress and a shift from aerobic to anaerobic metabolism (resulting from aerial exposure). Interestingly, some features in the metabolite profile of reimmersed abalone resembled those of pre-transported individuals, suggesting progressive recovery after reimmersion in water. Evidence of recovery was observed in the reduction of some stress biomarkers (e.g., lactic acid, succinic acid) following reimmersion. This study revealed insights into the metabolic responses to transport stress in abalone and highlights the importance of reimmersion practices in the supply chain of live animal exports.

Perna canaliculus is an aquaculture species vulnerable to ocean acidification (OA). Returning shell waste to the sea after commercial processing has potential to provide localized buffering to OA. We investigated whether seawater enrichment with crushed shell buffers carbonate chemistry and improves P. canaliculus larval performance under current (400 μatm) and future (1,100 μatm) PCO₂ conditions. Fertilized eggs from two parent pools were reared for 42 hr in seawater previously enriched with shell or non‐enriched. Aragonite saturation state (Ω_A) decreased in high PCO₂ seawater (Ω_A 1.26, compared to 2.54 under present‐day conditions). This was partially mitigated by shell enrichment (Ω_A 1.44). In high PCO₂ ethylenediaminetetraacetic acid (EDTA)‐treated seawater, shell enrichment resulted in minor increases in the proportion of larvae developing into normal veligers (no shell = 3.7 ± 3.0%, shell = 9.6 ± 4.7%; mean ± SD). Larvae failed to develop normally in the absence of EDTA, with the exception of ambient PCO₂ seawater enriched with shell, which yielded a pool‐dependent mean 2.3–17.8% normal veligers, possibly reflecting other properties of crushed shell including metal uptake. Non‐buffering effects of crushed shell, parental pool, and inclusion of a chelator (EDTA) in seawater appeared to have a greater influence upon larval performance than buffering per se, warranting further investigation.

New Zealand has a large exclusive economic zone (EEZ) of which the area between the 30 and 50 m bathymetric zone offers the most prospects for shellfish production. Only 0.3% of this zone would be required to increase New Zealand’s shellfish production by 150,000 t. The Enabling Open Ocean Aquaculture Program, funded by the New Zealand Ministry of Business, Innovation and Employment, is a collaboration aiming to develop technologies that will enable the extension of aquaculture into New Zealand’s harsh and challenging open ocean conditions, and facilitate adaptation to the escalating effects of climate change in inner shore environments. New Zealand has started expanding aquaculture into exposed environments, allowing farm expansion to meet increasing demand for aquaculture products but also enabling ventures into new aquatic products. Expansion into offshore developments is in direct response to mounting stakeholder interaction in inshore coastal areas. This document presents a brief overview of the potential zones for open ocean aquaculture, the influence of climate change, and two potential shellfish operational systems that may facilitate the expansion of shellfish aquaculture onto New Zealand’s exposed ocean sites.

Pressure in academia and science is rapidly increasing and early career researchers (ECRs) have a lot to gain from being involved in research initiatives such as large international projects. But just how inclusive are they? Here we discuss experiences of ECRs directly involved in the Marine Ecosystem Assessment for the Southern Ocean (MEASO), an Australian led international research project to assess the status and trends of Southern Ocean ecosystems. We review the benefits of ECR involvement in large-scale initiatives to the project deliverables, the leadership team and ECRs themselves. Using insights from MEASO, we outline the obstacles that may become barriers to ECRs in scientific research in general but with a focus on large-scale research projects and suggest potential actions to overcome these at the individual, institutional and scientific community level. We consider the potential for ECRs to lead future Antarctic science programmes with a focus on science communication and applied research for policy makers within a global setting.

Antarctic krill (Euphausia superba) are a key component of the Antarctic food web with considerable lipid reserves that are vital for their health and higher predator survival. Krill lipids are primarily derived from their diet of plankton, in particular diatoms and flagellates. Few attempts have been made to link the spatial and temporal variations in krill lipids to those in their food supply. Remotely-sensed environmental parameters provide large-scale information on the potential availability of krill food, although relating this to physiological and biochemical differences has only been performed on small scales and with limited samples. Our study utilised remotely-sensed data (chlorophyllaand sea surface temperature) coupled with krill lipid data obtained from 3 years of fishery-derived samples. We examined within and between year variation of trends in both the environment and krill biochemistry data. Chlorophyllalevels were positively related to krill lipid levels, particularly triacylglycerol. Plankton fatty acid biomarkers analysed in krill (such as n-3 polyunsaturated fatty acids) increased with decreasing sea surface temperature and increasing chlorophyllalevels. Our study demonstrates the utility of combining remote-sensing and biochemical data in examining biological and physiological relationships between Antarctic krill and the Southern Ocean environment.