Julie McInnes

Julie McInnes
University of Tasmania · Institute for Marine and Antarctic Studies (IMAS)

Doctor of Philosophy
Post-doctoral fellow

About

19
Publications
8,272
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Citations
Featured research
Article
Full-text available
Seabird foraging activities are constrained by the heterogeneous distribution of prey, intra-specific competition, and the varying energy requirements throughout their life history. Investigations of intra-seasonal variation in foraging habitat will, therefore, provide clues to understand how predators respond to changes in the marine environment. As an abundant, central-place foraging mesopredator, we selected to examine this with Adélie penguins (Pygoscelis adeliae) breeding in the Prydz Bay region where the sea-ice environment is heterogeneous and the largest populations in East Antarctica occur. In the summer of 2011/12, using GPS tracks, we calculated First Passage Time to extract Area Restricted Search (ARS) zones to indicate foraging intensity, and classified the ARS zones by K-means clustering. In total, 47, 64, 23 and 10 ARS zones were detected during early and late incubation, chick-guard and crèche stages (n = 4, 11, 6 and 3 birds). Higher and more stable sea-ice concentration and increased distance from the nearest major colony had positive effects on foraging intensity. The ARS zones were classified into nearshore, offshore and open water habitats. Birds used offshore areas and avoided open water during early incubation and crèche, when birds returned less frequently. During late incubation and chick-guard, when birds frequently returned, they used nearshore and open water areas as expected from the proportion of available habitats. Our results suggest that the pack ice and reduced intra-specific competition for prey were the preferred foraging condition for Adélie penguins, and highlight the importance of seasonal changes in sea-ice environment to their foraging habitat selectivity.
Article
Full-text available
Species inventories and biodiversity assessments are critical to conservation. Yet cryptic species or recolonizing species can be challenging to detect. DNA metabarcoding provides an alternative tool to identify species that can be difficult to observe during field surveys. We test the efficacy of DNA analysis to identify burrowing petrel species in a rapidly changing landscape, on a remote sub‐Antarctic island following pest eradication. Discarded feathers and scats provided high quality DNA for species identification, assisting in detection of new species arrivals and new breeding sites across Macquarie Island. We highlight how DNA metabarcoding informs species inventories and is a valuable tool to complement seabird field surveys. DNA metabarcoding provides a rapid assessment tool to identify seabird species presence in a recovering island ecosystem. We test the efficacy of DNA analysis to identify burrowing petrel species on a remote sub‐Antarctic island following pest eradication. This case study highlights how DNA metabarcoding extends our knowledge of species diversity and distribution and provides a valuable tool to complement field surveys.
Article
Full-text available
Detecting changes in marine food webs is challenging, but top predators can provide information on lower trophic levels. However, many commonly measured predator responses can be decoupled from prey availability by plasticity in predator foraging effort. This can be overcome by directly measuring foraging effort and success and integrating these into a measure of foraging efficiency analogous to the catch per unit effort (CPUE) index employed by fisheries. We extended existing CPUE methods so that they would be applicable to the study of generalist foragers, which introduce another layer of complexity through dietary plasticity. Using this method, we inferred species‐specific patterns in prey availability and estimated taxon‐specific biomass consumption. We recorded foraging trip duration and body mass change of breeding little penguins Eudyptula minor and combined these with diet composition identified via non‐invasive faecal DNA metabarcoding to derive CPUE indices for individual prey taxa. We captured weekly patterns of availability of key fish prey in the penguins’ diet and identified a major prey shift from sardine Sardinops sagax to red cod Pseudophycis bachus between years. In each year, predation on a dominant fish species (~150 g/day) was replaced by greater diversity of fish in the diet as the breeding season progressed. We estimated that the colony extracted ~1,300 tonnes of biomass from their coastal ecosystem over two breeding seasons, including 219 tonnes of the commercially important sardine and 215 tonnes of red cod. This enhanced pCPUE is applicable to most central‐placed foragers and offers a valuable alternative to existing metrics. Informed prey‐species biomass estimates extracted by apex and meso predators will be a useful input for mass‐balance ecosystem models and for informing ecosystem‐based management. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article
Article
Full-text available
There is growing evidence that gelatinous zooplanktonic organisms ("gelata") are regular prey for marine endotherms. Yet the consumption of gelata is intriguing in terms of the energy reward, because endotherms have a high energy demand and the consumption of gelata provides little energy return. In this paper, we take advantage of recent advances in diet analysis methods, notably animal-borne video loggers and DNA analysis in seabirds, to examine our current understanding of this interaction. We suggest that several hypotheses commonly raised to explain predation on gelata (including increased biomass, reduced prey availability, and secondary ingestion) have already been tested and many lack strong support. We emphasize that gelata are widely consumed by endotherms (121 cases reported across 82 species of seabirds, marine mammals, and endothermic fishes) from the Arctic to the Antarctic but noticeably less in the tropics. We propose that in line with research from terrestrial ecosystems atypical food items might be beneficial to the consumers in a non-energetic context, encompassing self-medication, and responding to homeostatic challenges. Changing the "last resort" context for a "functional response" framework may improve our understanding of widespread predation on gelata. Further biochemical analyses are needed to formally examine this perspective.
Article
Full-text available
High precision, high coverage DNA-based diet analysis tools allow great insight into the food web interactions of cryptic taxa. We used DNA fecal-metabarcoding to look for unrecorded taxa within the diet of a generalist central-placed predator, the little penguin Eudyptula minor. We examined 208 scats from 106 breeding pairs throughout August–February in a large colony at Phillip Island, Australia. While we confirmed a largely piscivorous diet, we also recovered DNA sequences from gelatinous and crustaceous plankton groups that have not previously been detected in the little penguin diet using other diet analysis methods. Gelatinous plankton, including salps, appendicularians, scyphozoans, and hydrozoans were present in 76% of samples and represented 25% of all sequences. DNA recovered from minute copepods and appendicularians may indicate links between trophic levels through secondary predation. Percentage frequency of occurrence (%FOO) demonstrated that little penguin diet composition changed over months and stages (incubation, guard, and post-guard) of the breeding season (month: χ2 = 201.91, df = NA, p < 0.01; stage: χ2 = 33.221, df = NA, p = 0.015). Relative read abundance (RRA) uncovered variations in the relative abundance of taxa in the diet over months and stages (month: F = 53.18, df = 59, p < 0.001; stage: F = 66.56, df = 29, p < 0.001). The diet became progressively fish-focused over months of the season and stages, while salps were only present in 4 out of 6 months, with a peak in September. Based on their prevalence in this dataset, in this year of very high breeding success (2.15 chicks per pair), salps may constitute a food source for this largely piscivorous generalist. Our work highlights how DNA metabarcoding can improve our understanding of the trophic role of gelatinous plankton and other cryptic taxa.
Additional affiliations
February 2019 - present
Department of Primary Industries, Parks, Water and Environment.
Position
  • Wildlife Officier
March 2018 - February 2019
FRDC funded grant
Position
  • Seabird Ecologist contractor
November 2017 - February 2018
University of Queensland
Position
  • Group Leader

Publications

Publications (19)
Article
Maximising survey efficiency can help reduce the tradeoff between spending limited conservation resources on identifying population changes and responding to those changes through management. Burrow‐nesting seabirds are particularly challenging to survey because nests cannot be counted directly. We evaluated a stratified random survey design for ge...
Article
Full-text available
Seabird foraging activities are constrained by the heterogeneous distribution of prey, intra-specific competition, and the varying energy requirements throughout their life history. Investigations of intra-seasonal variation in foraging habitat will, therefore, provide clues to understand how predators respond to changes in the marine environment....
Article
Full-text available
Species inventories and biodiversity assessments are critical to conservation. Yet cryptic species or recolonizing species can be challenging to detect. DNA metabarcoding provides an alternative tool to identify species that can be difficult to observe during field surveys. We test the efficacy of DNA analysis to identify burrowing petrel species i...
Article
Full-text available
Detecting changes in marine food webs is challenging, but top predators can provide information on lower trophic levels. However, many commonly measured predator responses can be decoupled from prey availability by plasticity in predator foraging effort. This can be overcome by directly measuring foraging effort and success and integrating these in...
Article
Full-text available
There is growing evidence that gelatinous zooplanktonic organisms ("gelata") are regular prey for marine endotherms. Yet the consumption of gelata is intriguing in terms of the energy reward, because endotherms have a high energy demand and the consumption of gelata provides little energy return. In this paper, we take advantage of recent advances...
Article
Full-text available
High precision, high coverage DNA-based diet analysis tools allow great insight into the food web interactions of cryptic taxa. We used DNA fecal-metabarcoding to look for unrecorded taxa within the diet of a generalist central-placed predator, the little penguin Eudyptula minor. We examined 208 scats from 106 breeding pairs throughout August–Febru...
Article
Full-text available
Advances in DNA sequencing technology have revolutionised the field of molecular analysis of trophic interactions and it is now possible to recover counts of food DNA sequences from a wide range of dietary samples. But what do these counts mean? To obtain an accurate estimate of a consumer's diet should we work strictly with datasets summarising fr...
Preprint
Advances in DNA sequencing technology have revolutionised the field of molecular analysis of trophic interactions and it is now possible to recover counts of food DNA barcode sequences from a wide range of dietary samples. But what do these counts mean? To obtain an accurate estimate of a consumer’s diet should we work strictly with datasets summar...
Article
Full-text available
Almost all of the world's fisheries overlap spatially and temporally with foraging seabirds, with impacts that range from food supplementation (through scavenging behind vessels), to resource competition and incidental mortality. The nature and extent of interactions between seabirds and fisheries vary, as does the level and efficacy of management...
Article
Full-text available
Gelatinous zooplankton are a large component of the animal biomass in all marine environments, but are considered to be uncommon in the diet of most marine top predators. However, the diets of key predator groups like seabirds have conventionally been assessed from stomach content analyses, which cannot detect most gelatinous prey. As marine top pr...
Article
Full-text available
1. DNA metabarcoding of food in animal scats provides a non-invasive dietary analysis method for vertebrates. A variety of molecular approaches can be used to recover dietary DNA from scats; however, many of these also recover non-food DNA. Blocking primers can be used to inhibit amplification of some non-target DNA, but this may not always be feas...
Article
Full-text available
Many seabird populations are threatened by interactions with commercial fisheries, and climate change. Understanding their prey requirements and dietary flexibility in this context is important for effective conservation and management. However, changes in the methods used to assess diet, as well as the spatial and temporal coverage of monitoring s...
Article
Full-text available
As central place foragers, breeding penguins are restricted in foraging range by the need to return to the colony to feed chicks. Furthermore, breeding birds must balance energetic gain from self-feeding with the costs of returning to provision young. Non-breeding birds, however, are likely to be less restricted in foraging range and lack the high...
Article
Full-text available
Reconstructing the diet of top marine predators is of great significance in several key areas of applied ecology, requiring accurate estimation of their true diet. However, from conventional stomach content analysis to recent stable isotope and DNA analyses, no one method is bias or error free. Here, we evaluated the accuracy of recent methods to e...
Article
Full-text available
Sex identification of birds is of great interest in ecological studies, however this can be very difficult in many species because their external features are almost monomorphic between the sexes. Molecular methodology has simplified this process but limitations still occur with widely accepted methods using polymerase chain reaction and gel electr...
Article
Full-text available
The Adélie penguin is the most important animal currently used for ecosystem monitoring in the Southern Ocean. The diet of this species is generally studied by visual analysis of stomach contents; or ratios of isotopes of carbon and nitrogen incorporated into the penguin from its food. There are significant limitations to the information that can b...
Article
Full-text available
Sub-populations within species can exhibit differing population growth trajectories in relation to one another depending on various environmental factors. In threatened species, negative population growth in some sub-populations can ultimately cause the demise of the species; therefore, understanding causal factors of population change is critical...
Article
1. Invaded ecosystems present complex management issues. This problem is exacerbated in many situations by a lack of knowledge about the ecosystem. However, delaying conservation action to collect further data and so reduce such uncertainty is often either impractical or inadvisable. 2. The Macquarie Island Pest Eradication Project, currently under...
Article
Full-text available
DNA barcoding of faeces or stomach contents is an emerging approach for dietary analysis. We pyrosequenced mtDNA 16S markers amplified from faeces of captive little penguins (Eudyptula minor) to examine if recovered sequences reflect the proportions of species consumed. We also analysed wild little penguin faeces collected from 100 nests in southea...

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Projects

Projects (2)
Project
Information related to diet and energy flow is fundamental to a diverse range of Antarctic and Southern Ocean biological and ecosystem studies. The SCAR Expert Groups on Antarctic Biodiversity Informatics (EG-ABI) and Birds and Marine Mammals (EG-BAMM) are collating a centralised database of such information to assist the scientific community in this work. It will include data related to diet and energy flow from conventional (e.g. gut content) and modern (e.g. molecular) studies, stable isotopes, fatty acids, and energetic content. It will be a product of the SCAR community and open for all to participate in and use.
Project
My project uses DNA metabarcoding to investigate albatross diet using prey DNA in their scats. This technique is exciting as it provides a non-invasive way to identify albatross resource requirements and any overlap with fisheries. I am developing field and laboratory protocols to optimise dietary results from scats samples. Using these methods, I'm investigating the diet of a globally distributed albatross species and local endemic species.