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9.8 Oceanography: 5. Environments and communities

Syllabus reference: (October 2002 version)
5. The physical conditions at different depths in the oceans constitute different environments and can support different communities of organisms	*Students learn to:* describe what is meant by a ‘community of organisms’ review the range of abiotic characteristics of an environment that determines the nature of a community within that environment describe and compare examples of food chains that occur in the top layers of the oceans and those found at great depth, explaining the differences explain, using examples, why organisms living on the ocean floor will be different from organisms living in the top thirty metres of the ocean explain how increased understanding of ocean currents and sea floor topography can change the utilisation of ocean resources by society	Students: process and analyse information on life forms at different depths in the oceans to compare the deep ocean environment and its organisms to that in the top thirty metres of ocean gather and process information and use available evidence to assess the range of resources provided by the ocean, including: fishing and food aquaculture minerals from seawater specific chemicals: sulfur, manganese and heavy metals power

Extract from Earth and Environmental Science Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW.

[Edit: 28 July 09]

Prior learning: Science Stages 4 and 5 Syllabus, Outcome 4.10, 4.11 and 5.10.

Biology Stage 6 Syllabus, 8.2.

Background: There have been huge advances in discoveries of communities on the ocean floor. The finding of whole communities that rely on organisms that do not photosynthesise contravenes the idea that the sun is the source of original energy for all organisms on the Earth.

describe what is meant by a ‘community of organisms’

Organisms found in an area that are interdependent on each other for food, shelter and/or protection.

process and analyse information on life forms at different depths in the oceans to compare the deep ocean environment and its organisms to that in the top thirty metres of ocean

Use the web links below (in the next dot point) and/or information from your teacher.
Process the information by organising it into animal, plant and other life forms that live in the top thirty metres of ocean and life forms in the deep ocean environment.
Analyse the information to identify trends and relationships for the organisms in the different environments. Are there any contradictions observed?

describe and compare examples of food chains that occur in the top layers of the oceans and those found at great depth, explaining the differences

The main difference in these food chains is that the food chains in the top layers of the ocean have living photosynthetic organisms such as sea grass, algae, phytoplankton and cyanobacteria at the beginning of the food chains whereas food chains in the deep ocean have autotrophic organisms that have died and fallen to the bottom of the ocean or in the case of hydrothermal vents, they have most of the organisms at the beginning of the food chain using sulfur from the hydrothermal vents as the energy source.
Choose some specific organisms found at the websites below and describe how they have adaptations to suit their environment. The adaptation might be a large mouth to help them obtain enough food when there is less food available, no eyes where it is impossible to see in the dark environment, no obvious gut; instead, a specialised organ which has dense concentrations of chambers that contain sulfide-oxidising bacteria.

Foodwebs and challenges of the marine environment Coastal Carolina University, Conway, South Carolina, USA. Scroll down to notes on the marine environment.

Hot oases in chill darkness Explore the deep sea, Venture Deep Ocean.Read about life near vents in the deep and construct food chains from the information.

review the range of abiotic characteristics of an environment that determines the nature of a community within that environment

The range of abiotic characteristics of an environment would vary depending on whether it was a deep ocean environment or shallow water. They could be:

temperature
salinity
dissolved gas levels in water
light wavelength & intensity
pressure
current characteristics (speed, depth and direction)
pH
substratum (if any)
tides
waves
exposure to air.

The ocean has a particular range of abiotic factors that play varying degrees of importance in the distribution and abundance, that is, where organisms are found and how many are found there.

explain, using examples, why organisms living on the ocean floor will be different from organisms living in the top thirty metres of the ocean

Abiotic characteristics

Light
Pressure
Temperature

Biotic characteristics

Members of same species – low population density means having to mate at every opportunity whenever they meet the opposite sex
Members of other species – must be efficient predators to catch what little ‘live’ food swims in darkness, e.g. huge teeth and a stomach able to distend to swallow prey of large size. Light-emitting lures.

These are all important adaptations that certain organisms have to live in this specialised environment.

For further information

Deep sea biome by Rob Nelson, Untamed science.com.
Vertical Life Zones and Biodiversity The Natural History Museum, Fathom Knowledge Network, Columbia University

gather and process information and use available evidence to assess the range of resources provided by the ocean, including:

fishing and food
marine aquaculture
minerals from seawater
specific chemicals: sulfur, manganese and heavy metals
power

Gather information from a range of resources including the Internet, popular and scientific journals, digital technologies and books. You may need different resources for the different parts of the question.

A starting point for the Internet could be:

Fishing and food

This website gives the increase in fishing over 50 years and the types of animals that are fished.
Department of Geology, University of Illinois at Urbana-Champaign, Illinois, USA

Marine aquaculture
Aquaculture click on any of the articles in this section Sea Grant, Woods Hole Oceanographic Institution, Massachusetts, USA

Minerals from sea water

Economic aspects Mineral resources, Minerals from seawater and alluvial deposits, Encyclopaedia Britannica Online, USA

Ocean resources Click on an article below to read about the resources such as LNG

Specific chemicals

Oceanic Food, Energy and Mineral Resources Scroll down to VII. Mineral resources East Carolina University, Greenville, North Carolina, USA

Ocean resources Scroll down to mining Marinebio.org, Houston, Texas, USA

Process the information by choosing the most reliable information.

explain how increased understanding of ocean currents and sea floor topography can change the utilisation of ocean resources by society

The main resources obtained from the ocean are fish and invertebrates such as crustaceans (lobster, prawns), molluscs (such as octopus and squid) and echinoderms (sea cucumbers or beche de mer). Oil and gas are mined from offshore drilling rigs and a new venture is mining in deeper oceans for minerals such as iron, manganese, copper, nickel and sulfur.
The deep oceans have not been accessible for mining and fisheries but as vessels are now doing research into the abyss more is being discovered. Due to the expense of bringing minerals to the surface mining is still uneconomic. However ongoing research is resulting in more being known about minerals in the abyss and as mining on land becomes more expensive a time will come when it will be economic to mine minerals in the ocean. This will also be due to improved technology.
When deep, cold water currents meet landmasses, they rise up from the seafloor, carrying nutrients into the surface waters. The upwelling of high nutrient waters stimulates the growth of microscopic photosynthetic organisms and contributes to the rich diversity of life found in coastal waters.