The Antarctic Marine Food Web – scientific issue by British Antarctic Territory

The Antarctic Marine Food Web – scientific issue by British Antarctic Territory
6 votedvote

StampNews.com got information that British Antarctic Territory Post has released six stamps on theme "The Antarctic Marine Food Web". It is believed to be a real scientific stamp issue that is dedicated to the study of food chains and food webs in general.

In this case, the Southern Ocean makes an excellent case-study: the feeding relationships are relatively simple, the diversity of species is not particularly high, and some food chains consist of few trophic levels.

When examining the feeding relationships within an ecosystem, it is important to be aware of the distinction between a food chain and a food web. A food chain is a linear transfer of energy (in the form of food) from the autotroph (self-feeding organism) at the bottom, through the primary consumer, secondary consumer, and perhaps tertiary consumer at the top. Using the example of baleen whales, the food chain simply consists of phytoplankton → krill → whale: three types of organisms representing three trophic levels.

Within the Southern Ocean ecosystem, a longer chain involves phytoplankton → krill → fish → penguin → killer whale. To complicate matters, some organisms may feed at different levels along the chain, such as penguins which eat both fish and krill. The food web, therefore, is a way of depicting the multiple food chains that exist within an ecosystem and the complex interrelationships between different organisms.

Phytoplankton underpin the Southern Ocean food web by fixing the energy from the Sun into chemical energy. The main consumers of phytoplankton in the Southern Ocean are zooplankton and crustaceans, such as copepods and krill. Antarctic krill is a shrimp-like crustacean, measuring about 6cm long, that dominates the primary consumer level in the Southern Ocean ecosystem.

Although numbers of krill fluctuate, there are likely to be over 500 million tonnes of krill in the Southern Ocean. Krill plays a central role in the ecosystem as a key source of food for many other animals:

  • Fish – e.g. the Antarctic cod.
  • Squid – Very abundant in the Southern Ocean. There are many species of squid and they can range in size from 15cm to over 15m in length.
  • Whales – Baleen whales such as the blue, humpback, fin, and minke have evolved mouths with fibrous plates instead of teeth that enable them to filter out huge quantities of krill from the ocean. During the main feeding season, a blue whale consumes about 3,600kg of krill a day!
  • Seals – The crabeater seal in particular relies almost exclusively on krill. The 'crab' in its name comes from the word 'krebs' in German, which is a general term for crustaceans, not because the seal eats crabs! It is the most abundant species of seal in the world, and consumes more krill than all of the baleen whales put together.
  • Penguins – There are 17 different species of penguin (all in the Southern Hemisphere) but only five breed along the continent and/or the Antarctic Peninsula (emperor, Adélie, gentoo, chinstrap, macaroni). In the Antarctic, penguins (especially the Adélie) feed on krill as well as on fish and squid.

In turn, these krill-eating animals are the prey for animals higher up the trophic ladder. For example, among other things, killer whales hunt seals, squids, and penguins; and seabirds (such as the albatross) hunt fish and squid.

In turn, these krill-eating animals are the prey for animals higher up the trophic ladder. For example, among other things, killer whales hunt seals, squids, and penguins; and seabirds (such as the albatross) hunt fish and squid.

The Antarctic Marine Food Web - Block of stamps

Leave a Comment

error: Alert: Content is protected!