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

סביבות ימיות לעיתים קרובות דלות בחומרים מזינים, ומעדיפות מיקרובים אוליגוטרופיים שנוטים להיות בעלי גודל תאים קטן יותר בהשוואה למים מתוקים.פעילות גאות והגאות גורמת לתנודות במליחות בשפכים ובאזורים חופיים, התומכת בשפע של מיקרובים סובלניים להלוטלריים. אזורים אלו הופכים לאנוקסיים לסירוגין עקב קצב נשימה גבוה, מה שמאפשר לחיידקים המפחיתי סולפט לשגשג ולייצר מימן גופריתי.ה-100 עד 200 המטרים העליונים של מי הים הפלאגיים מכילים את האזור הפוטי, שבו חומרי הזנה ממוחזרים באופן רציף דרך הלולאה המיקרוביאלית.מיקרובים הטרוטרופיים קטנים צורכים את החומר האורגני המומס בים, הכולל פוטוסינתזה מפוטואוטוטרופיים ושאריות חלקיקים מניתוק תאים.פרוטיסטים הטרוטרופים גדולים יותר ניזונים ממיקרואורגניזמים קטנים ומייצרים חלקיקים אורגניים לפלנקטון גדול יותר.סביבות ימיות חוות לעיתים שינויים משבשים. לדוגמה, דליפות נפט עשויות לעורר פריחות של חיידקים המפרקים פחמימנים.ההתחממות הגלובלית מרחיבה את אזורי מינימום החמצן על ידי הגברת הסטרטיפיקציה והפחתת אספקת החמצן לשכבות עמוקות יותר, מה שמפריע לאקולוגיה ימית.

אקולוגיה מיקרוביאלית ימית

מערכות אקולוגיות מיקרוביאליות ימיות מעוצבות על ידי מגבלות פיזיקוכימיות מובחנות, כולל מליחות גבוהה, זמינות תזונתית נמוכה ורמות חמצן משתנות. תנאים אלו מעדיפים גדלי תאים מיקרוביאליים קטנים יותר, שממקסמים את יחס פני השטח לנפח שלהם לספיגת חומרים מזינים יעילה.פעילות מיקרוביאלית והרכב הקהילה קשורים קשר הדוק למחזורים ביוגיאוכימיים, במיוחד בסביבות דינמיות כמו שפכי נהרות, שבהן מיקרובים עמידים להלוטלרנטי משגשגים בתגובה למליחות משתנה ולדלדול חוזר של חמצן.תנאי אנוקסיה בשפכי הנהרות ובאזורים חופיים תומכים בפעילות חיידקים מפחיתים סולפט, המייצרים מימן גופריתי. הגמישות המטבולית שלהם מאפשרת להם לשרוד גם במצבי רדוקס משתנים, מה שתורם למחלוקת חומרים מזינים. ליזה ויראלית גם מעצבת את הדינמיקה המיקרוביאלית על ידי שחרור חומר אורגני מומס (DOM) ושינוי מבנה הקהילה.במים פלגיים, האזור הפוטי (עד כ-200 מטרים) הוא מרכז התפוקה הראשונית. כאן, פוטואוטוטרופיים כמו ציאנובקטריה ומיקרואצות מקבעים פחמן ומשחררים DOM, שמזין את הלולאה המיקרוביאלית. חיידקים הטרוטרופיים וארכאות משתמשים ב-DOM זה, בעוד זיהומים ויראליים מאיצים את מיחזור החומרים המזינים. אינטראקציות טרופיות נמשכות כאשר פרוטיסטים גדולים יותר רועים מיקרובים, וממירים ביומסה לחלקיקים אורגניים שיכולים לשמש זואופלנקטון ורמות טרופיות גבוהות יותר.קהילות מיקרוביאליות גם מגיבות במהירות להפרעות סביבתיות. דליפות נפט, למשל, יכולות לבחור חיידקים המפרקים פחמימנים שמשנים את מבנה הקהילה ואת התהליכים הביוגאוכימיים. שינויי האקלים מרחיבים את אזורי המינימום של חמצן, אשר בתורם דוחפים את חילוף החומרים המיקרוביאלי לכיוון מסלולים אנאירוביים, ובכך משפיעים על מחזורי התזונה והפחמן העולמיים.

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

מיקרוביולוגיה

Unit

יחידה

Microbial Ecology

אקולוגיה מיקרוביאלית

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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

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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, ...

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Enthalpies of Reaction

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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

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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

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Coordinates and Map Projections

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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

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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
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The Nitrogen Cycle

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The Phosphorus Cycle

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The Sulfur Cycle

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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

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Overview

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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.

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Determination Of NOx in Automobile Exhaust Using UV-VIS Spectroscopy

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Microbial Bioremediation of Hydrocarbons

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Microbial Bioremediation of Pesticides

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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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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

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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

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Gene Flow

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This ...

Conservation of Small 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

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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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