School of Science - Te Kura Pūtaiao

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https://hdl.handle.net/10292/1333

Research at AUT's School of Science - Te Kura Pūtaiao is focused on key scientific issues with regional and global significance. The common theme connecting all research areas is sustainability – in the broadest sense as it relates to environmental and human health. Our research is closely allied to teaching and learning opportunities at undergraduate and postgraduate level within the school. Research is organised in five main areas:

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Annual (2023) Taxonomic Update of RNA-Directed RNA Polymerase-Encoding Negative-Sense RNA Viruses (Realm Riboviria: Kingdom Orthornavirae: Phylum Negarnaviricota)
(2023-08) Kuhn, Jens H; Abe, Junya; Adkins, Scott; Alkhovsky, Sergey V; Avšič-Županc, Tatjana; Ayllón, María A; Bahl, Justin; Balkema-Buschmann, Anne; Ballinger, Matthew J; Kumar Baranwal, Virendra; Beer, Martin; Bejerman, Nicolas; Bergeron, Éric; Biedenkopf, Nadine; Blair, Carol D; Blasdell, Kim R; Blouin, Arnaud G; Bradfute, Steven B; Briese, Thomas; Brown, Paul A; Buchholz, Ursula J; Buchmeier, Michael J; Bukreyev, Alexander; Burt, Felicity; Büttner, Carmen; Calisher, Charles H; Cao, Mengji; Casas, Inmaculada; Chandran, Kartik; Charrel, Rémi N; Kumar Chaturvedi, Krishna; Chooi, Kar Mun; Crane, Anya; Dal Bó, Elena; Carlos de la Torre, Juan; de Souza, William M; de Swart, Rik L; Debat, Humberto; Dheilly, Nolwenn M; Di Paola, Nicholas; Di Serio, Francesco; Dietzgen, Ralf G; Digiaro, Michele; Drexler, J Felix; Duprex, W Paul; Dürrwald, Ralf; Easton, Andrew J; Elbeaino, Toufic; Ergünay, Koray; Feng, Guozhong; Firth, Andrew E; Fooks, Anthony R; Formenty, Pierre BH; Freitas-Astúa, Juliana; Gago-Zachert, Selma; Laura García, María; García-Sastre, Adolfo; Garrison, Aura R; Gaskin, Thomas R; Gong, Wenjie; Gonzalez, Jean-Paul J; de Bellocq, JoëlleGoüy; Griffiths, Anthony; Groschup, Martin H; Günther, Ines; Günther, Stephan; Hammond, John; Hasegawa, Yusuke; Hayashi, Kazusa; Hepojoki, Jussi; Higgins, Colleen M; Hongō, Seiji; Horie, Masayuki; Hughes, Holly R; Hume, Adam J; Hyndman, Timothy H; Ikeda, Kenichi; Jiāng, Dàohóng; Jonson, Gilda B; Junglen, Sandra; Klempa, Boris; Klingström, Jonas; Kondō, Hideki; Koonin, Eugene V; Krupovic, Mart; Kubota, Kenji; Kurath, Gael; Laenen, Lies; Lambert, Amy J; Lǐ, Jiànróng; Li, Jun-Min; Liu, Ran; Lukashevich, Igor S; MacDiarmid, Robin M; Maes, Piet; Marklewitz, Marco; Marshall, Sergio H; Marzano, Shin-Yi L; McCauley, John W; Mirazimi, Ali; Mühlberger, Elke; Nabeshima, Tomoyuki; Naidu, Rayapati; Natsuaki, Tomohide; Navarro, Beatriz; Navarro, José A; Neriya, Yutaro; Netesov, Sergey V; Neumann, Gabriele; Nowotny, Norbert; Nunes, Márcio RT; Ochoa-Corona, Francisco M; Okada, Tomoyuki; Palacios, Gustavo; Pallás, Vicente; Papa, Anna; Paraskevopoulou, Sofia; Parrish, Colin R; Pauvolid-Corrêa, Alex; Pawęska, Janusz T; Pérez, Daniel R; Pfaff, Florian; Plemper, Richard K; Postler, Thomas S; Rabbidge, Lee O; Radoshitzky, Sheli R; Ramos-González, Pedro L; Rehanek, Marius; Resende, Renato O; Reyes, Carina A; Rodrigues, Thaís CS; Romanowski, Víctor; Rubbenstroth, Dennis; Rubino, Luisa; Runstadler, Jonathan A; Sabanadzovic, Sead; Sadiq, Sabrina; Salvato, Maria S; Sasaya, Takahide; Schwemmle, Martin; Sharpe, Stephen R; Shi, Mang; Shimomoto, Yoshifumi; Kavi Sidharthan, Venkidusamy; Sironi, Manuela; Smither, Sophie; Song, Jin-Won; Spann, Kirsten M; Spengler, Jessica R; Stenglein, Mark D; Takada, Ayato; Takeyama, Sawana; Tatara, Akio; Tesh, Robert B; Thornburg, Natalie J; Tian, Xin; Tischler, Nicole D; Tomitaka, Yasuhiro; Tomonaga, Keizō; Tordo, Noël; Tu, Changchun; Turina, Massimo; Tzanetakis, Ioannis E; Maria Vaira, Anna; van den Hoogen, Bernadette; Vanmechelen, Bert; Vasilakis, Nikos; Verbeek, Martin; von Bargen, Susanne; Wada, Jiro; Wahl, Victoria; Walker, Peter J; Waltzek, Thomas B; Whitfield, Anna E; Wolf, Yuri I; Xia, Han; Xylogianni, Evanthia; Yanagisawa, Hironobu; Yano, Kazutaka; Ye, Gongyin; Yuan, Zhiming; Zerbini, F Murilo; Zhang, Guilin; Zhang, Song; Zhang, Yong-Zhen; Zhao, Lu; Økland, Arnfinn Lodden
In April 2023, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by one new family, 14 new genera, and 140 new species. Two genera and 538 species were renamed. One species was moved, and four were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.
Climatic Conditions Affect Shoot Flammability by Influencing Flammability-Related Functional Traits in Non-Fire-Prone Habitats
(Wiley, 2023-03-23) Cui, Xinglei; Dai, Dachuan; Huang, Congde; Wang, Bilei; Li, Shuting; You, Chengming; Paterson, Adrian M; Perry, George Lw; Buckley, Hannah L; Cubino, Josep Padullés; Wyse, Sarah V; Alam, Md Azharul; Zhou, Shixing; Xiao, Lin; Cao, Dongyu; Xu, Zhenfeng; Curran, Timothy J
Plant flammability is an important driver of wildfires, and flammability itself is determined by several plant functional traits. While many plant traits are influenced by climatic conditions, the interaction between climatic conditions and plant flammability has rarely been investigated. Here, we explored the relationships among climatic conditions, shoot-level flammability components, and flammability-related functional traits for 186 plant species from fire-prone and non-fire-prone habitats. For species originating from non-fire-prone habitats, those from warmer areas tended to have lower shoot moisture content and larger leaves, and had higher shoot flammability with higher ignitibility, combustibility, and sustainability. Plants in wetter areas tended to have lower shoot flammability with lower combustibility and sustainability due to higher shoot moisture contents. In fire-prone habitats, shoot flammability was not significantly related to any climatic factor. Our study suggests that for species originating in non-fire-prone habitats, climatic conditions have influenced plant flammability by shifting flammability-related functional traits, including leaf size and shoot moisture content. Climate does not predict shoot flammability in species from fire-prone habitats; here, fire regimes may have an important role in shaping plant flammability. Understanding these nuances in the determinants of plant flammability is important in an increasingly fire-prone world.
Directional Changes Over Time in the Species Composition of Tropical Vascular Epiphyte Assemblages
(WILEY, 2021-11-28) Mendieta-Leiva, G; Buckley, HL; Zotz, G
Understanding the degree to which deterministic and stochastic processes drive community assembly is an ongoing focus of research in community ecology. This effort is strongly biased towards ground-rooted plants, resulting in a limited understanding of communities of other life-forms, such as structurally dependent plants. Vascular epiphytes are sessile organisms growing non-parasitically on three-dimensional dynamic patches, their host plants. Since negative biotic interactions are thought to play a minor role in vascular epiphyte assembly, in some forests, epiphytes are fascinating model organisms to understand the prevalence of environmental filtering in shaping community assembly. We assessed the contribution of deterministic processes on the temporal dynamics of vascular epiphyte assemblages by tracking the direction of changes in composition, species richness and abundance in time at different ecological and spatial scales. We made use of a globally unique dataset from a lowland forest in Panama. We predict that if niche-based mechanisms dominate, (a) temporal changes will be directional and (b) differences in the species composition of epiphyte assemblages will be primarily related to host plant characteristics and, to a lesser degree, to the distance between host trees. We show that temporal changes in vascular epiphyte assemblages were directional at different ecological scales, such as the forest patch, host species or individual tree assemblages. Epiphyte assemblages on host trees became more similar in their composition over time than expected by chance, and these changes were not due to homogenisation. While host characteristics were related to these directional changes, host structure rather than host identity was more strongly related to variation in assemblage dissimilarity, while spatial distance among trees was of minor importance. The observed directionality was primarily due to environmental filtering. This study provides the first evidence that niche-based mechanisms dominate the dynamics of vascular epiphyte assemblages. Analysing temporal patterns of vascular epiphyte assemblages is a first important step towards understanding the relative importance of deterministic processes for diversity maintenance of one of the most diverse plant groups in the tropics. Synthesis. Directionality in the temporal changes of epiphyte assemblages suggests that niche-based mechanisms dominate these temporal changes. Host size over host identity is the most important environmental filter for epiphyte assemblages establishment.
Diversity of the Squid Genus Leachia (Oegopsida: Cranchiidae) in the Pacific Ocean
(Springer Science and Business Media LLC, 2023-05-08) Evans, AB; Bolstad, KSR
Leachia is a cosmopolitan tropical/temperate genus of ‘glass’ squids (Cranchiidae) whose taxonomy has been plagued with instability typical of the family. Eight species are currently believed to exist worldwide, including some not yet described. This review assesses the Pacific taxa, describes a novel species, L. separata, and provides updated diagnoses for the other Pacific species. Type material and original descriptions are compared, and brief remarks provided on the Atlantic taxa. The most useful characters for identifying Leachia species appear to be the number of ocular photophores and the configuration of the ventral cartilaginous strips and associated tubercles on the mantle, with arm and sucker-ring dentition also proving useful in some taxa. Further work on the genus is needed, ideally including molecular tools.
Ecosystem Integrity of Active Sand Dunes: A Case Study to Implement and Test the SEEA-EA Global Standard, From Aotearoa New Zealand
(Elsevier BV, 2023-05-01) Ryan, C; Case, BS; Bishop, CD; Buckley, HL
Biodiversity and ecosystem functions are deteriorating worldwide, and there is an urgent need to reverse these declines and set ecosystems on a path to recovery. Effective monitoring, including a fit for purpose indicator framework, is essential to track progress towards targets but, as yet there is no universal framework that delivers timely data on biodiversity and ecosystem change. Ecosystem integrity is a unifying concept that refers to the capacity of an ecosystem to be resilient to natural or anthropogenic perturbations, and to maintain characteristic species composition, structure, functioning and self-organisation over time within a natural range of variability. Using a case study which can be generalised to international contexts, we implement and test a new global standard for the assessment, monitoring and ranking of ecosystem integrity of active sand dunes in Aotearoa New Zealand.
Emerging Intrinsic Therapeutic Targets for Metastatic Breast Cancer
(MDPI AG, 2023-05-09) Li, Jiawei; Goh, Eyleen LK; He, Ji; Li, Yan; Fan, Zhimin; Yu, Zhigang; Yuan, Peng; Liu, Dong-Xu
Breast cancer is now the most common cancer worldwide, and it is also the main cause of cancer-related death in women. Survival rates for female breast cancer have significantly improved due to early diagnosis and better treatment. Nevertheless, for patients with advanced or metastatic breast cancer, the survival rate is still low, reflecting a need for the development of new therapies. Mechanistic insights into metastatic breast cancer have provided excellent opportunities for developing novel therapeutic strategies. Although high-throughput approaches have identified several therapeutic targets in metastatic disease, some subtypes such as triple-negative breast cancer do not yet have an apparent tumor-specific receptor or pathway to target. Therefore, exploring new druggable targets in metastatic disease is a high clinical priority. In this review, we summarize the emerging intrinsic therapeutic targets for metastatic breast cancer, including cyclin D-dependent kinases CDK4 and CDK6, the PI3K/AKT/mTOR pathway, the insulin/IGF1R pathway, the EGFR/HER family, the JAK/STAT pathway, poly(ADP-ribose) polymerases (PARP), TROP-2, Src kinases, histone modification enzymes, activated growth factor receptors, androgen receptors, breast cancer stem cells, matrix metalloproteinases, and immune checkpoint proteins. We also review the latest development in breast cancer immunotherapy. Drugs that target these molecules/pathways are either already FDA-approved or currently being tested in clinical trials.
First Reports of Trace Element Bioaccumulation in the Antarctic Deep-Sea Squid Psychroteuthis glacialis
(Springer Science and Business Media LLC, 2023-10-16) Lischka, A; Braid, HE; Gaw, S; Bolstad, KSR
Trophic interactions in the Antarctic Ocean are likely to be affected by changing environmental conditions. Some of these impacts can be observed, and predicted, by monitoring trace element concentrations in the tissues of animals at certain trophic levels. The ‘glacial’ squid (Psychroteuthis glacialis) is an ideal indicator species for measuring trace element bioaccumulation in the Ross Sea because it plays a central role in local marine food webs. Trace elements (Al, As, Cd, Co, Cu, Fe, Hg, Ni, Mn, Pb, U, V, and Zn) were measured in mantle and digestive gland tissues of 57 P. glacialis specimens, including juvenile and mature individuals. Significant differences in Al, As, Cd, Cu, Fe, Mn, V, and Zn concentrations were observed across life stages, with juveniles generally having the highest concentrations. As the bioaccumulation of most trace elements is influenced by diet, our results suggest different feeding patterns between juvenile and mature P. glacialis. In turn, it is likely that the life stage of P. glacialis individuals consumed by predators will determine trace element exposure higher up the trophic web. Overall, this Antarctic squid appears to be influenced by the trace element cycling in the Ross Sea and contains lower concentrations of trace elements than have been observed in squids in warmer waters.
Histopathological Changes in the Greenshell Mussel, Perna canaliculus, in Response to Chronic Thermal Stress
(Elsevier, 2023-09-01) Copedo, Joanna S; Webb, Stephen C; Ragg, Norman LC; Ericson, Jessica A; Venter, Leonie; Schmidt, Alfonso J; Delorme, Natalí J; Alfaro, Andrea C
Climate change associated temperature challenges pose a serious threat to the marine environment. Elevations in average sea surface temperatures are occurring and increasing frequency of marine heatwaves resulting in mortalities of organisms are being reported. In recent years, marine farmers have reported summer mass mortality events of the New Zealand Greenshell mussel, Perna canaliculus, during the summer months; however, the etiological agents have yet to be determined. To elucidate the role of thermal stress, adult P. canaliculus were exposed to three chronic temperature treatments: a benign control of 17 °C and stressful elevations of 21 °C and 24 °C. Eight mussels per treatment were collected each month throughout a 14-month challenge period to identify and investigate histopathological differences among P. canaliculus populations exposed to the three temperatures. Histopathology revealed several significant deleterious alterations to tissues associated with temperature and exposure time. Increasing temperature and progression of time resulted in 1) an increase in the number of focal lipofuscin-ceroid aggregations, 2) an increase in focal hemocytosis, 3) an increase in the thickness of the sub-epithelial layer of the intestinal tract and 4) a decreased energy reserve cell (glycogen) coverage in the mantle. Prolonged exposure, irrespective of temperature, impacted gametogenesis, which was effectively arrested. Furthermore, increased levels of the heat shock protein 70 kDa (HSP 70) were seen in gill and gonad from thermally challenged mussels. The occurrence of the parasite Perkinsus olseni at month 5 in the 24 °C treatment, and month 7 at 21 °C was unexpected and may have exacerbated the fore-mentioned tissue conditions. Prolonged exposure to stable thermal conditions therefore appears to impact P. canaliculus, tissues with implications for broodstock captivity. Mussels experiencing elevated, temperatures of 21 and 24 °C demonstrated more rapid pathological signs. This research provides further insight into the complex host-pathogen-environment interactions for P. canaliculus in response to prolonged elevated temperature.
Host Individual and Gut Location Are More Important in Gut Microbiota Community Composition Than Temporal Variation in the Marine Herbivorous Fish Kyphosus sydneyanus
(Springer Science and Business Media LLC, 2023-09-29) Pisaniello, Alessandro; Handley, Kim M; White, W Lindsey; Angert, Esther R; Boey, Jian Sheng; Clements, Kendall D
Background Gut microbiota play a key role in the nutrition of many marine herbivorous fishes through hindgut fermentation of seaweed. Gut microbiota composition in the herbivorous fish Kyphosus sydneyanus (family Kyphosidae) varies between individuals and gut sections, raising two questions: (i) is community composition stable over time, especially given seasonal shifts in storage metabolites of dietary brown algae, and (ii) what processes influence community assembly in the hindgut? Results We examined variation in community composition in gut lumen and mucosa samples from three hindgut sections of K. sydneyanus collected at various time points in 2020 and 2021 from reefs near Great Barrier Island, New Zealand. 16S rRNA gene analysis was used to characterize microbial community composition, diversity and estimated density. Differences in community composition between gut sections remained relatively stable over time, with little evidence of temporal variation. Clostridia dominated the proximal hindgut sections and Bacteroidia the most distal section. Differences were detected in microbial composition between lumen and mucosa, especially at genus level. Conclusions High variation in community composition and estimated bacterial density among individual fish combined with low variation in community composition temporally suggests that initial community assembly involved environmental selection and random sampling/neutral effects. Community stability following colonisation could also be influenced by historical contingency, where early colonizing members of the community may have a selective advantage. The impact of temporal changes in the algae may be limited by the dynamics of substrate depletion along the gut following feeding, i.e. the depletion of storage metabolites in the proximal hindgut. Estimated bacterial density, showed that Bacteroidota has the highest density (copies/mL) in distal-most lumen section V, where SCFA concentrations are highest. Bacteroidota genera Alistipes and Rikenella may play important roles in the breakdown of seaweed into useful compounds for the fish host.
Interactive Effects of Elevated Temperature and Photobacterium swingsii Infection on the Survival and Immune Response of Marine Mussels (Perna canaliculus): A Summer Mortality Scenario
(Elsevier BV, 2024-02-03) Azizan, Awanis; Venter, Leonie; Zhang, Jingjing; Young, Tim; Ericson, Jessica A; Delorme, Natalí J; Ragg, Norman LC; Alfaro, Andrea C
The New Zealand Greenshell™ mussel (Perna canaliculus) is an economically important aquaculture species. Prolonged increases in seawater temperature above mussel thermotolerance ranges pose a significant threat to mussel survival and health, potentially increasing susceptibility to bacterial infections. Using challenge experiments, this study examined the combined effects of increased seawater temperature and bacterial (Photobacterium swingsii) infection on animal survival, haemocyte and biochemical responses of adult mussels. Mussels maintained at three temperatures (16, 20 and 24 °C) for seven days were either not injected (control), injected with sterile marine broth (injection control) or P. swingsii (challenged with medium and high doses) and monitored daily for five days. Haemolymph and tissue samples were collected at 24, 48, 72, 96, 120 h post-challenge and analysed to quantify bacterial colonies, haemocyte responses and biochemical responses. Mussels infected with P. swingsii exhibited mortalities at 20 and 24 °C, likely due to a compromised immune system, but no mortalities were observed when temperature was the only stressor. Bacterial colony counts in haemolymph decreased over time, suggesting bacterial clearance followed by the activation of immune signalling pathways. Total haemocyte counts and viability data supports haemocyte defence functions being stimulated in the presence of high pathogen loads at 24 °C. In the gill tissue, oxidative stress responses, measured as total antioxidant capacity and malondialdehyde (MDA) levels, were higher in infected mussels (compared to the controls) after 24h and 120h post-challenge at the lowest (16 °C) and highest temperatures (24 °C), indicating the presence of oxidative stress due to temperature and pathogen stressors. Overall, this work confirms that Photobacterium swingsii is pathogenic to P. canaliculus and indicates that mussels may be more vulnerable to bacterial pathogens under conditions of elevated temperature, such as those predicted under future climate change scenarios.
Microplastic Pollution Distribution: Differences Between Marine Reserves and Urbanised Areas
(Elsevier BV, 2023-09-09) Ribó, Marta; Watson, Sally J; Novikova, Nina I; Deppeler, Stacy; Seabrook, Sarah; Hale, Rachel; Strachan, Lorna J
Microplastic particles (<5 mm) have been observed to be widely distributed in the oceans, from estuaries the deep ocean trenches. While plastic pollution in the marine environment is a growing concern worldwide, relatively little is known about microplastic distribution and accumulation on the seafloor, particularly in marine protected area (MPAs). The delimitation of MPAs frequently follow jurisdictional or political boundaries, however the distribution of species, habitats and ecosystems does not always follow these same confines. Likewise, pollution in the marine environment do not have boundaries. This study compares microplastic content in sediment cores from two sites: an urbanised area, near the coastal township of Picton; and a site distal from the township (∼30 km) but proximal to open ocean, adjacent to the Kokomohua Marine Reserve, in the region of Queen Charlotte Sound/Tōtaranui (QCS), Aotearoa/New Zealand. Microplastic particles were identified throughout the sediment cores from both locations, reaching depths of ∼45 cm below the seabed. Our findings revealed that marine sediments adjacent to the marine reserve had four times the microplastic accumulation of marine sediments from near the coastal township. The abundance of microplastics across the sediment depth profiles also varied between the two sites, suggesting different accumulation of microplastics on the seafloor due to differences in the frequency and extent of seabed disturbance experienced by the two locations. Our study demonstrates the extent to which human stressors such as microplastic pollution proliferate and concentrate in the environment, particularly in areas considered to be near-pristine with strict environmental protections.
Optimal Stomatal Theory Predicts Co₂ Responses of Stomatal Conductance in Both Gymnosperm and Angiosperm Trees
(Wiley, 2022-11-13) Gardner, Anna; Jiang, Mingkai; Ellsworth, David; MacKenzie, A Rob; Pritchard, Jeremy; Bader, Martin Karl-Friedrich; Barton, Craig; Bernacchi, Carl; Calfapietra, Carlo; Crous, Kristine Y; Dusenge, Mirindi Eric; Gimeno, Teresa E; Hall, Marianne; Lamba, Shubhangi; Leuzinger, Sebastian; Uddling, Johan; Warren, Jeffrey; Wallin, Göran; Medlyn, Belinda
Optimal stomatal theory predicts that stomata operate to maximize photosynthesis (Anet ) and minimize transpirational water loss to achieve optimal intrinsic water-use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO2 (eCO2 ), and whether it can capture differences in responsiveness among woody plant functional types (PFTs). We conducted a meta-analysis of tree studies of the effect of eCO2 on iWUE and its components Anet and stomatal conductance (gs ). We compared three plant functional types (PFTs), using the Unified Stomatal Optimisation (USO) model to account for confounding effects of leaf-air vapour pressure difference (D). We expected smaller gs , but greater Anet , responses to eCO2 in gymnosperms compared to angiosperm PFTs. We found that iWUE increased in proportion to increasing eCO2 in all PFTs, and that increases in Anet had stronger effects than reductions in gs . The USO model correctly captured stomatal behaviour with eCO2 across most datasets. The chief difference among PFTs was a lower stomatal slope parameter (g1 ) for the gymnosperm, compared to angiosperm, species. Land surface models can use the USO model to describe stomatal behaviour under changing atmospheric CO2 conditions.
Propagating Uncertainty in Predicting Individuals and Means Illustrated with Foliar Chemistry and Forest Biomass
(Springer Science and Business Media LLC, 2024-01-22) Yanai, RD; Drake, JE; Buckley, HL; Case, BS; Lilly, PJ; Woollons, RC; Gamarra, JGP
Quantifying uncertainty is important to establishing the significance of comparisons, to making predictions with known confidence, and to identifying priorities for investment. However, uncertainty can be difficult to quantify correctly. While sampling error is commonly reported based on replicate measurements, the uncertainty in regression models used to estimate forest biomass from tree dimensions is commonly ignored and has sometimes been reported incorrectly, due either to lack of clarity in recommended procedures or to incentives to underestimate uncertainties. Even more rarely are the uncertainty in predicting individuals and the uncertainty in the mean both recognized for their contributions to overall uncertainty. In this paper, we demonstrate the effect of propagating these two sources of uncertainty using a simple example of calcium concentration of sugar maple foliage, which does not require regression, then the mass of foliage and calcium content of foliage, and finally an entire forest with multiple species and tissue types. The uncertainty due to predicting individuals is greater than the uncertainty in the mean for studies with few trees—up to 30 trees for foliar calcium concentration and 50 trees for foliar mass and calcium content in the data set we analyzed from the Hubbard Brook Experimental Forest. The most correct analysis will take both sources of uncertainty into account, but for practical purposes, country-level reports of uncertainty in carbon stocks can safely ignore the uncertainty in individuals, which becomes negligible with large enough numbers of trees. Ignoring the uncertainty in the mean will result in exaggerated confidence in estimates of forest biomass and carbon and nutrient contents.
Temperature Dependency of Litter Decomposition Is Not Demonstrated Under Reciprocal Transplantation of Tussock Leaves Along an Altitudinal Gradient
(Wiley, 2023-01-17) Krna, Matthew A; Tate, Kevin R; Saggar, Surinder; Buckley, Hannah L; Rapson, Gillian L
Decomposition rates are an important component of carbon sequestration rates in soils, potentially mitigating future climate change. Here we aim to better understand decomposition's relationship with temperature in natural conditions. In snow-tussock grassland dominated by Chionochloa rubra on Mount Tongariro, Tongariro National Park, New Zealand, we measured decomposition of Chionochloa leaf litter along an ≈ 700 m altitudinal gradient, as a space-for-temperature experiment, representing 4.2°C of warming. We examined decomposition rates in a full reciprocal translocation of litter bags between eight plots as both the origin of eight litter types and the eight destinations of plating out of litter bags, over 4 years using six replicates, and modelled their relationships to environmental variates. Litter decomposed progressively over time, but at the same rate along the altitudinal gradient. There was no home-field advantage. In terms of litter quality, decomposition rates were related only to litter lignin, or fibre or litter N. Only decomposition at Year 4, and that only when organised by litter destination, showed a relationship to mean annual temperature jointly with soil C, and this was only weak and implausible. When studied across the full reciprocal transplant, there were no significant interactions between Origin and Destination data with or without Years. Therefore litter from each plot decomposed at the same rate as other plots' litter at all altitudes, allowing for small, often irregular differences in litter quality and micro-environment. Despite the few modelled differences, decomposition rates show no plausible trends in our altitude-for-temperature substitution. We suggest this may be a universal finding, except perhaps under different moisture regimes. Thus, under projected climate warming scenarios, changes in temperature will not directly affect decomposition rates, and cannot influence C sequestration in nature. Read the free Plain Language Summary for this article on the Journal blog.
The Effect of Simulated Marine Heatwaves on Green-Lipped Mussels, Perna canaliculus: A Near-Natural Experimental Approach
(Elsevier BV, 2023-09-04) Venter, L; Alfaro, AC; Ragg, NLC; Delorme, NJ; Ericson, JA
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 seawater temperature regimes: 1) low (sustained 18 °C), 2) medium MHW (18–24 °C, using a +1 °C per week ramp) and 3) high MHW (18–24 °C, using a +2 °C per week ramp). Sampling was performed over 11 weeks to establish the effects of temperature on P. canaliculus survival, condition, specific immune response parameters, and the haemolymph metabolome. A transient 25.5–26.5 °C exposure resulted in 61 % mortality, with surviving animals showing a metabolic adjustment within aerobic energy production, enabling the activation of molecular defence mechanisms. Utilisation of immune functions were seen within the cytology results where temperature stress affected the percentage of superoxide-positive haemocytes and haemocyte counts. From the metabolomics results an increase in antioxidant metabolites were seen in the high MHW survivors, possibly to counteract molecular damage. In the high MHW exposure group, mussels utilised anaerobic metabolism in conjunction with aerobic metabolism to produce energy, to uphold biological functions and survival. The effect of exposure time was mainly seen on very long-, and long chain fatty acids, with increases observed at weeks seven and eight. These changes were likely due to the membrane storage functions of fatty acids, with decreases at week eleven attributed to energy metabolism functions. This study supports the use of integrated analytical tools to investigate the response of marine organisms to heatwaves. Indeed, specific metabolic pathways and cellular markers are now highlighted for future investigations aimed at targeted measures. This research contributes to a larger program aimed to identify resilient mussel traits and support aquaculture management.
When Things Get MESI: The Manipulation Experiments Synthesis Initiative – A Coordinated Effort to Synthesize Terrestrial Global Change Experiments
(Wiley, 2023-01-06) Van Sundert, Kevin; Leuzinger, Sebastian; Bader, Martin K-F; Chang, Scott X; De Kauwe, Martin G; Dukes, Jeffrey S; Langley, J Adam; Ma, Zilong; Mariën, Bertold; Reynaert, Simon; Ru, Jingyi; Song, Jian; Stocker, Benjamin; Terrer, César; Thoresen, Joshua; Vanuytrecht, Eline; Wan, Shiqiang; Yue, Kai; Vicca, Sara
Responses of the terrestrial biosphere to rapidly changing environmental conditions are a major source of uncertainty in climate projections. In an effort to reduce this uncertainty, a wide range of global change experiments have been conducted that mimic future conditions in terrestrial ecosystems, manipulating CO2 , temperature, nutrient and water availability. Syntheses of results across experiments provide a more general sense of ecosystem responses to global change, and help to discern the influence of background conditions such as climate and vegetation type in determining global change responses. Several independent syntheses of published data have yielded distinct databases for specific objectives. Such parallel, uncoordinated initiatives carry the risk of producing redundant data collection efforts and have led to contrasting outcomes without clarifying the underlying reason for divergence. These problems could be avoided by creating a publicly available, updatable, curated database. Here, we report on a global effort to collect and curate 57,089 treatment responses across 3,644 manipulation experiments at 1,145 sites, simulating elevated CO2 , warming, nutrient addition and precipitation changes. In the resulting Manipulation Experiments Synthesis Initiative (MESI) database, effects of experimental global change drivers on carbon and nutrient cycles are included, as well as ancillary data such as background climate, vegetation type, treatment magnitude, duration, and, unique to our database, measured soil properties. Our analysis of the database indicates that most experiments are short-term (one or few growing seasons), conducted in the USA, Europe or China, and that the most abundantly reported variable is aboveground biomass. We provide the most comprehensive multifactor global change database to date, enabling the research community to tackle open research questions, vital to global policymaking. The MESI database, freely accessible at doi.org/10.5281/zenodo.7153253, opens new avenues for model evaluation and synthesis-based understanding of how global change affects terrestrial biomes. We welcome contributions to the database on GitHub.

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