ESS Unit 2 Ecology 2.pdf - Environmental Systems & Societies DP 1

Environmental Systems and Societies DP 1 Unit 2 : Ecology Syllabus 2.1 Individuals and Populations, Communities and Ecosystems This subtopic introduces the basic fundamentals of ecology including the concept of a niche, population biology, measuring populations, carrying capacity, keystone species, biosphere integrity and planetary… 2.2 Energy and Biomass in Ecosystems Ecosystems rely on the flow of energy (from sunlight to chemical) and cycling of nutrients. These transfers can be modelled using food chains and diagrams. However, human actions disrupt this flow, having a significant impact on the health of ecosystems. 2.3 Biogeochemical cycles Nature has its own recycling mechanisms that are built into the environment. In this section, you can learn about geochemical recycling and how human activities impact these natural systems. The focus is on how human activities affect nutrient cycling and the consequences of such impacts on the sustainability of environmental systems. 2.4 Climate and Biomes This section explores the differences between the terms climate and weather and how climate factors govern biome distribution around the world. The topic also considers the effects of atmospheric circulation… 2.5 Zonation, Succession and change in ecosystems This section explores the concept of change, both over time (succession) and over an environmental gradient (zonation). We will look at the Broadbalk Wilderness at Rothamsted as a case study of secondary... Individuals and Populations, Communities and Ecosystems Enquiry Question: How can natural systems be modelled, and can these models be used to predict the effects of human disturbance? Objective: - This subtopic introduces the fundamentals of ecology including the concept of a niche, population biology, measuring populations, carrying capacity, keystone species, biosphere integrity and planetary boundaries. - At HL evolutionary relationships in taxonomy, the concept of a fundamental versus a realised niche and the evolutionary strategies of r-selected and K-selected species. Prescribed reading: InThinking Topic 2 Chapter 2.1 ATL Skill: Thinking & Research Vocabulary; Biosphere: The biosphere is an ecological system composed of individuals, populations, communities and ecosystems. A biosphere represents the parts of the Earth where life exists. Species: An individual organism is a member of a species. According to the biological species concept, a species is a group of organisms that can interbreed and produce fertile offspring. Scientists can have a lot of fun naming species. For example, this webpage, gives plenty of examples of weird and wonderful scientific names assigned to new species. have a look through to identify which one is your favourite! How and why do we name species? Species Definition: A group of organisms capable of interbreeding and producing fertile offspring. Estimated 8.7 million plant and animal species exist. Only 1.2 million species have been identified and described (mostly insects). Scientific names are used to uniquely identify each species. Classification of Organisms: Enables efficient identification and prediction of characteristics. Necessary due to the immense diversity of species. All species have a two-part binomial name: ○ First part: Genus ○ Second part: Species Example: Lion and tiger can interbreed to produce a liger, but ligers are infertile, so lions and tigers are still considered separate species. Which of your two names (first name and surname) is equivalent to the genus and which to the species? Binomial Name - Common name Panthera leo - Lion Panthera tigris - Tiger Population: A population is a group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding. A population is an interbreeding unit. One species may consist of any number of populations, from one to many. Community: A collection of interacting populations within an ecosystem. Example: Coral reef community includes interactions among coral, algae, fish, and invertebrates. Habitat: The location where a community, species, population, or organism lives. Described by geographical, physical, and ecosystem characteristics needed for survival. Example: Clownfish inhabit shallow tropical reefs and live symbiotically in anemones for protection. Ecosystem: An open system where energy and matter can enter and exit. Consists of a community and its physical environment. Example: Forest ecosystem includes biotic components (e.g., trees, animals, fungi) and abiotic components (e.g., sunlight, soil, water). Dichotomous keys, applications and databases for the identification of species. One of the most well-known ways to identify species is through the use of a DICHOTOMUS KEY. However, in recent years lots of great apps have come onto the market. Here are 2 of the best. Download one of these and have a go at using it. Think about some of the limitations while you experiment. Name of App What it can be used for PlantNet Free to use; allows you to instantly recognise a plant and know more about it. With a simple snapshot using your mobile phone's camera, you will be able to identify and better understand all kinds of plants living in nature. iNaturalist iNaturalist lets you identify quickly and easily plants and animals. It is also now partnered with the National Geographic Society. Factors that determine the distribution of a population can be abiotic or biotic. Biotic refers to the living components of an ecosystem Abiotic refers to non-living physical factors that may influence organisms. Abiotic factors Factor & Impact/examples - Temperature (0C) = Important for organism survival and metabolic processes. Affects enzyme activity, development rates, and geographic distribution of species. - Light intensity (candela or lux) = Essential for photosynthesis in plants. Affects the growth and reproduction of many organisms. - pH = Affects the availability of nutrients, enzyme activity, and organism physiology. Most organisms have a preferred pH range for optimal function - Dissolved oxygen (%, mg/L, or ppm) = Critical for respiration in aquatic organisms. Low oxygen levels can cause stress and mortality. - Soil texture = Soil texture can be determined using the "Hand identification chart for soil texture analysis" Influences water drainage, aeration, and nutrient availability for plants. - Turbidity (cm) = Turbidity is the cloudiness of a water body. It is measured using a Secchi disk -Reduces light penetration in water, impacting photosynthesis and visual feeding by aquatic organisms. Niches An ecological niche is the role of a species in an ecosystem. The niche comprises all biotic and abiotic interactions that influence the growth, survival and reproduction of a population, including how food is obtained. Population Interactions: Populations within an ecosystem do not exist in isolation. They interact with each other in various ways, shaping their population dynamics and influencing their evolution. Some of the ways in which they interact are described below. Herbivory: ○ Consumption of plants by herbivores. ○ Can decrease plant abundance and diversity, impacting other herbivores and the food web. ○ Plants may develop defensive traits like thorns to deter herbivory. Predation: ○ Involves a predator consuming prey. ○ Regulates prey populations and prevents overexploitation of resources. ○ Predation pressure leads to evolutionary adaptations in prey for improved survival (e.g., speed, camouflage). Parasitism: ○ A symbiotic relationship where one species benefits and the other is harmed. ○ Parasites rarely kill their hosts as it is counterproductive for their survival. ○ Leads to evolutionary adaptations in hosts (e.g., stronger immune systems) and counter-adaptations in parasites. Mutualism: ○ A symbiotic relationship where both species benefit. ○ Example: Mycorrhizal fungi and plant roots exchange nutrients, or nitrogen-fixing bacteria and legumes. ○ Over time, mutualistic relationships may co-evolve, increasing efficiency and interdependence. Disease: ○ Caused by pathogens (viruses, bacteria, fungi) and can spread rapidly through populations. ○ Example: Chytridiomycosis caused by fungus Batrachochytrium dendrobatidis (Bd) has devastated amphibian populations. Panamanian Golden Frog: Once abundant, now vanished due to chytridiomycosis. Mountain Yellow-legged Frog: Suffered severe declines and is critically endangered due to Bd. Competition: ○ Interaction where organisms strive for the same resources (e.g., food, mates, territory). ○ Interspecific competition: Between different species (e.g., green vs. brown anole in Florida). ○ Intraspecific competition: Between individuals of the same species (e.g., wolves competing for food or black grouse displaying to attract a mate). Classwork Activities; Complete the following activities and upload to your folder in google drive. - Activity 1 - Identify an ecosystem and identify all the components of the ecosystems by using the vocabulary in this unit. - Present as a slide show or table where the organisms and components are listed under the various vocabularies. - You will consistently be adding to it until the unit is complete and then present. - Activity 2 - Divide students into groups. - Instruct each group to explore the PlantNet app and familiarise themselves with its interface and features. - Students need to go out and observe a variety of plants or plant images. - Take pictures of the plants or use the provided images to identify the plants using the PlantNet app. - Record the scientiﬁc name of each plant they identify - Share the scientiﬁc names of the plants they identiﬁed and explain the meaning of each name. - Facilitate a discussion on the following questions: i. - What does the genus name of each plant reveal about the broader group of plants to which it belongs? - What speciﬁc characteristics of each plant are reﬂected in its species name? - How does the scientiﬁc name provide a unique and universal identiﬁer for each plant species? Modelling Populations Predator-Prey Populations The Canada lynx and snowshoe hare relationship is a classic predator-prey dynamic. Lynx rely almost entirely on snowshoe hares for food. When hare populations increase, lynx populations also rise due to ample food availability. Increased lynx predation eventually leads to a decline in the hare population. With fewer hares available, lynx reproduction and survival rates drop, reducing their population. This predator-prey cycle repeats approximately every 8-10 years. The relationship illustrates ecosystem interconnectedness and the balance between predator and prey. The lynx-snowshoe hare relationship is an example of negative feedback that regulates predator and prey populations. Snowshoe Hare Increase: ○ High hare population provides abundant food for lynx. ○ Lynx reproduction and survival increase, leading to population growth. Lynx Predation: ○ Increased lynx population leads to greater predation pressure on hares. ○ Hare population decreases due to frequent hunting. Limited Food for Lynx: ○ Fewer hares mean limited food for lynx. ○ Lynx reproduction and survival decrease, leading to a decline in their population. Less Pressure on Hares: ○ As lynx population declines, predation pressure on hares reduces. ○ Snowshoe hare population begins to recover. This cycle creates a negative feedback loop, keeping both lynx and hare populations in balance and preventing uncontrolled growth. Carrying Capacity As individuals get older, they reproduce and this repeated pattern leads to exponential growth. However, limiting factors such as predation, disease and severe weather will limit this growth. Carrying capacity: The average size of a population determined by competition for limited resources. The carrying capacity is not a fixed number. It can fluctuate over time as environmental conditions change. Human activities like deforestation, pollution, and overfishing can also significantly alter the carrying capacity of ecosystems. In the table below there is an outline of how different resources can impact carrying capacity Density Dependent and Density Independent Factors Population growth is regulated and does not increase indefinitely. Population regulation mechanisms are influenced by population density, particularly density-dependent factors: Competition for Resources: ○ Higher population density leads to more competition for limited resources (food, water, shelter). ○ This competition reduces reproduction and survival rates, limiting population size. Predation Risk: ○ Dense populations are more visible and accessible to predators. ○ Predation acts as a natural check, reducing prey populations and preventing them from exceeding carrying capacity. Disease Transmission: ○ Diseases spread more easily in crowded conditions. ○ Disease outbreaks can significantly reduce population size. These factors create a negative feedback loop, regulating population growth and maintaining it near the carrying capacity—the ecosystem's sustainable long-term population size. Density-Independent Factors: ○ Factors that impact population size regardless of density, such as natural disasters, climate change, and human activities (e.g., overfishing). ○ These factors cause population fluctuations but do not regulate populations around carrying capacity. Density-Dependent Factors: ○ Play a key role in regulating population size around the carrying capacity. ○ Act as a self-regulating mechanism for long-term population sustainability. S-Curve: ○ Represents population growth that initially grows exponentially but then stabilizes around the carrying capacity. ○ Growth slows down and fluctuates due to limiting factors, reaching a stable population size. J-Curve (e.g., yeast population): ○ Population grows exponentially in a closed environment but eventually crashes due to limiting factors. ○ Crash may result from running out of resources or accumulation of toxins. Limiting Factors: ○ Can be density-dependent (related to population density) or density-independent (unrelated to density). ○ Both types of factors determine population dynamics in natural conditions. Reindeer on St Mathew Island The story of reindeer on St. Matthew Island is a classic example of a population undergoing a boom-and-bust cycle, contrasting with the typical S-shaped population growth curve. Here's a great little comic about it Introduction and Initial Growth: A small number of reindeer were introduced to the island in 1944. With an abundance of food (lichens) and no natural predators, the reindeer population experienced exponential growth. This initial growth phase resembles the lower portion of an S-curve, where the population increases rapidly. Boom and Bust: As the reindeer population grew, they began to deplete the available food resources. Competition for limited food intensified, leading to malnutrition and decreased reproduction rates. This lack of food resources, combined with harsh winter conditions, resulted in a dramatic population crash in the following years. Key Points: St. Matthew Island lacked natural predators or density-dependent factors to regulate the reindeer population. This is why the initial growth resembled a J-curve rather than the logistic (S-shaped) growth curve seen in populations with limitations. The S-curve typically shows a gradual slowdown in growth as the population approaches the carrying capacity. The carrying capacity of the island (the maximum sustainable population) was exceeded due to the rapid growth. Resource depletion triggered a rapid decline in the population, showcasing the "bust" phase of the boom-and-bust cycle. This example highlights the importance of understanding carrying capacity and the consequences of exceeding it. In the absence of natural controls, introduced species can have devastating impacts on the ecosystem they are introduced to. Activities Complete the following activities and upload to your google drive The Unit 2.1 Activity 3 great predator-prey activity is here The Unit 2.1 Activity 4 Modelling Population Growth activity will explore the yeast population and a bee population. Human Population Growth Historical Population Growth Limits: Human population growth was historically limited by factors such as predation, disease, and resource scarcity. Reduced Natural Predation: Advancements in weaponry and habitat alteration have largely eliminated natural predators, allowing human populations to grow unchecked. Technological Advancements: Medicine, vaccines, antibiotics, and public health improvements have reduced mortality rates, increasing human lifespans and population numbers. Agricultural Revolutions: Innovations like fertilisers, pesticides, and mechanised farming have boosted food production, supporting larger populations but causing environmental strain. Consequences for Ecosystems: ○ Resource Depletion: Larger populations consume more resources (water, food, fossil fuels), leading to resource depletion and environmental degradation. ○ Habitat Destruction: Human expansion for housing, agriculture, and infrastructure destroys habitats, displacing wildlife and reducing biodiversity. ○ Pollution: Industrialisation, waste generation, and intensive farming pollute air, water, and soil, disrupting ecosystems. Complexity of Human Carrying Capacity: Unlike other species, determining Earth's human carrying capacity is complex and debated. How many people the planet can support remains an open question. Broad and Changing Niche: Humans are highly adaptable, expanding their ecological niche through technology, agriculture, and resource use, unlike herbivores or carnivores, which are constrained by specific food sources. Mobile Resources: Humans can transport and trade resources across vast distances, making it difficult to pinpoint carrying capacity based on local resource availability. Population Equilibrium: In ecosystems, populations often stabilise around carrying capacity, but humans seem less bound by these limits due to innovation and resource flexibility. Technological Advancements: Humans continually develop tools and technologies that improve resource efficiency and expand access to new resources, complicating predictions of carrying capacity. Changing Consumption Patterns: Human consumption evolves, including shifting between resources, creating synthetic alternatives, and altering dietary habits, making fixed limits difficult to estimate. Ecological Footprint: This metric measures the biologically productive land and water needed to support a population’s consumption and waste. Carrying Capacity as Reciprocal: In theory, the inverse of the ecological footprint could estimate carrying capacity, indicating how many people can be supported based on current consumption. Conclusion: Estimating the human carrying capacity is complex due to adaptability, technology, and changing consumption patterns, but managing the ecological footprint is crucial for a sustainable future. Sustainability and Tipping Points in Ecosystems Sustainability in Ecosystems: Healthy ecosystems maintain a balance between inputs and outputs, allowing them to function sustainably for long periods. Closed Loop Function: Ecosystems operate in a closed loop where inputs (energy and nutrients) are balanced by outputs (waste and energy dissipation), ensuring long-term stability. Long-Lived Ecosystems: Examples like tropical rainforests demonstrate ecosystems that have thrived for millions of years due to this balance. Inputs: ○ Solar radiation (primary energy source) ○ Organic matter (from dead organisms) ○ Inorganic nutrients (minerals taken from the environment) Processes: ○ Photosynthesis ○ Energy transfer through food chains ○ Nutrient cycling Outputs: ○ Heat (dissipated energy) ○ Dead organic matter (detritus) ○ Gases released back into the atmosphere These inputs, processes, and outputs interact to support the sustainability and resilience of ecosystems. Human activity can lead to tipping points in ecosystem stability. Amazon as a Water Pump: The Amazon rainforest releases vast amounts of water vapor into the atmosphere, contributing to regional rainfall patterns and creating a cool, humid environment that sustains the ecosystem. Impact of Deforestation: Disrupts transpiration, reducing the release of water vapor. Leads to reduced rainfall, creating drier conditions that make the forest more prone to fires. Causes increased temperatures due to less evapotranspiration, reducing the cooling effect in the region. Tipping Point Risk: Continued deforestation could push the Amazon past a tipping point, transitioning it to a drier, savanna-like ecosystem. This new state would be stable but less diverse and significantly less effective in storing carbon dioxide. Practical tasks - Activity 5 Select one of the following options to explore ecology; Bottle Terrarium Make a wormery To monitor your progress provide feedback in the following manner; - List of biotic and abiotic factors in your ecosystem - Journal the progress of you ecosystem indicating how you created, monitored and interacted with your ecosystem and also what changes took place in you ecosystem. - Take pictures of your ecosystem as it develops to compliment your journaling. Student Task - Activity 6 Wolf Wars – Population Growth Curve When the new wolves in Yellowstone first came calling, the area’s elk and moose stood their ground as though they were still dealing with coyotes. Bad idea. Today, Yellowstone holds half the elk it did 15 years ago. Yet by most measures, the population had swelled too high and their range was deteriorating. Shortly after killing the last Yellowstone wolves in 1926, park officials were culling elk by the thousands. The elk kept rebounding and overgrazing key habitats, creating a perpetually unnatural situation for a park intended to preserve nature. With a near-unlimited meat supply, Yellowstone’s new wolves rapidly multiplied. But the count abruptly fell in 2005. It increased again, reaching 171 in 2007, then sank to 124 by the end of 2008, a 27 percent drop this time. Doug Smith, leader of the Yellowstone Wolf Project, recorded the fewest breeding pairs since 2000 in 2010. “We have a declining wolf population,” he says. “Numbers never got as high as we expected based on the availability of prey. This suggests that once wolves reach a certain density, you start to get social regulation of their numbers.” National Geographic Magazine Objective: Evaluate the population growth curve for wolves in Yellowstone post-reintroduction. Procedures: 1. Since the reintroduction of wolves in 1995, the National Park Service has posted annual reports on the wolf populations in Yellowstone National Park. 2. Review the Abstract/ Summary of each of the annual reports from 1995 to the most recent year. 3. Within the abstract, identify the total number of wolves in Yellowstone National Park at the end of each year. Begin with the first year – 1995. 4. Create a table and properly scaled graph to show the wolf population vs. time. Be sure to title your table and graph and to label your axes. Use Microsoft Excel or Google Sheets to do this. 5. Label the following on your graph. Create a key with definitions for each: 1. Exponential Growth 2. Carrying Capacity (K) 3. Overshoot 4. Dieback Analysis Questions: 1. Based on the 2014 annual report, how would you describe the population density of the wolf population? (Random, Uniform, or Clumped) Why? Is this what you would expect for wolves? 2. Refer to your graph. What is the relationship between the birth (or reproductive) rate and the death rate? a. Between the years 1995 and 1998 b. Between the years 2002 to 2004 3. Refer to your graph and describe the effect of environmental resistance / limiting factors on the population growth at the time of wolf dieback. 4. Environmental resistance / Limiting factors can be classified in two broad categories – density-dependent factors and density-independent factors. Based on your graph, explain which category you think is impacting the wolf population. 5. Describe what would happen to the elk population of YNP during the wolf population dieback. Sketch a graph of the interactions between elf and wolf from 1995 to the present. This is just a sketch – I’m more interested in your knowledge of their interactions than specific numbers. 6. In recent years, there has been information documenting the wolves’ reintroduction as a success for the entire ecosystem. This phenomenon has been referred to as the cascade effect. What is the cascade effect and how has the return of wolves in Yellowstone benefited the entire ecosystem? Site specific examples. 7. What is the estimated carrying capacity of Yellowstone? Understand that there are many factors that influence this number. You may be able to decipher two different time periods where it appears that the wolf population has stabilized and reached a carrying capacity. What do you think happened to cause a destabilization in the population size? Site specific examples from the wolf reports. KEYSTONE SPECIES Keystone Species Role: ○ Keystone species are like the cornerstones of an ecosystem, crucial for the entire structure to function. ○ Despite not being the most abundant, they have a powerful influence on the community. Key Functions of Keystone Species: ○ Control Populations: Keystone predators like wolves keep prey populations in check, preventing overexploitation of resources. ○ Facilitate Processes: Species like beavers create habitats that benefit other organisms, altering the ecosystem. ○ Maintain Diversity: They promote biodiversity by influencing prey populations and habitat structure. Disproportionate Impact: ○ Loss of a keystone species causes significant ecosystem disruption. ○ Trophic Cascades: Without keystone predators, prey populations can grow unchecked, disrupting the food web. ○ Habitat Alteration: Loss of keystone herbivores, such as elephants, changes vegetation and habitat for other species. ○ Biodiversity Loss: The loss of species reliant on the keystone species leads to decreased ecosystem diversity. Examples: Purple Sea Star: Controls mussel populations on the North Pacific Coast, preventing them from dominating and smothering other organisms. Sea Otters, Sea Urchins, and Kelp: A similar relationship exists where sea otters control sea urchin populations to protect kelp forests. Elephants as Keystone Herbivores: ○ African elephants are crucial to maintaining savanna ecosystems. ○ They feed on shrubs and trees, preventing them from outcompeting grasses. ○ Role in Savanna Landscape: ○ Elephants help keep the savanna open, which supports a variety of grazing animals. ○ Without elephants, trees and shrubs would take over, transforming the savanna into woodland. ○ Ecosystem Impact: ○ Loss of elephants would alter the landscape, affecting organisms that depend on the open savanna for survival. PLANETARY BOUNDARIES Planetary Boundaries Model: Identifies 9 critical environmental processes essential for Earth's stability. Biosphere integrity is one key boundary, crucial for ecosystem health and function. Human Impact on Biosphere Integrity: Activities like deforestation, pollution, and climate change have pushed this boundary beyond safe limits. Disruption of ecosystems leads to habitat loss, pollution, and overexploitation of resources. Consequences of Crossing the Boundary: Weakened ecosystem functions and reduced biodiversity. Current extinction rates far exceed natural levels, signaling a breach of this boundary. Loss of ecosystem services and reduced resilience to environmental change. Urgent Need for Action: Solutions include sustainable practices, biodiversity conservation, and international cooperation. Restoring biosphere integrity is vital for ensuring planetary health for future generations. (HL) There are benefits of using clades to illustrate evolutionary relationships. This video explains how to construct and use them Organisation: Clades provide a hierarchical framework for classifying organisms. They group species based on their evolutionary history, placing them into nested categories that reflect shared ancestry. This classification system helps us organise the vast diversity of life on Earth. Prediction: Knowing an organism's clade can give us clues about its likely characteristics and evolutionary history. For example, knowing a mammal belongs to the clade Carnivora (carnivores) tells us it likely eats meat and has specific anatomical features associated with hunting and feeding on flesh. Carl Linnaeus: Swedish botanist and doctor who developed a classification system to organise Earth's biodiversity. Linnaeus' Classification System: a. Original hierarchy: empire, kingdom, class, order, genus, species, variety. b. Modern hierarchy: kingdom, phylum, class, order, family, genus, species. c. Based on physical characteristics like morphology, anatomy, and behaviour. Limitations of Traditional Systems: a. Did not always reflect evolutionary relationships (e.g., birds and bats both have wings but evolved from different ancestors). b. Modern systems incorporate DNA sequencing for a more accurate understanding of relationships. Advances in Modern Classification: a. DNA sequencing has identified new species (e.g., a new Amazon frog species in 2016). b. Reclassification based on DNA data (e.g., a group of fish reclassified from tuna to being more related to mackerel in 2017). Impact: Modern systems offer a more accurate and comprehensive understanding of life's diversity and have revolutionised species classification. You can learn more about Covergent Evolution here Fundamental and Realised Niches The fundamental niche describes the full range of conditions and resources in which a species could survive and reproduce. The realized niche describes the actual conditions and resources in which a species exists due to biotic interactions. The green anole is native to Florida and the brown anole is an introduced, non-native species to the area. The fundamental niches of these two species overlapped and through competition the green anole developed a narrower realised niche. The Resources have been partitioned You can learn more about the realised niches and resource partitioning with the anoles as an example here and with barnacles here. Activity 7 - Student Task: In order to explore this concept of the realised niche and resource partitioning further, we are going to look at some case studies of species. Your task is to produce a graphical summary of an example from the resources provided. Choose only two of the resources provided to make your graphical summary presentation. Upload to your google drive folder once completed. Remember to use annotations which will aid understanding. Realized Niche of Cane Toads in Australia ○ Lecture notes from Montana University with several summarised examples ○ Avoiding a Sticky Situation ○ Resource Partitioning and Why It Matters ○ Blog post on fundamental and realised niches (helps understanding) ○ 4 min video clip explaining niche partitioning from HHMI HL only: Evolutionary Strategies - r- and K- strategist species r- and K-strategist species have reproductive strategies that are better adapted to pioneer and climax communities, respectively. r-strategist species: Produce large numbers of offspring to colonize new habitats quickly and exploit short-lived resources. Habitat preference: Thrive in young, changeable habitats, especially in the early stages of succession. Reproductive traits: Lay many eggs or have many offspring with minimal parental care. Survival rate: A significant proportion of the offspring die before reaching maturity. Example: Frogs and their spawn illustrate typical r-strategist reproductive behavior. K-strategist species: Produce a small number of offspring with a higher survival rate. Habitat preference: Thrive in long-term, stable environments, often in climax communities. Reproductive traits: Provide significant parental care and invest more energy into each offspring. Survival strategy: Offspring have a higher chance of reaching maturity due to greater parental care. Example: The Iberian Lynx is an example of a K-strategist, well-adapted to stable environments. HL Only: Knowledge of niches, classification and life cycles can help us understand human impacts Species Classification: Identifying an organism's taxonomic position helps understand its biology and vulnerabilities. For example, classifying polar bears as apex predators highlights their risks from habitat loss and climate change. Niche Requirements: Each species has specific survival needs (e.g., food, temperature, habitat). Understanding these needs helps assess threats from human activities, like how dams and pollution impact salmon, which require cold, clean water to spawn. Life Cycles: Understanding a species' life cycle, including sensitive stages (e.g., migration, breeding), can help minimize human disturbances, such as protecting marine mammals' breeding cycles or bird migration paths. Impact of climate change on life cycles: Pika (Ochotona daurica) Habitat: Pikas thrive in cool, high-altitude environments. As temperatures rise, suitable habitats shrink, forcing them higher up mountains. Limited room: The problem is, these mountain dwellers already live very high. Unlike some species that can migrate long distances, pikas can't easily relocate as they reach the top of mountain ranges. Tough conditions: Warmer temperatures make it harder for pikas to survive. They have to spend more time hiding in rocks to avoid the heat, reducing their foraging time for food. This can be especially critical in winter when they rely on stockpiles. Domino effect: The decline of pikas can disrupt the whole ecosystem. They are herbivores that help control plant growth. Their disappearance could lead to changes in vegetation, impacting other species. Classwork Activities; Complete these activities and post it to your google drive folder; Activity 8: Whitebark Pine Trees and Clark's Nutcrackers Activity 9: Sampling strategy for non-motile Organisms Discuss SDG Activity Energy and Biomass in Ecosystems Enquiry Question: How can flows of matter and energy be modelled? What are some of the impacts humans can have on these? Objective: - This subtopic introduces the fundamentals of how energy is used, stored and transferred throughout an ecosystem with examples of food chains, webs and pyramids. - The impact of human activities on the flow and transfer of matter will be discussed and explored Prescribed reading: InThinking Topic 2 Chapter 2.2 ATL Skill: Thinking & Research The First Law of Thermodynamics Ecosystems are open systems, meaning they exchange both energy and matter. As energy flows through ecosystems it can change from one form to another (such as from light to chemical energy or from chemical energy to heat energy). This relates to the first law of thermodynamics which states that, "that energy can be transformed but cannot be created or destroyed". Photosynthesis Photosynthesis is the biological process by which energy from the sun (radiant energy) is transformed into chemical energy in the form of sugar molecules. You might think that photosynthesis is performed only by plants but some algae and chemosynthetic bacteria also use photosynthesis as a means of creating biomass. Carbon dioxide + water → Glucose + oxygen 6CO2 + 6H2O → C6H12O6 + 6O2 These sugar molecules form the foundation of the biomass in most ecological systems. The energy captured by plants via photosynthesis is transferred to the organisms that eat the plants on higher trophic levels. Oxygen is a very important product of photosynthesis and provides an essential ecosystem service. The chemical reaction of photosynthesis can be approached as a system, with inputs and outputs. You can see this in the picture. Respiration Cellular respiration is the process whereby chemical energy captured in photosynthesis is released within cells of plants and animals. Glucose (a sugar molecule) reacts with oxygen to produce carbon dioxide, water, and chemical energy. C6H12O6 + 6O2 → 6CO2 + 6H2O (+ energy ATP) This energy is used to do biological work such as creating new cells, reproduction, movement, etc. It is essential to note that the reaction of respiration produces a lot of energy in the form of heat which is dissipated (lost) from the organism, thus maintaining the the relatively low entropy of the organism but increasing the entropy in the whole system. This illustrates the second law of thermodynamics. Respiration can also be viewed as a system with inputs and outputs. Basics of Food Chains Energy Flow: Food chains model how energy flows through ecosystems. They typically have 3-5 levels, starting with producers (plants) and ending with top predators. Each level gets less energy than the one before due to energy loss during processes like eating and moving. Arrows in food chains show the direction of energy flow, not where it came from pieces (e.g., vultures), while decomposers(e.g., bacteria, fungi) break them down further. Organisms and Levels: Producers (Level 1): Make their own food using sunlight (photosynthesis) or chemicals (chemosynthesis). Examples: plants, algae, and some bacteria. Consumers (Levels 2+): Eat other organisms. ○ Herbivores (Level 2): Eat plants. Examples: deer, rabbits, birds. ○ Carnivores (Higher Levels): Eat other animals. Examples: foxes, snakes, owls. ○ Omnivores (Higher Levels): Eat both plants and animals. Examples: humans, raccoons, and bears. Detritivores and Decomposers: Break down dead organisms and wastes. Detritivores eat large pieces (e.g., vultures), while decomposers(e.g., bacteria, fungi) break them down further. Exploring Ecosystems; Coastal food webs - Generate a table where you indicate the role players in the coastal ecosystem such as producers, primary, secondary and tertiary consumers etc. Energy Flow Basics - Discuss how energy ﬂows through ecosystems and provide examples of some you have interacted with. Productivity Gross productivity (GP) is the total gain in biomass by an organism. Net productivity (NP) is the amount remaining after losses due to cellular respiration. Imagine a plant (producer) grows 100 units of biomass (GP) through photosynthesis. The plant uses some of this energy, say 20 units, to maintain itself through cellular respiration. The remaining 80 units (NP) is the plant's net growth. Herbivores (consumers) eating these plants will get less energy than the plant produced. This is because the herbivores use even more energy, say 40 units, for their activities. So the actual usable energy they get from the plant is 100 (GP) - 40 (cellular respiration) = 60 units (NP). This pattern continues. Less and less energy is available as we move up the food chain because organisms use energy to survive. That's why food chains are limited in length, typically 4-5 levels. There's just not enough energy left to support higher levels. And lastly, a misconception: a lion doesn't need to eat a massive amount of zebra to get enough energy. The zebra already has less usable energy than the plants it ate, and the lion will use even more energy than the zebra. But the lion gets by with a smaller amount of food because it gets a concentrated source of energy from the zebra. The conversion of light energy into a primary producer's biomass in a given amount of time is measured as Primary Productivity. The initial conversion is known as the Gross Primary Productivity (GPP). After respiration losses have been accounted for, this is Net Primary Productivity (NPP). NPP = GPP - R There are two methods for measuring Primary productivity. These can be explored via Introducing Primary Productivity. Food Webs Arrows in food chains and food webs indicate the direction of energy flow and transfer of biomass. In a food web, species may feed at more than one trophic level. In food chains and webs, arrows depict the unidirectional transfer of energy and biomass. They point from the food source (consumed organism) to the consumer (organism doing the eating). Energy: Captured sunlight by producers flows through consumers, with a portion lost as heat at each level due to cellular respiration. Biomass: Organic matter (mass of living organisms) is transferred as consumers eat. Food webs acknowledge the complexity of ecosystems, where: Species can have diverse diets, feeding at multiple trophic levels. (e.g., an omnivore like a fox might eat both plants and rabbits) There are interconnected feeding relationships, creating a web-like structure instead of a linear chain. This highlights the dynamic energy flow within ecosystems, where multiple consumers may interact with various food sources. Biomass To determine the amount of organic matter (biomass) in a sample, it is often useful to measure its dry mass. This is because water, which is the main component of inorganic matter in most organisms, can be removed from the sample through drying. Thus, the dry mass of the sample can be approximately equal to its biomass. Furthermore, the energy contained within the biomass can be measured by combusting the samples and extrapolating the results. This process involves burning the sample in a controlled environment and measuring the heat released. By knowing the mass of the sample and the amount of heat released during combustion, the energy content of the sample can be calculated. How to calculate biomass activities can be found here ACTIVITIES Complete the following activities and upload to your google drive folder Activity 10 1) Find a video showcasing and ecosystems and the various role players in that ecosystem. Place the link in your document. 2) Identify and tabulate the various role players in the ecosystem such as producers, primary consumers etc. 3) Sketch a web food highlighting the interaction and ﬂow of energy between the various stakeholders. PYRAMIDS Ecological pyramids are another method of modelling the feeding relationships in communities and ecosystems and ultimately showing the flow of energy and matter in the system. Howard Odum famously did this for Silver Springs. You can read more in summary 5. Estimating Biomass and Energy Flow. You need to be able to construct and interpret pyramids of numbers, biomass, and productivity, linking to the laws of thermodynamics. Ecological pyramids provide information about trophic levels in ecosystems. The type of pyramid is chosen depending on the type and quantity of data collected. Ecological pyramids are graphical models that illustrate the quantitative differences that exist between the trophic levels of a single ecosystem. According to the second law of thermodynamics, the pyramids tend numbers and quantities of biomass and energy to decrease along food chains, therefore the pyramids generally become narrower as one ascends. Pyramids of numbers Pyramids of numbers provide a diagrammatic representation of the numbers of different organisms at each trophic level in an ecosystem at any one time. Generally, as the pyramid ascends, the number of organisms decreases, but the size of each individual increases. They represent a store at that particular trophic level. Exceptions: Exceptions to the “normal” shape occur when the producer is very large e.g. an oak tree, or parasites feed on the consumers, e.g. bird lice on owl. Pyramids of biomass: Pyramids of biomass represent the biomass (number of individuals x mass of each individual at each trophic level at any one time. It eliminates the effect of body mass and represents the standing stock at each trophic level. These are used so that a fair comparison can be made between different ecosystems. The dry mass of organisms is used to negate the variability of water content in organisms. The units are expressed in grams per square metre (gm-2) but energy can also be used, such as Joules per square metre (Jm–2 ) such as calculated in the "energy content of biomass" experiment. Both pyramids of numbers and pyramids of biomass represent storages. Exceptions In some aquatic ecosystems, the pyramid of biomass can be inverted because phytoplankton grow and reproduce rapidly, i.e. they have a high turnover rate and so at a particular time of year, due to seasonal variations, higher trophic levels may be larger than the producer. This is because the pyramid represents the biomass at a given time and when there are marked seasonal variations, the producers may have died while the primary consumers are still alive. The pyramids of biomass also represent the stores present in a particular trophic level. Pyramids of Productivity: Pyramids of productivity represent the rate of flow of energy through each trophic level of an ecosystem during a fixed time period (usually 1 year, to account for seasonal effects). Pyramids of biomass simply represent the momentary stock, whereas pyramids of productivity show the rate at which that stock is being generated. The values can be expressed as biomass (gm-2yr-1) or as energy, e.g. as kilojoules per square metre per year (kJ m-2yr-1). Pyramids of productivity are never inverted when one entire year is considered. The solar input of energy may be included as an extra rectangle at the base. Although there is variation in the literature, for this syllabus “pyramids of biomass” refers to a standing crop (a fixed point in time) and “pyramids of productivity” refer to the rate of flow of biomass or energy. Bioaccumulation and Biomagnification Bioaccumulation Imagine the circles in the image are organisms in a population. Over time each organism, by chance, may accumulate different amounts of toxin in its tissue. The red dots illustrate the toxin. Non-biodegradable toxins can accumulate in the tissues of organisms. When this happens over the lifespan of one organism it is called bioaccumulation Normally the toxins are fat soluble and build up in fatty tissue Here's an interesting and sad example from polar bears in the arctic which are suffering from bioaccumulation of persistent organic pollutants (POPs). Biomagnification In the diagrams, we see that the concentration of a pollutant can be magnified along a food chain. "Classic Examples of Biomagnification" There are two tragic, classic studies of the effect of the bioaccumulation/biomagnification of toxic substances in organisms. Rachel Carson published Silent Spring in 1962 highlighting the effect of the organochlorine pesticide, DDT on birds. DDT was widely banned after this research but recently a directive from the World Health Organisation has stated that limited use of DDT may be advised in malaria prone areas. See The Dilemma of DDT. Rachel Carson, Silent Spring and the Story of DDT Rachel Carson published Silent Spring in 1962 Highlighted the effect of the organochlorine pesticide, DDT on birds Predatory bird populations in USA were crashing as their egg shelves were not developing properly DDT was banned from use in the USA in 1972. More recently the WHO has advocated its limited use again due to its effectiveness against malaria - this is very controversial In the 1950s, one of the most severe incidents of industrial pollution and mercury poisoning occurred in the small seaside town of Minamata, Japan. A local petrochemical and plastics company, Chisso Corporation, dumped an estimated 27 tons of methylmercury into Minamata Bay over 37 years. Residents of Minamata relied heavily on fish for food. The high contamination levels in the people of Minamata led to severe neurological damage and killed more than 900 people. An estimated 2 million people from the area suffered health problems or were left permanently disabled by the contamination. The expression "mad as a hatter" and the Mad Hatter character in Lewis Carroll's Alice in Wonderland are based on symptoms common amongst 19th-century English hat makers, who inhaled mercury vapours when they used a mercurous nitrate solution to cure furs. Many hatters developed severe muscle tremors, distorted speech, and hallucinations as a result. Doctors struggled to diagnose the mysterious disease when it first was noticed in the early 1950's. Local cats were seen acting strangely before falling over and birds would fall from the sky. In 1959, doctors at Kumamoto University determined that organic mercury poisoning was the cause of the symptoms exhibited by so many of the townspeople. In 1977, the Japanese government took on the huge task of cleaning the sediments in the bay by vacuuming up 1.5 million cubic meters of mercury-contaminated sludge. After 359 million dollars and 14 years, the project was completed in 1997. Mercury encyclopedia resource Mercury occurs naturally in the lithosphere from volcanic action and the weathering of rocks. The biggest source of man-made mercury pollution is the burning of coal. Mercury is methylated by bacteria and in this form can be incorporated into the food chain naturally. In longer marine food chains the top carnivores, such as swordfish and tuna, can accumulate quite a lot of mercury in their tissues. This is why it is not recommended to eat these fish more than once a week. Link between microplastics and non-biodegradable pollutants An estimated 33 billion pounds of the world's plastic trash enters the oceans every year, according to the nonprofit conservation group Oceana, eventually breaking down into tiny fragments called microplastics. Microplastics are minute plastic particles under 5mm in size. A 2020 study found 1.9 million microplastic pieces in an area of about 11 square feet in the Mediterranean Sea. Non-biodegradable pollutants are absorbed within microplastics, which increases their transmission in the food chain. Studies have illustrated the potential for plastic debris to sorb, concentrate and transport POPs in the marine environment as well as their ingestion by marine organisms. You can see this represented diagrammatically here. These tiny fragments absorb harmful chemicals and other pollutants, which accumulate within larger species. This accumulation of plastic and toxins can also put human health at risk. Associated with this story is the possibility that cats were parachuted into Sarawak to help restore the balance. Decide what you think by reading this article and watching this video ACTIVITIES Complete the activities below and submit on your google drive folder. Activity 11 Activity 12 Activity 13 Activity 14

ESS Unit 2 Ecology 2.pdf - Environmental Systems & Societies DP 1

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