Name: microbial life in the ocean
Uploaded: 2026-03-12T13:57:29.000Z
Duration: 1 min 30 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Environmental Science

Earth and Human Activity

9-12.EVS.4.8.a

Marine Microbial Ecology

البيئات البحرية غالبا ما تكون منخفضة في المغذيات، مما يفضل الميكروبات القليلة التغذية التي تميل إلى أن تكون حجمها أصغر مقارنة بنظيراتها في المياه العذبة.يسبب النشاط المدي تقلبات في الملوحة في المصبات والمناطق الساحلية، مما يدعم وفرة من الميكروبات المقاومة للهالوت. تصبح هذه المناطق خالية من الأكسجين بشكل متقطع بسبب ارتفاع معدلات التنفس، مما يسمح للبكتيريا المختلة بالكبريتات بالازدهار وإنتاج كبريتيد الهيدروجين.تحتوي المياه البحرية السطحية العليا التي تتراوح بين 100 إلى 200 متر على المنطقة الضوئية، حيث يتم إعادة تدوير المغذيات باستمرار عبر الحلقة الميكروبية.تستهلك الميكروبات الصغيرة غير المتجانسة المادة العضوية المذابة في البحر، والتي تشمل التمثيل الضوئي الناتج عن الأنظمة الضوئية الذاتية التغذية والحطام الجسيئي الناتج عن تحلل الخلية.تتغذى البروتيستات غير المتجانسة الأكبر حجما على ميكروبات أصغر وتولد جسيمات عضوية للعوالق الأكبر.غالبا ما تشهد البيئات البحرية تغييرات مدمرة. على سبيل المثال، قد تحفز تسرب النفط تدهور البكتيريا التي تحلل الهيدروكربونات.يؤدي الاحتباس الحراري إلى توسيع مناطق الحد الأدنى للأكسجين من خلال زيادة التدرج وتقليل وصول الأكسجين إلى طبقات أعمق، مما يعطل البيئة البحرية.

علم البيئة الميكروبية البحرية

تتشكل النظم البيئية الميكروبية البحرية بواسطة حدود فيزيائية كيميائية مميزة، بما في ذلك ارتفاع الملوحة وانخفاض توفر العناصر الغذائية، وتقلب مستويات الأكسجين. تفضل هذه الظروف أحجام الخلايا الميكروبية الأصغر، مما يعظم نسبة السطح إلى الحجم لكفاءة امتصاص المغذيات.النشاط الميكروبي وتركيب المجتمع مرتبطان ارتباطا وثيقا بالدورات الكيميائية الحيوية الحيوية، خاصة في البيئات الديناميكية مثل المصبات، حيث تزدهر الميكروبات المقاومة للهالوتات استجابة للملوحة المتغيرة واستنزاف الأكسجين المتكرر.تدعم ظروف نقص الأكسدة في المصبات والمناطق الساحلية نشاط البكتيريا المختلة للكبريتات، التي تنتج كبريتيد الهيدروجين. تسمح مرونتها الأيضية بالبقاء من خلال حالات الأكسدة الاختزاز المتغيرة، مما يساهم في تغير العناصر الغذائية. كما يشكل التحلل الفيروسي ديناميكيات الميكروبات من خلال إطلاق المادة العضوية المذابة (DOM) وتغيير بنية المجتمع.في المياه السطحية، تعد المنطقة الضوئية (حتى حوالي 200 متر) مركز الإنتاجية الأولية. هنا، تقوم الكائنات الضوئية مثل البكتيريا الزرقاء والطحالب الدقيقة بتثبيت الكربون وتطلق DOM، الذي يغذي الحلقة الميكروبية. تستخدم البكتيريا غير المتجانسة والعتائق هذا الدومين، بينما تسرع العدوى الفيروسية من إعادة تدوير المغذيات. تستمر التفاعلات الغذائية مع رعي البروتيستات الأكبر حجما على الميكروبات، محولة الكتلة الحيوية إلى جسيمات عضوية يمكن استخدامها من قبل العوالق الحيوانية والمستويات الغذائية الأعلى.تستجيب المجتمعات الميكروبية بسرعة أيضا للاضطرابات البيئية. على سبيل المثال، يمكن لتسربات النفط اختيار بكتيريا تحلل الهيدروكربونات التي تغير بنية المجتمع والعمليات الكيميائية الحيوية الجيوكيميائية. تغير المناخ يوسع مناطق الحد الأدنى للأكسجين، والتي بدورها تدفع الأيض الميكروبي نحو مسارات لاهوائية، مما يؤثر على دورات المغذيات والكربون العالمية.

Marine microbial ecosystems are shaped by distinct physicochemical limits, including high salinity, low nutrient availability, and fluctuating oxygen ...

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Education

JoVE Core

Microbiology

علم الأحياء الدقيقة

Unit

وحدة

Microbial Ecology

علم البيئة الميكروبية

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

microbial life in the ocean

Marine microbial life is shaped by salinity, low nutrients, and changing oxygen levels. These physical and chemical limits influence which microbes can survive and how they function. They also affect how ocean microbes help drive nutrient and carbon cycling.

Small cell size is common in these environments because it gives microbes a larger surface-to-volume ratio. That helps them take up nutrients more efficiently when nutrients are scarce. In estuaries, where salinity changes often, halotolerant microbes can thrive. These microbes tolerate salt and also cope with recurring oxygen depletion.

Anoxic conditions, or conditions without oxygen, are important in estuaries and coastal waters. They support sulfate-reducing bacteria, which produce hydrogen sulfide. Many of these microbes can switch their metabolism as redox conditions change, and that flexibility helps them keep recycling nutrients.

Viruses also shape marine microbial communities. When viruses break open cells, they release dissolved organic matter, or DOM, into the water. That release changes community structure and can increase the flow of organic material through the system.

In open ocean waters, the photic zone is the sunlit surface layer down to about 200 meters. This is where most primary productivity happens. Photoautotrophs such as cyanobacteria and microalgae fix carbon and release DOM, which feeds the microbial loop. Heterotrophic bacteria and archaea use that DOM, and viral infections help speed nutrient recycling.

Larger protists also interact with microbes by grazing on them. This transfers microbial biomass into particulate organic matter that can be used by zooplankton and organisms at higher trophic levels. Microbial communities can also shift quickly after disturbances such as oil spills, when hydrocarbon-degrading bacteria become more common. Climate change is expanding oxygen minimum zones, which pushes microbial metabolism toward anaerobic pathways and affects global nutrient and carbon cycles.

Microbial Life in the Ocean

introduction to microbial ecology

Microbial Communities in Soil and Extremes

Microbial ecology looks at how microorganisms live, interact, and adapt in different ecosystems. It also shows how these tiny organisms help shape nutrient cycling, energy flow, and environmental balance. An ecosystem includes living parts and non-living parts, and microbes respond to both. Microorganisms can form populations, which are groups of the same species living together at the same time. When populations from different species live and interact in the same place, they form a microbial...

ecological niche

Microbial Niches in Ecosystems

Microbial niches describe how microorganisms survive, grow, and interact in an ecosystem. A niche includes how a microbe gets resources, reproduces, and relates to other species in its environment. This idea helps explain microbial community dynamics, biogeography, and ecosystem function. A microorganism’s fundamental niche is the full range of conditions where it could survive, grow, and reproduce. These conditions include both biotic factors, such as living interactions, and abiotic factors,...

methods to assess microbial populations

Measuring Microbes in Samples

Measuring microbes in a sample helps scientists study health, ecology, and industry. Microbial counts can show how many cells are present, how diverse they are, and what they may be doing. To do this, researchers use both culture-based and molecular methods. A viable plate count is a classic culture method for estimating living microbes. The sample is first diluted step by step, then spread on nutrient agar plates. Each viable cell can grow into a visible colony, so the colonies can be counted.

methods to assess microbial communities

Measuring Microbial Diversity and Activity

Microbial communities include bacteria, archaea, and eukaryotic microorganisms. They live in many ecosystems and affect important environmental and biological processes. Scientists study these communities by looking at how many species are present, how many individuals each species has, and how evenly the species are spread out. Species richness is the number of different species in a sample. Species abundance is the relative amount of each species. Species evenness describes how uniformly the...

the winogradsky column

Microbial Layers Inside a Winogradsky Column

A Winogradsky column shows how microbial layers form in a simple, sealed ecosystem. It is a clear model for studying microbial ecology and how different metabolisms interact in sediment over time. The setup uses a transparent glass cylinder. Half of it is filled with sediment mixed with cellulose, such as shredded paper, calcium carbonate, and gypsum. The cellulose provides a carbon source. Calcium carbonate buffers pH, and gypsum supplies sulfate. The rest of the cylinder is filled with pond...

microenvironments

Microbial Niches in Tiny Habitats

Microorganisms live in tiny habitats called microenvironments. These spaces have their own physical and chemical conditions. Oxygen level, pH, temperature, light, and nutrient supply can all differ from the surrounding area. These local conditions strongly affect microbial growth, metabolism, and which species can live there. Microenvironments often have sharp gradients over very small distances. In soil, oxygen may be available at the particle surface but drop off just a few millimeters below.

microbial mats

Microbial Mats and Oxygen Gradients

Microbial mats are layered communities of microbes that grow in response to changes in light, oxygen, and nutrients. These ecosystems are highly organized, and different microorganisms live at different depths. Biofilms are the early stage of this growth and are only a few millimeters thick. Mature microbial mats can grow to centimeter scale and show clear vertical structure. This layered arrangement lets microbes fill separate niches within a very small space. In cyanobacterial mats from hot...

microbial interactions: mutualism

Mutualistic Partnerships in Nature

Mutualistic partnerships in nature show how two or more organisms can benefit from living together. These symbiotic relationships can be obligate, meaning the partners depend on each other, or facultative, meaning the association is helpful but not required. Mutualism helps support many ecosystem functions across land and water. One common example is the partnership between plant roots and mycorrhizal fungi, such as Rhizophagus species. The fungal hyphae grow into the root hairs and epidermis,...

microbial interactions: cooperation

Microbial Cooperation in Soil and Hosts

Microbial cooperation describes helpful interactions between different species. In these partnerships, microbes work together for one or mutual benefit. These interactions can shape ecosystems and evolution. They also play major roles in symbiosis and disease. One clear example involves the Gram-negative bacterium Xenorhabdus nematophila and the parasitic nematode Steinernema carpocapsae. Juvenile nematodes carry the bacteria in the soil and need an insect host to mature. When the nematode...

microbial interactions: predation

How Microbes Hunt and Defend

Microbial predation is a form of interaction in which one microorganism kills and eats another to gain nutrients and energy. It includes both bacterial predators and protozoan predators. This process helps shape microbial communities and affects how nutrients move through the environment. Some bacterial predators attack from the outside, while others enter the prey cell. Epibiotic predators, such as Vampirococcus, attach to the surface of a prey cell and release hydrolytic enzymes. These...

microbial interactions: competition

Microbial Competition and Niche Partitioning

Microbial competition shapes how bacteria and other microbes share space and resources. In shared environments, they compete for nutrients, space, or light. The strength of this competition depends on the environment, including nutrient levels, space limits, and how many microbial species are present. These interactions help determine the structure, function, and resilience of microbial communities. Microbial competition is usually grouped into exploitative competition and interference...

microbial interactions: parasitism

Microbial Parasites and Host Dependence

Microbial parasites depend on a host for nutrients and shelter, and this dependence often harms the host. In parasitism, only the parasite benefits. This is different from mutualism, where both organisms gain from the relationship. Microbial parasites are classified by where they live in or on the host. Ectoparasites stay on the host’s surface, such as the skin or outer tissues, and take in nutrients from outside. Endoparasites live inside the host’s body and invade tissues or organs.

microbe-plant interactions

How Plant Microbes Affect Growth

Plant microbes can help, harm, or simply live alongside their hosts. These microbe-plant interactions shape plant growth, health, and ecosystem function. The plant microbiome includes bacteria, fungi, archaea, protists, and viruses, and these organisms may live on the plant surface, inside plant tissues, or in symbiosis throughout the plant. Some of the most important beneficial partnerships involve mycorrhizal fungi. These fungi form close connections with roots and are grouped as arbuscular...

microbes and the carbon cycle

How Microbes Move Carbon Through Earth

Microbes move carbon through Earth’s major reservoirs and help drive the carbon cycle. Carbon shifts among the biosphere, lithosphere, atmosphere, and hydrosphere, where it supports life and helps regulate climate. It commonly cycles as carbon dioxide (CO2), the oxidized form of carbon, but methane (CH4) and organic compounds also matter. Photosynthetic microbes take in atmospheric CO2 and turn it into organic carbon. Cyanobacteria are especially important because they carry out oxygenic...

microbes and methanogenesis

How Microbes Produce Methane

Methane production in anaerobic ecosystems depends on methanogenic archaea and the microbes that work with them. This process happens where oxygen is absent, such as wetlands, sediments, and animal gastrointestinal tracts. In these anoxic habitats, aerobic respiration cannot run, so microbes use other pathways to break down organic matter. Anaerobic decomposition starts when cellulolytic bacteria, or cellulose-digesting bacteria, hydrolyze dead organic material into simple sugars. Other...

microbes and the nitrogen cycle

Microbial Steps in the Nitrogen Cycle

Microbes drive the nitrogen cycle by changing nitrogen into forms that plants and other organisms can use. This biogeochemical cycle keeps nitrogenous compounds balanced in ecosystems. It also supports plant growth and microbial growth. Nitrogen fixation begins the cycle by converting inert atmospheric nitrogen gas, N2, into ammonia, NH3. This step depends on nitrogenase enzymes. Free-living diazotrophs do this on their own. Aerobic bacteria such as Azotobacter spp. and anaerobic bacteria such...

microbes and the sulfur cycle

Sulfur Cycling Through Microbial Reactions

Sulfur cycling depends on microbial reactions that move sulfur through rocks, water, soil, and the air. In Earth systems, sulfur shifts among inorganic forms such as sulfate, elemental sulfur, and sulfide. These changes happen through both abiotic processes and biological activity in oxic and anoxic environments. Sulfate is the most oxidized form of sulfur. It is stored mainly in rocks, marine sediments, and ocean water, where it acts as a long-term reservoir in the global sulfur cycle. In...

microbes and other elemental cycles

Microbes Driving Iron and Manganese Cycles

Microbes drive iron and manganese cycling in aquatic environments by changing these metals between reduced and oxidized forms. These reactions are especially important along redox gradients, where oxygen levels shift across stratified water layers. The microbes use these metals for energy, growth, and structural needs. In oxygen-rich surface waters, iron is usually present as insoluble ferric iron, Fe(III). Some bacteria release siderophores, which are small organic molecules that bind ferric...

marine microbial ecology

Marine microbial life is shaped by salinity, low nutrients, and changing oxygen levels. These physical and chemical limits influence which microbes can survive and how they function. They also affect how ocean microbes help drive nutrient and carbon cycling. Small cell size is common in these environments because it gives microbes a larger surface-to-volume ratio. That helps them take up nutrients more efficiently when nutrients are scarce. In estuaries, where salinity changes often,...

deep sea microbial ecology

Deep Sea Microbes and Extreme Conditions

Deep sea microbes live in one of Earth’s harshest environments. The deep ocean is far below the sunlit photic zone, which usually reaches the upper 100 to 200 meters of open water. Below that layer, the bathypelagic and abyssal zones stretch from about 1,000 to 6,000 meters, and hadal trenches go even deeper. This region is dark, cold, and highly pressurized. Temperatures are usually around 2 to 3°C, although hydrothermal vents can be slightly warmer. Pressure rises by about 1 atmosphere for...

freshwater microbial ecology

Microbes in Streams, Lakes, and Rivers

Freshwater microbes live in streams, rivers, lakes, ponds, and marshes, but their communities change with water movement, light, depth, and nutrients. These systems are often grouped into lotic waters, which flow, and lentic waters, which are still or slow-moving. The physical setting shapes where microbes grow and how they get energy. In lentic systems, phytoplankton are the main producers. They make autochthonous organic carbon, which means carbon made within the water body. In lotic...

soil microbial ecology

How Soil Microbes Cycle Nutrients

Soil microbes drive nutrient cycling, organic matter turnover, and ecosystem stability. A gram of soil can contain thousands of bacterial and archaeal taxa, but their shared job is what helps sustain land ecosystems. Their activity changes the way carbon, nitrogen, and other nutrients move through soil. Soil is a patchwork of minerals, organic matter, water, and air. Microbes live in tiny microhabitats shaped by pore size, moisture, oxygen, and nutrients. Sandy soils drain fast and tend to...

key terms and concepts

Explore how salinity, oxygen, viruses, and sunlight shape marine microbes. Learn how bacteria, protists, and algae drive ocean nutrient and carbon cycles.

Microbial Life in the Ocean | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

biofuels-producing-ethanol-from-cellulosic-material

Biofuels: Producing Ethanol from Cellulosic Material

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In this experiment, cellulosic material (such as corn stalks, leaves, ...

Biofuels

The microbial conversion of organic matter into biofuels holds potential as a renewable energy source. Among biofuel sources, microalgae are recognized as ...

Enthalpy and Heat of Reaction

Combustion, commonly known as burning, is a reaction in which a substance reacts with an oxidizing agent, which in most cases is molecular oxygen, to ...

Enthalpies of Reaction

Hess&rsquo;s law can be used to determine the enthalpy change of any reaction if the corresponding enthalpies of formation of the reactants and products ...

Proton Exchange Membrane Fuel Cells

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy &#8211; the current ...

6. Obtain, evaluate, and communicate information to describe the use of renewable and nonrenewable energy sources. Examples: Describe the similarities and differences among fossil fuels. Gather and share information to describe different sources of renewable energy from biomass such as biodiesel, cellulosic ethanol, and algae.

9-12.EVS.4.6

Dye-sensitized Solar Cells

Source: Tamara M. Powers, Department of Chemistry, Texas A&#38;M University
Today&#39;s modern world requires the use of a large amount of energy. While ...

Light as Energy

The energy required to carry out photosynthesis is light&#8212; typically electromagnetic radiation from the sun. The range of all possible wavelengths is ...

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GIS Software, Hardware, and Sources of GIS Data

A Geographic Information System (GIS) combines specialized software and hardware to effectively manage, analyze, and present spatial and related data. GIS ...

a. Analyze and interpret data on the origins and availability of renewable and nonrenewable forms of energy to predict consumption trends. Examples: Use a solar irradiance map to predict the best area for a solar thermal power plant. Analyze the distribution of fossil fuel reserves around the globe to identify energy-rich and energy-poor areas and predict future trends in types of fuel used and rates of consumption.

9-12.EVS.4.6.a

Manipulation and Analysis

GIS manipulation and analysis functions are vital for decision-making and planning. These activities range from data retrieval tasks, such as selecting ...

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The certainty of climate change remains a public controversy despite the consensus among approximately 97% of active climate researchers, who not only ...

Microbes and Climate Change

Microorganisms are pivotal agents in Earth's biogeochemical cycles, significantly influencing climate dynamics through their metabolic activities. These ...

Coordinates and Map Projections

Coordinates and map projections are essential tools in accurately representing the Earth's surface for various applications, ranging from navigation to ...

b. Construct an argument based on data about the risks and benefits of using renewable and nonrenewable energy sources in Alabama.

9-12.EVS.4.6.b

Quarrying of Stone

Quarrying involves the meticulous extraction of stone from a quarry by either using controlled explosions or precision cutting techniques to remove the ...

Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3&#8211;12 are ...

Microbial Bioremediation of Plastics

Polyethylene terephthalate (PET) is a synthetic polymer widely utilized in the packaging industry, particularly for bottles and containers. Due to its ...

Bioplastics

Bioplastics derived from microbial processes present a sustainable alternative to conventional petroleum-based plastics. Among these, ...

7. Obtain, evaluate, and communicate information to describe the development, management, and recycling of mineral resources. Example: Research technologies used to mine and process rare Earth metals for electronics. Gather information and draw conclusions about the sustainability of plastics recycling.

9-12.EVS.4.7

Nutrients in Aquatic Ecosystems

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Nitrogen and phosphorus are essential plant nutrients found in aquatic ...

The Nitrogen Cycle

Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of ...

The Phosphorus Cycle

Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, ...

The Sulfur Cycle

Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the ...

Using GIS to Investigate Urban Forestry

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped ...

Biological Clocks and Seasonal Responses

The circadian&#8212;or biological&#8212;clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities ...

Pollination and Flower Structure

Flowers are the reproductive, seed-producing structures of angiosperms. Typically, flowers consist of sepals, petals, stamens, and carpels. Sepals and ...

8. Construct or revise a claim based on evidence of the effects of human activities on Earth's systems, natural resources, and ecosystem services. Examples: Construct a claim that excess nitrogen and phosphorus causes algal blooms, deforestation disrupts carbon storage, or excess atmospheric sulfur leads to acid rain. Construct a claim that changing rain patterns cause flooding or desertification. Construct a claim that temperature cycles affect the timing of migrations and the flowering of plants, causing a disjunction in pollination.

9-12.EVS.4.8

What is Photosynthesis?

All living organisms on Earth are directly or indirectly dependent on photosynthesis. It is the only biological process that can capture energy from ...

The Calvin Cycle

Overview

Oxygenic photosynthesis converts approximately 200 billion tons of carbon dioxide (CO2) annually to organic compounds and produces approximately ...

a. Evaluate published information from computational models which illustrate the effects of an increase in atmospheric carbon dioxide on photosynthesis and the effect of ocean acidification on marine populations.

determination-of-nox-in-automobile-exhaust-using-uv-vis-spectroscopy

Determination Of NOx in Automobile Exhaust Using UV-VIS Spectroscopy

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In the troposphere, ozone is naturally formed when sunlight splits nitrogen ...

Bioremediation

Bioremediation is the use of prokaryotes, fungi, or plants to remove pollutants from the environment. This process has been used to remove harmful toxins ...

Microbial Bioremediation of Hydrocarbons

Bioremediation is an environmentally sustainable process that employs living organisms&#8212;primarily microorganisms&#8212;to degrade or neutralize ...

Microbial Bioremediation of Pesticides

Pesticides often feature structurally complex chemical architectures, incorporating halogen groups and multiple aromatic rings. These characteristics ...

b. Use engineering practices to evaluate and refine a current solution designed to protect natural resources from anthropogenic sources of atmospheric, terrestrial, or aquatic pollution. Example: Create mechanisms to remove plastic from the ocean or particulates from industrial exhaust.

9-12.EVS.4.8.b

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Applications of GIS: Disaster Management and Emergency Response

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Ecological Disturbance

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What are Biogeochemical Cycles?

The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited ...

9. Obtain, evaluate, and communicate information based on evidence to explain how key natural resources, natural hazards, and climate variability influence human activity and welfare.

9-12.EVS.4.9

Stratified Sampling Method

Sampling is a technique to select a portion (or subset) of the larger population and study that portion (the sample) to gain information about the ...

a. Communicate scientific information about how environmental change may disproportionately impact people in certain socioeconomic groups or geographic locations. Examples: People in lower socioeconomic groups or those who are unhoused are more affected by rising temperatures and heat islands than others. Populations living at lower sea levels are more impacted by sea level rise than those who live at higher elevations. People living in floodplains are more likely to experience seasonal flooding than those living on higher ground.

9-12.EVS.4.9.a

Genetic Drift

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Gene Flow

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This ...

Conservation of Small Populations

Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens ...

Conservation of Declining Populations

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Habitat Fragmentation

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10. Use mathematics and graphic models to communicate how human activity may affect genetic variation in organism populations, including threatened and endangered species.

9-12.EVS.4.10

Population Growth

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Population Models
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Key Elements for Plant Nutrition

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11. Construct an explanation of how human populations undergo growth and decline. Examples: Explain how birth and death rates, infant mortality, nutrition, and other factors increase or decrease human populations. Clarification: Use of mathematical calculations to determine growth rate is not required.

9-12.EVS.4.11

Microbial Life in the Ocean

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