Norman Ragg

• B.Sc. (hons), M.Sc., PhD
• Senior Researcher at Cawthron Institute

Increasing seawater temperatures coupled with more intense and frequent heatwaves pose an increasing threat to marine species. In this study, the New Zealand green-lipped mussel, Perna canaliculus, was used to investigate the effect of genetics and ontogeny on thermal resilience. The culturally and economically significant mussel P. canaliculus (Gm...

The mechanistic approach and the potential predictive power of Dynamic Energy Budget (DEB) models are making this modelling framework increasingly popular in aquaculture management. The potential to mechanistically simulate life-history traits of a species in a changing environment has already been applied to many commercial species, including the...

Improved sustainability of aquaculture can be achieved by reducing product wastage post-harvest. Aquaculture of the green-lipped mussel, Perna canaliculus, is an important industry for New Zealand, which increasingly exports to live markets. Live transport can keep mussels fresh, but mussels could also be susceptible to handling stresses. To remedy...

The New Zealand geoduck (Panopea zelandica) has seen considerable interest from the NZ aquaculture industry. A major bottleneck in culturing P. zelandica is early life stages mortality (e.g., embryo). Therefore, in this study, we investigated the embryonic performance and their transition to the first feeding larval stage (D-veliger) under differen...

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. canalic...

The black-foot abalone (pāua), Haliotis iris, is a unique and valuable species to New Zealand with cultural importance for Māori. Abalone are marine gastropods that can display a high level of phenotypic variation, including slow-growing or ‘stunted’ variants. This investigation focused on identifying factors that are associated with growth perform...

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 a...

Marine heatwaves (MHW) are projected for the foreseeable future, affecting aquaculture species, such as the New Zealand green-lipped mussel (Perna canaliculus). Thermal stress alters mussel physiology highlighting the adaptive capacity that allows survival in the face of heatwaves. Within this study, adult mussels were subjected to three different...

Climate extremes, such as heatwaves, are expected to become more intense and of longer duration in the near future. These climatic conditions may have a significant impact on the prospects of establishing a new aquaculture industry for the endemic New Zealand geoduck, Panopea zelandica. This study focused on characterising animal behaviour, haemocy...

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 fi...

Broad phenotypic variation in shell morphology is a common phenomenon across wild abalone populations worldwide. Many shellfish species, such as abalone, show slower growth rates, smaller maximum size of individuals , and reduced biomass in some habitats compared to others. Such habitats are often inferred to be sub-optimal and, for a fishery, the...

Incidences of mortality and deteriorating health of farmed New Zealand Greenshell™ mussels (kūtai; Perna canaliculus; GSM) are increasing in summer on marine farms. Laboratory studies have investigated what elevated seawater temperatures are physiologically stressful for GSM, and the results provide valuable insight into the biological mechanisms i...

New Zealand aquaculture is experiencing recurring marine heatwaves impacting marine farms, presenting a need to adapt to this challenge. The well established family based breeding programmes for the principal NZ farmed species Greenshell mussels (Perna canaliculus) and Chinook salmon (Oncorhynchus tshawytscha ) provide a potential opportunity to br...

Marine heatwaves and elevated sea surface temperatures are expected to increase in frequency and intensity, with catastrophic effects on New Zealand aquaculture species, such as the green-lipped mussel (Perna canaliculus). Thermal stress affects mussel health, metabolic regulation and physiological functions, illustrating the kind of adaptive capac...

Farming of green-lipped mussels (Perna canaliculus) can be seen as the cornerstone of the New Zealand aquaculture industry. Yet, warming sea surface temperatures are threatening aquaculture species due to disease outbreaks and associated mortalities. Large research efforts are being invested to better understand how climate change stressors, such a...

Marine farmers have reported increased incidence of mass mortalities of New Zealand green-lipped mussels, Perna canaliculus, grown on near-shore long-line aquaculture farms. While the causative agents remain unknown, die-off events typically occur during the warmest months of the austral summer and appear correlated to unprecedented summer marine h...

GreenshellTM mussels (Perna canaliculus) are important ecosystem engineers, with an established position within the New Zealand aquaculture sector. Increased incidence of mass mortalities of P. canaliculus, have been reported in recent years, especially during the warmest months of the austral summer. Even though the exact cause of these mortaliti...

The New Zealand Greenshell™ mussel (Perna canaliculus) is an endemic bivalve species with cultural importance, that is harvested recreationally and commercially. However, production is currently hampered by increasing incidences of summer mortality in farmed and wild populations. While the causative factors for these mortality events are still unkn...

Cultured Greenshell™ mussels (Perna canaliculus) are exposed to biotic and abiotic stresses, all of which can negatively impact growth, fecundity, and survival. These impacts are especially pronounced in sensitive larval and spat stages and may result in substantial losses when spat are transferred from hatchery to grow-out farms. Immersion in solu...

Marine heatwaves and elevated sea surface temperatures are expected to increase in frequency and intensity, with catastrophic effects on New Zealand aquaculture species, such as the greenlipped mussel (Perna canaliculus). Thermal stress affects mussel health, metabolic regulation and physiological functions, illustrating the kind of adaptive capaci...

Stress and survival of the juvenile New Zealand green-lipped mussel, Perna canaliculus, is a poorly understood bottleneck in the ecological and economic performance of a significant aquaculture crop. This species was therefore selected as a model organism for the development of a new method to quantify oxidative stress in whole individuals. An in v...

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...

New Zealand aquaculture has grown into a significant primary industry, with the Greenshell mussel (Perna canaliculus) sector being the largest in terms of value and production quantity. Extreme events such as heat waves have increased in frequency over the last decades and are responsible for mass mortalities in mussels, threatening economic and ec...

The steady increase in abalone aquaculture production throughout the world has attracted growing interest in the application of new technologies, such as omics approaches for abalone research. Many omics techniques, such as genomics, transcriptomics, proteomics, and metabolomics are becoming established in abalone research and are beginning to reve...

The early stages of intertidal mussels, including the green-lipped mussel, Perna canaliculus, face both direct and indirect environmental threats. Stressors may influence physiological status and, ultimately, survival. An understanding of the nature of stress experienced is critical to inform conservation and aquaculture efforts. Here, we investiga...

As in many other parts of New Zealand, the Chatham Islands are experiencing declining pāua stocks that have resulted in significant biomass losses, with stunting of abalone contributing to this reduction. Considering that fisheries support >80% of the pāua exported from NZ, investigations linked to the stunting of pāua is crucial to support this in...

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 (...

The use of ethylenediaminetetraacetic acid (EDTA) during bivalve hatchery production is thought to improve larval yields due to the reduced exposure to toxic metals (such as Cu); however, few studies have focused on the bioavailability of metals during the rearing process. Greenshell™ mussels (Perna canaliculus) were reared for 48 h with and withou...

The chelating agent ethylenediaminetetraacetic acid (EDTA) is used throughout the world to improve the yield of early stage D-larvae during bivalve hatchery production. Adding EDTA (12 μM) to seawater significantly increases the survival of Greenshell™ mussel (Perna canaliculus) larvae during their first 48 h of development. However, whether there...

Harvest and transport of farmed mussels are known to impose stress on the crop species. However, not much is known about molecular pathways underlying these physiological stresses. The present study investigated the effects of harvesting on the metabolome of the haemolymph and hepatopancreas of green-lipped mussels (Perna canaliculus), complemented...

Ocean acidification (OA), the change in ocean chemistry caused by carbon dioxide emissions, poses a serious imminent threat to marine organisms, especially those with calcium carbonate shells. The green-lipped mussel (Perna canaliculus), endemic to New Zealand, is common in coastal ecosystems and is an economically important aquaculture species. As...

Green-lipped mussels (Perna canaliculus) are a commercially and culturally important bivalve species in New Zealand (NZ). As the highest value export aquaculture product in NZ, understanding and safeguarding the health of this species is imperative. The identification and characterization of hemocytes can provide useful information regarding the he...

Call for abstracts now open!

The major cultured mussel species Perna canaliculus is now supported by hatchery production, providing the opportunity to explore and optimize environmental parameters to enhance production. Other cultured bivalve larvae have demonstrated performance that is directly correlated to the aragonite saturation state (Ωar) of their tank water, with low o...

Ambient seawater temperature is an important factor during the early life stages of marine invertebrates. Temperature is often manipulated in hatcheries to shorten the incubation period before the larval rearing phase. In this study, the effect of temperature on the early development of the geoduck Panopea zelandica was investigated over a 48‐hr pe...

The trace elemental composition of biogenic calcium carbonate (CaCO3) structures is thought to reflect environmental conditions at their time of formation. As CaCO3 structures such as shell are deposited incrementally, sequential analysis of these structures allows reconstructions of animal movements. However, variation driven by genetics or ontoge...

Farmed adult Greenshell™ mussels were exposed to a range of conditions immediately after harvest to evaluate the effects on emersion survival and the implications for live transport. Two experiments were performed, coinciding with the mussel harvest season during summer and winter 2017. In the summer experiment, a wide range of conditions were test...

We sought to determine how pCO2 will affect the incorporation of trace elements into bivalve shell. This was to validate that under high pCO2 conditions reconstruction of animal movements is still viable; and to investigate potential trace element proxies for ocean carbonate chemistry. Here, we examined shell of the bivalve Perna canaliculus formed...

Pacific oyster (Crassostrea gigas) farming in New Zealand (NZ) began in the 1970’s and has grown into a NZ$ 30 million industry, producing over 2,000 t per year. NZ aquaculture is a fast-growing sector estimated to be worth over NZ$ 500 million per year, with a strategic goal of NZ$ 1 billion in sales by 2025. In this context, selective breeding, d...

Aquaculture is an important primary industry for New Zealand and the three flagship species, Greenshell™ mussels (Perna canaliculus), Pacific oysters (Crassostrea gigas), and Chinook salmon (Oncorhynchus tshawytscha), currently produce over NZD $400 million p.a. in export revenue (www.aquaculture.org.nz). The aquaculture industry has set an ambitio...

Cultivation of the geoduck Panopea zelandica (Quoy & Gaimard, 1835) requires knowledge on embryonic development to produce spat in hatcheries. This study investigated the development of P. zelandica embryos at 158C and 35 ppt and the optimal sperm:egg ratios for fertilization under hatchery conditions. Panopea zelandica broodstock were induced to s...

We evaluated the thermotolerance (LT50) of adult green-lipped mussels (Perna canaliculus) following an acute thermal challenge in the summer of 2012 and the winter of 2013. Mussels were grouped into two treatments, naïve (N, no prior heat treatment) and heat-hardened (HH = 1 h at 29 °C, 12 h recovery at ambient) before being immersed for 3 h in wat...

We describe here the first complete genome assembly of the New Zealand green-lipped mussel, Perna canaliculus, mitochondrion. The assembly was performed de novo from a mix of long nanopore sequencing reads and short sequencing reads. The genome is 16,005 bp long. Comparison to other Mytiloidea mitochondrial genomes indicates important gene rearrang...

The threat posed by ocean acidification (OA) to the diversity and productivity of New Zealand marine ecosystems is assessed in a synthesis of published trends and impacts. A 20-year time series in Subantarctic water, and a national coastal monitoring programme, provide insight into pH variability, and context for experimental design, modelling and...

Breeding Greenshell mussel (Perna canaliculus) families resilient to live shipment stress offers an opportunity to increase export revenue for the New Zealand mussel industry. We tested two key phenotypic responses (enzyme activity and shell gape) of selectively bred mussel families grouped (n = 3 × families/grouping) into those that showed ‘good’...

In New Zealand, three quarters (by value) of national aquaculture exports are based on the production of an endemic species, the green-lipped mussel, Perna canaliculus, yet there remains a paucity of information describing its underpinning biology. The majority of seed stock is still derived from wild capture from two main geographic locations, how...

Geoduck clams (Panopea spp.) are the longest-lived and largest deep burrowing bivalve. Their unique morphology allows them to live buried in the sediment at depths of up to 1m. The endemic New Zealand geoduck (Panopea zelandica Quoy and Gaimard, 1835) has recently been identified as a potential species for aquaculture. However, very little is known...

The New Zealand geoduck clam Panopea zelandica (Quoy and Gaimard, 1835) is among the largest burrowing clams throughout the world. However, the effects of size scaling on physiology have not been studied for any geoduck species. In this study, we determined the allometric coefficients of respiration rate (RR) and clearance rate (CR) for P. zelandic...

There is an urgent need to develop sub-lethal stress detection tools to differentiate health status and forecast adult success, in the early-life of aquaculture shellfish species. In addition, the NZ coastal seascape is experiencing rapid change whereby numerous biotic and abiotic stressors are likely to influence biological processes, therefore bo...

OsHV-1 is a proliferating virus that causes mortality in the larvae and juveniles of several bivalve species including the Pacific oyster Crassostrea gigas, Ostrea edulis, Ruditapes decussatus, R. philippinarum and Pecten maximus. The virus can be found in adult bivalves but without any mortality. Infected larvae show a reduction in feeding and swi...

Immunological defence systems in marine invertebrates are poorly understood compared to other taxa. For example, recent studies are demonstrating that the line between innate and adaptive immunity in marine molluscs is unprecedentedly blurred and challenges our entire theses on the evolution of molecular defence pathways. One relatively well-charac...

The Greenshell mussel, Perna canaliculus, represents a key component of the benthic ecosystem and supports New Zealand’s largest aquaculture industry. This study explores the effects of aragonite saturation (ΩA) manipulation upon embryogenesis and larval performance of P. canaliculus, providing an indication of the extent to which commercial hatche...

Geoduck clams are amongst the most valuable cultured shellfish available on the world market, driving interest in the establishment of the native New Zealand species, Panopea zelandica (Quoy & Gaimard, 1835), as a candidate for aquaculture. A critical element of domestication is the effective management of breeding stock to optimize gamete and offs...

The development of new tools for assessing the health of cultured shellfish larvae would be highly valuable for the New Zealand aquaculture industry, which is seeking to develop and refine hatchery methodologies. A semi-commercial scale trial was established using embryos of the economically important Greenshell mussel, Perna canaliculus. We induce...

Abalone are enigmatic, displaying subtle responses to stress, including a delayed onset of morbidity, and death after severe stress. The present study therefore sought to further elucidate the nature of stress responses in the blackfoot abalone Haliotis iris and develop practical indices to quantify stress and forecast survival. Abalone were challe...

Heart rate monitoring has been shown to be a valuable tool for assessing health in bivalves. With the advancement in sensor technology, new heart beat monitoring approaches have evolved from invasive to non-invasive method and from short distance to long distance. Heart beats of bivalves were initially recorded with impedance technology, which invo...

The green-lipped mussel (Perna canaliculus Gmelin, 1791) is an economically and ecologically important marine species within New Zealand, yet the ability of adult mussels to cope with acute temperature change remains unknown. To address this, we sought to characterize the thermotolerance capacity of P. canaliculus adults and, using metabolomics, id...

In most animals, significant increases in metabolic rate are due to activity and to feeding (known as apparent specific dynamic action). We determined the energetic costs of activity and feeding in adult green-lipped mussels (Perna canaliculus). Maximal metabolic rate was determined, using closed-chamber respirometry, during byssus re-attachment, d...

We report the first measures of thermotolerance (recorded as percent mortality and induced HSP70 production) for pelagic larvae of three populations of the New Zealand Greenshell (green-lipped) mussel Perna canaliculus. Our goal was to determine whether distinct populations of P. canaliculus were more susceptible to predicted climate change than ot...

The diatom Chaetoceros calcitrans forma pumilum is an important dietary component for cultured Greenshell™ mussel larvae, Perna canaliculus. However concerns surrounding potentially deleterious side effects have motivated a series of experimental trials to optimise the safe usage of this alga. Bioassays involved raising veliger larvae in the purpos...

The morphology and nature of the adhesive secretion from Perna canaliculus mussel larvae settled on glass and on Teflon1 was observed by scanning electron microscopy techniques. The settled larvae were imaged by field emission scanning electron microscopy and the adhesive footprints left on the substrate after the organisms’ removal by cryo-scannin...

The adhesion of Perna canaliculus mussel larvae on a germanium (Ge) prism in filtered seawater at 16 degrees C has been investigated by in situ attenuated total reflection infrared (ATR-IR) spectroscopy. The adhesive from the mussel larvae was spectrally monitored over 2 h and the IR spectrum showed its glycoproteinaceous nature with sulphated and...

The New Zealand Blackfoot abalone or paua, Haliotis iris uses both tactile and chemosensory cues to detect and feed on drifting seaweed in its natural habitat. In aquaculture situations, abalone are usually provided with static artificial food pellets, effectively removing the tactile stimulus. This study investigated the effects of tactile stimuli...

Extant abalone retain an ancestral system of gas exchange consisting of paired bipectinate gills. This paper examines the hypothesis that fundamental inefficiencies of this arrangement led to the extensive radiation observed in prosobranch gas exchange organs. Oxygen uptake at 15 degrees C was examined in the right gill of resting adult blackfoot a...

The abalone Haliotis iris retains the ancestral gastropod arrangement of a pair of bipectinate gills (ctenidia). The gills share a single branchial chamber, are supplied from a common haemolymph sinus and effectively support the whole of oxygen uptake by the animal. Using chronic indwelling cannulae and pulsed Doppler probes, post-branchial haemoly...

Measurement of extracellular fluid volume (ECFV, haemolymph or blood volume) of abalone is important for understanding respiratory and circulatory functions and for investigation of factors affecting meat recovery in the fishery. The compounds ¹⁴C-inulin and ⁵¹Cr-ethylenediaminetetraacetic acid (EDTA) were evaluated as markers for the determination...

The archaeogastropod Haliotis iris possesses paired bipectinate gills and normally four to six shell holes. In still water, endogenous water flow entered the branchial chamber anteriorly to the left of the head and was exhaled primarily from the three most posterior holes. The first or second anterior aperture was occasionally weakly inhalant. Card...

Abalone use a combination of tactile and chemosensory feeding cues to detect suspended seaweed in their natural environment. However, in a commercial situation, adult abalone (Haliotis iris) caught for broodstock or pearling, show reluctance to start feeding on stationary artificial food. If they cannot be induced to feed, they may lapse into a sta...

The nutritional value to abalone of Ulva lactuca L with different tissue nitrogen levels was studied. The seaweed was cultured at two levels of ammonia-N enrichment. Cultures receiving 0.5 g ammonia-N m-2 d-1 ("Iow-N") yielded 164 g m-2 d-1 of fresh thalli containing 12% cmde protein in dry matter and 12 kJ g-l energy; cultures receiving 10 g ammon...

A pilot-scale system for the intensive land-based culture of abalone was established using an integrated design aimed at eliminating the dependence on external food sources, whilst reducing water requirements and nutrient discharge levels. The system was the first and simplest trial in a series of progressive complexity of the concept of integrated...

An integrated description of the respiratory system of the abalone Haliotis iris is presented. These animals are believed to be inherently primitive and still bear the ancestral gastropod gill arrangement, thus allowing physiological examination of a 'living fossil'. Ventilation, gaseous diffusion, blood transport and the anatomical arrangement of...