Science Term 1 2009

Miss Simpson

This term we are going to be looking at 2 main topics…

• “Eco warriors”• “Under the sea”

• The strands you will be tested on are :investigating life and living

earth and beyond

• We will also go to Scitech once a week to conduct experiments and see the new displays they have there.

• We will try to organise an excursion where we go to Mettam’s Pool (coral reef) or perhaps even AQUA

But the bad news…• You will have homework!!!

• There will always be things that you need to finish off from class

• You also have a Science homework book that we will use throughout the term.

• If you need some help with your homework or access to a computer after school, I will organise a ‘homework club’ for you.

So lets get into it…

___ __ _______ What is ecology?

• The scientific study of the interactions that determine the distribution and abundance of organisms

• Distribution = where an organism is found

• Abundance = how common an organism is

Questions for Ecologists:

• Why are organisms found where they are?

• Why do some places have more organisms than others?

• Why do the numbers of individuals change over time?

• Before we go any further, lets have a look at the way things are structured here on

Earth…

Levels of Biological Organisation:

• biosphere• ecosystems• communities• populations• organisms• organ systems• organs• tissues• cells• organelles• molecules

BiosphereBiosphere

Ecosystems

Communities

Populations

Organisms

What is the role of Ecology in society?

• To provide impartial information gathered from scientific study that can be used to guide public policy (laws etc)

• It is NOT to make moral judgments on issues and policies

An Example:Otters, oil, and killer whales

• In 1989: the Exxon Valdez ran aground in Prince William Sound, Alaska

The largest oil spill ever in the US

Plants and animals devastated

• One role of ecologists was to document the short term impact on the organisms

• NOT decide whether or how much Exxon should pay

What about the sea otters?

• Its been almost 20 years since the spill and they still haven’t recovered

• Should Exxon pay more -- are they at fault?

Sea otter (Enhydra lutris)

• A small (≈ 25kg) marine mammal

• Relies on fur, not fat, for insulation

• Oil mats fur and reduces insulation

• Historically hunted for fur (nearly driven to extinction in 1800’s)

• They recovered in parts of US, but still protected by law

Ecologists job

• So is Exxon responsible ?

• Ecologists have been studying the sea otters and this is what they found:

— Sea otter populations throughout Alaska began crashing in 1980’s

— Most of these populations were not impacted by the oil spill

Indicates that the current problem with otters is not due to the oil spill…

But what then?

• We need to look at the eating habits of the killer whales…

• Scientists observed killer whales eating otters (which they don’t usually do)

• A single killer whale could eat 2000 otters a yearBut why are they only eating otters now?

What’s going on?

• The killer whales used to eat sea lions & seals

• But now these prey items have become rare

• Why?

Overfishing• Pollock and Salmon – the 2 foods that sea lions &

seals love to eat.

• If there is not enough food for sea lions & seals they will starve

• If there are not enough sea lions & seals, the Killer whales will starve

• As a result: Killer whales started eating sea otters

Food web: before overfishing

Killer whaleHumans

Urchins

Kelp

Sea OtterSea lion &

Seal

Pollock &

Salmon

Urchins Sea otter eating an urchin

Sea lion eating a salmon

A killer whale eating a Sea lion

Food web: after overfishing

Killer whaleHumans

Urchins

Kelp

Sea otter

Sea lion &

Seal

Pollock &

Salmon

• Now it’s time for you to do some work…

ACTIVITIES

• 1. Complete the wordsearch.

• 2. Using the word ECOLOGY, write down as many things as you can that relate to this topic – you can use single words or write down sentences about what you already know.

• 3. Research the definitions for the words you found in your wordsearch.