Ocean Ecology
Year Level: 7-9
Going Further: Sample Activities
Cycling of matter and flow of energy
Organisms require a supply of elements to maintain themselves and to grow and reproduce. These elements are obtained through biogeochemical cycles. The words ‘bio geochemical cycles’ come from:
- Bio- relating to life and living organisms, and
- Geochemical- relating to the physical and chemical interactions between rocks, water and the atmosphere, and
- Cycles- referring to the circular nature of relationships between living things and their physical environment, such as the marine carbon cycle.
Marine carbon cycle
Provide students with a copy of the marine carbon cycle. Ask students to research additional essential elements for the survival of the ocean (such as oxygen). Ask students to draw a diagram of this biogeochemical cycle.
Food chains and food webs
In almost all ecosystems, the organisms fall into three nutritional groups:
• Producers
• Consumers, and
• Decomposers.
Students are to find, sketch or draw images of a variety of ocean flora and fauna and group them into producers, consumers and decomposers. The images can then be formatted into a food web showing the feeding relations within an ocean community.
Analyse the ecological consequences of removing particular layers of the food web from oceans. Consider energy pyramids and explain why herbivores generally obtain their food from a smaller space than the carnivores.
Class debate
Divide students into teams and call upon them to debate topics such as:
- Oceans are for everybody. People should be able to take as much as they want from the ocean;
- Humans need energy. We should mine the ocean for oil and natural gas;
- Tourism makes money. More tourists should be allowed use our ocean areas; and
- Biotechnology can generate lifesaving medicines from the animals and plants of the ocean. Increased funding should be given to biotechnology research.
Making Connections: Sample Activities
Autecology investigation
An autecology investigation sets out to identify all the important aspects of the ecology of a single species. For example when studying the autecology of eucalyptus trees, the following ecological questions could be asked:
• What proportion of gum nuts germinate?
• What happens to gum nuts that do not germinate?
• What sort of soil do gum nuts need in order to germinate, grow into seedlings and eventually become young trees?
• What are the climatic factors that limit the distribution of eucalyptus?
• What are the light requirements of eucalyptus?
• Which organisms feed on eucalyptus?
• What proportion of eucalyptus seedlings go on to reproduce?
• What is the generation time of eucalyptus?
• What factors affect the flowering of eucalyptus trees?
• How is pollination achieved? And
• What factors affect the size and numbers of gum nuts produced?
Students select a marine reef animal or plant and outline how they might carry out an autecology investigation by devising their own questions like those above. Further research, experimentation and field study could generate answers to the questions.
Associations between species
Many individual organisms form close associations with one another. Such associations may occur within the same species (intraspecific associations) or between different species (interspecific associations).
The term used to describe associations between pairs of species is symbiosis. The three major categories of symbiosis distinguished by the consequences of the association to each individual are:
• Parasitism;
• Commensalism; and
• Mutualism.
Students choose a number of marine animals or plants that have symbiotic associations and outline how they might determine whether the relationship is parasitic, commensalitic or mutualistic.
Symbiotic organisms and their hosts seem to have evolved in response to each other, a process called coevolution. The survey of parasitism, commensalism and mutualism can raise the interesting question of which came first? Ask students the following question: “Can we assume that commensalism is the most primitive association and parasitism and mutualism followed later, or could the order be different?”
What are possible, probable and preferable futures for our oceans?
Ask students to work in small groups to plot significant events in the history of our oceans on a timeline. Students should distinguish between those events over which they think local societies had some control (e.g. human-induced events, such as trawling), and those over which they had little control (e.g. natural events, such as tsunamis).
Encourage students to consider the probable and preferable futures for our oceans while you model the continuation of the futures timeline. Invite students to form groups to discuss the process and decisions needed to enable their preferred future to eventuate.
Students plot probable futures along the upper axis and preferable futures along the lower axis. The ‘probable futures’ should reflect students’ expectations of the future, having regard both to their own lives and to the wider ocean. The ‘preferable futures’ should reflect what students would like the future to be, with regard both to their own lives and to the wider ocean.
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