Take a look at this video clip:
Ciguatera and the Fisherman - www.youtube.com/watch?feature=player_embedded&v=k_Y0TpVrGsc
You can also get ciguatera poisoning from the waters around The Caribbean.
Have you ever had ciguatera poisoning?
How does the toxin enter the human body?
Why is ciguatera dangerous?
Toxins produced by living organisms also cause problems in the Netherlands. Take a look at this short clip about blue-green algae in the Netherlands:
Negative swimming advice cyanobacteria - www.youtube.com/watch?v=aP_pxuf0gX0
What are the differences and similarities between these two problems? What measures are taken in each case to combat poisoning? This module focuses on the effects of biotic and abiotic factors on ecosystems.
We also look at food chains in different ecosystems.
Good luck!
1. True or false?
For each statement below indicate whether it is true or false.
a. A community is made up of all the organisms living in an ecosystem.
 true
 false
b. The biotope is the combined effect of all the abiotic factors in an ecosystem.
 true
 false
c. The ecosystems in a certain area together make up a community.
 true
 false
d. The different organisms living in an ecosystem have an effect on one another.
 true
 false
2 Plants are producers. This means:
 that a plant produces inorganic material from organic material.
 that a plant produces organic material from inorganic material.
 that a plant does not need food.
 that a plant does not need energy.
3 A heterotroph organism that feeds on organic material in order to acquire energy is called a …
 decomposer
 producers
 consumer
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4 What do all producers have in common?
 Producers are always plants.
 Producers do not take in food.
 Producers have chloroplasts.
5 Which group of organisms are responsible for making nutrients available for plants?
 decomposer
 producers
 consumer
6 A birding enthusiast says that a group of Griffon vultures belong to the same population.
For a group of animals to belong to a single population they must meet certain requirements.
Name two such requirements.
………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………
7 The numbers of black-tailed godwits in the Netherlands have increased since 1900.
A number of factors involved in this increase are: groundwater levels, farmyard manure and grassland.
Which of these factors is/are biotic?
 groundwater levels
 farmyard
 grassland
8 Write the following organisms in their correct places in the food web:
Perennial ryegrass/grass – buzzard – leatherjacket/crane fly larva – black-tailed godwit – stoat – earthworm - harrier
Final product
You will finish off this module by writing a press release about the issues surrounding ciguatera.
You can use a Word template for this press release.
More information about writing a press release can be found www.wikihow.com/Write-a-Press-
Release .
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Assessment
When assessing the final product your teacher will take into account the following points:
 You have included answers to the four questions (see step 5).
 Where possible you have provided recent information on the situation on The Caribbean and in the surrounding area.
 You have included an image, photograph or map to support your press release.
Learning goals
 naming the relationships in a food chain;
 explaining the causes and effects of an accumulation of toxic substances in a food chain;
 naming differences between ecosystems based on differences in populations (biotic) and in abiotic factors;
 describing the changes in abiotic and biotic factors in an ecosystem and the effects such changes have;
 explaining how measures taken by humans can affect self-regulation in ecosystems.
Subconcepts habitat, trophic level, limiting factor, persistence, producer, consumer, decomposer, eutrophication, biomass, photosynthesis.
Skills
A1 Information-seeking strategies
A2 Communicating
A5 Investigating
A8 Scientific instrumentarium
A12 Reasoning in terms of ecology
A14 Reasoning in terms of systems
Format
Individually or in groups of 2.
For the theory you will need your textbook.
For most assignments several sources of information are provided.
Materials required
 Worksheet A - www.studiobiologie.nl/havo_bb/CARIBBEAN/Warme%20soep/Word/Worksheet_A.doc
 Worksheet B - www.studiobiologie.nl/havo_bb/CARIBBEAN/Warme%20soep/Word/Worksheet_B.doc
 Ciguatera brochure - www.studiobiologie.nl/havo_bb/CARIBBEAN/Warme%20soep/Word/Ciguatera.pdf
 Collage maker - www.toggle.com/lv/group/view/kl39771/Collage_Maker.htm
Time required
For this module you will need about 8 hours.
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Biotic and abiotic factors
Organisms are affected by the other organisms around them, which are known as biotic factors. Of vital importance to an organism are the levels of nutrients (minerals) in the ground or in the water, but also the availability of water and air. These are called abiotic factors.
Read the information in your textbook about biotic and abiotic factors.
Then take a look at the following video clips for an overview:
Abiotic and biotic factors - www.youtube.com/watch?v=E1pp_7-yTN4
Assignment Discovery: Abiotic and biotic factors - science.howstuffworks.com/life/30707-assignmentdiscovery-abiotic-and-biotic-factors-video.htm
Questions
1 All organisms are affected by both abiotic and biotic factors in their surroundings.
Write each factor in the correct column.
Rainfall – predators – parasites – light – prey – temperature – soil type – vegetation – wind - rivals
Abiotic factors
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
Biotic factors
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
……………………………………………………………………………………………
2 Ecosystems are made up of two components that influence one another. Name these two components.
Biotic component - …
 biotope
 community
Abiotic component - …
 biotope
 community
Experiment
Main research question: What are the effects of wind direction and sunlight on plant growth?
Subquestions:
1 How does wind direction affect the shape of a tree's crown?
2 How does sunlight affect the growth of leaves and/or needles?
The materials and methods for these experiments can be found on worksheet A and worksheet B .
 Read through the whole experiment once and gather together the materials required.
 Discuss with your teacher when and where you will carry out the experiment.
 Carry out the experiment.
 Write a report on your experiment.
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Finished?
First assess the report yourself and then give it to your teacher for assessment.
Ecosystems, communities and populations
The organisms and abiotic factors in a certain area interact to form a coherent entity. Such an area that is more or less naturally defined is known as an ecosystem. An ecosystem can be large, such as a desert or ocean, but also small, such as a pond or a single tree. All the living organisms in an ecosystem together form a community. All individuals of a single species living in the same interconnected area are said to form a population. The individuals can interact with one another to reproduce.
Assignment 1
Read the information in your textbook about ecosystems, communities and populations.
Then take a look at the following video clips for an overview:
Population community ecosystem - www.youtube.com/watch?v=cIfpKL0brwQ
Assignment Discovery: Ecosystem - videos.howstuffworks.com/discovery/29495-assignment-discoveryecosystem-video.htm
Create a mind map around the theory on this subject.
Questions
Take a look at the photographs of several different ecosystems.
Add the correct descriptions to each ecosystem.
Wet-dry seasonal climate variations & high temperatures – Seasonal changes & deciduous vegetation –
Lack of oxygen & dry lakes.
……………………………………………………… ……………………………………………………… ………………………………………………………
……………………………………………………… ……………………………………………………… ………………………………………………………
Large temperature differences & low rainfall – Permafrost & low-growing vegetation – High humidity & competition for light.
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……………………………………………………… ……………………………………………………… ………………………………………………………
………………………………………………………
Assignment 2
………………………………………………………
The Caribbean have a number of different ecosystems:
……………………………………………………… coastal region, shrubland, deciduous forest, evergreen forest, tropical rainforest and tropical cloud forest.
In groups of 2:
 Choose one of these ecosystems.
 Look for information about the community in this ecosystem and the main abiotic factors that affect it. You should consider not only plants and animals, but also fungi and bacteria.
 Visualise the ecosystem using clear photographs (digital or printed).
 Use them to create a collage. You can do this online using www.toggle.com/lv/group/view/kl39771/Collage_Maker.htm
, for example. Make sure that you can explain what the collage shows. What can you see and what is unique or unusual about this ecosystem?
Keep your collage for step 3.
Food chains
A food chain is a sequence of different species, starting with a green plant, whereby each species is a source of food for the next. Each ecosystem has its own food chains. All the food chains in a single ecosystem together form a food web. Since most organisms have more than one source of food, they will have a varied diet, some more varied than others. In turn, each organism is also eaten by more than one other species.
Read the information in your textbook about food chains, food webs and trophic levels.
Then take a look at this video clip:
What are Trophic Levels? – Ecology and Environment - www.youtube.com/watch?v=mCHdhXMFhcU&list=PL9262CF2DC192E090
Take a look at the following pictures:
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The number of organisms in a food chain can be represented graphically in a pyramid. Each bar represents the number of individuals at each trophic level (feeding level) in the food chain. The pyramid of numbers has the shape of a pyramid, but there are exceptions.
Pyramids of biomass always have a pyramid shape.
Assignment
1 Visualise a food chain from your chosen ecosystem on a large piece of paper (A3 format) using photographs and/or pictures from the Internet or from magazines.
2 Draw the pyramid of biomass for this food chain.
3 What would happen if the ...
 producers disappeared?
 herbivores (primary consumers) disappeared?
 carnivores (secondary consumers) disappeared?
Describe how this would affect the other populations.
4 What might cause these three situations?
In other words: what are the threats to the populations in the different trophic levels in this ecosystem?
Give a suitable example for these three situations.
Presentation
Give a presentation to your classmates about your collage (step 2) and the food chain and pyramid of biomass (step 3).
Make sure that you include the following terms in your presentation:
 ecosystem
 biotic factors
 abiotic factors
 trophic level
 producer
Extra:
 persistent
 accumulation
 consumer
 decomposer
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Green and blue soup in the Netherlands
In the summer, signs such as these are often seen next to Dutch lakes and ponds where people go swimming. Blue-green algae and green algae can turn clear water into a turbid, stinking, soup-like mass. People who come into contact with water containing blue-green algae may suffer abdominal pains, skin irritation, nausea and eye irritation. Green algae turn the water cloudy, which also has a number of consequences.
 Which abiotic factors cause the increased growth of blue-green algae and green algae?
 How does the increased growth affect the abiotic factors?
 How does the increased growth affect the food chains in the ecosystem?
 Why is it that people get ill from blue-green algae after going swimming?
Complete the following four assignments using the sources of information suggested.
Assignment 1
1 Bodies of water containing blue-green algae and green algae are also ecosystems.
Look for photographs on the Internet of such an ecosystem showing excessive growth of algae
(algal bloom).
2 Over the course of history biologists have classified organisms in different ways.
The most recent classification consists of three domains: the archaea, the bacteria and the eukaryotes.
To which domain do blue-green algae belong?
 archaea
 bacteria
 eukaryotes
And green algae?
 archaea
 bacteria
 eukaryotes
3 How are blue-green algae similar to green algae? And how are they similar to ‘normal’ bacteria?
………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………
4 Which ecological function do green algae and blue-green algae fulfil in an ecosystem?
In other words: to which ecological group do blue-green algae belong?
 producer
 consumer
 decomposer
And green algae?
 producer
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 consumer
 decomposer
Sources:
Blue-green algae are also known as blue-green bacteria or cyanobacteria:
Cyanobacteria: Photosynthetic prokaryotes - www.youtube.com/watch?v=uU00tg98Jjw
Prokaryotic and eukaryotic cells - www.youtube.com/watch?v=yWy4o_UfZ4A
Assignment 2
Populations of blue-green algae and green algae grow rapidly when water contains high levels of phosphates and nitrates. When combined with long periods of warm weather this leads to an algal bloom, which inhibits the growth of other species. The water in a pond can turn into green soup.
1 How does an algal bloom affect the food chain? In your answer, use the organisms in the food chain pictured shown to the right.
2 How does an algal bloom affect the light and oxygen in the water (the abiotic factors)?
3 What are the dangers for the organisms in the water when the algal bloom continues for a long period?
4 The pike is a predator that feeds on other fish. Important factors during its development are water plants to provide shelter and clear water for successful hunting. Explain why an algal bloom could cause the pike to disappear.
5 Blue-green algae and green algae also die. Decomposers are responsible for breaking them down. Explain why this causes an even further reduction in the oxygen levels in the water.
6 Phosphate levels have gone down in recent years, partly due to the use of phosphate-free laundry detergents. How might this reduction in phosphate levels affect the numbers of fish in this food chain?
Explain your answer.
Sources:
Algal blooms why they happen - www.youtube.com/watch?v=Jaq6B3fMe3Y&playnext=1&list=PL1A0QJSdwltAyn2aF0kHOZl1qFgYg4j
0C
Eutrophication – Ecology and environment - www.youtube.com/watch?v=6LAT1gLMPu4
Assignment 3
Pondweed is a submerged aquatic plant. It is found in habitats with clear, light, still or slowmoving, fresh to brackish water that is low in nutrients. Most pondweeds are very sensitive to water pollution and in phosphate-rich water pondweed is often outcompeted by blue-green algae.
Because the competition takes too much of the light that it needs to grow, pondweed loses the struggle for life.
Habitats
The physical surroundings of a population are also known as the habitat. A habitat is the actual place where a species lives, and is also the place where that species has its niche (way of life).
A habitat contains the optimal microclimate for the organism.
1 What are the limiting factors for pondweed growth named above?
Limiting factors
Limiting factor that keeps the number of individuals in a population low.
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2 What is the limiting factor for blue-green algae growth named above?
The graph below shows the population sizes of blue-green algae and pondweed plotted against the level of nutrients.
Which of the 2 lines shows the population size of pondweed?
Select the correct line.


Assignment 4
The problem is even more complex. Blue-green algae produce toxins, of which there are many different types. Bird livers have been found to contain high levels of a type of toxin called microcystins. The levels of microcystins are higher than those found in the blue-green algae themselves. The toxins are said to be persistent, which means that they are difficult to break down.
Take a look at this video clip:
Ecological Pyramids – Ecology and environment - www.youtube.com/watch?v=wGfOoRrICto&list=PL9262CF2DC192E090
1 Which of the following organisms will contain the highest concentration of toxins per kilogram body weight as a result of accumulation?
 soil fauna-eating fish, plankton-eating fish
 phytoplankton
 mussels, soil fauna, zooplankton
 mussel-eating birds
 predatory fish, fish-eating birds, fish-eating humans
2 Explain why the concentrations of toxins in the producers are lower than those in the consumers at higher trophic levels.
3 What is this process called?
………………………………………………………………………………………………………………………………………………………………………………………
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Ciguatera in the news
A section of the Saba Bank is known as the 'Poison Bank'. There are certain algae living in this area that produce the poisonous 'ciguatoxin'. The algae that produce ciguatoxin are eaten by reef fish.
The ciguatoxin is a persistent substance and therefore cannot be broken down by fish.
Larger predatory fish are particularly likely to store high concentrations in their body.
This is what is known as accumulation in the food chain.
Ciguatera is the disease caused by eating fish containing ciguatoxin.
The symptoms of ciguatera can develop quite quickly and consist of nausea, vomiting, diarrhoea and neurological symptoms.
You will finish off this module by writing a press release about the issues surrounding ciguatera.
Make sure you include answers to the following questions:
1. Which algae produce ciguatoxin?
2. Which abiotic and biotic factors have the most impact?
3. How does ciguatoxin accumulate in the food chain?
Construct a realistic example of a food chain to show such accumulation.
4. What is done on Saba to prevent ciguatera poisoning?
What measures are taken?
Are these measures effective?
You can use a Word template for this press release. More information about writing a press release can be found www.wikihow.com/Write-a-Press-Release .
Make sure your information on the situation on Saba is as recent as possible.
Include an image, photograph or map to support your press release.
Sources:
Ciguatera brochure - www.studiobiologie.nl/havo_bb/CARIBBEAN/Warme%20soep/Word/Ciguatera.pdf
Interviews with residents who have been poisoned with ciguatera - www.youtube.com/watch?feature=player_embedded&v=5C-SDCiFyfU# !
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