Antarctic crustaceans-sea snails relationship


This video says about itself:

10 September 2018

Pteropod mollusks such as Clione and Spongiobranchaea produce chemical compounds that are known to deter other organisms and prevend the pteropods from being eaten. This molecule is called pteroenone a ketone that deters many predators such as icefish.

Hyperiid amphipods are common prey of icefishes, other fish and seabirds of the Southern Ocean.

To protect themselves, some, called Hyperiella, have evolved the habit of abducting pteropods, and carrying them around on their back. It was shown that fish catching such a tandem, immediately release it.

From the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in Germany:

‘Kidnapping’ in the Antarctic animal world?

A puzzling relationship between amphipods and pteropods

September 10, 2018

Pteropods or sea snails, also called sea angels, produce chemical deterrents to ward off predators, and some species of amphipods take advantage of this by carrying pteropods piggyback to gain protection from their voracious predators. There is no recognisable benefit for the pteropod. On the contrary they starve: captured between the amphipod’s legs they are unable to feed. Biologists working with Dr Charlotte Havermans at the Alfred Wegener Institute have investigated this phenomenon as part of a cooperation project with the University of Bremen. In an article in the journal Marine Biodiversity, they talk about kidnapping and explain the potential advantages of this association for both the host and its passenger.

Amphipods of the suborder Hyperiidea are popular prey for fish and sea birds. They play an important role in the Southern Ocean food web, which is why biologist Dr Charlotte Havermans is investigating the distribution, abundance and ecological role of various species of amphipods. To do so, she is taking samples on board the Research Vessel Polarstern from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI). She works at the University of Bremen’s working group Marine Zoology. The project is funded by the DFG (German Research Foundation) in the Priority Programme on Antarctic Research.

During a Polarstern expedition that took place in the austral summer from 2016 to February 2017, she made an extraordinary discovery: “A few of the amphipods carried something unusual on their backs. On closer inspection I realised that they were carrying pteropods piggyback,” reports the biologist. A literature search revealed that US researchers had already described this behaviour back in 1990 — although only for the high-Antarctic coastal waters and not for the open Southern Ocean where the ship was underway.

“We were wondering whether these tandems occur as frequently in the open ocean as in coastal waters — and whether both animals benefit from the relationship,” explains Charlotte Havermans. In the coastal areas of the McMurdo Sound, most of the amphipods studied carried a pteropod rucksack. Subsequent genetic and morphological investigations provided new insights. Previously, such tandems were completely unknown for the open, ice-free waters of Southern Ocean, and now the biologists have discovered this behaviour in two species: the amphipod species Hyperiella dilatata carried a type of pteropod known as Clione limacina antarctica, while the crustacean Hyperiella antarctica was associated with the pteropod Spongiobranchaea australis. Our sample size was too small to say without doubt whether these are species-specific pairs, where only a certain amphipod carries a certain pteropod species. During the expedition along the Polar Front to the eastern Weddell Sea, the AWI biologist’s team found only four such tandems.

The research team’s findings regarding the benefits for the animals are very exciting. Behavioural observations of the free-living pteropods show that cod icefishes and other predators are deterred by the chemicals the gastropods produce. When amphipods take pteropods “hostage”, they are not affected by their poison. Icefishes quickly learn that amphipods with rucksacks are not tasteful and so avoid those with a pteropod on their back.

Because the conditions in the open Southern Ocean are different to those in coastal ecosystems, several open questions remain: whether or not predatory squid and lanternfish, commonly found in the area, are also deterred by the chemicals has not yet been investigated. It is also still unclear to which extent the pteropod benefits from saving energy by being carried by its host. The researchers observed that the amphipod uses two pairs of legs to keep the gastropod on their back so that they are completely unable to actively hunt for suitable food where it is available. “On the basis of our current understanding, I would say that the amphipods kidnap the pteropods,” sums up Charlotte Havermans with a wink.

The biggest lesson the authors draw from their discovery: “We are probably overlooking numerous such associations between species, because they are no longer visible after net sampling.” Unlike shelled gastropods and crustaceans, which remain relatively intact, jellyfish and other delicate animals are crushed in the nets. “In the future we will hopefully be able to use suitable underwater technologies with high-definition cameras to investigate even the smallest life forms in their habitat. This will provide insights into the numerous exciting mysteries of interspecific interactions, which have so far remained hidden for biologists — but which undoubtedly play an important role in predator-prey relationships in the ocean.”

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Arctic, Antarctic seas, 10 hour video


This 6 June 2018 video is called Frozen Seas: 10 Hours of Relaxing Oceanscapes | BBC Earth.

A bird’s eye view of the Arctic. Unmanned aircraft systems for Arctic research: here.

Antarctic leopard seals, new research


This 2013 video says about itself:

Face-to-Face with a Leopard Seal | Nat Geo Live

Photographer Paul Nicklen receives an unexpected gift … free food from a major predator.

From the British Antarctic Survey:

Secret life of an enigmatic Antarctic apex predator

June 5, 2018

Scientists from British Antarctic Survey (BAS) have, for the first time, tracked the lives of leopard seals as they migrate around Antarctica. The team followed these formidable predators as they move from the frozen Antarctic sea-ice to the more northerly sub-Antarctic islands where they prey on penguins, seals and krill. The study is published this week (Tuesday 5 June) in the journal PLOS ONE.

During the harsh polar winter, leopard seals are regularly sighted on islands such as South Georgia, where BAS scientists have studied them for over 20 years. However, very little is known about their behaviour during the long Antarctic night.

Seal ecologist Dr Iain Staniland, lead author of the study says:

Leopard seals are notoriously difficult to study because they live and hunt in inaccessible places: they are relatively scarce, lead solitary lives and live mostly in the water or ‘hauled out’ on sea ice around Antarctica.

“As one of the Antarctic’s apex predators, leopard seals can have large local impacts on their prey populations. They could be limiting the recovery of some fur seal colonies, for example, and are known to take a significant proportion of penguins from some smaller colonies — around 15% of the colony of gentoo penguins at one study site*. As ocean sentinels, they can reveal a lot about the health of an ecosystem and alert us to problems further down the food chain.”

To find out more about the leopard seal’s distribution and behaviour, the team attached 31 miniature tags to leopard seals between 2003 and 2012. The tags record sunrise and sunset times and have a wet/dry sensor. The tags have a long battery life, enabling them to track leopard seals for extended periods, but they do not transmit data so recovering the data is challenging. It requires that the seals are located and their tags removed while they are sleeping.

To date the BAS team has succeeded in recovering tags from five of the leopard seals. The data recovered shows that during the summer, the seals move south in and around the Antarctic sea ice where they feed on krill and fish and breed. In the winter, as sea ice around Antarctica expands, the seals return to the shallow coastal waters around the Antarctic and sub-Antarctic islands, where penguins, seals and krill provide them with the food they need to survive the long dark Antarctic winter.

As well as recording the complete migration of leopard seals for the first time, the study also reveals they spend up to one-third (31%) of their time out of the water but this behaviour changes markedly throughout the year. This fact will help improve the accuracy of population counts conducted using aircraft and drones.

Dr Iain Staniland continues:

“This study presents several important breakthroughs in our study of these fearsome predators. This is the first long-term deployments of tracking devices on leopard seals, the first opportunity to record the complete annual migration of leopard seals between the Antarctic pack ice and sub-Antarctic islands, and the first to record their haul-out behaviour.

“These findings will enable more robust population size estimates and to assess the role of leopard seals within the Southern Ocean ecosystem. It is a major advance in our knowledge about the secret life of one of the Antarctic’s true ‘apex’ predators.”

When I was in the Antarctic, I was privileged to see a leopard seal on an ice floe.

Antarctic seals help ice sheet research


This video says about itself:

Introduction to Weddell seals

28 October 2010

The southernmost mammal on Earth. Includes footage of Weddell seal mothers and pups, and underwater footage of seals swimming beneath the sea ice. Interview on location with ecologist Jay Rotella on the population study of Weddell seals in the Erebus Bay area of Antarctica’s Ross Sea. This is one of the longest running studies of a long-lived mammal in existence. Video production by Mary Lynn Price.

More information is here.

From the University of East Anglia in England:

Antarctic seals can help predict ice sheet melt

May 15, 2018

Two species of seal found in Antarctic seas are helping scientists collect data about the temperature and salinity of waters around vulnerable ice sheets in West Antarctica.

Environmental scientists at the University of East Anglia (UEA) have been investigating ways of studying warm, salty, deep water in the Amundsen Sea, in the Southern Ocean. Understanding more about how this water gets towards the ice shelves by measuring its temperature, salinity and depth, will help climate change modellers make more accurate predictions about how rapidly the Antarctic ice sheet is melting.

As the ice in west Antarctica melts, it has been estimated that sea levels could rise by up to 3.2 metres, with much of the water draining through two glaciers — Pine Island Glacier and Thwaites Glacier — in the Amundsen Sea. Estimates of future sea level rise vary a lot and scientists need year-round observations to assess and improve climate change models.

Gathering data in summer months is relatively straightforward but getting ships near the area during the winter is impossible because the area is covered in a thick blanket of sea ice. The only information available is from ‘moorings’, strings of measurement devices anchored to the sea floor. These can collect data from a few fixed locations, but they cannot measure near the sea surface at all because the huge icebergs would collide with them.

To address this, the UEA team set up a collaboration with the Sea Mammal Research Unit at the University of St Andrews who were interested in recording the feeding behaviours of seals in the region. The expedition built on an idea originally suggested by scientists at the British Antarctic Survey when they became aware of a large elephant seal haulout on islands near the Pine island Glacier.

Funded by the Natural Environment Research Council‘s Ice Sheet Stability Research Programme (iSTAR), the experiment began in February 2014, when the team tagged seven southern elephant seals and seven Weddell seals with devices that can send information via satellite. Measurements of the warmth and saltiness of the water were sent by the seals as they moved around the area and dived from the surface of the ocean down through the water to the sea bed in their hunt for food.

Over a period of nine months, throughout the Antarctic winter, the team collected data from more than 10,000 dives over an area of around 150,000 square km. The seals continued to send back signals until they moulted and the devices dropped off.

Analysing the findings, published in Geophysical Research Letters, the researchers discovered that not only is the layer of CDW thicker in winter, it is also warmer and saltier than during summer months. This suggests that there is likely to be more melting of the ice sheets during the winter months. The temperature differences were less marked closer to one of the glaciers, in a region called Pine Island Bay, possibly because ocean currents, called gyres, recirculate the water.

“We knew very little about what to expect from this research, since this is the first time that data has been collected in this way in this area,” says Helen Mallett, who led the study at UEA. “We were able to collect much more information from the seals than all the previous ship-based surveys in the area combined and it was clear that, at least during the seasons we observed, there were substantial differences in temperature between the seasons.

“Although more will need to be done to measure these differences over a number of years, it’s clear that enlisting seals to collect this kind of ocean data will offer useful insights for climate change modellers who are attempting to predict how fast sea levels will rise.”

The data will be useful to marine biologists as well, as it will provide new understanding of the foraging behaviour of seals in the Amundsen Sea, and how that might be affected by climate change, as well as commercial fisheries.

The UEA and St Andrews team are heading back to the Amundsen Sea in 2019 to enlist the help of another group of seals to monitor this remote region as part of the recently announced International Thwaites Glacier Collaboration.

Antarctic Deception Island, penguins and volcano


This video says about itself:

Explore Deception Island, the Active Antarctic Volcano That’s Home to [Chinstrap] Penguins | National Geographic

20 March 2018

Over 100,000 breeding pairs of penguins nest on this island—which also happens to be an active volcano.

I had the privilege to see Deception Island and its penguins and other birds.

Over a million Adélie penguins discovered in Antarctic


This 2 March 2018 video says about itself:

Huge penguin colony discovered on remote Antarctic islands

Danger Islands host more breeding pairs of Adélie penguins than rest of the Antarctic Peninsula region combined.

From Scientific Reports today:

Abstract

Despite concerted international effort to track and interpret shifts in the abundance and distribution of Adélie penguins, large populations continue to be identified. Here we report on a major hotspot of Adélie penguin abundance identified in the Danger Islands off the northern tip of the Antarctic Peninsula (AP).

We present the first complete census of Pygoscelis spp. penguins in the Danger Islands, estimated from a multi-modal survey consisting of direct ground counts and computer-automated counts of unmanned aerial vehicle (UAV) imagery.

Our survey reveals that the Danger Islands host 751,527 pairs of Adélie penguins, more than the rest of AP region combined, and include the third and fourth largest Adélie penguin colonies in the world. Our results validate the use of Landsat medium-resolution satellite imagery for the detection of new or unknown penguin colonies and highlight the utility of combining satellite imagery with ground and UAV surveys.

The Danger Islands appear to have avoided recent declines documented on the Western AP and, because they are large and likely to remain an important hotspot for avian abundance under projected climate change, deserve special consideration in the negotiation and design of Marine Protected Areas in the region.

This 2016 is video is called All About the Adélie Penguin | Continent 7: Antarctica.

Antarctic minke whale’s camera video


This video says about itself:

Explore the Antarctic From the Back of a Minke Whale | National Geographic

21 February 2018

Little is known about Antarctica’s elusive minke whales, but for the first time, scientists attached a camera to the back of one of the giant creatures to get a glimpse into their secretive underwater world.