Rocky shore haliotids are frequently exposed to significant environmental fluctuations in temperature, salinity and dissolved oxygen. We investigated how acclimation temperature influenced the physiological and biological responses of blackfoot Pāua ( Haliotis iris ) to acute temperature change, reduced salinity and progressive hypoxia. Individuals were acclimated to one of four constant temperatures (12, 15, 18 or 21 °C) for 2 weeks before exposure to four acute temperatures (12, 15, 18 and 21 °C). In the salinity experiment, Pāua were acclimated to three constant temperatures (12, 15 or 18 °C) and then exposed to stepwise lowered salinity from 34‰ to 22‰. Pāua in the hypoxia experiment were acclimated to either 15 or 18 °C and then exposed to progressive hypoxia at four acute temperatures. Oxygen uptake and heart rate increased at higher exposure temperatures, while decreased with reducing salinity. During hypoxia, oxygen uptake was the highest in well‐oxygenated water and rates declined slowly to a critical level. Pāua have a limited ability to acclimate to temperatures above 18 °C and are more stressed by combinations of stressors than individual ones. Pāua are sensitive to environmental changes and they would be vulnerable to increased seawater conditions associated with global warming. These findings improve understanding of Pāua responses to warming, salinity and declined oxygen fluctuations, with implications for aquaculture, fisheries management and conservation under climate change.
This study investigates how food availability aligns with nutritional requirements of the snail Lunella smaragda , a potential biological control agent for managing biofouling in recreational vessel hubs. Biofouling communities were assessed during two contrasting seasons to gain insights into the quantity and quality of food available for agent consumption. Nutritional availability was higher in spring/summer and increased with biofouling age, whereas the increase plateaued after 32 days of the 54‐day deployment period in autumn/winter. Biofouling communities were predominantly composed of saturated fatty acids, with proportions of polyunsaturated and monounsaturated fatty acids varying between seasons. In the laboratory, snails were exposed to one of three feeding scenarios over a 7‐day period (nil, low and high food) and changes in physiological condition (i.e., protein, lipid, carbohydrate content and malondialdehyde levels) were evaluated. Short‐term food limitation resulted in a marginally significant decrease in protein and increase in wet weight for snails on a high food diet, when compared to other treatments. When compared to baseline data, lipid content significantly decreased across all treatments, while protein and water content in the nil and low food treatments and wet weight in the high food treatment increased significantly. Malondialdehyde levels were lower in the nil and low food treatments, while increasing in snails fed the high food diet, indicating a higher metabolic response in well‐fed snails. These results suggest that alternative management strategies, such as adjusting grazing density and providing supplemental feed, may be required to prevent starvation and maintain treatment efficiency during periods of poor food availability.
The 2025 Environmental Perceptions Survey provides unique insight into a nationally representative sample ( n = 1024) of New Zealanders’ perceptions of freshwater fish. About 8% of the sample had fished in the past 12 months and 30% had fished ever, and fisher subsamples were more male, more Māori and younger than the New Zealand population. Perceived awareness of local freshwater fish presence was higher for fishers than non‐fishers for all species, but both shared highest awareness of eel/tuna, whitebait and trout, which are also the most commonly fished species. Assessment of national fishing popularity and fishing pressure was mixed, but regional trends are evident. Respondents agreed that there are not enough freshwater fish, that fishers should be able to eat what they catch and that fish are healthy enough to eat. Respondents prefer more of all freshwater fish species rather than only one or two species. This data can help understand how people's relationships with freshwater and fish are changing and possibilities for building alliances for freshwater stewardship.
In 2023, the gold / Asian clam ( Corbicula fluminea ) was first recorded in Aotearoa New Zealand (Aotearoa‐NZ). This non‐native species (NNS) could impact Aotearoa‐NZ freshwater ecosystems more than any previous invader. It could alter food webs, physical habitats and water clarity, disrupt nutrient cycling and restructure plankton / macroinvertebrate / fish assemblages. I have reviewed clam impacts on trophic ecology, water chemistry and fish habitat from international studies, focusing on native and non‐native fish species also present in Aotearoa‐NZ and on ecological analogues. I identified fish that could be negatively affected and those which could benefit. Small benthic ‘riffle‐run specialists’ could be vulnerable to some extent, facing both habitat modification and competition for shared food resources. Fish frequenting backwaters or slower‐flowing reaches could be even more vulnerable, as clam densities are often highest here. Native galaxiids, already threatened by habitat fragmentation/degradation, may be at further risk from additional pressures of a clam invasion. Among introduced fish, salmonids may lose spawning habitats, whereas generalist ‘pests’ such as catfish and koi may benefit from clam‐derived food resources. C. fluminea may represent a significant new stressor for Aotearoa‐NZ freshwater ecosystems. The hyptheses generated in this article are important to help anticipate species‐specific responses, which will be essential for strategies to protect native fish.
Terrestrial mushrooms dominate mycology; their aquatic relatives are a fascinating and ecologically significant group. Psathyrella aquatica , the sole single‐gilled genus with underwater‐reported fruiting bodies, and marine‐dwelling genera such as Nia and Halocyphina illustrate how Basidiomycota radiated to aquatic environments. These freshwater, marine, and brackish aquatic fungi are principal nutrient cyclers, wood decayers, and symbionts of aquatic habitats, but their biology and ecology are poorly known. Herein, our current knowledge of their diversity, evolutionary adaptations such as floatation spores, halotolerant enzymes, and hydrophobic fruiting bodies, and their potential biotechnological applications is reviewed. Marine mushrooms are a source of bioactive compounds with reported antimicrobial and anti‐inflammatory activities, and their enzymatic profiles, adapted to saline or submerged conditions, suggest potential for bioremediation applications. With global warming, there is a need to research aquatic mushrooms not just to preserve biodiversity but also to tap their potential for green technology. This review synthesizes current knowledge on targeted research and conservation efforts for aquatic mushrooms. This information is essential for both understanding global biodiversity and advancing biotechnological innovations.
Shifting climatic averages and extremes are affecting both environmental and anthropogenic communities. This is a growing concern, especially for social–ecological systems (SES) such as lakes and their catchments, which integrate ecological and societal subsystems. Models are frequently used for research and management of these SESs, although these tools may not be capable of simulating processes from both subsystems. We conducted a literature review to assess the ability of ten catchment models commonly applied in Aotearoa New Zealand to simulate broad climate change effects. Assessment criteria represented the ecological system (hydrology, sediment transport, contaminants) and social system (economics, cultural values) of lake catchments. All of the reviewed catchment models demonstrated capacity for simulating one or more ecological criteria, while only three addressed the economics criteria within the social system. Based on these findings, we discuss model trade‐offs and highlight options for more holistically incorporating the social system into models of SESs. Advancing the development and applications of such models will provide a basis for more integrated and effective management in the years to come.
Mangrove rehabilitation is increasingly implemented to restore degraded coastal ecosystems, yet most evaluations remain dominated by structural indicators such as canopy cover or seedling survival. This study conducts a systematic literature review under the PRISMA 2020 protocol to identify and classify functional indicators used in mangrove rehabilitation assessments. From 55 Scopus‐indexed publications, 17 articles met the inclusion criteria, yielding 82 functional indicators. These indicators were grouped into 12 categories, with carbon emerging as the most dominant, particularly carbon sequestration and soil organic carbon. In contrast, other functional dimensions such as trophic interactions, microbial processes, and socio‐cultural services remain underexplored. This imbalance indicates that current monitoring approaches still emphasise structural and conceptual aspects rather than functional recovery. The study highlights the need to integrate functional indicators into rehabilitation monitoring to comprehensively capture ecosystem processes, resilience, and socioeconomic benefits. The findings provide a scientific basis for developing holistic evaluation approaches and guiding sustainable mangrove management, while also offering comparative insights relevant to the Southern Hemisphere context, where mangroves play critical ecological roles.
For several decades, the assumption that Aotearoa New Zealand freshwater eels spawn near Tonga (for longfin, Anguilla dieffenbachii ) or east of Samoa (for shortfin, A. australis ) has been widely repeated across scientific literature, governmental reports, public resources and community narratives, despite limited direct evidence. These claims originated from early scientific speculation and were not updated as new evidence emerged. This illustrates how preliminary ideas can become entrenched as accepted truth through repetition and raises a broader question: how can new scientific findings be communicated effectively when they challenge long‐standing narratives?.
Indonesia is home to a high diversity of seaweeds, encompassing both wild and cultivated species. Over the past two decades, seaweed aquaculture production has increased 23‐fold, primarily driven by the eastern regions of the archipelago. This review systematically synthesizes two decades of research and development efforts, focusing on cultivation practices, the diversity of bioactive compounds isolated from Indonesian seaweeds, and their broad applications. It also evaluates literature and production data, highlighting the remarkable potential of Indonesian seaweeds as sources of bioactive components such as peptides, pigments, polyphenols, and polysaccharides, offering various health benefits, including antioxidant, anti‐inflammatory, anticancer, and antiviral properties. Furthermore, the review explores the potential use of seaweed across sectors, including animal feed, agriculture, cosmetics, and food, while specifically addressing the dynamics of carrageenan production in Indonesia‐currently the world's largest producer of carrageenan seaweed. Nonetheless, several challenges remain, particularly regarding sustainable farming practices, efficient bioprospecting, value chain development, and scalability of industrial applications. Addressing these issues is essential to ensure the long‐term viability and competitiveness of Indonesia's seaweed industry. This review underscores the strategic importance of integrating biodiversity utilization with biotechnological and industrial innovation to unlock the full socioeconomic and environmental potential of Indonesia's seaweed resources.
This study evaluated the effects of increasing stocking density under a fixed aeration capacity on water quality, growth performance, and economic efficiency of Nile tilapia (Oreochromis niloticus) cultured in concrete ponds equipped with a semi-movable paddlewheel aeration configuration. Three stocking densities (80, 120, and 160 fish m(-3)) were tested over a 90-day production cycle using a completely randomized design with triplicate ponds per treatment (each 99 m(3)). The aerators were operated continuously (1.5 hp, 24 h day(-1)), and aeration power was kept constant across treatments. Water quality showed a clear density-dependent deterioration: dissolved oxygen (DO) decreased from 5.0 +/- 0.17 mg L-1 at 80 fish m(-3) to 3.3 +/- 0.17 mg L-1 at 160 fish m(-3) (p < 0.05), while unionized ammonia (UIA) increased from 0.028 +/- 0.01 mg L-1 to 0.056 +/- 0.01 mg L-1. In line with this, the growth performance decreased as density increased: the final body weight decreased from 304.3 +/- 0.882 g to 272.7 +/- 5.903 g, and the feed conversion ratio increased to 1.68. Survival rate showed a moderate decline to 93.2%. Whereas the highest density had the highest total biomass (3,969 kg) and gross revenue (US$8,972), the intermediate density (120 fish m(-3)) had the most balanced result between growth performance, survival, and profitability (benefit-cost ratio = 1.49). The highest stocking density was associated with lower DO, increased nitrogen loading, and reduced size uniformity, suggesting that production efficiency was mainly constrained by oxygen availability and overall biomass loading rather than by acute ammonia toxicity. These results imply that, when the aeration capacity in concrete pond systems is held constant, moderate stocking density can be best suited to a trade-off between biological performance and economic payoff and can be useful in the context of intensive Nile Tilapia production in situations with limited aeration capacity.
The mostly marine nematode order Desmoscolecida is globally distributed with over 270 species known to date. Here, we describe Greeffiella bellula n. sp., the first desmoscolecid species to be described from New Zealand waters, from deep-sea sediments. The new species is most similar to G. japonica, described from coastal sediments in the Sea of Japan, in having relatively few (<70) cuticle annules, a conical terminal ring with spines and single terminal tube, uniform spine thickness and vulva surrounded by dense setae. Greeffiella bellula n. sp. can be most easily differentiated from the latter by the different body shape and in having fewer pairs of subdorsal setae. A dichotomous key to the 15 valid species of the genus is presented. Results of SSU phylogenetic analyses based on 19 Desmoscolecidae sequences confirmed the genus assignment of the new species, but unlike previous analyses did not provide support for the monophyly of the subfamilies Desmoscolecinae and Tricominae, or of the closely related genus Desmoscolex.
The invasive Asian paddle crab Charybdis japonica continues to expand its range across northern Aotearoa New Zealand, raising ecological, social, and economic concerns. This study theoretically assesses whether harvest-based management-potentially including commercial, recreational, or customary fisheries-could contribute to population suppression. Five key factors were examined: consumer demand, fisher willingness to supply, population abundance in Whangarei Harbour, comparison with the native Ovalipes catharus fishery, and legal constraints, making up a theoretical framework within which to assess the feasibility of harvest exploitation as a management tool. Consumer surveys revealed strong interest in purchasing invasive crab products, with respondents valuing both taste and the ecological benefits of control. Fisher surveys indicated moderate to strong willingness to harvest C. japonica, though uncertainty remains around saleability and regulatory permissions. However, a stratified trap survey in Whangarei Harbour found unexpectedly low catches of the crab, suggesting the current population there cannot sustain a fishery. Comparison with the declining O. catharus fishery highlights potential market space, but also underscores ecological risks. Legally, regional vs national pest designations under the Biosecurity Act, as well as fishery regulations, present significant barriers to the ability to enact harvest control. Overall, while market and fisher interest appear promising, biological and regulatory constraints currently limit the feasibility of a harvest-control fishery for C. japonica. This study contributes to the ongoing discourse of methods available for invasive species management.
Seagrasses are important ecosystem engineers that create nursery habitat for fish, support high biodiversity, enhance water quality and store carbon. However, seagrasses are declining globally, including in many places in New Zealand. One approach to counter these losses is shoot-based seagrass restoration, which involves transplanting adult seagrass plants together with their surrounding sediment and associated communities. We investigated the feasibility of shoot-based restoration by transplanting 150 mm plugs of seagrass (Zostera muelleri) from donor seagrass meadows to nearby unvegetated soft sediment at two sites in Nelson Haven, New Zealand. Sites differed in donor meadow age (old vs. new) and environmental conditions. We also tested whether transplant season (winter vs. summer) influenced success. Transplant success was monitored over 2 years and determined by an increase in seagrass area, blade number, and blade length. Bayesian modelling showed that both site and season influenced success. The best-fit model showed greater success when transplants from the 'older' donor meadow, which had higher seagrass cover, lower mud content and shorter tidal exposure, performed better than those from the 'newer' meadow. Model predictions also indicated greater success in winter than in summer. Empirical observations supported these patterns; for example, we observed 30% survival of transplants at the older site after winter transplantation, whereas zero transplants survived after summer transplantation or at the 'newer' meadow. There were no obvious detrimental effects of seagrass removal from donor meadows, and this study shows that transplanting Z. muelleri with an intact sediment community can be an effective restoration method in intertidal habitats, though success is highly context dependent. This study gives practical insights to guide future seagrass-restoration efforts.
Suspended sediment (SS) is a major stressor to coastal marine ecosystems worldwide, with SS loads expected to increase under future anthropogenic and climatic pressures. Sponges, as obligate filter feeders, are often assumed to be sensitive to elevated SS, yet responses vary widely among species, and little is known about physiological impacts of SS. Here, we examined the response of the abundant temperate sponge Suberites australiensis to prolonged pulses of suspended sediment, simulating conditions in Wellington Harbour, New Zealand, during rain and storm events. Sponges (n = 42) were exposed to daily 7 h pulses (to mimic natural variation) of fine kaolin clay (25-35 mu m) over 19 days at suspended sediment concentrations (SSC) of 120-150 mg l-1, while controls received only filtered seawater. Physiological responses were assessed through changes in buoyant weight and respiration rates at four time points. No significant differences in respiration rates were detected between treatments and controls, and there was no visible tissue necrosis or morphological deterioration in any of the sponges. Treatment sponges exhibited a significant increase in buoyant weight relative to controls. These findings indicate that short periods of high level exposure to suspended sediment load have no physiological impact on S. australiensis and this species likely uses passive mechanisms to survive SS stress. This resilience may enable the persistence of S. australiensis in sediment-impacted coastal environments; however, thresholds that may impact physiological performance remain unknown.
Asparagopsis armata has international commercial relevance due to its high bromoform content, which can reduce the methane emissions from cattle when incorporated into their diet. However, few studies have reported on at-sea cultivation techniques and their effect on bromoform content in A. armata. In this study, we assessed the effects of seeding density (150, 300 and 600 g WW m-1) on the specific growth rate (SGR) and bromoform content of A. armata in suspended culture on a marine farm. We also tested whether transport conditions affected bromoform content, comparing emersed and immersed A. armata biomass after 3.5 h. Seeding density had a strong effect on the SGR of A. armata with the lowest seeding density having significantly greater growth (1.5 to 5 times) than higher seeding densities. Transporting the A. armata biomass in seawater increased its bromoform content (by 73.6%) relative to the immersed material. These findings will inform efficient approaches to the sea-based culture of A. armata.
Acid and metalliferous drainage (AMD) reduces fish diversity with effects extending downstream. Discharges may also create chemical barriers for migratory species into otherwise unimpacted headwaters. We investigated k & omacr;aro (Galaxias brevipinnis) response to remediation of an AMD-impacted tributary in a 5(th)-order West Coast, New Zealand river. K & omacr;aro communities were surveyed once pre-remediation and on seven subsequent occasions between 2005 and 2024, at six sites within the Ng & amacr;kawau catchment and two reference streams, using backpack electric-fishing. Aluminium, pH and turbidity measurements were analysed for temporal patterns and exceedances of threshold values of fish sensitivity, derived for naturally acidic West Coast streams. Significant differences in k & omacr;aro demographics were observed between pre- and post-remediation surveys. 2 years post-remediation, k & omacr;aro abundance had increased, dominated by juveniles <100 mm. Ten years post-remediation size structure had stabilised to be predominantly individuals >100 mm. Current abundance and size distribution, plus interannual demographic constancy, suggest the population is stable and not recruitment limited.
The New Zealand fur seal/kekeno (Arctocephalus forsteri, NZFS) is a marine predator native to Aotearoa/New Zealand. Little is known about its fine-scale dispersal around New Zealand in the nonbreeding season. As an alternative to external marking or electronic tracking, stable isotope analysis was trialed to determine the origin of stranded (deceased) NZFS young-of-the-year (YOY). Vibrissae were collected opportunistically from YOY at nonbreeding sites on the east and west coasts of Northland and Hawkes Bay, New Zealand. Vibrissa growth rates and estimated vibrissa lengths at birth were calculated using samples from pups at established breeding colonies and stranded YOY. The delta 13C and delta 15N values at breeding colonies and in YOY were not sufficiently isotopically distinct to determine the colony of origin. Isotopic niche widths were greater for YOY than for pups from the same breeding season. For YOY, isotopic niche widths were greater after weaning than preweaning, implying weaned NZFSs foraged more diversely than their mothers. Based on the assumed median pupping date, the estimated maximum age at weaning for stranded YOY was 223-247 days, which is considerably less than previously published weaning data for NZFSs. Early weaning may contribute to increased juvenile mortality.
Galaxiids are a family of scaleless and mostly small freshwater fish which are distributed across the temperate latitudes of the southern hemisphere. The largest member of this family is the giant k & omacr;kopu (Galaxias argenteus), which has the added distinction of being the first New Zealand freshwater fish of any kind to be scientifically described. This description was produced by naturalists on board James Cook's HMS Resolution when they visited Dusky Sound in the far south of New Zealand in the autumn of 1773, and it represents, among other things, a fascinating intersection of history and science. This article, which is primarily historical in its approach, revisits the original documentary records describing the giant k & omacr;kopu that were left by Cook's naturalists, and argues that the descriptive process involving this fish was much more of a team effort than has previously been assumed.
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.
