Biology 112 Exam 5

Energy & Nutrients Cycle through Ecosystems

What does an Ecosystem consist of?

  • Biotic & Abiotic Factors/Interactions

  • Energy cycles

  • Nutrient cycles

Net Primary Productivity

  • What is it?

    • The rate at which producers in an ecosystem convert solar energy into chemical energy stored in biomass

  • Global patterns of NPP

    • Variation among biomes

  • Energy Flow

    • How energy moves through trophic levels

    • Only about 10% of the energy is transferred from one level to the next

  • Bioaccumulation

    • When pollutants build up over the life time of an organism

  • Biomagnification

    • Increasing concentration (magnification) from one trophic level to the next

Nutrient Flow

  • Global Water Cycle

    • How water moves between different reservoirs, including oceans, atmosphere, land, and living organisms

      • How much fresh water is available?

        • Freshwater is limited

        • Much of it is trapped in glaciers and ice caps

        • Only a small percentage is readily available in lakes, rivers, and groundwater, which are essential for supporting life and human activities

        • Understanding the distribution and availability of fresh water is crucial for managing water resources and addressing issues like drought and water scarcity

  • Nitrogen, Phosphorous and Carbon cycle through living and non-living reservoirs (be familiar with the various reservoirs)

    • Nitrogen cycle

      • Nitrogen is crucial for building proteins and nucleic acids

      • The major reservoirs include the atmosphere, soil, and living organisms

      • Nitrogen fixation converts atmospheric nitrogen into forms usable by plants

    • Phosphorous cycle

      • Phosphorus is essential for DNA, RNA, and ATP

      • The major reservoirs are rocks and sediments Weathering of rocks releases phosphate into the soil, which plants absorb

    • Carbon cycle

      • Carbon is the backbone of organic molecules

      • The major reservoirs include the atmosphere, oceans, land (including fossil fuels), and living organisms

  • Nitrogen/phosphorous as fertilizers

    • When applied to crops, these nutrients enhance plant growth, leading to higher yields

  • Global Carbon Cycle

    • Ocean = major reservoir but can only hold so much

      • The ocean acts as a major carbon sink, absorbing CO2 from the atmosphere

    • CO2 important form for plants

    • Human activities impacting the Carbon Cycle

      • Deforestation reduces the number of trees available to absorb CO2, leading to increased atmospheric CO2 levels

      • Burning fossil fuels release large amounts of stored carbon into the atmosphere as CO2CO2, intensifying the greenhouse effect and contributing to climate change

Impacts of Climate Change

  • Predicated changes in temperature, soil moisture, food production etc.

    • Temperature shifts

    • Soil moisture increases

    • Food production decreases

  • 5 general categories

    • Geographic range shifts

      • Species move to different areas in response to changing climate conditions

    • Phenology shifts

      • Changes in the timing of biological events, such as flowering, migration, or breeding

    • Evolutionary adaptations

      • Genetic changes that allow populations to better cope with new environmental conditions

    • Extinction

      • The disappearance of species that cannot adapt quickly enough to changing conditions

    • Ocean acidification

      • The decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2) from the atmosphere

      • When CO2 dissolves in seawater, it forms carbonic acid, which reduces the availability of carbonate ions that marine organisms need to build their shells and skeletons

Biodiversity & Conservation Biology

3 Levels

  • Genetic Diversity

    • Variety of genes within a species

    • ex. number of different breeds in a species

  • Species Diversity

    • Involves the number of different species in an ecosystem or on Earth

  • Ecosystem Diversity

    • The variety of ecosystems in a given region

Importance of functional groups

  • Functional groups are classifications of organisms based on their roles and how they contribute to an ecosystem (producers or decomposers for example)

  • These groups help us understand how ecosystems function and maintain balance

Endemic vs. cosmopolitan species

  • Endemic species

    • Species that are unique to a particular geographic location

  • Cosmopolitan species

    • Species that are found worldwide or in many different regions across the globe

How many species are there?

  • How to assess species #/diversity

    • Taxa specific

      • Focuses on particular groups, such as birds or insects, to estimate their diversity in a given area

    • Census a region

      • A comprehensive count of all species present, often used in smaller, well-defined areas

    • e-DNA

      • Analyzes environmental samples like soil or water to detect the genetic material of different species, providing a broad overview of biodiversity in a region

  • Species diversity not equally distributed

  • Biodiversity Hotspots

    • Has exceptionally high numbers of species

Threats to Biodiversity

  • Habitat Destruction/Degradation

    • Land use

      • Deforestation for agriculture or urbanization, directly destroy habitats and displaces species

    • Artificial Light

      • Disrupts the natural behavior and physiology of many organisms, affecting their reproduction, foraging, and migration patterns

    • Noise

      • Pollution from human activities, like traffic and construction, can interfere with animal communication, hunting, and overall survival

  • Overexploitation 

    • The unsustainable removal of wildlife or natural resources from their habitat for human use

  • Invasive species

    • How do they impact native habitats

      • They can outcompete native species for resources like food and habitat, leading to a decline in native populations

    • How did they get there?

      • Accidental

        • Through ballast water in ships

      • Intentional

        • When people release exotic pets into the wild

    • Impact on islands

      • Islands are particularly vulnerable to the impacts of invasive species because their isolated ecosystems often lack natural defenses against new predators or competitors

    • Disease

      • Invasive species can introduce diseases that native species have no immunity to, further threatening their survival

  • Pollution

    • Industrial

      • Releases harmful chemicals and toxins into the environment, contaminating soil, water, and air, thereby affecting the health and survival of various species

    • Pharmaceutical

      • Occurs when medications and their byproducts enter water systems, disrupting aquatic ecosystems and potentially affecting human health

    • Nutrient runoff

      • Often from agricultural activities, leads to excessive nutrient enrichment in water bodies, causing algal blooms and oxygen depletion, which can harm aquatic life

    • Garbage

      • Garbage and plastic waste accumulate in ecosystems, causing habitat destruction, entanglement of wildlife, and the release of toxic substances

Preserving Biodiversity & Ecosystem Function

  • Ecosystem Equilibrium/Resistance/Resilience

    • Equilibrium

      • The state of balance within an ecosystem, where the populations of different species remain relatively stable over time, and the flow of energy and nutrients is balanced

    • Resistance

      • The ability of an ecosystem to withstand disturbances without undergoing significant changes, like a forest resisting a mild drought

    • Resilience

      • The ability of an ecosystem to recover from disturbances, like a forest regrowing after a fire given enough time

  • Ecosystem Services

    • Provisioning

      • Include things like food and water

    • Regulating

      • Include climate regulation and disease control

    • Supporting

      • Include nutrient cycling and pollination

    • Cultural

      • Include recreational and aesthetic benefits

  • Conservation Strategies

    • Genetic Restoration (from another wild pop or ex-situ)

      • Introducing genetic material from another wild population or from ex-situ conservation efforts to increase genetic diversity

    • Seed Banks

      • Store seeds to preserve plant species

    • Legislation that establishes legal protection

      • Establishes legal protection for endangered species and their habitats

    • Connecting fragmented populations (fish ladders, wildlife corridors)

      • Can be achieved through fish ladders, which help fish migrate upstream, and wildlife corridors, which allow animals to move between habitat patches

    • Ecosystem restoration (pollution clean-up)

      • Involves cleaning up pollution to restore degraded ecosystems