Browsing by Author "Mazumder, D"
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- ItemAllochthonous and autochthonous contributions to carbon accumulation and carbon accumulation and carbon store in southeastern Australian coastal wetlands(Estuarine, Coastal and Shelf Science, 128, 84-92, 2013-08-10) Saintilan, N; Rogers, K; Mazumder, D; Woodroffe, CDEstimates of carbon store and carbon accumulation rate in mangrove and saltmarsh are beset by issues of scale and provenance. Estimates at a site do not allow scaling to regional estimates if the drivers of variability are not known. Also, carbon accumulation within soils provides a net offset only if carbon is derived in-situ, or would not otherwise be sequestered. We use a network of observation sites extending across 2000 km of southeastern Australian coastline to determine the influence of geomorphic setting and coastal wetland vegetation type on rates of carbon accumulation, carbon store and probable sources. Carbon accumulation above feldspar marker horizons over a 10-year period was driven primarily by tidal range and position in the tidal frame, and was higher for mangrove and saltmarsh dominated by Juncus kraussii than for other saltmarsh communities. The rate of carbon loss with depth varied between geomorphic settings and was the primary determinant of carbon store. A down-core enrichment in delta C-13 was consistent with an increased relative contribution of mangrove root material to soil carbon, as mangrove roots were found to be consistently enriched compared to leaves. We conclude that while surface carbon accumulation is driven primarily by tidal transport of allocthonous sediment, in-situ carbon sequestration is the dominant source of recalcitrant carbon, and that mangrove and saltmarsh carbon accumulation and store is high in temperate settings, particularly in mesotidal and fluvial geomorphic settings. © 2013, Elsevier Ltd.
- ItemApplication of isotope mixing models to discriminate dietary sources over small-scale patches in saltmarsh(Marine Ecology Progress Series, 2013-07-30) Alderson, B; Mazumder, D; Saintilan, N; Zimmerman, K; Mulry, PIntertidal grazing crabs play an important role in estuarine ecosystems, transforming carbon fixed by autotrophs into forms available to a wide range of consumers. Whether the autotrophic carbon is derived primarily from intertidal vegetation or microalgae is an important question to be resolved, as the modification of estuaries alters the balance between these potential food sources, and restoration efforts are best guided by an understanding of the primary drivers of ecosystem energy flow. We utilised the mosaic of C3 and C4 vegetated patches in a temperate saltmarsh to clarify the relative contributions of potential sources of carbon and nitrogen to the diet of 2 species of grapsid crabs: Paragrapsus laevis and Helograpsis haswellianus. The 2 vegetation communities occupied the same position in relation to tidal elevation. We analysed stable isotopes of carbon (δ13C) and nitrogen (δ15N) to discriminate 3 potential sources of dietary carbon using an IsoSource mixing model: microphytobenthos (MPB); fine benthic organic matter (FBOM); and fresh plant material. We found enrichment of δ13C and depletion of δ15N in crabs sampled from patches of the C4 grass Sporobolus virginicus, consistent with the use of C4 derived carbon compared to those sampled in the C3 chenopod Sarcocornia quinqueflora. However, microphytobenthos was similarly depleted within large patches of S. virginicus, implying uptake of dissolved inorganic carbon originating from plant respiration. Multiple-source mixing (IsoSource) models indicated a primary role for MPB and FBOM in crab diets, with locally derived plant material making little contribution to crab diet. The result contrasts with those of studies from subtropical and tropical systems. © 2013, Inter-Research.
- ItemApplication of stable isotopic techniques to wetlands conservation(Sydney Olympic Park Authority, 2013-01-01) Mazumder, DIdentification of food chain linkages between high trophic order species (particularly those of commercial and recreational importance) and different wetland resources (e.g. saltmarsh, mangrove and seagrass) is fundamental to resource management. The source of energy and trophic connectivity among species in the ecosystem can be quantified using stable isotopic techniques. Stable nitrogen isotopes can be used for tracking of pollutant derived from urban effluent or other anthropogenic sources that contribute to eutrophication and other management issues in aquatic environment. Analysis of non-radioactive, naturally occurring carbon and nitrogen isotopes is one of the most powerful techniques that can be considered in clarifying management questions related to wetland conservation.
- ItemAuthenticating genuine Kakadu plum (Terminalia ferdinandiana) powders from fakes using stable isotope analysis and elemental profiling(Elsevier, 2024-08) Keaney, M; Mazumder, D; Tadros, CV; Crawford, J; Gadd, PS; Saeki, P; Sammut, J; Saintilan, NKakadu plum (Terminalia ferdinandiana) is a plant species endemic to northern Australia, attracting increasing consumer interest due to its multiple nutritional qualities. As a consumer product at a premium price point, the Kakadu plum may be susceptible to food fraud. This paper determines the prevalence of food fraud in the e-commerce Kakadu plum market. We applied stable isotope analysis (SIA) and elemental profiling using X-ray fluorescence (XRF) through Itrax to evaluate the authenticity of 13 commercially available Kakadu plum powdered samples purchased from Australian and overseas suppliers against four powdered samples directly provided by First Nations harvesters. Overseas and Australian-sourced powders were found to have distinct isotopic and elemental profiles. All overseas powders showed highly enriched δ13C values indicating they are fakes, not derived from Kakadu plum. Non-metric multi-dimensional scaling (nMDS) of elements also displayed distinct groupings between Australian-sourced and overseas powders, whilst analysis of similarity percentages (SIMPER) differentiated the elemental composition between groups. It was also observed that 89% of overseas products sold as Kakadu plum were deceptively labelled as other products. These results showed food fraud occurred along the supply chain of overseas-sourced product. Given the complexities of multi-national food systems, utilising a combination of stable isotopes and elemental profiling are straightforward applications for detecting fraudulent products. © 2024 Crown Copyright Published by Elsevier Ltd.
- ItemBioaccumulation and retention kinetics of cadmium in the freshwater decapod Macrobrachium australiense(Elsevier, 2014-03) Cresswell, T; Simpson, SL; Smith, REW; Nugegoda, D; Mazumder, D; Twining, JRThe potential sources and mechanisms of cadmium bioaccumulation by the native freshwater decapods Macrobrachium species in the waters of the highly turbid Strickland River in Papua New Guinea were examined using 109Cd-labelled water and food sources and the Australian species Macrobrachium australiense as a surrogate. Synthetic river water was spiked with environmentally relevant concentrations of cadmium and animals were exposed for 7 days with daily renewal of test solutions. Dietary assimilation of cadmium was assessed through pulse-chase experiments where prawns were fed separately 109Cd-labelled fine sediment, filamentous algae and carrion (represented by cephalothorax tissue of water-exposed prawns). M. australiense readily accumulated cadmium from the dissolved phase and the uptake rate increased linearly with increasing exposure concentration. A cadmium uptake rate constant of 0.10 ± 0.05 L/g/d was determined in synthetic river water. During depuration following exposure to dissolved cadmium, efflux rates were low (0.9 ± 5%/d) and were not dependent on exposure concentration. Assimilation efficiencies of dietary sources were comparable for sediment and algae (48–51%), but lower for carrion (28 ± 5%) and efflux rates were low (0.2–2.6%/d) demonstrating that cadmium was well retained by M. australiense. A biokinetic model of cadmium accumulation by M. australiense predicted that for exposures to environmentally relevant cadmium concentrations in the Strickland River, uptake from ingestion of fine sediment and carrion would be the predominant sources of cadmium to the organism. The model predicted the total dietary route would represent 70–80% of bioaccumulated cadmium © 2014, Elsevier B.V.
- ItemBioaccumulation kinetics and organ distribution of cadmium and zinc in the freshwater decapod crustacean macrobrachium australiense(ACS Publications, 2014-12-24) Cresswell, T; Simpson, SL; Mazumder, D; Callaghan, PD; Nguyen, APThis study used the radioisotopes 109Cd and 65Zn to explore the uptake, retention and organ distribution of these nonessential and essential metals from solution by the freshwater decapod crustacean Macrobrachium australiense. Three treatments consisting of cadmium alone, zinc alone, and a mixture of cadmium and zinc were used to determine the differences in uptake and efflux rates of each metal individually and in the metal mixture over a three-week period, followed by depuration for 2 weeks in metal-free water using live-animal gamma-spectrometry. Following exposure, prawns were cryosectioned and the spatial distribution of radionuclides visualized using autoradiography. Metal uptake and efflux rates were the same in the individual and mixed-metal exposures, and efflux rates were close to zero. The majority of cadmium uptake was localized within the gills and hepatopancreas, while zinc accumulated in the antennal gland at concentrations orders of magnitude greater than in other organs. This suggested that M. australiense may process zinc much faster than cadmium by internally transporting the accumulated zinc to the antennal gland. The combination of uptake studies and autoradiography greatly increases our understanding of how metal transport kinetics and internal processing may influence the toxicity of essential and nonessential metals in the environment. © 2014 American Chemical Society
- ItemBiokinetics and discrimination factors for delta C-13 and delta N-15 in the omnivorous freshwater crustacean, Cherax destructor(CSIRO Publishing, 2012-10-29) Carolan, JV; Mazumder, D; Dimovski, C; Diocares, R; Twining, JRKnowledge and understanding of biokinetics and discrimination factors for carbon-13 (delta C-13) and nitrogen-15 (delta N-15) are important when using stable isotopes for food-web studies. Therefore, we performed a controlled laboratory diet-switch experiment to examine diet-tissue and diet-faeces discrimination factors as well as the biokinetics of stable-isotope assimilation in the omnivorous freshwater crustacean, Cherax destructor. The biokinetics of delta C-13 could not be established; however, the delta N-15 value of C. destructor tissue reached equilibrium after 80 +/- 35 days, with an estimated biological half-time for N-15 of 19 +/- 5 days. Metabolic activity contributed to the turnover of N-15 by nearly an order of magnitude more than growth. The diet-tissue discrimination factors at the end of the exposure were estimated as -1.1 +/- 0.5% for delta C-13 and +1.5 +/- 1.0% for delta N-15, indicating that a delta N-15 diet-tissue discrimination factor different from the typically assumed +3.4% may be required for freshwater macroinvertebrates such as C. destructor. The diet-faeces discrimination factor for delta N-15 after 120 days was estimated as +0.9 +/- 0.5%. The present study provides an increased understanding of the biokinetics and discrimination factors for a keystone freshwater macroinvertebrate that will be valuable for future food-web studies in freshwater ecosystems. © 2012, CSIRO Publishing.
- ItemCarbon isotope fractionation in the mangrove Avicennia marina has implications for food web and blue carbon research(Elsevier B. V., 2018-05-31) Kelleway, JJ; Mazumder, D; Baldock, JA; Saintilan, NThe ratio of stable isotopes of carbon (δ13C) is commonly used to track the flow of energy among individuals and ecosystems, including in mangrove forests. Effective use of this technique requires understanding of the spatial variability in δ13C among primary producer(s) as well as quantification of the isotopic fractionations that occur as C moves within and among ecosystem components. In this experiment, we assessed δ13C variation in the cosmopolitan mangrove Avicennia marina across four sites of varying physico-chemical conditions across two estuaries. We also compared the isotopic values of five distinct tissue types (leaves, woody stems, cable roots, pneumatophores and fine roots) in individual plants. We found a significant site effect (F3, 36 = 15.78; P < 0.001) with mean leaf δ13C values 2.0‰ more depleted at the lowest salinity site compared to the other locations. There was a larger within-plant fractionation effect, however, with leaf samples (mean ± SE = −29.1 ± 0.2) more depleted in 13C than stem samples (−27.1 ± 0.1), while cable root (−25. 8 ± 0.1), pneumatophores (−25.7 ± 0.1) and fine roots (−26.0 ± 0.2) were more enriched in 13C relative to both aboveground tissue types (F4, 36 = 223.45; P < 0.001). The within-plant δ13C fractionation we report for A. marina is greater than that reported in most other ecosystems. This has implications for studies of estuarine carbon cycling. The consistent and large size of the fractionation from leaf to woody stem (∼2.0‰) and mostly consistent fractionation from leaf to root tissues (>3.0‰) means that it may now be possible to partition the individual contributions of various mangrove tissues to estuarine food webs. Similarly, the contributions of mangrove leaves, woody debris and belowground sources to blue carbon stocks might also be quantified. Above all, however, our results emphasize the importance of considering appropriate mangrove tissue types when using δ13C to trace carbon cycling in estuarine systems..© 2018 Elsevier Ltd
- ItemCarbon uptake in surface water food webs fed by paleogroundwater(American Geophysical Union, 2019-04-05) Mazumder, D; Saintilan, N; Hollins, SE; Meredith, KT; Jacobsen, GE; Kobayashi, T; Wen, LThe use of 14C to elucidate sources of carbon within freshwater aquatic ecosystems is challenging the assumption that modern autochthonous carbon dominates energy flows. We measured the uptake of old carbon through several trophic levels of a wetland fed by groundwater of the Great Artesian Basin, Australia, the largest artesian basin in the world. Stable isotopes (δ13C and δ15N) and radiocarbon (14C) were used to quantify food chain links and connection between groundwater and surface water food webs. Our results suggest that old groundwater was the dominant carbon source even at the highest trophic levels, with predatory fish returning apparent carbon ages of up to 11 ka. Stable isotope analysis (δ13C and δ15N) identified trophic links between fish, aquatic insects, and algae with smaller contributions from particulate organic matter to the food webs. As natural mound springs and associated wetlands are the only source of reliable water during dry periods over vast areas of the western Great Artesian Basin, the result has potential implications for the interpretation of archaeological artefacts associated with indigenous passage within the interior. ©2019. ANSTO, Macquarie University, Commonwealth of Australia.
- ItemChanges to fish assemblages visiting estuarine wetlands following the closure of commercial fishing in Botany Bay, Australia(Ingenta, 2006-04-19) Saintilan, N; Mazumder, D; Cranney, KData on commercial landings of fish and crustaceans are available for 52 estuaries in New South Wales. These same estuaries have been mapped with regards to the distribution of fish habitat, including mangrove, saltmarsh, and seagrass, along with a suite of geomorphic units. A multiple regression analysis demonstrated strong relationships between the area of mangrove and the catch of a number of commercially important species, including long-finned eel, and the mud crab Scylla serrata. © 2007 Rosenstiel School of Marine and Atmospheric Science
- ItemChanges to fish assemblages visiting estuarine wetlands following the closure of commercial fishing in Botany Bay, Australia(Taylor & Francis, 2008-10) Saintilan, N; Mazumder, D; Cranney, KA Before-After, Control-Impact sampling design was used to measure changes in fish assemblages in intertidal mangroves and saltmarsh prior to and following the closure of commercial fishing in the Botany Bay estuary, New South Wales, Australia. Of commercial species found as juveniles in the wetlands, there was a consistent pattern of decrease in numbers compared to the pre-closure surveys. Other small wetland fish (such as the Gobiidae) were also found to have decreased in numbers, with the exception of the Common Toadfish (Tetractenos hamiltoni Gray and Richardson, 1843) and the Glassfish (Ambassis jacksoniensis Macleay, 1881). Results suggest that the immediate response of an estuarine fishery to commercial fishing closure may be a predator-mediated decline in juvenile fish of both prey and predator species. © 2008 Taylor & Francis Ltd. Open Access
- ItemA combined multidisciplinary kinetic modeling approach for determination of coastal ecosystem contaminant fluxes(Goldschmidt, 2006-08-26) Szymczak, R; Twining, JR; Hollins, SE; Mazumder, D; Creighton, NMThe historical operation of manufacturing, chemical and other industries in the Sydney Harbour catchment over many decades has left a legacy of high chemical contamination in the surrounding catchment. These contaminants are now seriously impacting on incident commercial fisheries and public utilisation of estuarine resources. Elucidation of environmental processes is the key to effective ecosystem management, however few tools are available to predict their inter-relationships, rates and directions. This work seeks to combine GIS, contaminant transport, ecological, and bioaccumulation models to improve the accuracy and specificity of a probabilistic ecological risk assessment strategy. This study has four components: (1) determination of chemical linkages between high trophic order species and different habitats resources using stable isotopic analyses of carbon and nitrogen. These studies identify trophic cascades forming the basis for selection of biota for contaminant transfer experiments; (2) short-term (weeks – months) chronology and geochemistry of sediment cores and traps in Homebush Bay to determine rates of sedimentation and resuspension (using environmental/cosmogenic 7-Be). Models derived from these studies provide the contaminants levels against which risk is assessed; (3) biokinetic studies using proxy radiotracer isotopes (eg. 75-Se & 109-Cd for analogous stable metals) of the uptake and trophic transfer of contaminants by specific estaurine biota. Here we identify the rates and extent to which contaminants accumulated and transferred to predators/seafoods; and (4) application of a probabilistic ecological risk assessment model (AQUARISK) set to criteria determined by stakeholder consensus. Here we report initial results of the distribution of natural isotopes and redistribution of artificial isotopes injected into ecological compartments to determine the key trophic linkages, contaminant pathways and their rates in temperate estuarine systems of Sydney Harbour & Botany Bay (Australia).
- ItemCombined use of stable isotope analysis and elemental profiling to determine provenance of black tiger prawns (Penaeus monodon)(Elsevier, 2019-01-01) Gopi, K; Mazumder, D; Sammut, J; Saintilan, N; Crawford, J; Gadd, PSGlobal demand for seafood is rising, with a commensurate increase in supply from farmed and wild-caught products. Determining seafood provenance is important to reduce food fraud, and food safety and biosecurity risks. DNA and fatty acid profiling cannot independently distinguish between farmed, wild-caught and geographic origins of seafood. This study applied stable isotope analysis (SIA) and X-ray fluorescence (XRF), using Itrax, to test their effectiveness as tools to distinguish the origin and production methods of black tiger prawns (Penaeus monodon) from a range of Asia-Pacific locations. Isotopic and elemental data (31 elements) were analysed using multivariate methods, linear discriminant analysis (LDA), and randomForest. LDA and randomForest had consistent results: XRF effectively distinguished the production method and geographic origin of P. monodon (up to 100% accuracy), while SIA had a lower accuracy (up to 95% accuracy). However, SIA and XRF are effective complementary methods for determining provenance of black tiger prawns. Crown Copyright © 2018 Published by Elsevier Ltd.
- ItemComparisons of fish catches using fyke nets and buoyant pop nets in a vegetated shallow water saltmarsh flat at Towra Point, NSW(Coast and Wetlands Society, 2005) Mazumder, D; Saintilan, N; Williams, RJThe selection of appropriate sampling methods is a prerequisite for the design of any survey detailing nekton assemblages. In the present study two commonly used saltmarsh fish sampling methods, the fyke net and the buoyant pop net, were used to compare the assemblages of fish caught in a saltmarsh flat during monthly spring tides over a twelve month period. Both nets were made of 2mm mesh. A total of 3514 fish and crustaceans of 21 species were captured by 48 fyke net sets and 818 fish of 16 species were captured by 48 pop net releases. Fyke and pop nets recorded significantly different (ANOSIM: P<0.001) assemblages, with higher proportions of Pseudomugil signifer caught in the fyke nets and Ambassis jacksoniensis in the pop nets. Five species, Sillago cilliata, Rhabdosargus sarba, Redigobius macrostoma, Taeniodes mordax and Metapenaeus macleayi, were caught in the fyke nets only. Significant differences in the size of fish caught were recorded for two species, Gobiopterus semivestitus and Gerres subfasciatus, with larger fish on average caught in the pop nets. The result suggested that pop nets are less efficient at catching smaller fish. © The Authors, CC-BY-ND 3.0
- ItemConvictfish on the move: variation in growth and trophic niche space along a latitudinal gradient(Oxford Academic, 2019-06-30) Miranda, T; Smith, JA; Suthers, IM; Mazumder, D; Cruz, DO; Schilling, HT; Searle, K; Vergés, AThe range expansion of tropical fish into temperate waters is increasing markedly in response to climate change. Range-expanding fish encounter novel diets and environments, but we know little about how these conditions facilitate or hinder distribution shifts. Here, we quantified relative growth rate, morphometric condition and trophic niche of juvenile Acanthurus triostegus, a dominant range-expanding tropical surgeonfish, at four locations across 10° of latitude off eastern Australia. We related these metrics to differences in temperature and nutritional quality of dominant seaweeds and the epilithic algal matrix. Temperate food sources were richer in nitrogen than tropical diets. Stable isotope analysis (δ13 carbon and δ15 nitrogen) of fish muscle revealed a large trophic niche breadth at the highest latitude indicating a generalist foraging strategy, and more nitrogen-enriched isotopic signatures compared to tropical regions. Fish length was strongly correlated to δ13C in all regions, suggesting an ontogenetic shift in diet independent of latitude. Despite temperature differences of 4°C, fish growth and body condition were similar across tropical and temperate regions. These results suggest that more nutritious temperate diets may compensate for the effects of cooler water temperatures. Neither summer water temperatures nor dietary factors appear to limit the success of juvenile tropical vagrants as they continue to expand their range along eastern Australia. © 2019 ICES/CIEM
- ItemDetermining the provenance and authenticity of seafood: a review of current methodologies(Elsevier B. V., 2019-09) Gopi, K; Mazumder, D; Sammut, J; Saintilan, NBackground: Globally, food provenance has become a concern for government authorities, the seafood industry and consumers due to increasing food safety and authenticity requirements. Wild-catch fisheries and aquaculture are both important industries; aquaculture is seen as an opportunity to strengthen food security for the growing global population. However, unregulated aquaculture can expose consumers to health risks from pathogens, antibiotics and banned chemicals. Consumers and retailers, and the reputation of the global seafood industry, is affected by food fraud through species substitution and the exchange of aquaculture produce with wild-caught product and vice versa. To ensure consumer confidence and to allow authorities to effectively enforce regulations and contain risks, methods to determine the species, production methods and geographic origin of seafood need to be readily available. Scope and approach This review summarises the currently available and emerging methodologies to determine the provenance and authenticity of seafood. The main focus of this review is to give an overview of the methods that could potentially be used by authorities to enforce regulations and to contain risks, and for the seafood industry to self-regulate and protect itself from food fraud. Key findings and conclusions The most common methods used are DNA profiling, fatty acid profiling, different methods of inductively coupled plasma spectrometry and stable isotope analysis. Additionally, methods such as blockchain, radio frequency identification and x-ray fluorescence through Itrax are currently being tested for their effectiveness in determining seafood provenance. However, these methods have drawbacks and it is likely that a combination of methods would be best suited to determine the provenance of seafood considering its complex supply chain. Crown Copyright © 2019 Published by Elsevier Ltd.
- ItemDeveloping a MySQL database for the provenance of black tiger prawns (Penaeus monodon)(MDPI, 2023-07-11) Gopi, K; Mazumder, D; Crawford, J; Gadd, PS; Tadros, CV; Atanacio, AJ; Saintilan, N; Sammut, JAs the demand for seafood increases, so does the incidence of seafood fraud. Confirming provenance of seafood is important to combat fraudulent labelling but requires a database that contains the isotopic and elemental “fingerprints” of authentic seafood samples. Local isotopic and elemental databases can be scaled up or combined with other databases to increase the spatial and species coverage to create a larger database. This study showcases the use of isotopic and elemental fingerprints of the black tiger prawn (Penaeus monodon) to develop a database that can be used to securely store the data necessary for determining provenance. The utility of this database was tested through querying and building seven different datasets that were used to develop models to determine the provenance of P. monodon. The models built using the data retrieved from the database demonstrated that the provenance of P. monodon could be determined with >80% accuracy. As the database was developed using MySQL, it can be scaled up to include additional regions, species, or methodologies depending on the needs of the users. Combining the database with methods of determining provenance will provide regulatory bodies and the seafood industry with another provenance tool to combat fraudulent seafood labelling. © 2023 The Authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/)
- ItemDiet type influences the gut microbiome and nutrient assimilation of genetically improved farmed tilapia (oreochromis niloticus)(PLOS One, 2020-08-19) Parata, L; Mazumder, D; Sammut, J; Egan, SNile tilapia, Oreochromis niloticus is the third most commonly farmed finfish species in the world, accounting for nearly 5% of global aquaculture production. In the past few decades much of the success of this species has been attributed to the development and distribution of Genetically Improved Farmed Tilapia (GIFT). Despite the increasing availability of GIFT, the productivity of small-scale farming remains highly variable, particularly in developing nations. Commercial fish-feed pellets can increase fish farm productivity; however, many small-scale farmers rely on other means of feeding fish due to the high cost and limited availability of commercial fish feed pellets. Therefore, understanding how locally-sourced feeds affect the production of GIFT is an important step towards improving feeding practices, particularly for farmers with low financial capital. This study used stable isotope analysis (SIA) and 16S rRNA gene sequencing to compare the effects of a locally-sourced vegetable-based diet and commercial pellet-based diets on the relative condition, nutrient assimilation patterns and gastrointestinal microbiota of GIFT. GIFT fed a locally-sourced diet were smaller, and in a significantly poorer condition than those fed with commercial fish feeds. SIA showed no differences in dietary carbon between the two diets; however, δ13C, poor fish condition and the abundance of specific bacterial taxa (of such as Fusobacteria) were correlated. SIA revealed that GIFT fed locally-sourced diets that predominantly consisted of vegetables were significantly enriched in δ15N despite a perceived lack of dietary protein. This enrichment suggests that GIFT fed a locally-sourced diet may be supplementing their diet via cannibalism, a behaviour representative of poor farming practice. Overall this study highlights the need to increase the availability of suitable GIFT feeds in developing nations. The development a low-cost feed alternative could improve the success of small-scale GIFT farmers in PNG, increasing both food and income security within the region. © 2020 Parata et al. Open access under CC Attribution licence
- ItemDiet-tissue discrimination of δ13C and δ15N in freshwater crustacean(University of Western Australia, 2013-07-10) Mazumder, D; Johansen, MP; Davis, EKnowledge and understanding of discrimination factors (d13C and d15N) for carbon-13(d13C) and nitrogen-15 (d15N) are important when using stable isotopes for trophodynamic studies. We performed a controlled laboratory diet-switch experiment to examine diet–tissue discrimination factors for muscle, carapace and stomach tissues of freshwater crustacean, Cherax destructor. A range of diets of differing d13C and d15N isotopic values were fed to C. destructor until equilibrium. For the various tissue types, d15N discrimination was highest in muscle, followed by carapace then stomach, whilst d13C was highest in carapace followed by stomach, then muscle. The resulting diet–muscle discrimination factors were similar to, but varied from the 1‰ for d13C and 3.4‰ for and d15N values that are often used for diet-muscle discrimination. The results highlight variation among differing diet types, and consumer tissue types as applied to stable carbon and nitrogen isotopes in the food-web studies.
- ItemDifferentiating between the d13C signature from environmental conditions and SOM cycling in eastern Australian peat sediments(Australasian Quaternary Association (AQUA), 2021-07-08) Forbes, MS; Cohen, TJ; Marx, SK; Sherborne-Higgins, B; Cadd, HR; Francke, A; Cendón, DI; Peterson, MA; Mooney, SD; Constantine, M; Boesl, F; Kobayashi, Y; Mazumder, DThe analysis of stable carbon isotopes is commonly used in Quaternary science to reconstruct the environmental conditions and vegetation contributions to sedimentary sequences. However, the measured d13C signature of the total organic matter (OM) pool can also reflect other complexities within depositional environments. The peats of the Thirlmere Lakes system in the southern section of the Blue Mountains World Heritage Area provides an excellent opportunity to closely scrutinise such d13C dynamics. These deposits are rich in TOC (20-40%) meaning analytical techniques such as 13C-NMR, used to characterise the OM pool, can be applied effectively. Furthermore, the identification of several peat units deposited over the last ~130 ka allows for temporal comparisons. d13C values determined for a 7 m sediment sequence from Lake Couridjah representing both the MIS 1 and MIS 5e interglacial periods vary by up to 4 to 6‰. These trends were subsequently identified in two other sediment sequences (Lake Baraba and Lake Werri Berri) proximal to Lake Couridjah. Initially we interpreted our results as reflecting a C3 dominated vegetation environment with MIS 1 wetter than MIS 5e, following the established relationship between water stress and d13C enrichment. However, spectral analysis of the OM pool indicates that d13C is driven by changing OM dynamics rather than large changes in environmental conditions. In these environments, the greater presence of carbohydrates (i.e. cellulose) in MIS 1 result in more depleted d13C values. In contrast, the MIS 5e peat is dominated by relative inert OM C fractions including charcoal and lipids (such as leaf waxes), which influences environmental proxies such as C/N. Thus, it is likely that the older MIS 5e peat is a more decomposed version of the active MIS 1 peat, and thus differentiating environmental conditions between the two using d13C alone is not particularly illuminating. To overcome this, we describe the d13C values for a coarse charcoal and high temperature hydrogen pyrolysis fractions, modern vegetation, catchment POC and DOC, and n-alkanes composition and generate catchment carbon models for both MIS 1 and MIS5e. Finally comparing the size of the OM pools of both interglacial deposits can provide useful information in estimating the carbon storage capacity of peat deposits in eastern Australia over these time scales. © The Authors.