Cawthron Institute
  • Nelson, New Zealand
Recent publications
The nutritional condition of seed mussels (spat) at the time of seeding is thought to play a major role in influencing spat losses on mussel farms, with nutritionally compromised spat thought to be more likely to be lost from aquaculture substrata than those in good condition. New Zealand's Greenshell ™ mussel (Perna canaliculus) aquaculture industry relies almost exclusively (∼85%) on wild caught spat, with the vast majority, typically > 90%, lost shortly after being seeded onto coastal mussel farms. This study sought to quantify the extent of the variability in the nutritional condition (i.e., calorific, protein, lipid and carbohydrate content) of samples of spat used by the Greenshell ™ industry between 2014 and 2021 (i.e., wild caught and hatchery produced) as a first step towards determining whether variability in nutritional condition may be a significant contributor to the marked variation observed in spat performance after it is seeded onto coastal farms. All parameters measured were highly variable among wild spat samples, with all but lipid content varying, including for samples of wild spat harvested at different times within the same month. Furthermore, there were no clear patterns in the nutritional condition of spat across months or years, suggesting environmental factors that limit feeding during the harvest and transport of spat may be contributing to marked differences in the quality of spat being used by the industry to seed farms. These results provide a baseline for assessing the nutritional condition of Greenshell ™ spat and point towards a need to develop interventions to improve the quality of wild spat supply for this industry to help and prevent the ongoing massive losses of spat from farms. These measures could include, testing nutritional condition of spat at harvest or prior to seeding, development of nursery culture methods and development of artificial spat feeds that have the potential to replace live phytoplankton during nursery culture.
The combination of an efficient sampling method and high‐throughput analysis of environmental DNA (eDNA) can be a powerful approach for characterising biodiversity across aquatic ecosystems. Plankton net tows are one of the oldest, simplest, and least expensive methods for seston and eDNA collection, but require laborious filtration steps which often lead to clogging and/or the introduction of contaminants. In this study, we used a cruising speed net (CSN) device enabling the collection of seston‐derived eDNA at 5 knots speed combined with a novel modified cod‐end with 20 μm nylon mesh inserts enabling eDNA capture while towing. We compared the performance of the CSN sampling protocol with the original conventional filtration of water sample versus the modified cod‐end. Samples were collected in parallel horizontal tows along New Zealand's North‐Eastern coastline. Concentrated water was filtered on conventional 5 μm cellulose acetate membranes, while the 20 μm nylon mesh inserts were immediately isolated post‐towing. Metabarcoding of bacterial 16S rRNA, eukaryotic nuclear 18S rRNA and mitochondrial COI genes, revealed no significant difference in alpha diversity between filtration techniques. In terms of community composition, a clear and significant shift could be observed between sampling sites and environments. Significant differences could be detected between filtration methods for 16S and COI markers, likely driven by fine‐scale differences at more turbid sheltered sites. Nonetheless, each technique could detect shifts in communities between sites and environments with similar sensitivity. Our results demonstrate the promising potential of the modified cod‐end to enable practical and cost‐effective isolation of eDNA‐derived biodiversity data from any vessel types (at ≤5 knots) across a large range of aquatic ecosystems and biogeographic scales.
The ‘research system’ in Aotearoa New Zealand is rife with obstacles for entry and retention of diversity. The research system's complexity and longevity gives the impression of stability and fixity, but we argue it is characterised by a lack of imagination around leadership that generates change. In this article, we examine the embodied experiences of research leadership, as encountered by participants at Aotearoa New Zealand's universities and a nationally funded Centre of Research Excellence. It is within such institutions and organisations, built on colonial and patriarchal values, that experiences of marginalisation, oppression and harassment have been documented. We destabilise the apparently static nature of this ‘research system monolith’ by taking up MacLeavy, Fannin and Larner's (2021) provocation of a feminist approach to boldly do leadership differently. Drawing from interviews with researchers, we provoke that resistance to, and reworking of, the research system is hidden in feminist modes of practice: in the everyday, mundane practices of care‐full research leadership, that does leadership differently.
1. The island species–area relationship (ISAR) describes how species richness increases with increasing area of a given island or island-like habitat, such as freshwater lakes. While the ISAR is one of the most common phenomena observed in ecology, there is variation in both the form of the relationship and its underlying mechanisms. 2. We compiled a global data set of benthic macroinvertebrates from 524 shallow freshwater lakes, ranging from 1 to 293,300 ha in area. We used individual-based rarefaction to determine the degree to which ISAR was influenced by mechanisms other than passive sampling (larger islands passively sample more individuals from the regional pool and, therefore, have more species than smaller islands), which would bias results away from expected relationships between rarefied species richness (and other measures that capture relative abundances) and lake area. We also examined how climate may alter the shape of the ISARs. 3. We found that both rarefied species richness (the number of species standardized by area or number of individuals) and a measure of evenness emphasizing common species exhibit shallow slopes in relationships with lake area, suggesting that the expected ISARs in these lakes most likely result from passive sampling. While there was considerable variation among ISARs across the investigated lakes, we found an overall positive rarefied ISAR for lakes in warm (i.e. tropical/subtropical) regions (n = 195), and in contrast, an overall negative rarefied ISAR in cool (i.e. north temperate) lakes (n = 329). This suggested that mechanisms beyond passive sampling (e.g. colonization–extinction dynamics and/or heterogeneity) were more likely to operate in warm lakes. One possible reason for this difference is that the area-dependent intensity of fish predation, which can lead to flatter ISARs, is weaker in warmer relative to cooler lakes. 4. Our study illustrates the importance of understanding both the pattern and potential processes underlying the ISARs of freshwater lakes in different climatic regions. Furthermore, it provides a baseline for understanding how further changes to the ecosystem (i.e. in lake area or climate) might influence biodiversity patterns.
Ocean warming and extreme heatwaves threaten marine species supporting commercial fisheries and aquaculture. Predicting the responses of these industries to chronic and acute warming depends on understanding which life stages are most vulnerable, the potential for stocks to adapt to changing thermal environments, and the availability of thermally adapted genotypes to help enhance stock resilience through strategic interventions. Here, we shed light on some of these knowledge gaps by quantifying the critical thermal maximum (CTmax) of ~ 10–210 g hybrid abalone (Haliotis rubra × H. laevigata) from two farms representing contrasting thermal environments from south-eastern Australia. CTmax was not dependent on body size or provenance (farm) when heating rates were rapid (1 °C per h), but a significant relationship between CTmax and body size was observed when heating rates were slower and more ecologically realistic (1 °C per 12 h). Histological analyses revealed a negative relationship between CTmax and the stage of gonadal development when abalone were exposed to chronic thermal stress conditions. These results suggest that marine heatwaves and ongoing ocean warming might favour smaller, less fecund animals in natural and farm settings. This could potentially impact future harvestable biomass, recruitment and population dynamics in wild-capture fisheries, and production of larger, high-value animals in farm settings. This study adds to a growing body of literature pointing to complex and often negative effects of climate change on commercial fisheries, and the potential need for interventions aimed at bolstering fisheries resilience against the effects of ocean warming.
This study assessed the effectiveness of using video cameras mounted on commercial trawls for a deep-sea lobster, the New Zealand scampi Metanephrops challengeri , for acquiring information on habitat associations of demersal species and fishing efficiency. Randomly selected frames from 1 h of recording replicated over 12 trawls and conducted over three fisheries management areas (FMA), were analysed for counts of visible scampi, scampi burrows, visible topographical features and visible epifauna and fish taxa. Poisson regression analysis indicated a positive relationship between the distribution of scampi burrows (a proxy of scampi abundance) and conical mounds (formed by bioturbators), but a negative relationship with smooth topography. Counts of scampi burrows were also positively associated with counts of visible scampi for four trawls, while significant relationships were seldom found between counts of scampi burrows and other commonly observed individual taxa. Scampi trawl efficiency was low, with only 56 of the 186 observed scampi (30%) passing over the footrope and into the trawl net. The results confirm the effectiveness of video sampling from commercial trawls to improve our understanding of habitats and fishing efficiency in deep-sea fisheries.
Simple Summary It is widely accepted that climate change is a rapidly increasing threat to the aquaculture industry, with the biggest issue being a slow but continuous rise in water temperature and an associated decrease in dissolved oxygen in some areas. In New Zealand fish farms, during the hottest period of the year (January/February), increased water temperatures have been shown to be detrimental to Chinook salmon performance and are associated with mortalities. We report on the responses of Chinook salmon to a chronic, long-term increase in temperature and decrease in oxygen over a three-month period. We also identified, characterised, and developed relevant biomarkers for Chinook salmon and applied them to monitor responses to changes in the fish’s environment. This paper provides evidence on how the use of molecular tools, alongside general health and haematological parameters, have the potential to better inform the aquaculture industry of stock health status, thereby enhancing resilience, efficiency, and productivity. Abstract In New Zealand, during the hottest periods of the year, some salmon farms in the Marlborough Sounds reach water temperatures above the optimal range for Chinook salmon. High levels of mortality are recorded during these periods, emphasising the importance of understanding thermal stress in this species. In this study, the responses of Chinook salmon (Oncorhynchus tshawytscha) to chronic, long-term changes in temperature and dissolved oxygen were investigated. This is a unique investigation due to the duration of the stress events the fish were exposed to. Health and haematological parameters were analysed alongside gene expression results to determine the effects of thermal stress on Chinook salmon. Six copies of heat shock protein 90 (HSP90) were discovered and characterised: HSP90AA1.1a, HSP90AA1.2a, HSP90AA1.1b, HSP90AA1.2b, HSP90AB1a and HSP90AB1b, as well as two copies of SOD1, named SOD1a and SOD1b. The amino acid sequences contained features similar to those found in other vertebrate HSP90 and SOD1 sequences, and the phylogenetic tree and synteny analysis provided conclusive evidence of their relationship to other vertebrate HSP90 and SOD1 genes. Primers were designed for qPCR to enable the expression of all copies of HSP90 and SOD1 to be analysed. The expression studies showed that HSP90 and SOD1 were downregulated in the liver and spleen in response to longer term exposure to high temperatures and lower dissolved oxygen. HSP90 was also downregulated in the gill; however, the results for SOD1 expression in the gill were not conclusive. This study provides important insights into the physiological and genetic responses of Chinook salmon to temperature and oxygen stress, which are critical for developing sustainable fish aquaculture in an era of changing global climates.
Information about population connectivity, including the rates and routes of larval transport as well as source-sink dynamics, is important for the sustainable management of harvested species. For marine species whose primary mode of dispersal is transport during the pelagic larval stage, biophysical modelling of larval dispersal represents a valuable tool that is not subject to some of the same limitations as genetic connectivity analyses. In particular, a model that encompasses the entire distribution of a species can provide novel insights by identifying potentially important source populations or stepping-stone sites from which molecular samples may not be available. This study employed a Lagrangian particle-tracking model to simulate larval releases from all potential mussel habitats along ~15000 km of coastline for an endemic New Zealand bivalve, the green-lipped mussel. A northern and a southern cluster with a break near Cook Strait were identified, confirming the structure reported by earlier genetic analyses and a previous biophysical modelling study. The present study revealed, for the first time, that connectivity between the 2 clusters is largely asymmetrical, with more particle transport from the south to the north. Because this study simulated spawning events across the entire distribution of the species, several previously unknown source populations and stepping-stone populations were identified. These findings highlight the utility of a multidisciplinary approach to understanding marine connectivity and provide evidence for new strategies, including the protection of source and stepping-stone populations, to sustainably manage this endemic species.
In the current study we investigate the antifouling potential of three polyphenolic resveratrol multimers (-)-hopeaphenol, vaticanol B and vatalbinoside A, isolated from two species of Anisoptera found in the Papua New Guinean rainforest. The compounds were evaluated against the growth and settlement of eight marine microfoulers and against the settlement and metamorphosis of Amphibalanus improvisus barnacle cyprids. The two isomeric compounds (-)-hopeaphenol and vaticanol B displayed a high inhibitory potential against the cyprid larvae metamorphosis at 2.8 and 1.1 μM. (-)-Hopeaphenol was also shown to be a strong inhibitor of both microalgal and bacterial adhesion at submicromolar concentrations with low toxicity. Resveratrol displayed a lower antifouling activity compared to the multimers and had higher off target toxicity against MCR-5 fibroblasts. This study illustrates the potential of natural products as a valuable source for the discovery of novel antifouling leads with low toxicity.
Aotearoa New Zealand’s Northern region is a major gateway for the incursion and establishment of non-indigenous species (NIS) populations due to high numbers of recreational and commercial vessels. This region also holds a unique marine ecosystem, home to many taonga (treasured) species of cultural and economic importance. Regular surveillance, eradication plans and public information sharing are undertaken by local communities and governmental organizations to protect these ecosystems from the impact of NIS. Recently, considerable investments went into environmental DNA (eDNA) research, a promising approach for the early detection of NIS for complementing existing biosecurity systems. We applied eDNA metabarcoding for elucidating bioregional patterns of NIS distributions across a gradient from harbors (NIS hotspots) to open seas (spreading areas). Samples were collected during a research cruise sailing across three Aotearoa New Zealand harbors, Waitematā, Whangārei and Pēwhairangi (Bay of Islands), and their adjacent coastal waters. The small-ribosomal subunit (18S rRNA) and mitochondrial cytochrome c oxidase I (COI) genes were screened using the online Pest Alert Tool for automated detection of putative NIS sequences. Using a probabilistic modelling approach, location-dependent occupancies of NIS were investigated and related to the current information on species distribution from biosecurity surveillance programs. This study was collaboratively designed with Māori partners to initiate a model of co-governance within the existing science system.
Ever closer to the brink of global environmental collapse, it is vital that we work collaboratively and collectively as global, national, and local communities to design multi‐scale change. Protecting future generations and reversing (or substantively slowing) the current trends requires rapid sustainable progress at the required scale. It is more urgent than ever we understand and more fully realise the power of transdisciplinary (Td) research to support sustainable practice. A defining factor of Td is the focus on collaboration and co‐design and the extent that participation and attention to local context is integral to the knowledge building. Specifically there is greater ability for community knowledge, values and aspirations to influence and shape research inquiries to effect meaningful change in real world decision‐making and outcomes. Business as usual (BAU) approaches that perpetuate unequal knowledge sharing and dismiss other forms of knowledge beyond traditional science no longer suffice. Transdisciplinary approaches seek to achieve and support sustainable change, but the extent of transformation required to meet ecological protection and regenerative sustainability needs very different operating models for knowing and doing science than the limited traditions of positivist science. However, these powerful defaults and operating paradigms are more deeply ingrained than we might realise, and hence challenges persist. This paper illustrates how Td science differs from typical research paradigms, particularly in terms of the underlying epistemology, the focus on knowledge/power, attention to boundaries and scope, and the degree to which local knowledge, context and community participation underpin the research process. Active conversations are required to better identify and overcome fundamental challenges for science and Td research approaches to support the necessary transformational change. Importantly, we suggest that Indigenous partnerships, knowledge and values are vital in achieving the potential of transdisciplinary research to provide transformational interventions to address complex social and environmental issues like pollution.
Improving our understanding of the effects of satellite tags on large whales is a critical step in ongoing tag development to minimise potential health effects whilst addressing important research questions that enhance conservation management policy. In 2014, satellite tags were deployed on 9 female southern right whales Eubalaena australis accompanied by a calf off Australia. Photo-identification resights (n = 48) of 4 photo-identified individuals were recorded 1 to 2894 d (1-8 yr) post-tagging. Short-term (<22 d) effects observed included localised and regional swelling, depression at the tag site, blubber extrusion, skin loss and pigmentation colour change. Broad swelling observable from lateral but not aerial imagery (~1.2 m diameter or ~9% of body length) and depression at the tag site persisted up to 1446 d post-tagging for 1 individual, indicating a persistent foreign-body response or infection. Two tagged individuals returned 4 yr post-tagging in 2018 with a calf, and the medium-term effects were evaluated by comparing body condition of tagged whales with non-tagged whales. These females calved in a typical 4 yr interval, suggesting no apparent immediate impact of tagging on reproduction for these individuals, but longer-term monitoring is needed. There was no observable difference in the body condition between the 2 tagged and non-tagged females. Ongoing monitoring post-tagging is required to build on the sample size and statistical power. We demonstrate the value of long-term monitoring programmes and a collaborative approach for evaluating effects from satellite-tagging cetaceans to support species management.
Knowledge of the dispersive characteristics and time of travel of microbiological contamination is a key consideration in determining impacts on shellfish growing areas following wastewater overflows. In this study, norovirus genogroup I and II, indicators of viral contamination (F-RNA bacteriophage genogroup II (F-RNA GII), crAssphage, pepper mild mottle virus) and Escherichia coli were monitored during periods of normal harvesting and following overflows in two commercial shellfish growing areas in Otago Harbour (Aotearoa New Zealand). Hydrographic studies (dye tracing, drogue tracking and analysis of particle tracking modelling) were undertaken to assess the dispersion, dilution and time of travel of wastewater discharged from a pump station discharge that impacts the growing areas. Norovirus was not detected in any of the 218 shellfish samples tested. PMMoV and crAssphage were more prevalent than F-RNA GII as determined by RT-qPCR. The dye study indicated long residence time of the waters (≥ 5 days) in the embayment impacted by the discharge. No relationships were found between the concentrations of viral indicators or E. coli and wastewater dilution, distance between the discharge and the growing areas or time since the last overflow. For the three spills studied (≤ 327 m ³ ), there was little evidence of microbiological impact on the growing areas. This was likely associated with a deep shipping channel that enhances water flushing in the harbour and reduces contaminant transport to the growing areas. We recommend flexibility in the approach for closure/reopening growing areas impacted by spills, particularly for small duration/volume spills and when norovirus is not present in the community.
There is a lack of cost-effective, environmentally-friendly tools available to manage marine biofouling accumulation on static artificial structures such as drilling rigs, wind turbines, marine farms, and port and marina infrastructure. For there to be uptake and refinement of tools, emerging technologies need to be tested and proven at an operational scale. This study aimed to see whether biofouling accumulation could be suppressed on marine infrastructure under real-world conditions through the delivery of continuous bubble streams. Submerged surfaces of a floating marina pontoon were cleaned in-situ by divers, and the subsequent colonisation by biofouling organisms was monitored on treated (bubbles applied) and untreated sections. Continuous bubble streams proved highly effective (>95%) in controlling macrofouling accumulation on the underside surface of the marina pontoon for the first 2 months after deployment, but efficacy dropped off rapidly once bubble stream delivery was partially obscured due to biofouling accumulation on the diffuser itself. Although extensive macrofouling cover by mussels, bryozoans and hydroids was observed on treated surfaces by 4 months (27.5%, SE = 4.8%), biofouling % cover and diversity was significantly higher on untreated surfaces (79.6%, SE = 2.9%). While this study demonstrates that continuous bubble streams greatly restrict biofouling accumulation over short-to-medium timescales, improved system design, especially the incorporation of diffusers resistant to fouling, is needed for the approach to be considered a viable long-term option for biofouling management on static artificial structures.
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140 members
Calum Macneil
  • Freshwater Ecosystems
Matthew R Miller
  • Analytical Research and Method Development
Julien Vignier
  • Aquaculture Group
98 Halifax Street-East, 7010, Nelson, New Zealand
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