Ryan R Reisinger

University of Southampton · National Oceanography Centre Southampton (NOCS)

Multiple initiatives have called for large-scale representative networks of marine protected areas (MPAs). MPAs should be ecologically representative to be effective, but in large, remote regions this can be difficult to quantify and assess. We present a novel bioregionalization for the Southern Ocean, which uses the modelled circumpolar habitat im...

In Antarctica, abundant consumers rely on Antarctic krill for food, but krill are also the subject of a commercial fishery. The fishery overlaps in time and space with the foraging areas of these consumers, thus potential competition between krill fisheries and krill consumers is a major management concern. The fishery is managed by the Commission...

Marine mammalsMarine mammals move through dynamic and heterogeneous environments to fulfill maintenance functions. These movements can be studied with various techniques that yield different types of information, and this is increasingly revealing the diversity of movement behaviors among marine mammals. These behaviors vary extensively in their ch...

A new collaborative report from WWF and science partners provides the first comprehensive look at whale migrations and the threats they face across all oceans, highlighting how the cumulative impacts from industrial fishing, ship strikes, pollution, habitat loss, and climate change are creating a hazardous journey. Protecting Blue Corridors report...

Aim Climate change will likely lead to a significant redistribution of biodiversity in marine ecosystems. We examine the potential redistribution of a community of marine predators by comparing current and future habitat distribution projections. We examine relative changes among species, indicative of potential future community-level changes and c...

Climate variability and changes in sea ice dynamics have caused several ice-obligate or krill-dependent populations of marine predators to decline, eliciting concern about their demographic persistence and the indirect ecological consequences that predator depletions may have on marine ecosystems. Pack-ice seals are dominant ice-obligate predators...

Variation in the distribution and abundance of food resources are key factors affecting animal sociality. In environments with variable resources, dynamic social organization, such as the fission and fusion of groups, is thought to increase the benefits of group living, while reducing the costs. We investigated the relationship between social organ...

Sexual competition is increasingly recognized as an important selective pressure driving species distributions. However, few studies have investigated the relative importance of inter‐ vs. intrapopulation competition in relation to habitat availability and selection. To explain spatial segregation between sexes that often occurs in non‐territorial...

Machine learning algorithms are often used to model and predict animal habitat selection the relationships between animal occurrences and habitat characteristics. For broadly distributed species, habitat selection often varies among populations and regions; thus, it would seem preferable to fit region- or population-specific models of habitat selecti...

Important findings from the second decade of the 21st century on the impact of environmental change on biological processes in the Antarctic were synthesised by 26 international experts. Ten key messages emerged that have stakeholder-relevance and/or a high impact for the scientific community. They address (i) altered biogeochemical cycles, (ii) oc...

Important findings from the second decade of the 21st century on the impact of environmental change on biological processes in the Antarctic were synthesised by 26 international experts. Ten key messages emerged that have stakeholder-relevance and/or a high impact for the scientific community. They address (i) altered biogeochemical cycles, (ii) oc...

p>Important findings from the second decade of the 21st century on the impact of environmental change on biological processes in the Antarctic were synthesised by 26 international experts. Ten key messages emerged that have stakeholder-relevance and/or a high impact for the scientific community. They address (i) altered biogeochemical cycles, (ii)...

The massive number of seabirds (penguins and procellariiformes) and marine mammals (cetaceans and pinnipeds) – referred to here as top predators – is one of the most iconic components of the Antarctic and Southern Ocean. They play an important role as highly mobile consumers, structuring and connecting pelagic marine food webs and are widely studie...

Killer whales, Orcinus orca, are a cosmopolitan species with large ecological and demographic variation across populations. Population-specific demographic studies are, therefore, crucial in accurately assessing the status and trends of local killer whale populations. Such studies require long-term datasets and remain scarce, particularly in the So...

To mediate competition, similar sympatric species are assumed to use different resources, or the same but geographically separated resources. The two giant petrels (Macronectes spp.) are intriguing in that they are morphologically similar seabirds with overlapping diets and distributions. To better understand the mechanisms allowing their coexisten...

Seasonal and annual climate variations are linked to fluctuations in the abundance and distribution of resources, posing a significant challenge to animals that need to adjust their foraging behavior accordingly. Particularly during adverse conditions, and while energetically constrained when breeding, animals ideally need to be flexible in their f...

Background: Precise and accurate retrospective geolocation of marine predators via their tissues' isotopic composition relies on quality reference maps of relevant isotopic gradients ("isoscapes"). Additionally, a good working knowledge of any discrimination factors that may offset a marine predator's isotopic composition from baseline isotopic va...

Southern Ocean ecosystems are under pressure from resource exploitation and climate change1,2. Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally...

The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Biodiversity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for mul...

The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Biodiversity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for mul...

Seal biologists at Marion Island (Southern Ocean) are in frequent contact with seals. During research activities, biologists may be bitten by seals, yet no standardised protocol for treating such bites is in place. Information on 22 seal bite cases at Marion Island was collected. Treatment of these bites varied, reflecting a need for standardised p...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Plain Language Summary Polar ecosystems are threatened by future loss of sea ice. The availability of satellite sea ice products has facilitated a better assessment of the impact of sea ice on polar species. Yet most studies have focused on coarse spatial scale sea ice products hampering an understanding of the mechanisms by which sea ice affects s...

The Patagonian Shelf Large Marine Ecosystem supports high levels of biodiversity and endemism and is one of the most productive marine ecosystems in the world. Despite the important role marine predators play in structuring ecosystems, areas of high diversity where multiple predators congregate remains poorly known on the Patagonian Shelf. Here, we...

In highly social top predators, group living is an ecological strategy that enhances individual fitness, primarily through increased foraging success. Additive mortality events across multiple social groups in populations may affect the social structure, and therefore the fitness, of surviving individuals. This hypothesis was examined in a killer w...

Fisheries may generate new feeding opportunities for marine predators, which switch foraging behaviour to depredation when they feed on fish directly from fishing gear. However, the role of diet in the propensity of individuals to depredate and whether the depredated resource is artificial or part of the natural diet of individuals is often unclear...

Anomalous pelage colourations are not uncommon amongst pinnipeds but have not been documented in sub-Antarctic fur seals (Arctocephalus tropicalis). Fur seals (Arctocephalus spp.) have been monitored on Marion Island since 1973, and as part of the long-term monitoring programme, any atypical sightings of fur seals were recorded. Fourteen sub-Antarc...

Biologging technologies have revolutionised our understanding of the foraging ecology and life history traits of marine predators, allowing for high resolution information about location, and in some cases, foraging behaviour of wild animals. At the same time, stable isotope ecologists have independently developed methods to infer location and fora...

Occurrences of killer whales (Orcinus orca) in the waters surrounding Sub-Antarctic Macquarie Island have been recorded since the 1820s; however, their presence only became the focus of scientific research in the mid-1990s. The analyses of sightings data collected from the island between 1986 and 2015 are presented herein. The study provides eviden...

Demographic parameters of wild animals are often closely associated with their foraging distribution and behaviour, and understanding these attributes can assist in identifying causes of population changes. The Indian Yellow-nosed Albatross (Thalassarche carteri) is endangered but little information is available on its at-sea distribution and behav...

Antarctic (Arctocephalus gazella) and Subantarctic (A. tropicalis) fur seals are important predators in the Southern Ocean. Marion Island (southern Indian Ocean) hosts the largest sympatric breeding populations of these two species. Environmental and population changes here over two decades may have influenced their diet and trophic interactions. T...

The distribution of marine predators is driven by the distribution and abundance of their prey; areas preferred by multiple marine predator species should therefore indicate areas of ecological significance. The Southern Ocean supports large populations of seabirds and marine mammals and is undergoing rapid environmental change. The management and...

ABSTRACT: Insight into the trophic ecology of marine predators is vital for understanding their ecosystem role and predicting their responses to environmental change. Juvenile southern elephant seals (SES) Mirounga leonina are considered generalist predators within the Southern Ocean. Although mesopelagic fish and squid dominate their stomach lavag...

Prey selection for models: A Bayesian statistical mixing modelling approach was used for the dietary reconstruction, using the Stable Isotope Analysis in R (SIAR v. 4.2) package (Parnell et al. 2010). The SIAR method utilises a tissue-and species-specific trophic discrimination factor (TDF) to adjust prey isotopic values to the isotopic values obta...

Herein, we demonstrate how southern elephant seals whiskers can provide fine-scale dietary data. We used the isotopic data contained in the whiskers segments to quantify the contribution of crustaceans to the diet of juvenile southern elephant seals at Marion Island, in the Southern Ocean.

Social structure is a core element of population biology, influenced by intrinsic and environmental factors. Intra-taxon comparisons of social organization are useful in elucidating the role of such ecological determinants of sociality. Killer whales Orcinus orca are widely distributed, social delphinids with diverse morphology, diet, behaviour, an...

King penguins make up the bulk of avian biomass on a number of sub-Antarctic islands where they have a large functional effect on terrestrial and marine ecosystems. The same applies at Marion Island where a substantial proportion of the world population breeds. In spite of their obvious ecological importance, the at-sea distribution and behavior of...

To help meet the high energy demands of raising the young, some seabirds alternate between short, frequent foraging trips to maximize food delivery to the young, and infrequent, long foraging trips that serve towards self-maintenance. Our study is the first to investigate the foraging behaviour of gentoo penguins at Marion Island, which we did thro...

Diet seems to be a key factor driving diversity and isolation among killer whale populations. Killer whales at Marion Island, Southern Ocean, have been observed preying on seals and penguins but are also know to depredate Patagonian toothfish from longline fishing vessels. However, their diet is poorly known especially when they occur offshore. We...

Recent pup population estimates of sympatric Subantarctic (Arctocephalus tropicalis) and Antarctic fur seals (A. gazella) at Marion Island are presented. Published pup population estimates of A. tropicalis (1995 and 2004) with an unpublished total island count in 2013, and annual counts on subsets of rookeries (2007–2015) were analyzed using a hier...

Assessing body mass in mammals is of importance as it influences virtually all aspects of mammal physiology, behavior and ecological parameters. However, the assessment of body mass of large mammals is potentially dangerous and logistically challenging. Photogrammetry (measurements through the use of photographs) is a well-established science. In z...

Eleven satellite tags were deployed on 9 killer whales at the Prince Edwards Islands in the Southern Ocean. State-space switching models were used to generate position estimates from Argos location data, while two behavioural modes were estimated from the data. Individuals were tracked for 5.6–53.2 days, during which time they moved 416–4470 km (m...

Several records describe pseudostalked barnacles Xenobalanus globicipitis attached to killer whales Orcinus orca, yet little is known of this association in South African waters. Here we describe Xenobalanus prevalence on killer whales in South African waters and assemble previous records. Killer whales were photographed opportunistically between J...

Understanding the distribution and foraging ecology of major consumers within pelagic systems, specifically in relation to physical parameters, can be important for the management of bentho-pelagic systems undergoing rapid change associated with global climate change and other anthropogenic disturbances such as fishing (i.e., the Antarctic Peninsul...

Remote tissue biopsy sampling and satellite tagging are becoming widely used in large marine vertebrate studies because they allow the collection of a diverse suite of otherwise difficult-to-obtain data which are critical in understanding the ecology of these species and to their conservation and management. Researchers must carefully consider thei...

Number of samples used in this study by predefined population. Table S2 Demographic estimates from ∂a∂i for the MI/AT/OS analysis. Table S3 Demographic estimates from ∂a∂i for the AT/OS/AR analysis. Table S4 Model comparisons for order of population splitting for the MI, AT, OS analysis. Table S5 Model comparisons for order of population splitting...

The evolution of diversity in the marine ecosystem is poorly understood, given the relatively high potential for connectivity, especially for highly mobile species such as whales and dolphins. The killer whale (Orcinus orca) has a worldwide distribution, and individual social groups travel over a wide geographic range. Even so, regional populations...

For many highly mobile species, the marine environment presents few obvious barriers to gene flow. Even so, there is considerable diversity within and among species, referred to by some as the 'marine speciation paradox'. The recent and diverse radiation of delphinid cetaceans (dolphins) represents a good example of this. Delphinids are capable of...

Sexual coercion is the use of force to achieve mating, while reproductive interference encompasses many forms of interspecific interactions during mating. We describe three new occurrences of the sexual coercion of king penguins (Aptenodytes patagonicus) by Antarctic fur seals (Arctocephalus gazella) on sub-Antarctic Marion Island. These recurrent...

Immobilization and anaesthesia of adult male southern elephant seals (Mirounga leonina) is potentially risky for animals and scientists. A tiletamine/zolazepam injection is considered the most appropriate drug combi-nation for field application in this species. Since appro-priate dosages are difficult to assess due to uncertainties in weight estima...

South Africa is reputed to host the world’s largest remaining population of white sharks, yet no studies have accurately determined a population estimate based on mark-recapture of live individuals. We used dorsal fin photographs (fin IDs) to identify white sharks in Gansbaai, South Africa, from January 2007 – December 2011. We used the computer pr...

Study shark ‘Demon’, demonstrating signficant change in the lower three quarters of the trailing edge. Despite having a large injury to the trailing ege of the dorsal fin, the fin identification can still be matched by using the shape of the leading edge and the top quarter of the fin. (TIF)

Immobilization and anaesthesia of adult male southern elephant seals (Mirounga leonina) is potentially risky for animals and scientists. A tiletamine/zolazepam injection is considered the most appropriate drug combination for field application in this species. Since appropriate dosages are difficult to assess due to uncertainties in weight estimati...

Killer whales at subantarctic Marion Island have been subjected to several scientific studies. In contrast, up until recently, there has been only one record of these animals documented for neighbouring Prince Edward Island. We here report on killer whale observations at Prince Edward Island during March 2012. During 3 days of opportunistic observa...

The Marine Mammal Programme (MMP) conducts research on pinnipeds and killer whales Orcinus orca at Marion Island, Prince Edward Islands, under the auspices of the Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria. The history of the MMP, which has benefited from collaboration with leading national and internati...

Killer whales are the oceans' apex predators and their potential effects on ecosystems have been demonstrated. In the Southern Ocean, the role of killer whale predation in population declines of southern elephant seals remains largely speculative. We aimed to assess whether top-down control of pinniped and penguin populations at the Subantarctic Pr...