A Local Ecosystem

The distribution, diversity and numbers of plants and animals found in ecosystems are determined by biotic and abiotic factors

Each local aquatic or terrestrial ecosystem is unique

ContentsUnit 1 The distribution, diversity and numbers of plants and animals fund in ecosystems are determined by biotic and abiotic factors3Basic Knowledge distinguish between the abiotic and biotic factors in the environment31.1 Compare the abiotic characteristics of aquatic and terrestrial environments41.2 identify the factors determining the distribution and abundance of a species in each environment51.3 describe the roles of photosynthesis and respiration in ecosystems61.4 Identify uses of energy by organisms71.5 Identify the general equation for aerobic cellular respiration and outline this as a summary of a chain of biochemical reactions.8Investigations91.a process and analyse information obtained from a variety of sampling studies to justify the use of different sampling techniques to make population estimates when total counts cannot be performed9Unit Review (part of guided instruction)10Unit 2 Each local aquatic or terrestrial ecosystem is unique162.1 examine trends in population estimates for some plant and animal species within an ecosystem162.2 Outline factors that affect numbers in predator and prey populations in the area studied.172.3 Identify examples of allelopathy, parasitism, mutualism and commensalism in an ecosystem and the role of organisms in each type of relationship182.4 describe the role of decomposers in ecosystems192.5 explain trophic interactions between organisms in an ecosystem using food chains, food webs and pyramids of biomass and energy202.6 define the term adaptation and discuss the problems associated with inferring characteristics of organisms as adaptations for living in a particular habitat202.7 identify some adaptations of living things to factors in their environment212.8 identify and describe in detail adaptations of a plant and an animal from the local ecosystem222.9 describe and explain the short-term and long-term consequences on the ecosystem of species competing for resources232.10 identify the impact of humans in the ecosystem studied24

Unit 1 The distribution, diversity and numbers of plants and animals fund in ecosystems are determined by biotic and abiotic factors Compare the abiotic characteristics of aquatic and terrestrial environments Identify the factors determining the distribution and abundance of a species in each environment Describe the roles of photosynthesis and respiration in ecosystems Identify uses of energy by organisms Identify the general equation for aerobic cellular respiration and outline this as a summary of a chain of biochemical reactions. Investigations: Process and analyze information obtained from a variety of sampling studies to justify the use of different sampling techniques to make population estimates when total counts cannot be performed. Basic Knowledge distinguish between the abiotic and biotic factors in the environmentAbiotic factors: the non-living factors, e.g. temperature, oxygen levelsBiome: Large regional system characterized by major vegetation type (e.g. desert); region of earth with similar ecosystems grouped together. Biotic Factors: The living factors, e.g. trees, birds predators Community: the organisms found together living in an area; groups of different populations in an area or habitatEcology: the study of the relationships living organisms have with each other and their environment. Ecosystem: an environment refers to the surroundings of an organisms whereas an ecosystem refers to the interactions between organisms, it is a community as opposed to observational surroundings. While an environment is just a physical setting an ecosystem is a more intangible system consisting of relations. Environment: surroundings of an organism including abiotic and biotic factors.Habitat: the place where an organism lives.Niche: Place of a species within a community involving relationships with other species

Abiotic Factors Amount of light Temperature; daily and seasonal variations Wind & rainfall pH, soil salinity oxygen topography (landscape) water availability, quality

Biotic Factors food availability; suitable for herbivores and predators number and variety of disease causing organisms number of mates available number of predators number of competitors1.1 Compare the abiotic characteristics of aquatic and terrestrial environmentsCharacteristicAquatic EnvironmentTerrestrial Environment

BuoyancyBuoyancy helps animals float with only a small expenditure of energy. They can alter their depth by changing the amount of gas inside their bodyLarger plants and animals do not notice buoyancy. However small insects and other invertebrates will experience a greater effect.

Chemical: Carbon DioxideCarbon dioxide solubility is low in water, but is more dissolved at low temperatures than at high. Thus there is more available for photosynthesis in colder water (including ocean upwellings) than in warm tropical Although carbon dioxide is 0.03% of the atmosphere, it is rarely a limiting factor in plant growth

Chemical: ionsGenerally, the concentration of ions outside of marine animals is higher than inside and they lose water by osmosis. They have to drink large amounts to replace it. Fresh water poses the reverse problem: water enters animals and they have to remove it by constant urinationThe availability of specific ions can vary widely. Excessive salinity is a serious problem in some parts of Australia. Yet some plants and animals suffer because of lack of specific ions in our ancient soils. In some parts of the world, salt licks are visited regularly by various animals

Chemical: oxygenOxygen has low solubility in water but is more soluble in cold water and is thus more available in colder waters. Also mixing air is a factor: water tumbling over waterfalls or rapids contains more oxygen than stagnant water in a swamp.Oxygen is rarely a limiting factor in terrestrial environments.

Chemical: waterObtaining water is rarely a problem in aquatic environments. However inland regions may dry out so that animals such as frogs burrow into mud to survive dry seasons. Animals in salt water have problems keeping water because of osmosis.Water availability varies a lot in terrestrial environments. Even in rainforests, epiphytes have to survive dry periods in the treetops. In deserts, plants and animals have many adaptations to survive the lack of water.

LightLight penetration decreases with depth. Photosynthesis occurs only in the upper layers. Thus many animals living below the level of light penetration depend on the rain of food material above.Generally light is not a limiting factor, however may be in lower strata of a rainforest. Plants living at lower levels in rainforests have leaves adapted to low light levels, or they may only grow quickly to reach upper levels when a hole appears in the rainforest canopy.

Pressure Pressure increases with depth. Changing depth by large amounts is difficult mammals such as whales and seals have special adaptations to tolerate high pressure and descent into large depths.Pressure has little effect in most animals. Humans who travel to very high regions can experience altitude sickness.

TemperatureThe temperature of a body of water has a specific heat and will absorb large amounts with little change in temperature. Land nearby has a much lower specific heat and will change temperature by a much greater amount. Large bodies of water also moderate local terrestrial temperatures. Temperature will vary more in shallow bodies of water and near the surface than at greater depths. Small ponds can have a large temperature range.Temperature Changes in terrestrial environments are much larger than in aquatic environments. Plants and animals are adapted to this: plants conserve water and have small leaves or change the orientation of the leaf to keep its edge directed to the sun. Animals may burrow into the soil to avoid the intense heat of the day.

ViscosityWater has high viscosity and energy must be expended for animals to move through water. Plants must be securely fastened if they are to avoid being swept away by moving water.Large animals are little affected by the low viscosity of air, unless the wind is intense. However small animals such as insects must be adapted to move through the air.

1.2 identify the factors determining the distribution and abundance of a species in each environmentDistribution Where an organism is found in an environment It is usually uneven throughout the ecosystem Organisms are found where abiotic and biotic factors favour them Organisms are distributed where survival rate is high, predation is low and requirements for survival are met. Abundance How many organisms in an ecosystem Not the same throughout the environment Changes over time Increases due to births and immigration Decreases due to deaths and emigration

Abiotic Factors affecting distribution and abundanceBiotic factors affecting distribution and abundance

Light Availability of food

Strength of windNumber of competitors

RainfallNumber of mates available

Temperature variationsNumber of predators

TopographyNumber and variety of disease causing organisms

Tides, currents and waves

Water (amount, salinity, pH)

Substrate

Space and shelter

Oxygen

Aquatic Environments

EnvironmentFactors and their effects

Rock platformEdge of rock platforms experience fast-flowing turbulent water. Species such as kelp and cunjevoi (sea squirt) cling to rocks to survive. Animals that are strong swimmers and are streamline can stay in these waters.

Ocean depthsLow water temperatures, low light and great pressure allow only certain species to survive. Some of the food sources may have sunk from higher levels where there was more light available for photosynthesis. Some fish use stealth or deception to capture food in lower levels in light.

EstuaryContinuous changes in turbidity, salinity, water level and water flow mean that plants with many adaptations, such as mangroves with pneumatophores, can survive.

WetlandsWaterlogged soils and low levels of oxygen in the soil dictate that many plants have to be able to cope with variations of water levels between wet and dry seasons.

Terrestrial environments

EnvironmentFactors and their effects

DesertsLow rainfall means plants are sparsely distributed. Many animals that survive by burrowing rely on soil of a suitable texture to support burrows.

RainforestsHigh rainfall and humidity result in high rates of nutrient recycling. Low levels of sunlight beneath the canopy restrict the distribution and abundance of some species. Others live as epiphytes or climbing vines and can utilise low light; some climb to the canopy.

HeathWinds carrying salt from the ocean can favour salt-tolerant species. Many heath plants are adapted to low soil nutrients and irregular rainfall.

Sand dunesTemperature variation, strong light, poor moisture retention and low nutrient levels in the soil influence the distribution and abundance of species. Often the early colonizers are legumes that are able to fix nitrogen from the air.

1.3 describe the roles of photosynthesis and respiration in ecosystemsIn any ecosystem there is a flow of energy through it recycling of some materials such as carbon and oxygen. It is a fundamental law of science that energy cannot be created or destroyed. Energy can, however, be changed from one form to another, but these energy transfers are not perfect whenever energy is changed from one form to another, some energy is lost.In ecosystems the initial source of energy is light from the sun. Some of this light energy is converted by photosynthesis into chemical energy in glucose molecules. This glucose can then be transported to other parts of the plants. About half of the glucose is broken down in respiration to make energy available for cellular processes. Energy transfer from light to plant cells:Light energy

PhotosynthesisrespirationTransported throughout the plant

chlorophyll

Energy for cell processesGlucose

Converted into other carbohydrates (starch, sugar)

Energy transfer from plants to animals:Energy for animal processesConverted into other substancesCarbohydrates digested to glucoseEaten by animalplant

Respiration

PhotosynthesisPhotosynthesis is the process in which plants prepare their food. Photosynthesis can only take place in the presence of sunlight. Leaves undertake photosynthesis for plants.Light EnergyCarbon dioxide + water glucose + oxygen + waterAbsorbed by chlorophyll

RespirationCellular respiration is a common process that is carried out by many organisms to make and release energy. Cellular respiration is basically a process through which the cells convert glucose and oxygen to carbon dioxide and water and hence release energy, for ATP. ATP stands for Adenosine triphosphate and stores the free energy that is used by cells.

The roles of photosynthesis and respiration in ecosystems:Photosynthesis and respiration are the basis of the carbon/oxygen cycle. Phtoosyntehsis absorbs carbon dioxide from the air. Respiration takes oxygen from the air.Energy is needed for all life processes. Photosynthesis uses light energy from the sun, water and carbon dioxide to produce glucose. Respiration releases the chemical energy stored in glucose.Respiration is a process carried out by all living cells to release energy for living. Photosynthesis occurs in all green parts of plants.

1.4 Identify uses of energy by organismsThe energy available to organisms in an ecosystem is used in a variety of ways: Synthesis (creation) of complex molecules (lipids, proteins, carbohydrates) Growth of cells (includes differentiation, division, elongation) Repair and maintenance of old or damaged cells Active transport of materials across cell membranes Functioning of special cells that need extra energy (nerves, muscles, kidney) to keep organs working Transport of substances within the organism (e.g. by phloem, circulatory system) To maintain body temperature For movement For chemical reactionsAs energy moves through an ecosystem, it is either used by a living thing or lost as heat. Because of this, a continual input of energy is needed to keep living systems functioning.

1.5 Identify the general equation for aerobic cellular respiration and outline this as a summary of a chain of biochemical reactions.Aerobic cellular respiration can be summarized using a chemical equation:Glucose + oxygencarbon dioxide + water + energyThe chemical formula:

This equation summarises aerobic (related to the presence of oxygen) cellular respiration. It occurs in the mitochondria of cells. Aerobic respiration occurs as a series of reactions. Respiration is a complicated process that converts high energy compounds (glucose, proteins, fats) to lower energy compounds through a series of biochemical reactions. All living things need energy to remain alive Respiration is the breakdown of glucose with oxygen to release energy Carbon dioxide and water are produced as waste products Aerobic means requiring oxygen The energy is held in the glucose bonds; when they are broken, energy is released. Respiration involves around 50 different reactions, each catalysed by a different enzyme ATP: Adenosine triphosphate (one adenosine attached to three phosphate groups) This is the energy carrier in all cells The enrgy produced by respiration is kept in these molecules The energy is stored in the phosphate bondsEnergy

ADP (adenosine diphosphate) + P (phosphate) ATP For every glucose molecule, 38 ATP molecules are producedADP + P + Glucose + Oxygen Carbon dioxide + Water + ATP38ADP + 38P + C6H12O6 + 6O2 6CO2 + 6H2O + 38ATPThere are 2 stages in Respiration: 1. Glycolysis: Occurs in cytoplasm Splits the 6-carbon glucose into two 3-carbon molecules (pyruvate - C3) ATP molecules are gained Does NOT require oxygen 2. Krebs Cycle: Occurs in the mitochondria Pyruvate is broken down into water and CO2 36 ATP molecules are gained Oxygen is required

Investigations1.a process and analyse information obtained from a variety of sampling studies to justify the use of different sampling techniques to make population estimates when total counts cannot be performedSampling techniques are used to make population estimates when total counts cannot be made, for example, when there are too many organisms, or when they are scattered over too big and area. Quadrats, transects and capture-mark-release-recapture are three sampling techniques used to make population estimates in studies of ecosystems. These techniques are suited to certain types of species and when conducting a field study you must infer which technique is most appropriate, efficient, and will give reliable accurate results that are representative of the abundance or distribution of a species. Transects are used to determine distribution and quadrats and capture-mark-recapture are for determining abundance.

Sampling TechniqueEquipment and methodAdvantagesSuitability/Disadvantages

Transects: plan sketches and profile sketches Rope or measuring tape marks the line that is drawn to scale The area is selected at random across the ecosystem Species are plotted along the line, in surface view for a plan sketch or in side-on view for a profile sketch Provides a quick, easy and inexpensive method for measuring species occurrence Minimal disturbance to the environment Only suitable for plants or slow-moving animals. Species occurring in low numbers may be missed

Quadrat sampling Measuring tape, metre rulers or quadrats are used to randomly place the 1m x 1m square areas The occurrence of organisms in the quadrat is recorded and repeated a number of times Individual species can be counted if in small numbers or percentage cover can be calculated for larger numbers by estimating the percentage cover for each quadrat and then finding an average of the quadrats taken Easy and inexpensive method for measuring abundance in large populations Minimal disturbance to the environment Quadrats can also be used for determining the distribution of a species along a transect Only suited for plants and slow-moving animals

Mark-release-recapture Animals are captured (e.g. traps, nets, pits), tagged or marked (e.g. limb bands) and then released After a suitable time to mix with others, a sample is recaptured The number of tagged or marked animals recaptured is counted Numbers are then entered into the formula:Abundance =

Note: Technology is sometimes used in marking very mobile animals using tracking bans and tracing their movements by GPS systems and satellites A simple method that provides an estimate of abundance for animals in large populations that are difficult to count Only suitable for mobile animals Can be time consuming depending on the type of species captured, method of tagging, and time suitable for waiting while tagged group mix with others Can be disturbing to the environment

Both distribution and abundance can change year by year The abundance can change even if the distribution does not When measuring the size of populations the method used depends on the type of species being sampledTransects Cross section of an area Used to record the type and number of species present Useful for recording the relationship between a species and the abiotic factors in the areaQuadrats Square, rectangular or circular frame of chosen size Marks out an area in which the vegetation is to be sampled Shape and size of quadrat depends on type of vegetation May be located randomly over the area being sampled or at regular intervals along a transect or gridCapture Recapture More difficult to estimate the population of animals than plants due to movement of animals, being nocturnal, hiding and being scared off by the researcher It involves tagging or marking a sample of the population then releasing it The proportion of tagged animals in following recaptured samples and equation applied gives a reasonable estimate of the total population: Total population = number of animals tagged x number of animals recapturednumber of tagged animals recaptured

Unit Review (part of guided instruction)Summary: The distributin, diversity and abundance of organisms in an ecosystem are determined by both abiotic and biotic factors. Ecosystems are the systems formed by organisms interacting with each other and with their environment. These systems can be terrestrial (on land), aquatic (in water), or a combination of both. Abiotic factors are the non-liviing components of an ecosystem, such as availability of gases, rainfall and temperature. The abiotic factors of terrestrial environments are very different from those of aquatic environments. Biotic factors are the living organisms in an ecosystem, such as vegetation, mates, predators and prey. Methods used to investigate ecosystems include observing, measuring, collecting and making estimates of populations by using particular sampling techniques, such as transects and quadrats. Photosynthesis is the process by which plants capture the radiant energy from sunlight to produce simple organic compounds (sugars). Respiration is the process by which all living organisms obtain energy to use to perform all their activities. In respiration, energy is released from reactions involving sugars and oxygen, and water and carbon dioxide are produced. This general statement for aerobic respiration in cells is a summary of a sequence of many biochemical reactions. Energy is used by organisms in all their activities, including growth, general body metabolism and reproduction.Questions1. Which statement best defines the term environment?A All the surroundings, conditions and influences that affect an organismB All the ecosystems in the worldC The layer containing living organisms that surrounds the EarthD The abiotic factors that interact with living organisms

2. Which group below contains abiotic factors only?A kangaroo, eucalyptus, possum, grass B potatoes, soil, fertilizer, tractor C rock, seawater, sand, oyster D humidity, soil pH, light, wind3. A small patch of native grassland of area 5000m2 contains a large number of the broad-leaved herb chamomile burr daisy (Calotis anthemoides) distributed randomly. Which of the following methods would be the simplest, most reliable method of estimating the abundance of these plants?ACount all the herbs individually BUse one quadrat in an average-looking area of the grasslandCUse a number of random quadrats DTake a line transect through the thickest patch of the herbs

4. The following features are part of a granite hilltop ecosystem. These features have been organised into abiotic and biotic factorsBioticAbiotic

Snow-grass, snail, earthworm, dragonfly, eucalypt, frog, wallaby, butterfly, moss, predator, bacteriaRain, air, sunlight, wind, temperature, phosphorous, rock, soil, shelter, altitude

5. Compare the abiotic characteristics of aquatic and terrestrial environments by completing this table.Abiotic characteristicAquatic environmentTerrestrial environment

ViscosityWater has high viscosity and energy must be expended for animals to move through water. Plants must be securely fastened if they are to avoid being swept away by moving water.Large animals are little affected by the low viscosity of air, unless the wind is intense. However small animals such as insects must be adapted to move through the air.

BuoyancyBuoyancy helps animals float with only a small expenditure of energy. They can alter their depth by changing the amount of gas inside their bodyLarger plants and animals do not notice buoyancy. However small insects and other invertebrates will experience a greater effect.

Temperature variationThe temperature of a body of water has a specific heat and will absorb large amounts with little change in temperature. Land nearby has a much lower specific heat and will change temperature by a much greater amount. Large bodies of water also moderate local terrestrial temperatures. Temperature will vary more in shallow bodies of water and near the surface than at greater depths. Small ponds can have a large temperature range.Temperature Changes in terrestrial environments are much larger than in aquatic environments. Plants and animals are adapted to this: plants conserve water and have small leaves or change the orientation of the leaf to keep its edge directed to the sun. Animals may burrow into the soil to avoid the intense heat of the day.

Pressure VariationPressure increases with depth. Changing depth by large amounts is difficult mammals such as whales and seals have special adaptations to tolerate high pressure and descent into large depths.Pressure has little effect in most animals. Humans who travel to very high regions can experience altitude sickness.

Availability of gasesOxygen has low solubility in water but is more soluble in cold water and is thus more available in colder waters. Also mixing air is a factor: water tumbling over waterfalls or rapids contains more oxygen than stagnant water in a swamp. Carbon dioxide solubility is low in water, but is more dissolved at low temperatures than at high. Thus there is more available for photosynthesis in colder water (including ocean upwellings) than in warm tropical

Oxygen is rarely a limiting factor in terrestrial environments. Although carbon dioxide is 0.03% of the atmosphere, it is rarely a limiting factor in plant growth

6. a) Distinguish between the distribution and the abundance of a species.Both distribution and abundance can change year by year. The abundance can change even if the distribution does not. Abundance is the quantity of organisms of a species in a habitat. Distribution is the spread of the organisms of a species in a habitat.b) Identify some factors that affect the distribution and abundance of a named aquatic organism and a named terrestrial organism.Humpback whale (Megaptera novaeangliae): Humpback whales feed exclusively on krill so are only found where this food source is plentiful, e.g. Arctic and Antarctic waters. They feed and grow in these cold waters and then need to move to warmer waters to breed. Their slow reproductive rate limits their abundance. Native bush rat (Rattus fuscipes): Amount of available water is the single most important factor. They are limited only by their need for water as they can only survive 4 days without. Bush rats live in a wide range of habitats from dry, sandy hills to open forests and tropical rainforests. Their diet includes a range of different foods such as insects, grasses, berries, mosses and roots. They have a high reproductive capability which encourages abundance.

7. a) Define what is meant by the resources that an organism needs.An organisms resources are the elements in the environment that it uses, such as food and shelter. b) Make a list of the general resources that must be available to the following organisms if they are to survive in their environments:i. a plant needs sunlight, water, carbon dioxide for photosynthesis, oxygen for cellular respiration, suitable temperatures and soil that can provide the right mineral nutrients.ii. an animal needs food for energy, oxygen for cellular respiration, water and shelter.

8. a) Define photosynthesis.Photosynthesis is the process in which plants prepare their own food. Photosynthesis can only take place in the presence of sunlight. Leaves undertake photosynthesis for plants. light energy, normally from the Sun, is converted by plants into chemical energy that can be later released to fuel the organisms' processes. The following equation shows that photosynthesis is the process by which plants make their own food using carbon dioxide, water and sunlight, in the presence of chlorophyll.

b) Describe the role of photosynthesis in ecosystemsPhotosynthesis is the process by which plants make their food using sunlight and the carbon-dioxide in the atmosphere. Without photosynthesis, there will be no plants in the ecosystem. Also there will be no way to convert the carbon-dioxide generated by animals to be converted back in oxygen and carbon. The absence of plants, resulting from non-existence of the process of photosynthesis, will start a chain of reactions that will end allanimallife in the ecosystem. All organisms in an ecosystem are part of a food chain. The primary source of energy, after the sun, is plants. Without plants, no animals in the food chain would be able to survive as there would be no chance for a flow of energy, and all organisms need energy to survive. Also, plants are at the bottom of a food pyramid and make up the bulk of energy. NO organism in higher trophic levels will be able to survive without this initial source.

9. a) Describe the role of respiration in ecosystems and identify a general equation for this processAerobic Respiration takes place in the mitochondria. Glucose is broken down in the presence of oxygen, which then forms carbon dioxide and water and through this process, energy is released for organisms to use. Therefore, the main role of respiration is the removal of oxygen from the air and providing organisms with energy by returning carbon dioxide so the cycle may continue. Through this process, energy in the form of ATP is also released as heat. There is no purpose in holding stored energy when you cannot expend it. Without respiration, expenditure of energy for bodily and cell functions such as growth, repair, maintenance, movement would not be possible. Without respiration survival would not be possible as active continuous energy expenditure is required to merely live. The formula for respiration is:

b) Identify the ways living organisms use the energy made available through cellular respirationThe energy available to organisms in an ecosystem is used in a variety of ways: Synthesis (creation) of complex molecules (lipids, proteins, carbohydrates) Growth of cells (includes differentiation, division, elongation) Repair and maintenance of old or damaged cells Active transport of materials across cell membranes Functioning of special cells that need extra energy (nerves, muscles, kidney) to keep organs working Transport of substances within the organism (e.g. by phloem, circulatory system) To maintain body temperature For movement For chemical reactions

10. a) Explain how transects and quadrats can be used to estimate the distributions and abundances of organisms. Use diagrams in your answers. A transect (shown below) is a narrow strip or line that extends across the area being studied, from one side to the other. All organisms that can be found along the transect are recorded. In this way an estimate of the distribution of species can be achieved.

A quadrat (shown below) is a small plot marked out in a much larger area. A quadrat is representative of the whole area. The number of organisms within the quadrat is counted, giving the number of organisms per unit area, usually per square metre. When the quadrat size is compared with the total area under study an estimate of the abundance of organisms can be calculated.

b) Animals cannot always be seen or captured during field studies. Describe other methods scientists can use to determine the presence and abundance of animals.scat analysis: studying droppings (scats) is a useful way of identifying animals and, in the case of carnivores, the kinds of animals that they have eaten track analysis: observation of footprints can help identify animals remains such as bones, which can be compared with museum specimens recognising the calls of animals such as birds and frogs the use of still or video cameras to record animals in the area Analysis of other material left by animals such as fur or feathers. c) Justify the use of different sampling techniques to make population estimates when total counts cannot be performedPopulations can never be 100% accurately counted; this is because of the difficulty of describing in detail large areas. Also it would be too time-consuming and attempting to count every individual in a large area can be damaging to the environment. Sampling techniques make an estimate, which is roughly accurate of the population. They are used to sample vegetation, slow moving animals, nests, burrows, soil fauna/characteristics. In some instances total count cannot be made and is not accurate because the whole population of a moving/frequently migrating animal is not present in a certain place at a given time, thus capture/recapture would be used. Transects provide a quick, easy and inexpensive method for measuring species occurrence and create minimal disturbance to the environment, however, transects are only suitable for plants or slow-moving animals, and species occurring in low numbers may be missed when observing and assembling data.Quadrat sampling is an Easy and inexpensive method for measuring abundance in large populations. Like transects, quadrat sampling causes Minimal disturbance to the environment and can also be used for determining the distribution of a species along a transect, however it is only suited for plants and slow-moving animals.Mark-release-recapture (or capture//recapture) is A simple method that provides an estimate of abundance for animals in large populations that are difficult to count. However, this method is only suitable for mobile animals; can be time consuming depending on the type of species captured, method of tagging, and time suitable for waiting while tagged group mix with others; and the most important concern to note is that it can be disturbing to the environment.

Unit 2 Each local aquatic or terrestrial ecosystem is unique Examine trends in population estimates for some plant and animal species within an ecosystem Outline factors that affect numbers in predator and prey populations in the area studied Identify examples of allelopathy, paratism, mutualism and commensalism in an ecosystem and the role of organisms in each type of relationship Describe the role of decomposers in ecosystems Explain trophic interactions between organisms in an ecosystem using food chains, food webs and pyramids of biomass and energy Define the term adaptation and discuss the problems associated with inferring characteristics of organisms as adaptations for living in a particular habitat Identify some adaptations of living things to factors in their environment Identify and describe in detail adaptations of a plant and an animal from the local ecosystem Describe and explain the short-term and long-term consequences on the ecosystem of species competing for resources Identify the impact of humans in the ecosystem studied

Investigations: Whole field study on Clarenza cross country area.2.1 examine trends in population estimates for some plant and animal species within an ecosystemIf the number of a species is studied over time in natural systems, the following trends become apparent: The population increases rapidly at first because food, space and shelter are available. As numbers increase, there are more individuals competing for available resources. The rate of increase slows. Eventually competition for limited resources (or sometimes disease) will slow the population growth. A point is reached where the numbers that die is approximately equal to the numbers that are born (death rate = birth rate)

General decline of populations can occur in ecosystems that are prone to human impacts such as pollution, soil degradation or the introduction of new species.

2.2 Outline factors that affect numbers in predator and prey populations in the area studied.Although animals eat living plants, this process is not referred to as predation. We only use predation in situations where one animal eats another animal. For example: Dingo eats Wallaby Lion eats Zebra Spider eats FlyBoth predator and prey have major impacts on each others distribution and abundance, and can cause the others population to rise and fall in fairly regular patterns, as shown in the graph below:

21

1, 2 and 3 repeat throughout time3

It is often thought that predators control prey populations and that is it, however it more the reverse. Note that the peaks and troughs of the predators population always occur after those of the prey species. What is happening in this graph:1. The numbers of the prey species increase because of its breeding cycle, or a seasonal increase in available food.2. This provides more food for predators, which survive in greater numbers and reproduce more successfully3. As predator numbers increase, more prey gets eaten so the prey population decreases as prey population decreases. As prey numbers decline, less predators can survive and breeding is less successful. This causes predator numbers to decline.

There are a number of different factors that may affect the numbers of predator and prey populations: Number of predators competing for the same prey Availability of preys food Birth rate (depending on the age of reproductive maturity and the number of reproductive episodes per lifetime) Death rate (increased by exposure to disease) Number of males and females Size of ecosystem for supporting the predator and prey numbers Movement between ecosystems Number of shelter sites available In the Clarenza ecosystem, the caterpillar population of black cup slug moths began to decrease as milkweed, the tree they live on, would not replenish at the rate they were eating the leaves. Because of this, the populations of a few types of birds, such as the silvereye, began to decrease as they fed on insects including the black cup slug moth caterpillars these caterpillars were the most prevalent insects in the area. This is an example of predator and prey populations being influenced by the availability of preys food. 2.3 Identify examples of allelopathy, parasitism, mutualism and commensalism in an ecosystem and the role of organisms in each type of relationshipCommensalism is a relationship in which one organism benefits while the other is neither harmed nor helped.Examples: Sharks and remoras The remora attaches itself to the shark and hitches a ride. This does not harm the shark. The remora also feeds off debris and scraps from the sharks meals. Birds nesting in a tree the birds gain a safe and secure nest site while the tree is unharmed. Cattle Egret and Cattle As cattle grazeon the field, they cause movements that stir up various insects. As the insects are stirred up, the cattle egrets following the cattle catch and feed upon them. The cattle are not disturbed by the egrets following them.

Mutualism arises when both species benefit from the relationship.Examples: Honey bees and flowering plants the plant gets pollinated and the bee gets food Herbivores and bacteria animals with a diet rich in cellulose rely on bacteria in their digestive tract to break it down. Both species obtain food from the relationship. Coral and algae the coral (microscopic animal) provides the algae with a home and the algae provide the coral with some food.

Parasitism occurs when an organism feeds on another, and the hosts health is usually compromised. However, sometimes the host is not killed or even necessarily harming the host greatly (e.g. head lice on humans).Examples: Humans and tapeworms the tapeworm absorbs food inside the host Leeches or ticks feed off the blood of the host Viruses, protozoa and fungi invade the body and feed/reproduce using the bodys resources

Allelopathy is a competitive relationship where an organism secretes or excretes a substance (called an allelchemical) that generally has an inhibitory effect on another organism. The substance may come from several parts of the plant and may persist in the soil for some time.Tasmanian Blue Gum (Eucalyptus globulus) and the River Red Gum (Eucalyptus camaldulensis) both produce poisons that give them a competitive edge because the inhibit the germination of seeds from the other plants and therefore the growth of plants under them.

Competition occurs when two different species need to use the same resource in the same way. Competition usually results in a winner and a loser. One species may be slightly more successfully than the other, and over a long enough period of time it will outcompete its rival. For example the numbers of Thylacine (Tasmanian Tigers) declined rapidly after the introduction of the dingo about ten thousand years ago. The dingo was a more successful predator and outcompeted the Thylacine on the mainland.2.4 describe the role of decomposers in ecosystemsAll organisms die. Animals also produce waste. Dead matter and waste are broken down by decomposers and returned to the soil and water. By this process, matter that makes up living organisms is recycled. Nitrogen, water, carbon and oxygen are examples of materials that are recycled. Rainforests are rich and diverse ecosystems that rely heavily on humid conditions, ensuring that nutrients are rapidly decomposed so that they become available for new growth. Mangroves also rely on decomposers that break down leaves of mangrove trees to make them available for the detritus feeders in the mud.A decomposer is an organism that absorbs nutrients from dead tissue or waste products of organisms and returns organic material to the soil, air or water.Bacteria and fungi are the main decomposer organisms in an ecosystem.Summary: Decomposers are the rubbish cleaners of the ecosystem and prevent accumulation of waste in the environment which, if not reduced, may give good habitat to unwanted pests and insects They feed on: the left overs of other organisms, dead organisms, decaying organisms and their wastes. They enable the materials of decomposition to be available to plants (e.g. worms leave nutrients in soil, which are absorbed by plants) They keep the biomass in circulation2.5 explain trophic interactions between organisms in an ecosystem using food chains, food webs and pyramids of biomass and energyTrophic interactions are essentially feeding relationships (e.g. predator prey or parasite host). They are important because they relate to the flow of energy. Energy flows one way from the sun through producers to the other organisms in an ecosystem.Food ChainsA simple food chain shows the transfer of energy through part of an ecosystem however they do not provide any idea of how many organisms are in habitat nor indicate figures of biomass. 3rd order consumer (carnivore)2nd order consumer (carnivore)1st order consumer (herbivore)Producer:Plant makes its own food through photosynthesis

Food WebsIn reality, the feeding relationships of living things are much more complicated than depicted in simple food chians. A branching diagram that shows the feeding relationships and energy flow of living things in an ecosystem; and is illustrative of the complex interrelated bonds organisms have with each other is called a food web.The arrow shows the direction of energy flow.The arrow means is broken down or decomposed.

Trophic LevelsThe feeding level of an organism is its trophic level. An example of a trophic level is a first order consumer (herbivore). The role that an organism plays is called a niche.

Scavengers & DecomposersTrophic levels

Level 3 3rd order consumerLevel 2 2nd order consumerLevel 1 first order consumerProducers

Pyramids of biomass and energyBiomass is a measure of the mass of all organisms at a particular trophic level. A biomass pyramid shows the total weight (biomass) of organisms at each trophic level for a particular habitat. The biomass of organisms decreases as you move up each trophic level. As you go up trophic levels, biomass decreases.Not all of the energy that is taken by plants is passed along the food chain. Much energy is used by each organism for metabolism (living processes) and some is lost as heat. Energy lost at each step means that each trophic level can only pass on part of its energy to the next level. Therefore it takes 1000 biomass units of phytoplankton to support fewer biomass units of zooplankton and so on. This is why biomass of a lower trophic level must be higher than the trophic level above, so that there is enough net energy to be transferred.

2.6 define the term adaptation and discuss the problems associated with inferring characteristics of organisms as adaptations for living in a particular habitatAn adaptation is any characteristic that increases an organisms likelihood and reproduction compared to organisms that lack that characteristic. An adaptation is a feature of an organisms that makes it well suited to its environment and its lifestyle. An adaptation is a result of a change occurring at random when organisms reproduce a new organism. This random difference just so happens to benefit the organism by making it more suited to the environment it lives in. Adaptations can be: Structural: A physical characteristic relating to the structure of an organism Physiological: Relating to the way an organism functions (e.g. digestive processes). Behavioural: How an organism relates and reacts to its environment; the way in which an organism actsAdaptations are always genetic; they are the result of natural selection.

Problems associated with inferring characteristics of organisms include: If you do not know the environment an organism lives in, then saying a characteristic is an adaptation is just guesswork It is difficult to relate a characteristic to a specific feature of an organisms environment when we do not know the exact habitats it has lived in over generations. Sometimes, organisms gain features that are advantageous to its survival, but are a result of the organisms live experience. This is not an adaptation, as adaptations are always genetically based. Sometimes it is unclear what a certain adaptations purpose/benefit is, or the purpose is much more complex than a seemingly obvious answer. For example, the common belief was that canine teeth on the gorilla are to help them tear meat, but later was confirmed that the canine teeth are actually to help the gorilla defend territory.

2.7 identify some adaptations of living things to factors in their environmentEnvironmental FactorsAdaptations

Living in waterStreamlined body shape, holdfasts for gripping rocks, muscular feet and rounded shells for hanging onto slippery surfaces

Predator avoidanceCamouflage, burrowing, communal living, mimicry, poisonous, thorny or bitter tasting

Heat and waterLarge ears help dissipate body heat, panting, licking limbs, sweating, nocturnal behaviour, concentrated urine, extensive root systems, slivery or hairy leaves, excretion of salt from Mangrove leaves when they are in saline water

The search for foodLarge eyes, mobile head, heat detection, sense of smell and hearing, large, dark green leaves (from chlorophyll, to help the plant photosynthesize and create energy)

In Aquatic Ecosystems

Mechanism For floating

Plant Animal

Spongy leaves with air spacesFat layers or oil droplets next to skin (as oil has lower density than water and will rise)

Air filled stemsLight bone structure

Large flat leaves that increase surface areaGas floats/ swim bladders

Large, flat fins that increase surface area

To reduce friction between water and body surface (only in animals)

Large, flat fins that increase surface area

Streamline shape and thin body

Mucous layer

Scales that point towards the tail

Aid in gas exchange (respiration)

PlantAnimal

Thin, flat leaf structuresGills providing external gas exchange

Floating on the surface of the water or growing out of the water in direct contact with the airInsects and spiders capture air bubbles using special hairs

Large intercellular air spaces in the leaves

Control of water balance (only in animals)

Shells reduce water loss

Marine birds, turtles and crocodiles excrete excess salt through special glands near the eye

In Terrestrial Ecosystems

For body support (only in animals)

Legs, rib cages, basically a skeletal system, spider webs

To Prevent dehydration

PlantAnimal

Plant cuticles which are waxy tough coverings to conserve waterImpermeable skin, body coverings, reduced number of sweat glands

To obtain light (only in plants)

Some plants can move their leaves to follow the sun

Leaves sometimes arranged on the plants to receive maximum light (e.g. leaves spread out and flat parallel to the ground for increased surface area to absorb light)

To Regulate Body Temperature

PlantAnimal

Hairy or shiny leaves with a layer of salt crystals to reflect heatIncreased body size and thick fur to retain heat.

Ability to orientate leaves at right angles to the sun to reduce surface area exposed to the sun and stop the leaf becoming hotHeat avoidance by burrowing

Leaf margins curled to protect the inner surfaceSalivating onto fur by licking

Whenbody temperaturerises,blood flow to the skin surface increases to cause transfer of metabolic heat from the core to theskin, thus lowering internal body temperature.

2.8 identify and describe in detail adaptations of a plant and an animal from the local ecosystemPlant: MangroveMangroves live in warm, shallow tidal saline water.To be stable in slippery mud, mangroves are anchored by complex root systems in the shifting environment of tidal mud flats. They have vertical anchor roots which are attached to spreading cable roots. Together, these form a dense mass that stabilizes the plant in the mud. There is a lack of oxygen in the water-logged soil, which is exposed at low tide but covered with water at high tide. To allow gaseous exchange to occur during high tide, mangroves have developed aerial roots or pneumatophores which push upwards through the mud and salt water. Their tips have pores of lenticels through which gaseous exchange occurs.Because they live in sea water (with high ion concentration) mangroves must be salt-tolerant, thus they are halophytes (salt-tolerant plants). Because they live in sea water they have developed methods to control the salt level, these are:Accumulation/storage (followed by shedding) salt accumulates in selected parts of the plant until it reaches a certain concentration. That part of the plant is then shed. Excretion salt glands on the upper surface of their leaves, which actively excrete salt.Exclusion membranes in the root system filter the sea water, allowing water to pass into the plant but excluding most of the salt

To obtain light, the shape of the plant and arrangement of leaves ensures that abundant light is available for photosynthesis. Higher leaves on the plant are angled and the lower leaves horizontal to best capture sunlight. Leaves are rich in chlorophyll (thus dark green) to enable photosynthesis.

For increased chance at successful reproduction, the seeds are buoyant and dispersed by tide. Their initial development, particularly of the root system, ensures that the new plant can rapidly anchor itself and grown quickly once it is deposited in the mud.

Animal: KangaroosPhysiological adaptations: to assist support and movement kangaroos have well-muscled hind legs that are far larger than their forelegs. Only the hind legs are used when the animal is travelling at high speed. This method of bounding along is more efficient in terms of energy use than when animals run on all four legs. When kangaroos move slowly, they are hopping. The long tail of the kangaroo is a useful structure and is used as a balancing counterweight when bounding, as an extra limb when hopping, and to help the kangaroo to remain upright when standing still.To control water balance, kangaroos reduce water loss by sweating only during exercise. When they stop moving, sweating stops. To regulate body temperature when the atmospheric temperature is high, kangaroos lick their forelimbs where the blood vessels run close to the surface, and because evaporation of saliva has a cooling effect, heat is lost from the body.Female kangaroos have reproductive biological adaptations. Even though female kangaroos mate again directly after giving birth, any new fertilized egg does not develop until the young leaves the pouch. This is known as delayed implantation, to prevent the kangaroo from tiring out and not having enough food. At any one time, a female kangaroo may have a joey being weaned, a young one being suckled in the pouch and an embryo in the uterus awaiting development. Kangaroos have the amazing ability to produce two kinds of milk at the same time. The milk produced by the teat for the developing young in the pouch contains much less fat than the milk produced by the teat being used by the joey outside the pouch. By being able to produce food customized for each of two different offspring, the health of one offspring is not compromised for the other.

2.9 describe and explain the short-term and long-term consequences on the ecosystem of species competing for resourcesCompetition in an ecosystem is the struggle between organisms for the same resource. A particular ecosystem can support only a certain number of each type of species. Competition may be between members of the same species, or between members of different species. In the short term, competition reduces the chance of survival and restricts the abundances and ranges of species. The availability of resources such as food and space decreases. The growth of the population may level off or decline. If the population decreases, there is less pressure on available resources.In the long term, one of the competitors will usually be more successful and drive out or significantly reduce the numbers of other competitors. Competition in a fixed environment can lead to: Degradation of the environment as resources become depleted Decline in the diversity of organisms Extinction one species may cause the other species (or a number of species) to become extinct Evolution if environmental conditions change, competing species may start to evolve. They minimize competition by evolving in slightly different directions and come to occupy different niches.Each year, most organisms produce many more offspring than can survive. While some young will be consumed as food by other organisms, many die in the competition for limited resources. A eucalyptus tree may produce thousands of gum nuts each year but only a few of the germinating seedlings will survive in the competition for light, nutrients and space.Species that are introduced into natural ecosystems by humans often successfully compete with the native inhabitants, because they may not have the same predators or diseases. For example, feral goats use rock shelters and food, of which is needed by rock wallabies in the Flinders Ranges of South Australia. This has caused a decline in the number of rock wallabies.More usually in ecosystems, organisms within the same habitat do not compete directly for the same resource. For example, different species of lizards living in the same desert ecosystem may eat different sizes of insects. Similarly, in urban gardens the common garden orb weaver spider, Eriphora transmarina, catches and eats larger insects than the St Andrews cross spider Argiope keyserlingi, does.2.10 identify the impact of humans in the ecosystem studiedHuman activities have a major impact on ecosystems. The need for space, water, air and soil results in problems that humans create for ourselves and other organisms.Loss of species has occurred naturally as part of the evolutionary process, but the current rate of habitat and species loss as a result of human activity is much higher than what is natural, and is now regarded as a major extinction process. Ecological imbalance is not only affecting human health, cultures and evolution, but the future of life on Earth.Human impact occurs locally and globally. It includes; Land clearance, resulting in habitat destruction Erosion and soil loss Salinization and desertification Contamination of soil and water through excessive use of fertilisers and pesticides Species loss Loss of diversity Exploitation and depletion of natural non-renewable resources Climate change (global warming) Damage to the ozone Production of non-biodegradable and poisonous wastes (polluting water, air and soil) Introduction of non-native species Large scale irrigation and damn construction interfering with the hydrological cycle Overpopulation of humans, which magnifies the above impacts.The human impact on Earth is accelerating and now, more than ever, there is a need to conserve, maintain and protect the quality of the environment. This may be done by reducing all packaging, developing environmentally friendly cars or better public transport, develop alternative and renewable forms of energy, develop more sustainable forms of agriculture, and by reducing population size (or rate of increase).In the Clarenza cross country track ecosystem, the amount of human impact is not too predominant however there are still some factors to consider:Recreational use: mowing for the cross country track; students running on the cross countrytrack this area coincides with Clarence Valley Anglican Schools Cross Country Track,which means a narrow path is cleared/mowed through a section of the field study area. This isa very minimal human impact, as the grass is simply cut and no plant species are destroyed.When people run and walk on this area they are trampling plants, and also will inevitably killsmaller animals such as beetles and ants. Therefore there is an impact on flora and fauna, theyare actually not completely in an untouched state and are fairly disturbed. Also when kids runaround in this area they also generate noise and may scare birds, chase away butterflies,agitate snakes. All this can impact the food web when a species that likes quiet realises thatthis area is subject to human intervention they may migrate. Also, when the lawn is mowedregularly, gas pollution is also released from the lawn mower. Insects are very susceptible toair pollution. Small fluctuations in air quality force certain insects to relocate, affecting otherplants and animals connected to them.Rubbish Pollution: As students do occasionally use this area (e.g. PDHPE orienteeringactivities, running, conducting field studies) rubbish will be found (although it shouldnt). Afew (1-3) pieces of rubbish were found and these were items such as pens, gum wrapper, anda bit of rubber (perhaps from somebodys shoe). Litter is extremely dangerous to wildlife as itcan result in poisoning, choking, suffocation or strangulation. And also, when it rains, litterthat is discarded on land often ends up in waterways. Therefore, marine biodiversity is alsoaffected. However, in the selected field study area, the amount of pollution is very minimal aspreviously stated.

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