Stories from the Antarctic Peninsula

 A view from Harmony Point over to Robert Island in the background (Chris Oosthuizen)

A view from Harmony Point over to Robert Island in the background (Chris Oosthuizen)

 William and Lucas with some chinstrap penguins

William and Lucas with some chinstrap penguins

“This could be Scott’s hut”, I thought, as I stepped through the door and into the kitchen. Pine food boxes filled the wall to the left, and contained tinned butter, mold-speckled and rusted cans of fish, and gold-with-brown rust-encrusted paraffin food tins. It was dark inside, and damp as if in a cave, as wooden planks were hammered into the outside wall to cover and protect the single window from the elements. Were you able to look through that window, you would have seen the blue ice of the glacier beyond the small cove. Outside it was light, although shortly after 01:00 AM. It was going to be a long morning of shifting gear from the landing beach to the hut. But after the drama of the previous day we were euphoric to be here, even if it meant being deserted at midnight alone on this Antarctic island. 

Our journey here had started with delayed flights and two missed connections, and long airport hours. We arrived in Punta Arenas, Chile, on 23 November and 18 hours later stepped aboard “Achilles”, a frigate of the Chilean Navy. There were six of us: Team Harmony Point (Nelson Island) (Chris [South Africa], William [France] and Lucas [Brazil]) and Team Kopaitic (O’Higgens base) (Audun [Norway], Newi [South Africa] and Magdalena [Chile]. Andy [England/Australia] and Heidi [Finland] had already arrived at Deception Island, having left Ushuaia with a 5-star Hurtigruter tourist ship a few days earlier. Our board were of the 1-star variety one associates with army rations. Breakfast was sweet tea and a type of bread-roll, which also featured during afternoon tea. Lunch and dinner was a cooked meal consisting of (s)mash potato (often), rice or pasta, and some form of gravy, a small piece of meat, or a single vienna. 

Together, our three teams make up the predator tracking side of “krilltokt”, the Norwegian Polar Institute study to krill, krill-fisheries and ecosystem responses in the Bransfield Strait, West Antarctic Peninsula. Also on the Achilles were scientists from INACh (Instituto Antarctica Chileno) and quite a number of tourists. The tourists never ate with us, and I assume they had a different cook. We departed Punta Arenas 15:00 on 24 November and sailed south through the channels and fjords that lead to the open ocean. The hills and mountains that bound the narrow straits were covered by lush forest, and waterfalls drained the slopes. We passed the Darwin mountains – I am told – and several glaciers. It was a spectacular passage. We were exited to see that night, only to enter the waterways again and to sail in the Beagle Channel past Ushuaia to Puerto Williams, where we docked and went ashore for some hours. We were supposed to leave that night again, but were delayed by stormy weather in the Drake Passage….

We woke at 01:00 AM on 29 November and were ready to go to the island at 02:30 when the zodiac and barge were put to sea. We waved our goodbyes and off we went, like conquering Vikings, splashing into the waves, and speeding to the shore. The barge is called a SKUA, but looked a little like the boats used at Normandy during the Second World War. Fortunately, we had no enemy force shooting at us; instead, Pintado petrels swooped along with us and glided above and ahead without flapping a wing. The fog was thick over the island, which looked inhospitable and cold with snow covering most of the ground. We turned close to the shore and returned to the barge, to tell them where to land. They had engine trouble, with only one of the engines working. We circled them like a vulture waiting for an animal to die. Then we tried to push to barge to shore with our zodiac. We proceeded some distance, but finally the Armada – the Chilean navy – decided to abort the attempt. We were so close.
Communication was difficult – Spanish and English. It took us some 30 minutes to get the barge back to the waiting ship. Our driver thought that the best way to turn the barge was to ram it. At one point we were nearly sunk by the barge as we carelessly drifted in front of it. We were back on the ship, somewhat shell-shocked that we had come so close to being landed but then our attempt was thwarted by an engine, not an uncontrollable variable like weather. The ship lifted anchor and immediately sailed for Fildes Station on King George Island. 

We successfully landed on the night of 30 November / 1 December, now nearly two weeks ago. We have settled in, and during a couple of good weather days deployed some 30 tags on penguins, and a camera.
We are currently inhabiting the old Argentinean hut, but will set our tents as soon as we get a decent weather break that does not require immediate work. Though cold and run down (the hut’s door fell off the hinges earlier today, but we have repaired it (like biologists, not engineers)) it has been a great comfort during this first weeks.
Regards from Harmony Point,
Chris 

 An image from a chinstrap penguin equipped with an underwater camera.

An image from a chinstrap penguin equipped with an underwater camera.

MIMMP contributing to krill fishing/predator study in Antarctica

15826338_10211905913225998_4536208926639912930_n.jpg

This summer, MIMMP postdoctoral fellow Chris Oosthuizen is partaking in a multinational expedition in the West Antarctic Peninsula which aims to uncover predator-prey relationships that can be used in feedback management of the krill fishery in this region of the Southern Ocean. The invitation to participate in the expedition arises from the MIMMP’s current collaboration with Dr Andrew Lowther of the Norwegian Polar Institute (NPI) within the South African National Antarctic Programme (SANAP) framework. The Chilean Antarctic Institute (INACH) and Chilean navy support this cooperation by providing logistical support to the expedition.

The large, multidisciplinary expedition in the Bransfield Strait spans most of the short Antarctic summer, from November 2018 to end February 2019. Using miniaturized telemetry devices, teams located on three different islands within the Bransfield Strait will study the foraging behavior of krill-dependent predators. Concurrently, the spatial distribution and abundance of the krill prey field will be obtained through ship-based acoustic monitoring. By combining predator foraging behaviour data and acoustic monitoring data, the spatio-temporal overlap between at-sea habitat use of penguins and fur seals and krill fishing effort can be estimated. The data on predator foraging behaviour collected during this (and past) field season(s) will assist in the development of spatially and temporally relevant feedback strategies for long-term management of the krill fishery, including the planning process for Marine Protected Areas (MPA’s).

 Chinstrap penguin (Chris Oosthuizen)

Chinstrap penguin (Chris Oosthuizen)

Chris (MIMMP, South Africa) will be based at Harmony Point on Nelson Island for the duration of the expedition, along with William Jouanneau (France) and Lucas Kruger (INACH, Chile).  Nelson Island is part of the South Shetland Islands, and an Antarctic Specially Protected Area. Though most of Nelson Island is covered by glaciers, Harmony Point is ice-free and supports breeding colonies of 12 seabird species, among which one of the largest single colonies of chinstrap penguin (Pygoscelis antarctica) in Antarctica. Large giant petrel (Macronectes gianteus) and gentoo penguin (Pygoscelis papua) colonies also occur here. Seals do not breed here, but often haul out to rest. Harmony Point is botanically interesting too, as moss carpets, as well as lichens, fungi and two species of vascular plants, occur here. There is no field station Nelson Island and thus the team will camp for the duration of the expedition.  

South Africa is further represented on this expedition by Dr Azwianewi Makhado from the Department of Environmental Affairs (DEA), who was a MIMMP sealer on Marion Island in 1999/2000. Together with Audun Narvestad (NPI, Norway) and Magdalena Huerta (INACH, Chile), Dr Newi Makhado will be camping on Kopaitic Island near the Bernardo O’Higgens Base (Chile) on the Antarctic Peninsula. The final team, comprising Dr Andrew Lowther (NPI, Norway) and Dr Heidi Ahonen (NPI, Norway) set up camp at Deception Island on 23 November.

The Harmony Point and Kopaitic Island teams sailed from Punta Arenas (Chile) on 24 November aboard the Frigate Achilles. They arrived at the South Shetland Islands on 29 November having navigated the Beagle Channel and Drake Passage on the way.

More updates coming soon!

Chris Oosthuizen wins British Ecological Society 2018 photo competition!

 “ Stand out from the crowd ” by Chris Oosthuizen. Overall winner of the 2018 BES photographic competition.

Stand out from the crowd” by Chris Oosthuizen. Overall winner of the 2018 BES photographic competition.

MIMMP postdoc, Dr. Chris Oosthuizen, has been announced as the overall winner of the British Ecological Society Annual Photography Competition 2018, for his image “Stand out from the crowd”!!

 “ Stinkpot special: Penguin a la King ” by Chris Oosthuizen, winner of the Dynamic Ecosystems category within the BES 2018 photographic competition.

Stinkpot special: Penguin a la King” by Chris Oosthuizen, winner of the Dynamic Ecosystems category within the BES 2018 photographic competition.

As if that is not wonderful enough, he also topped the “Dynamic Ecosystems” category with a winning shot entitled “Stinkpot special: Penguin a la King”, showing a Giant petrel preying on a king penguin chick at Marion Island.

For further interesting details behind these remarkable photos read this article.

To view all winning images visit the British Ecological Society website.

Blond pups and population recovery in Antarctic fur seals

  A. gazella

A. gazella

Evaluating how populations are connected by migration is important for understanding species resilience in changing environments. Gene flow can help recovery from demographic declines, sometimes quite dramatically as in the case of Antarctic fur seals (Arctocephalus gazella). In a study now published in Royal Society Open Science an international team (including the MIMMP) investigated the extent to which migration may have contributed to the global recovery of this circumpolar distributed marine mammal that was brought to the brink of extinction by the sealing industry in the eighteenth and nineteenth centuries. It is widely believed that animals emigrating from South Georgia, where a relict population escaped sealing, contributed to the re-establishment of formerly occupied breeding colonies across the geographical range of the species.

2006_04_25_Blondie 1.JPG

To investigate this, we interrogated a genetic polymorphism (S291F) in the melanocortin 1 receptor gene, which is responsible for a cream-coloured phenotype that is relatively abundant at South Georgia and which appears to have recently spread to localities as far afield as Marion Island in the sub-Antarctic Indian Ocean. By sequencing a short region of this gene in 1492 pups from eight breeding colonies, we showed that S291F frequency rapidly declines with increasing geographical distance from South Georgia, consistent with locally restricted gene flow from South Georgia mainly to the South Shetland Islands and Bouvetøya. The S291F allele was not detected farther afield, suggesting that although emigrants from South Georgia may have been locally important, they are unlikely to have played a major role in the recovery of geographically more distant populations.

Hoffman et al. 2018 Royal Society Open Science  (http://rsos.royalsocietypublishing.org/content/5/10/181227)

http://rsos.royalsocietypublishing.org/content/5/10/181227

Field assistant posts for Marion Island 2019-2020 - CLOSED

Research, People and structures_ (5).JPG

Three field assistant positions (2 x "Sealers" and 1 x "Whaler") are once again available at Marion Island, April 2019 - May 2020. All three positions are embedded within the research programme: "Marion Island Marine Mammals: Individual Variation and Population Processes in Changing Environments", maintained through the University of Pretoria.

For instructions please read the advertisements carefully here:

Mammalogist- Seals

Mammalogist- Killer Whales

Application link  below:

APPLICATIONS MUST BE SUBMITTED VIA OUR ONLINE SYSTEM*(click on text to redirect).

DEADLINE: 30 September 2018

*Emailed submissions will not be accepted.

An overview documentary of what you might expect in these positions can be viewed here and further insight about our science gained by listening to a public talk (here) or viewing our publications. Additional information about the positions and a background to the  programme can be found on our programme history, 'working with us' and FAQ pages.

If you want a good idea of what life as a sealer is all about on Marion, consider purchasing a copy of our book - 'Pain forms the Character' 

MIMMP postdoc Chris Oosthuizen in Svalbard, Arctic!

The MIMMP has a long history of conducting research in the sub-Antarctic and Antarctic ecosystems; one of our flagship projects, the demographic study of Marion Island’s southern elephant seal population, is now continuing into its 35th consecutive year. But we are always interested in collaborating with other research teams. For example, Marion Island sealers were represented on all seven of the seal and seabird research expeditions undertaken by the Norwegian Polar Institute (NPI) at Bouvetøya between 1996/97 and 2017/18. We have less experience of working in the Arctic, but it is within the context of our Bouvetøya collaboration that Chris Oosthuizen (current Marion Island Marine Mammal Programme postdoctoral researcher) recently found himself in the Svalbard Archipelago.

 Spitsbergen is the largest island of the Svalbard archipelago (Photo: Chris Oosthuizen)

Spitsbergen is the largest island of the Svalbard archipelago (Photo: Chris Oosthuizen)

 Dr Andrew Lowther at the team’s campsite on Midtøya. (Photo: Chris Oosthuizen)

Dr Andrew Lowther at the team’s campsite on Midtøya. (Photo: Chris Oosthuizen)

 Location map of Norway and Svalbard (encircled). (Image: Wikimedia Commons)

Location map of Norway and Svalbard (encircled). (Image: Wikimedia Commons)

Svalbard is a large archipelago located in the Arctic Ocean north of continental Norway. At 78°N, Longyearbyen on the island Spitsbergen is the northernmost year-round settlement on Earth and only 1300 km from the North Pole. Chris was invited to participate in the Svalbard expedition by Dr Andrew Lowther of the Norwegian Polar Institute, with whom he has worked on Bouvetøya for two summer seasons. Dr Lowther is leading a project investigating the impacts of drones (Unmanned Aerial Vehicles) on marine mammals in terms of disturbance and the use of drones as alternate research platforms. This project aims to provide best practise guidelines regarding the appropriate use of drones around wildlife by developing flight profile standards that are 1) capable of delivering scientific goals and 2) create insignificant levels of disturbance when used in both scientific and a recreational setting. For the work conducted during May and June, the team camped near a harbour seal colony on Midtøya, a small island adjacent to Prins Karls Forland. This is the only harbour seal colony in Svalbard and the northernmost one in the world.

 A drone passes over hauled out harbour seals during behavioural experiments. (Photo: Chris Oosthuizen)

A drone passes over hauled out harbour seals during behavioural experiments. (Photo: Chris Oosthuizen)

Managing for change: Using vertebrate at sea habitat use to direct management efforts

2011_12_P103092IMG_0098.JPG

Another Antarctic fur seal research output from our productive and ongoing collaboration with colleagues from Australia, the UK and USA. Here, Ben Arthur and co-authors put forward data on changing foraging patterns in the species from three Southern Ocean localities (including Marion Island) over several decades, and include some thoughts on management implications.

For the full article please see the following link: https://www.sciencedirect.com/science/article/pii/S1470160X18302735

Bigger is better: heavier seal pups gain a double advantage

2016_10_14_COosthuizen_KingGeorge_0821.jpg

A new study led by MIMMP postdoctoral fellow Chris Oosthuizen and published in the journal Oikos shows that size matters in more than one way for elephant seal pups.

This paper used data collected over a 30-year period to determine the relationship between weaning mass and fitness in elephant seal pups from Marion Island. Pups were marked and weighed at weaning – a considerable task for the sealers in the field given that elephant seal pups weigh 114 kg on average and up to 190 kg at weaning – and then followed through their lives.

 Weaning mass correlated positively with first-year survival (Figure left), but its influence was unimportant for survival of older pre-breeders and breeders. In contrast, a strong positive link persisted between weaning mass and the age of first reproduction, which typically occurs at ages three and four in female elephant seals (Figure right).

Weaning mass correlated positively with first-year survival (Figure left), but its influence was unimportant for survival of older pre-breeders and breeders. In contrast, a strong positive link persisted between weaning mass and the age of first reproduction, which typically occurs at ages three and four in female elephant seals (Figure right).

Heavier female elephant seal pups survived better in early life and started breeding at a younger age than lighter-weaned pups. The importance of weaning mass on early survival has been reported previously, but this paper draws particular attention to the previously unknown influence of weaning mass on the age at first reproduction. This is a noteworthy finding considering that recruitment only occurs several years after weaning, and because pre-recruitment mortality already imposed a strong selective filter on the population. Reproductive parameters such as age of first reproduction typically impact fitness less than survival in long-lived species, but still influences the dynamics of populations through ensuing effects on other traits (e.g., tradeoffs between reproduction and survival). In growing populations, however, early reproduction increases fitness, indicating the importance of taking the timing of reproduction within the life cycle of an organism into account.

Although variation in weaning mass did not translate to permanent survival differences among individuals in adulthood, it explained heterogeneity and positive covariation between survival and breeding in early life, which contribute to between-individual variation in fitness. Mothers that do not allocate sufficient energy to their pups thus risk reducing their own fitness through lower offspring survival and delayed breeding among surviving offspring.

Talk by Prof Nico de Bruyn: Seals and killers in the roaring forties

Join us at The Orbit in Braamfontein on the 27th of February to listen to Prof Nico de Bruyn talk about seals and killers in the roaring forties.

In this talk, Nico de Bruyn will give us a whirl-wind tour of the research that has driven three decades of scientific inquiry into the population dynamics of mammalian marine top-predators and explain how this research has helped to answer questions of global significance from a region experiencing increased environmental change.

2011_08_a.JPG

This talk is hosted Science & Cocktails which is an initiative that brings science and entertainment closer together by creating a series of public lectures intertwined with music/art performances and smoky dry-ice chilled cocktails in your hand.

Entrance to the event costs R20. Doors open at 18:30, no admittance after 20:00. For more info go to http://www.scienceandcocktails.org/jozi/2018/MarionIsland.html

See you there!

Mammals moving in the Anthropocene: new paper in SCIENCE

Sometimes a collaboration that started on one topic can turn into something productive on a somewhat different one! A paper published today in the journal Science, on which MIMMP PI, Nico de Bruyn, is a coauthor represents such a case. This paper, led by Marlee Tucker, uses tracking data from multiple terrestrial mammals to show that humans are causing major changes in the way wild mammals move in the landscape.  

Clearly, this terrestrially centered paper does not contain data from our Marion Island marine mammals. It was a collaboration started years ago with Marlee Tucker, using some tracking data from Marion Island seals (not used here), that resulted in Nico's intellectual involvement here. This paper makes for an interesting read and brings to mind the question of how the marine environment might compare........  

New study published on habitat importance for multiple marine predators

 Fig 1 taken from Reisinger et al (2017)  Diversity and Distributions , showing the tracks of 14 species of marine vertebrate predator over a decade.

Fig 1 taken from Reisinger et al (2017) Diversity and Distributions, showing the tracks of 14 species of marine vertebrate predator over a decade.

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. Research collaborator (and past student) of the MIMMP, Dr Ryan Reisinger along with a multinational research team used tracking data from 538 tag deployments on 14 species of marine predators from the Subantarctic Prince Edward islands to identify important habitat. Tracks were modelled as a response to 17 relevant environmental factors to identify such important habitat. The study, recently published in the journal Diversity and Distributions , helps to form the basis of future efforts to predict the consequences of environmental change.

Image 1.png

Tracking locations covered 39.75 million km2, up to 7,813 km from the Prince Edward Islands. Areas of high importance were located broadly from the Subtropical Zone to the Polar Frontal Zone in summer and from the Subantarctic to Antarctic Zones in winter. Such areas of importance were best predicted by factors including wind speed, sea surface temperature, water depth and ocean current speed.

To read the full story go to: http://onlinelibrary.wiley.com/doi/10.1111/ddi.12702/full

Prof Nico de Bruyn-category winner in a prestigious photographic competition!

Scientists from across the world were asked to submit their photographs for the 2017 Royal Society Publishing Photography Competition. The MIMMP's Principal Investigator, Prof Nico de Bruyn, was awarded the winner of the "Ecology and Environmental Science" category. The MIMMP team would like to congratulate Professor de Bruyn on this prestigious award! Please see the link below for the winning picture.

https://royalsociety.org/~/media/journals/photo-competition/2017-winners/5098.jpg

https://royalsociety.org/journals/publishing-activities/photo-competition/2017-winners-runners-up/

Field assistant positions for Marion Island 2018-2019- CLOSED

2011_09_27_9999_274thh.jpg

Three field assistant positions (2 x "Sealers" and 1 x "Whaler") are once again available at Marion Island, April 2018 - May 2019. All three positions are embedded within the research programme: "Marion Island Marine Mammals: Individual Variation and Population Processes in Changing Environments"

For instructions and more information:

Mammalogist- Seals

Mammalogist- Killer Whales

Please read the advertisements carefully and follow the application instructions therein.

 An overview documentary of what you might expect in these positions can be                       viewed here and further insight about our science gained by looking at our                           publications. Additional information about the positions and a background to the               programme can be found on our programme history, 'working with us' and                           FAQ pages.

If you want a good idea of what life as a sealer is all about on Marion, consider purchasing a copy of our book - 'Pain forms the Character' 

Inquiries and cover letters may be sent to Ms Kate du Toit (katedutoit@hotmail.com) and cc to the Principal Investigator of this specific project: Prof Nico de Bruyn (pjndebruyn@zoology.up.ac.za).

DEADLINE: 20 November 2017

MIMMP science putting Subantarctic animals on the map!

 Figure 1: From top left going clockwise, the Subantarctic fur seal, Antarctic fur seal, Killer Whale and Southern Elephant Seal.

Figure 1: From top left going clockwise, the Subantarctic fur seal, Antarctic fur seal, Killer Whale and Southern Elephant Seal.

MIMMP scientists have been involved in updating the Mammal Red List for the Endangered Wildlife Trust (EWT). These assessments are vital to assess the conservation status of a particular species. Scientists from the MIMMP were responsible for the assessments of four Subantarctic species, namely, the Antarctic and Subantarctic fur seal, the Southern Elephant Seal and the Killer Whale. Using long-term data gathered over the years by the MIMMP team, scientists are able to determine things such as population size, habitat use, distribution and the overall National Red List Status of each species. This information also provides critical information for future research targets and the state of the species living in the Southern Ocean.

If you would like to read more about the MIMMP Red List species please see the links below:

https://www.ewt.org.za/Reddata/Order%20Carnivora.html

https://www.ewt.org.za/Reddata/Order%20Cetacea.html

MEOP - Marine Mammals Exploring the Oceans Pole to Pole

 A CTD-SRDL device attached to a southern elephant seal on Marion Island

A CTD-SRDL device attached to a southern elephant seal on Marion Island

MEOP is an unprecedented collaborative effort! It is a consortium of international researchers dedicated to sharing animal-derived data and knowledge about the polar oceans. The MIMMP has been a key player in this global effort. A recent review of this MEOP (Marine Mammals Exploring the Oceans Pole to Pole) project, published in Oceanography, was spearheaded by MIMMP postdoc, Dr Anne Treasure! https://doi.org/10.5670/oceanog.2017.234 

The physical structure of the polar oceans plays a crucial role in the global ocean and climate system. Nevertheless, the polar seas are notoriously poorly sampled due to difficulties with data collection, such as high costs, logistic issues and rough weather. Marine mammals equipped with biologging devices provide a solution to this problem. The devices, conductivity-temperature-depth satellite relay data loggers (CTD-SRDLs), record location with vertical profiles of conductivity (from which salinity is calculated), temperature and pressure. Since 2002, marine mammals have provided novel observations of polar regions, including areas that are logistically difficult to sample (Fig. 2). In this way, the addition of marine mammals to the global array of ocean profilers (such as traditional Argo floats) provides a powerful and cost-effective means to drastically improve the ocean-observing system for both biological and physical oceanography communities.

 Figure 2: The data density distribution of CTD profiles from the Marine Mammals Exploring the Oceans Pole to Pole (MEOP)-CTD database.  

Figure 2: The data density distribution of CTD profiles from the Marine Mammals Exploring the Oceans Pole to Pole (MEOP)-CTD database.  

Instrumented animals have already generated extremely large sets of oceanographic data which are now freely available to the scientific community through the MEOP data portal (http://meop.net). The comprehensive quality-controlled MEOP database contains over 500 000 CTD profiles and is an exceptional resource for both biological and physical oceanographers.

Getting to the tip of the whisker…. Confirming the crustacean-based diet of juvenile southern elephant seals Mirounga leonina

How large is the contribution of crustaceans (krill) to the diet of juvenile southern elephant seals (SES) at the Subantarctic Marion Island?

Whiskers tell us what elephant seals eat.. and when!

 Juvenile southern elephant seals Mirounga leonina from Marion Island. Photo credit Nico Lubcker

Juvenile southern elephant seals Mirounga leonina from Marion Island. Photo credit Nico Lubcker

In this novel paper, we used the nitrogen and carbon stable isotope values measured chronologically along the length of whiskers sampled from juvenile southern elephant seals Mirounga leonina to test the recent suggestion that they “represent a new krill predator within the Southern Ocean” (Walters et al. 2014). Stable isotope analysis is based on the principle ‘you are what you eat’, and we have reconstructed the diet of juvenile SES based on the biomolecule composition of their whiskers. This paper follows from an earlier study that quantified the regrowth rate of the whiskers sampled from the juvenile SES (Lübcker et al. 2017). This first, time-integrated dietary reconstruction of juvenile SES at Marion Island showed that they consumed prey from a lower trophic level than previously assumed.

 Fig. 2. Representation of data indicating the 3 isotopically distinct portions of the vibrissal regrowths collected from juvenile southern elephant seals Miro - unga leonina. Life history events can be distinguished based on δ15N (mean ± SD) measured along the length of the vibrissae. The onset (indicated by the arrow) of the independent foraging (transitioning period) is characterised by a 3.7‰ δ15N depletion and we used only the period representing independent foraging for dietary reconstruction (red box). The solid black line with grey error bands represents the 15N mean ± SD of all the sampled juveniles

Fig. 2. Representation of data indicating the 3 isotopically distinct portions of the vibrissal regrowths collected from juvenile southern elephant seals Miro - unga leonina. Life history events can be distinguished based on δ15N (mean ± SD) measured along the length of the vibrissae. The onset (indicated by the arrow) of the independent foraging (transitioning period) is characterised by a 3.7‰ δ15N depletion and we used only the period representing independent foraging for dietary reconstruction (red box). The solid black line with grey error bands represents the 15N mean ± SD of all the sampled juveniles

The depleted stable isotope values of nitrogen (δ15N) (8.5 ± 0.6‰) measured in their whisker during the independent foraging period confirmed that up to 76% of their diets consisted of crustaceans, presumably Subantarctic krill species. This is contrary to earlier studies which suggested that they consumed mostly lantern fishes and squid. This first utilisation of the isotopic values captured along the length of whisker regrowths confirms the inclusion - and importance - of crustaceans in the diet of juvenile SES and has important implications for their conservation.

Read the full story here:

Marine Ecology Progress Series https://doi.org/10.3354/meps12240

Of Man, seals, cats and mice: Mongabay news commentary

 Feral cats are long gone from Subantarctic Marion Island. Photo: Valdon Smith, courtesy of the Antarctic Legacy of South Africa

Feral cats are long gone from Subantarctic Marion Island. Photo: Valdon Smith, courtesy of the Antarctic Legacy of South Africa

Many Subantarctic islands have historically felt the effects of seal hunters and the purposeful or accidental introduction of alien mammals. Mice, rats, rabbits, cats, goats, sheep, deer, cows... the list goes on, and the effects have often been devastating to native fauna and flora. Given the contemporary understanding of the negative effects of invasive species, many nations have increasingly ambitious eradication programmes. These are wise investments. Read why the Marion Island story is one to learn from at leading enviro-news website: Mongabay.

Elephant seals show remarkable consistency in 3D foraging behaviour!

In a changing ocean environment, would a deep-diving top predator consistently return to specific areas to find food? Would such a predator show consistent diving behaviour over multiple foraging trips? In the face of rapid environmental change, these were questions we were interested in exploring for southern elephant seals at Marion Island, using tracking and diving data spanning several years. 

 A young male southern elephant seal sporting a  SMRU tracking device . Photo: Nico de Bruyn

A young male southern elephant seal sporting a SMRU tracking device. Photo: Nico de Bruyn

Individual-level specialization in forage strategies may confer advantages to individual animals over longer time periods, even though it may also incur shorter-term costs. In a recently published paper in the journal Animal Behaviour, we illustrate long-term (up to 7-year!) fidelity of individual elephant seals to not only their foraging ranges, but also the depth layers targeted during foraging migrations. We hypothesize that the strong fidelity displayed by individual animals may limit the individual-level adaptability of elephant seals to rapid environmental changes. Furthermore, we recommend more long-term longitudinal studies to quantify the influence of individual specialization on our understanding of the population-level ecology of elephant seals, as well as other key predators.

Killer whale social life at Marion Island

 Marion Island killer whale Social Networks.  Reisinger  et al.  2017  Behavioral Ecology

Marion Island killer whale Social Networks. Reisinger et al. 2017 Behavioral Ecology

Killer whales are considered highly social animals, however, social structure has been quantitatively studied in few populations. We have been running a photographic identification programme of killer whales at Marion Island in the Southern Ocean since 2006, and we recently used this dataset to explore how individuals associate with each other and how this correlates with their genetic relatedness. In a new paper published in the journal Behavioral Ecology we show that killer whales at Marion Island have small social modules which are mostly stable over years, but that these can be dynamic over shorter time periods. This may be a response to environmental conditions. The social modules which we identified comprise non-kin as well as kin, in contrast to the highly matrifocal structure in some other killer whale populations.

Kinship and association in a highly social apex predator population, killer whales at Marion Island

Ryan R. Reisinger, Charlene Beukes (née Janse van Rensburg), A. Rus Hoelzel and P.J. Nico de Bruyn

Behavioral Ecology

https://doi.org/10.1093/beheco/arx034