In the Classroom
How do fish in the Southern Ocean keep from freezing?


On Biodiversity

Biodiversity refers to the variety of life and is the shortened form of two words - "biological" and "diversity (1)." Life has many levels of biological diversity, from DNA and genes to species, populations, ecosystems and communities. All these different levels are needed to keep the Earth healthy.

Genetic diversity is the variety of genes within individual plants and animals and between different species. No two organisms are exactly alike, and genetic diversity ensures that parents pass on the traits (such as disease resistance, physical form, etc.) that their offspring need to survive. When small populations are isolated from other populations of the same species, they may be forced to inbreed, possibly leading to loss of genetic diversity and extinction.

Species diversity is the variety of all the different plants and animals, from bacteria to mammals, plants, and everything in between! A species is a group or population of similar organisms that reproduce among themselves but do not naturally reproduce with any other kinds of organisms (for instance, humans, sugar maples, and Atlantic salmon). Species populations are composed of individuals, and the differences among them create diversity within and between species populations. Species diversity insures that necessary ecosystem functions (some only slightly but significantly different) are performed. For example, a leopard seal cannot feed on plankton, and jellyfish cannot eat large fish and penguins. Even among closely related species there are often significant differences in life history or biology that provide variability useful in adjusting to naturally occurring environmental changes.

Ecosystem diversity is the variety of habitats and climates on Earth. An ecosystem is any geographic area, the living organisms that live there, and the nonliving parts of the physical environment. Energy and matter move through and are stored in both living and nonliving things - and their interactions - within ecosystems. Marine ecosystems include coral reefs, estuaries, sea mounts and islands, and deep-sea trenches. The interactions between ecosystems and the species that live in them underpin all life.

The effects of biodiversity help keep our air and water clean, regulate our climate and provide us (and other plants and animals) with food, shelter, clothing, medicine and other useful products. This diversity and its interactions, which ensure the health of the entire planet, make the Aweb of life@ life so complex. For example, oceans absorb carbon dioxide, a well-known greenhouse gas that causes global warming. Wetlands and estuaries act as filters for fresh water and nurseries for marine populations. Without such ecosystems, life today would be very different.

There are numerous threats to biodiversity, many of them the result of a growing human population: there are 6 billion humans today, and that number may reach 9 - 12 billion in the next 50 - 100 years. We use more energy, land, water and natural resources (like trees, fossil fuels, minerals, plants and animals) than ever before, and our consumption and waste contribute to habitat fragmentation and degradation, global climate change, overfishing, hunting and poaching, and introductions of damaging non-native species.

The research performed on the ICEFISH Cruise will cover all levels of biodiversity, thus contributing to our understanding of the potential impact of climate change and other human-cause disturbances on the Sub- and High-Antarctic marine ecosystems.

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