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  • 1
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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
  • 2
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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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    Format: text
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    DOI: 10.1007/s00227-017-3281-z
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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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
  • 4
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    Mate replacement entails a fitness cost for a socially monogamous seabird (2010)
    Springer
    In:  Naturwissenschaften, 97 (1). pp. 109-113.
    Details
    Publication Date: 2020-06-22
    Description: Studies of the selective advantages of divorce in socially monogamous bird species have unravelled extensive variation among different lineages with diverse ecologies. We quantified the reproductive correlates of mate retention, mate loss and divorce in a highly philopatric, colonially breeding biparental seabird, the Australasian gannet Morus serrator. Estimates of annual divorce rates varied between 40-43% for M. serrator and were high in comparison with both the closely related Morus bassanus and the range of divorce rates reported across monogamous avian breeding systems. Mate retention across seasons was related to consistently higher reproductive success compared with mate replacement, while divorce per se contributed significantly to lower reproductive output only in one of two breeding seasons. Prior reproductive success was not predictive of mate replacement overall or divorce in particular. These patterns are in accordance with the musical chairs hypothesis of adaptive divorce theory, which operates in systems characterised by asynchronous territorial establishment.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00114-009-0618-6
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Sightings of New Zealand Fairy Tern Sternula nereis davisae in the Kaipara Harbour following nest failure (2013)
    Ornithological Society of New Zealand
    In:  Notornis, 60 (2). pp. 183-185.
    Details
    Publication Date: 2019-09-23
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Climate change affects low trophic level marine consumers: warming decreases copepod size and abundance (2015)
    Springer
    In:  Oecologia, 177 (3). pp. 849-860.
    Details
    Publication Date: 2017-04-13
    Description: Concern about climate change has re-ignited interest in universal ecological responses to temperature variations: (1) biogeographical shifts, (2) phenology changes, and (3) size shifts. In this study we used copepods as model organisms to study size responses to temperature because of their central role in the pelagic food web and because of the ontogenetic length constancy between molts, which facilitates the definition of size of distinct developmental stages. In order to test the expected temperature-induced shifts towards smaller body size and lower abundances under warming conditions, a mesocosm experiment using plankton from the Baltic Sea at three temperature levels (ambient, ambient +4 °C, ambient −4 °C) was performed in summer 2010. Overall copepod and copepodit abundances, copepod size at all life stages, and adult copepod size in particular, showed significant temperature effects. As expected, zooplankton peak abundance was lower in warm than in ambient treatments. Copepod size-at-immature stage significantly increased in cold treatments, while adult size significantly decreased in warm treatments.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00442-014-3130-4
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    First breeding report of black-winged petrel Pterodroma nigripennis on Burgess, Mokohinau Islands, Hauraki Gulf (2012)
    Ornithological Society of New Zealand
    In:  Notornis, 59 . pp. 176-179.
    Details
    Publication Date: 2019-09-23
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    A case of natural recovery after the removal of invasive predators – community assemblage changes in the avifauna of Burgess Island (2014)
    Ornithological Society of New Zealand
    In:  Notornis, 61 . pp. 188-195.
    Details
    Publication Date: 2019-09-23
    Description: Opportunities to monitor natural island ecosystem recovery following the eradication of introduced predators are rare, and provide a useful comparison for recovery programmes aided by active habitat restoration and species translocations. We present an assessment of the current avifauna on Burgess Island, Mokohinau Group, 2 decades after kiore (Pacific rat; Rattus exulans) removal. The 4 most abundant land bird species we recorded are red-crowned parakeet (Cyanorhamphus novaezelandiae), bellbird (Anthornis melanura), tui (Prosthemadera novaeseelandiae) and silvereye (Zosterops lateralis), all New Zealand native taxa. Our records confirm that 46 species now utilize the island’s habitats, compared with 24 species reported from the literature during the last decades of rat infestation. We also confirm breeding of 9 seabird species by 2011, only 4 of which maintained breeding populations on Burgess Island prior to rat eradication. More than 20 years after predator removal, Burgess Island hosts a rich avifauna, and provides a valuable example of natural recovery following predator eradication without any further active restoration measures
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    An opportunistic sighting of a flock of Black Petrels (Procellaria parkinsoni) at the Galapagos Islands, Ecuador (2016)
    Ornithological Society of New Zealand
    In:  Notornis, 63 . pp. 54-56.
    Details
    Publication Date: 2019-02-01
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Is the chemical composition of biomass the agent by which ocean acidification impacts on zooplankton ecology? (2017)
    Springer
    In:  Aquatic Sciences, 79 (3). pp. 733-748.
    Details
    Publication Date: 2020-02-06
    Description: Climate change impacts prevail on marine pelagic systems and food webs, including zooplankton, the key link between primary producers and fish. Several metabolic, physiological, and ecological responses of zooplankton species and communities to global stressors have recently been tested, with an emerging field in assessing effects of combined climate-related factors. Yet, integrative studies are needed to understand how ocean acidification interacts with global warming, mediating zooplankton body chemistry and ecology. Here, we tested the combined effects of global warming and ocean acidification, predicted for the year 2100, on a community of calanoid copepods, a ubiquitously important mesozooplankton compartment. Warming combined with tested pCO2 increase affected metabolism, altered stable isotope composition and fatty acid contents, and reduced zooplankton fitness, leading to lower copepodite abundances and decreased body sizes, and ultimately reduced survival. These interactive effects of temperature and acidification indicate that metabolism-driven chemical responses may be the underlying correlates of ecological effects observed in zooplankton communities, and highlight the importance of testing combined stressors with a regression approach when identifying possible effects on higher trophic levels.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00027-017-0532-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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