ANTARCTICA

Antarctic and antarctic biology and research have fascinated marine biologists for many years. While much of the Antarctic biota contains representatives that are familiar to us, the realm is very much isolated from the rest of the ocean, and several groups are confined to this southern end of the planet. It may surprise you that the Antarctic benthos is very diverse and extraordinarily beautiful, despite the extreme cold. A very productive water column provides in many areas a rich source of sedimenting organic matter for soft bottom benthos and a source of food for suspension-feeding animals. Thus we find a diverse community of benthic particle consumers and their predators. Of course the great ice cap, with its extremes of climate and local biota, has the greatest of fascinations. Every spring the edge of the ice cap begins to break and ships can approach the few research stations, such as the one at McMurdo Sound. In recent years the breakup of the ice has drawn special attention, owing to concerns about global warming.

 

What follows is a taste of the Antarctic biota.


 


Breakup of Ice, 1995

Photograph by Diane Stoecker


Minke Whale at Ice Edge

Photograph by Diane Stoecker


Adelie Penguins

Photograph by Diane Stoecker


Rookery of Adelie Penguins at McMurdo Sound

Photograph by Diane Stoecker


Sampling the water column at the ice edge

Photograph by Diane Stoecker


Dog skeleton - the dry cold climate results in many mummified carcasses that are found throughout Antarctica. Some areas are so dry that their climate has been likened to what might be expected on the Martian surface.

Photograph by Richard B. Aronson


Emporer Penguin

Photograph by Peter Ritchie


Antarctic Seal

Photograph by Peter Ritchie


Diver preparing to enter through a hole in the ice

Photograph by Diane Stoecker


Diving under an ice crack in Granite Harbor

Photograph by Richard Aronson


Seascape with the vase sponge Scolymastra joubini at 70 feet depth, Granite Harbor

Photograph by Richard Aronson


Ice and Brine Microorganisms

Photograph by Diane Stoecker

A flagellate- and ciliate-dominated microbial community has recently been described from brine channels and pockets in the upper land-fast ice in McMurdo Sound. This community has similarities to the assemblages reported from antarctic pack ice. An important feature of this community is the dominance of athecate, photosynthetic dinoflagellates. Above is a vegetable cell and below is a cyst. Bar is 10 micrometers long in both photos.



A group of the seastar Odontaster validus with the nermertean (purple) Parborlasia corrugatus

Photograph by Richard Aronson


The Cactus Sponge Dendrilla membranosa

Photograph by Richard Aronson


The Vase Sponge Scolymastra joubini

Photograph by Richard Aronson


The anemone Urcticinopsis antarctica

Photograph by Richard Aronson


The polychaete Flabelligera sp.

Photograph by Richard Aronson


The isopod Glyptonotus antarcticus

Photograph by Richard Aronson


Seascape, dominated by the Octocoral Alcyonium paessleri (light yellow)

Photograph by Richard Aronson


The pycnogonid Thavmastopygnon striata

Photograph by Richard Aronson


Unidentified Octopod

Photograph by Richard Aronson


The sea urchin Sterechinus neumayeri

Photograph by Richard Aronson


Group of the seastar Odontaster validus

Photograph by Richard Aronson


Special Physiological Features of Antarctic Fishes

Shallow-water members of the Antarctic suborder Notothenioidei include a number of species that have special physiological properties that apparently evolved for survival in cold water. Recall that the Antarctic Ocean surface waters are quite cold, and close to the freezing point of seawater. Bony fish have the special problem of having cellular fluids whose freezing point is higher than that of seawater. Because salt lowers the freezing point of seawater, the seawater surrounding the fish may actually be in a liquid state at a temperature at which water would normally freeze within the fish. This is a special problem for shallow-water fishes that must ingest seawater for osmotic balance and inevitably ingest ice crystals, which would nucleate further freezing within the body.

Trematomus bernachii

Photograph by Richard Aronson

This and other members of this genus synthesize special glycoproteins, which behave like an automobile antifreeze.

Trematomus hansoni

Photograph by Ian McDonald

 

Pagothenia borchgrevinski

Photograph by Ian McDonald

This species also contains glycoproteins, which prevent freezing of cellular fluids.

Photograph by Peter Ritchie

This shows a sample of blood of a species of Channichthyid fish, compared with a vial of blood from a more typical fish. Why do you think this fish and others, who live in icy surface waters, lack hemoglobin?

Photography by Peter Ritchie

A pool of P. borchgrevinski