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  • 1
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    Simultaneous shifts in elemental stoichiometry and fatty acids of Emiliania huxleyi in response to environmental changes (2018)
    Copernicus Publications (EGU)
    In:  Biogeosciences (BG), 15 . pp. 1029-1045.
    Details
    Publication Date: 2021-02-08
    Description: Climate-driven changes in environmental conditions have significant and complex effects on marine ecosystems. Variability in phytoplankton elements and biochemicals can be important for global ocean biogeochemistry and ecological functions, while there is currently limited understanding on how elements and biochemicals respond to the changing environments in key coccolithophore species such as Emiliania huxleyi. We investigated responses of elemental stoichiometry and fatty acids (FAs) in a strain of E. huxleyi under three temperatures (12, 18 and 24 °C), three N : P supply ratios (molar ratios 10:1, 24:1 and 63:1) and two pCO2 levels (560 and 2400 µatm). Overall, C : N : P stoichiometry showed the most pronounced response to N : P supply ratios, with high ratios of particulate organic carbon vs. particulate organic nitrogen (POC : PON) and low ratios of PON vs. particulate organic phosphorus (PON : POP) in low-N media, and high POC : POP and PON : POP in low-P media. The ratio of particulate inorganic carbon vs. POC (PIC : POC) and polyunsaturated fatty acid proportions strongly responded to temperature and pCO2, both being lower under high pCO2 and higher with warming. We observed synergistic interactions between warming and nutrient deficiency (and high pCO2) on elemental cellular contents and docosahexaenoic acid (DHA) proportion in most cases, indicating the enhanced effect of warming under nutrient deficiency (and high pCO2). Our results suggest differential sensitivity of elements and FAs to the changes in temperature, nutrient availability and pCO2 in E. huxleyi, which is to some extent unique compared to non-calcifying algal classes. Thus, simultaneous changes of elements and FAs should be considered when predicting future roles of E. huxleyi in the biotic-mediated connection between biogeochemical cycles, ecological functions and climate change.
    Type: Article , PeerReviewed
    Format: text
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    DOI: 10.5194/bg-15-1029-2018
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Multifactorial roles of interannual variability, season and sex for foraging patterns in a sexually size monomorphic seabird, the Australasian gannet (Morus serrator) (2018)
    Springer
    In:  Marine Biology, 165 . Art.Nr. 72.
    Details
    Publication Date: 2021-02-08
    Description: Marine top predators forage in environments that show potentially extreme temporal and spatial variation in prey availability, with reproductive success being crucially linked to food supply. Multiple factors of interannual and sexual variation, as well as variation across breeding stages, can shape patterns of spatial use in foraging seabirds, yet studies that address all of these variables simultaneously are rare. We present spatial assessment of foraging patterns by µGPS tracking of a sexually size monomorphic, long-lived species, the Australasian gannet (Morus serrator). The study spanned the incubation and chick-rearing stages in three consecutive breeding seasons. Our findings revealed high interannual variability in foraging distances and trip durations, but no consistent differences between birds across different breeding stages or the sexes. The exception was that core foraging areas were different for female and male Australasian gannets, although trip durations or distances were similar for both sexes. Our results also indicate bimodality in foraging distance and trip duration in this species, while highlighting interannual variability in the extent of bimodality. These findings contribute to a scarcely documented type of foraging behaviour in the seabird family of the Sulidae. Overall, these spatial use patterns provide a baseline for understanding the evolution of sex-specific foraging differences in biparental seabirds, and the extent to which these differences might help in securing breeding success across years of variable food availability.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-018-3332-0
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Breeding biology of Fluttering Shearwaters (Puffinus gavia) on Burgess Island in northern New Zealand (2018)
    Taylor & Francis
    In:  Emu - Austral Ornithology, 118 (2). pp. 173-182.
    Details
    Publication Date: 2021-02-08
    Description: The fluttering shearwater (Puffinus gavia) is an abundant seabird endemic to breeding colonies in northern and central New Zealand. The species remains poorly studied, and here we present the first study to examine its breeding biology in detail. Fluttering shearwater nests were monitored daily from laying in September 2015 to fledging in January 2016 on Burgess Island (Mokohinau Islands group) in the outer Hauraki Gulf, northern New Zealand. Burrows were generally simple and non-branched. Eggs were laid over a period of 39 days with laying peaking 12th September. Incubation was 50 ± 3.7 days and chicks fledged after an average of 74 ± 4.3 days, from late December to the end of January. Chick development corresponds to the pattern observed for other Procellariiformes, gaining body mass rapidly to a maximum of 115% of adult mass, and then losing weight until fledging. Chicks were fed most nights throughout chick-rearing, indicating adult birds have access to a stable food supply close to the colony. Breeding success was 63.8% and similar to other Puffinus species. This study provides baseline biological data for a poorly studied, yet common, New Zealand endemics seabird. The obtained new information will allow for further ecological investigations and improved conservation management for the species
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1080/01584197.2017.1366831
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Widespread gene flow between oceans in a pelagic seabird species complex (2017)
    Wiley
    In:  Molecular Ecology, 26 (20). pp. 5716-5728.
    Details
    Publication Date: 2020-10-20
    Description: Global-scale gene flow is an important concern in conservation biology as it has the potential to either increase or decrease genetic diversity in species and populations. Although many studies focus on the gene flow between different populations of a single species, the potential for gene flow and introgression between species is understudied, particularly in seabirds. The only well-studied example of a mixed-species, hybridizing population of petrels exists on Round Island, in the Indian Ocean. Previous research assumed that Round Island represents a point of secondary contact between Atlantic (Pterodroma arminjoniana) and Pacific species (Pterodroma neglecta and Pterodroma heraldica). This study uses microsatellite genotyping and tracking data to address the possibility of between-species hybridization occurring outside the Indian Ocean. Dispersal and gene flow spanning three oceans were demonstrated between the species in this complex. Analysis of migration rates estimated using bayesass revealed unidirectional movement of petrels from the Atlantic and Pacific into the Indian Ocean. Conversely, structure analysis revealed gene flow between species of the Atlantic and Pacific oceans, with potential three-way hybrids occurring outside the Indian Ocean. Additionally, geolocation tracking of Round Island petrels revealed two individuals travelling to the Atlantic and Pacific. These results suggest that interspecific hybrids in Pterodroma petrels are more common than was previously assumed. This study is the first of its kind to investigate gene flow between populations of closely related Procellariiform species on a global scale, demonstrating the need for consideration of widespread migration and hybridization in the conservation of threatened seabirds.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1111/mec.14330
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Genetic mating System of Australasian gannets (Morus serrator) (2018)
    Wilson Ornithological Society; BioOne
    In:  Wilson Journal of Ornithology, 130 (3). pp. 763-770.
    Details
    Publication Date: 2021-02-08
    Description: We studied genetic similarity between adults and nestlings in putative social families (i.e., 2 adults and a chick) of a seabird that provides obligate biparental care, the Australasian Gannet (Morus serrator), in New Zealand. We detected DNA fingerprint mismatches in 12% of 26 nests between the chick and 1 of the 2 attending adults sampled. No parent–offspring genetic mismatch was detected in nests with 4-week-old or younger and sedentary nestlings, whereas adult–nestling mismatches were detected only in nests with 5-week or older and more mobile young sampled. We conclude that the genetic mating system of this sulid species is predominantly monogamous.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1676/17-039.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    First genetic quantification of sex- and stage-specific feeding in the ubiquitous copepod Acartia tonsa (2018)
    Springer
    In:  Marine Biology, 165 (2). Art.No. 25.
    Details
    Publication Date: 2021-02-08
    Description: Marine copepods provide the major food-web link between primary producers and higher trophic levels, and their feeding ecology is of acute interest in light of global change impacts on food-web functioning. Recently, quantitative polymerase chain reaction (qPCR) protocols have been developed, which can complement classic diet quantification methods, such as stable isotope or fatty acid analyses tools. Here, we present first results of feeding experiments assessing sex- and stage-specific food intake by the ubiquitous calanoid copepod Acartia tonsa by 18S targeted qPCR and microscopic grazing assessment. In triplicated mixed-diet feeding treatments, three suitable A. tonsa diets, the cryptophyte Rhodomonas balthica, the haptophyte Isochrysis galbana, and the diatom Thalassiosira weissflogii, were offered in equal biomass proportions under constant conditions. Prey uptake substantially varied between different algal species, as did the extent of sex- and stage-specificity of prey uptake. Male adult copepods had higher R. balthica gut contents than females, and nauplii contained more of this prey source than copepodites or adult copepods in mixed treatments. A trend towards higher amounts of ingested T. weissflogii in adult females than in males and in nauplii than in other stages was detected. Genetic gut content quantifications indicated low feeding on I. galbana, and no consistent sex- or stage-specific differences of I. galbana content in A. tonsa. Our results highlight diet-specific feeding differences between Acartia life stages and sexes, which can have implications on food-web dynamics and specific nutrient transfer to higher trophic levels in copepod populations of varying age composition under changing environmental parameters, such as rising temperatures and increasing ocean acidification.
    Type: Article , PeerReviewed
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    DOI: 10.1007/s00227-017-3281-z
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Transcriptome, biochemical and growth responses of the marine phytoplankter Phaeodactylum tricornutum Bohlin (Bacillariophyta) to copepod grazer presence (2018)
    Karger
    In:  Cellular Physiology and Biochemistry, 46 (3). pp. 1091-1111.
    Details
    Publication Date: 2021-03-18
    Description: Background/Aims: As a model organism for a pleiomorphic marine planktonic primary producer, Phaeodactylum tricornutum has been studied on a molecular level under diverse cultural conditions. But little is known about its morphological, nutritional or transcriptomic responses under grazing stress. Methods: To assess microalgal molecular and cellular responses to grazer presence, we conducted transcriptome profiling in combination with growth rate, biovolume, fatty acid content, carbon and nitrogen content measurements in the model diatom Phaeodactylum tricornutum. RNA-sequencing was used to evaluate the transcriptomic response to grazing stress for P. tricornutum strain CCAP 1055/1. Results: Among the differentially expressed genes, we found down-regulation of genes involved in pathogen resistance, and in fatty acid biosynthesis pathways, while mitosis-involved genes were up-regulated. Experimentally testing morphological and biochemical responses in five strains of the species, we detected strain-specific significant effects of simulated grazing pressure in altered growth rates, biovolume and nutritional composition. Conclusion: Our research reveals the associated molecular and cellular responses to grazing effects in P. tricornutum and extends the understanding of co-evolutionary roles in regulating grazing defence between P. tricornutum and its grazer.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1159/000488839
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Sex-specific foraging during parental care in a size-monomorphic seabird (2017)
    Wilson Ornithological Society | BioOne
    In:  Wilson Journal of Ornithology, 129 (1). pp. 139-147.
    Details
    Publication Date: 2020-02-06
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1676/1559-4491-129.1.139
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    A virgin flight across the Tasman Sea? Satellite tracking of post-fledging movement in the Australasian Gannet Morus serrator (2010)
    Springer
    In:  Journal of Ornithology, 151 (3). pp. 755-759.
    Details
    Publication Date: 2020-07-20
    Description: New technologies enable tracking of the route, duration, and destination of previously unassessed long-distance movements. Fledgling Australasian Gannets Morus serrator from breeding populations in New Zealand had been reported to fly across the Tasman Sea to Australia, with this historic knowledge derived from the recovery of banded carcasses and from observations of initial flight direction. We deployed Argos satellite devices on ten M. serrator fledglings at Cape Kidnappers Gannetry, North Island, New Zealand, across 2 years. Birds that were tracked leaving the colony initially appeared to have landed on the sea. A male bird and two female birds were tracked moving along the east coast to the south tip of New Zealand. The two females then crossed the Tasman Sea to eastern Australian coastal waters in 4 and 5 days, respectively. We suggest that, contrary to historic reports, the route via Stewart Island constitutes a realized migration path for fledglings from Cape Kidnappers, which might minimize the distance traveled across the open sea to southeastern Australia or Tasmania. Our results further imply that initial direction of flight needs not be indicative of the subsequent migration route taken by M. serrator. This highlights the importance of direct tracking technology for adequate assessment of dispersal and migration in seabirds and other highly mobile species.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s10336-010-0504-1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    No evidence of Campylobacter, Salmonella and Yersiniain free–living populations of the red-crowned parakeet (Cyanoramphus novaezelandiae) (2009)
    Taylor & Francis
    In:  New Zealand Journal of Zoology, 36 (4). pp. 379-383.
    Details
    Publication Date: 2020-06-22
    Description: Screening for pathogenic micro-organisms is an essential component of translocation-based conservation management. While there are some data on pathogens in New Zealand passerines, little is known about the distribution and prevalence of pathogens infecting New Zealand Psittaciformes. We conducted a survey for pathogens of the vulnerable New Zealand endemic red-crowned parakeet Cyanoramphus novaezelandiae in two wild populations (Little Barrier Island and Raoul Island), and in a translocated population (Tiritiri Matangi Island). A total of 101 cloacal samples were tested for Salmonella and Yersinia. Of these, 82 samples were also tested for Campylobacter. None of these microorganisms were detected. Although our sampling effort was insufficient to detect a low prevalence of Campylobacter, modelling of minimum detectable prevalence of Salmonella and Yersinia indicates that these micro-organisms would have been detected if present as common or chronic conditions of red-crowned parakeets at these sites.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1080/03014223.2009.9651469
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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