Name: microbes in streams, lakes, and rivers
Uploaded: 2026-03-12T13:57:36.000Z
Duration: 1 min 24 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Environmental Science

Unity and Diversity

9-12.EVS.2.3.b

Freshwater Microbial Ecology

Ekologia mikrobiologiczna w wodach słodkowodnych kształtowana jest przez dostępność organicznego węgla, składników odżywczych, tlenu i światła.Blisko powierzchni fitoplankton wykorzystuje światło słoneczne do przekształcania dwutlenku węgla w węgiel organiczny.W płytkich wodach okrzemki przyczyniają się do produkcji organicznego węgla, podczas gdy mikroorganizmy heterotroficzne rozkładają ten organiczny węgiel, uwalniając dwutlenek węgla i recyklingując składniki odżywcze z powrotem do wody.Biofilmy na zanurzonych powierzchniach zatrzymują materię organiczną z wody, gdzie bakterie, grzyby i protisty współpracują, rozkładając ją i uwalniając dwutlenek węgla.Strefy bentosowe zazwyczaj otrzymują węgiel z opadu liści i zanurzonej materii organicznej, która jest degradowana przez mikroby heterotroficzne.Te mikroorganizmy uwalniają rozpuszczony węgiel organiczny z powrotem do wody, wspierając pobliskie społeczności mikrobiologiczne.Spływ miejski i rolniczy może wprowadzać odpady organiczne do wód słodkich, prowadząc do eutrofizacji.Sprzyja to rozkwitom cyjanobakterii na powierzchni i późniejszemu wyczerpaniu tlenu, gdy mikroby heterotroficzne rozkładają nadmiar biomasy, wpływając na ogólną strukturę społeczności mikroorganizmów.

ekologia mikrobiologiczna w wodach słodkich

Systemy słodkowodni, takie jak strumienie, rzeki i jeziora, wykazują odrębne cechy fizyczne i biologiczne, które wpływają na ich społeczności mikrobiologiczne. Środowiska te dzieli się ogólnie na systemy lotyczne — te z płynącymi wodami, jak strumienie i większość rzek — oraz systemy lentyczne, obejmujące wody spokojne lub wolno płynące, takie jak jeziora, stawy i bagna.W układach lentycznych fitoplankton napędza produkcję pierwotną, generując autochtonny węgiel organiczny. Natomiast układy lotyczne doświadczają turbulencji, słabego oświetlenia i szybkiego mieszania się, co ogranicza wzrost planktonu. Te płynące wody natomiast zależą od alochtonicznego dopływu węgla — zarówno rozpuszczonego, jak i cząstkowego — pochodzącego z otaczającej roślinności i działalności człowieka, wspierając kolonizację mikroorganizmów.Strumienie i rzeki często wspierają żywe bentosowe społeczności mikrobiologiczne, z biofilmami składającymi się zarówno z organizmów fotosyntetycznych, jak i heterotrofów. Te biofilmy odgrywają kluczową rolę w recyklingu składników odżywczych i rozkładzie materii organicznej. Jednak zakłócenia spowodowane spływem miejskim lub działalnością rolniczą mogą zaburzyć tę równowagę, prowadząc do obniżenia poziomu tlenu, znanego jako opadanie tlenu, oraz potencjalnej anoksji. Zanieczyszczenia punktowe, takie jak zrzuty ścieków, oraz zanieczyszczenia ze źródeł niepunktowych, jak spływ z gospodarstw rolnych, mogą zmieniać dynamikę mikroorganizmów i obniżać jakość wody.Jeziora różnią się znacznie ze względu na swój soczewkowy charakter. Ich struktura mikrobiologiczna zależy od głębokości, dostępności składników odżywczych oraz stratyfikacji termicznej. Płytkie jeziora mogą wspierać bentosowe autotrofy w całej kolumnie wodnej, podczas gdy głębsze jeziora latem tworzą wyraźne warstwy termiczne. Górny epilimnion jest bogaty w tlen i produktywny, podczas gdy głębszy hipolimnion często staje się beztlenowy z powodu ograniczonego mieszania i oddychania przewyższającego dyfuzję tlenu. Sezonowe przewroty jesienią i wiosną mogą przeprowadzić do przemijających się kwiatów.Jeziora tropikalne, choć latem podobne do jezior umiarkowanych, doświadczają całorocznego ciepła i dynamiki napędzanej opadami. To sprzyja ciągłej produktywności i częstym kwitnięciom, szczególnie dzięki cyjanobakteriom wiążącym azot. Jeziora różnią się również zawartością składników odżywczych, od ubogich w składniki odżywcze układów oligotroficznych, które pozostają natlenione przez cały rok, po bogate w składniki odżywcze eutroficzne jeziora wspierające duże populacje cyjanobakterii. Te drobnoustroje dobrze odnoszą się do zasadowych, ciepłych wód i mogą wypierać eukariotyczne glony, czasem produkując toksyny i zmieniając jakość wody.

Ekologia mikrobiologiczna w wodach słodkich

Freshwater systems such as streams, rivers, and lakes exhibit distinct physical and biological characteristics that influence their microbial communities. ...

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Education

JoVE Core

Microbiology

Mikrobiologia

Unit

Jednostka

Microbial Ecology

Ekologia mikroorganizmów

KEY TERMS AND CONCEPTS

KLUCZOWE TERMINY I POJĘCIA

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 systems, rapid mixing, low light, and turbulence limit plankton growth. These flowing waters depend more on allochthonous carbon, which is material that comes from outside the water, such as vegetation and human activity.

Streams and rivers often have active benthic microbial communities on the bottom. Their biofilms include photosynthetic organisms and heterotrophs, which must obtain energy from organic matter. These biofilms help recycle nutrients and break down organic matter. Urban runoff or agricultural activity can disturb this balance and lower oxygen levels, a pattern called oxygen sag, which can lead to anoxia, or very low oxygen.

Pollution also changes freshwater microbes. Point source pollution, such as wastewater discharge, and nonpoint source pollution, such as farm runoff, can shift microbial communities and reduce water quality. Lakes show another set of patterns because depth and thermal stratification, or layering by temperature, strongly affect them. Shallow lakes may support benthic autotrophs through much of the water column, while deeper lakes form separate layers in summer.

In deep lakes, the upper epilimnion is oxygen-rich and productive. The lower hypolimnion often becomes anoxic because mixing is limited and respiration uses oxygen faster than it can diffuse downward. Seasonal overturn in autumn and spring can move nutrients through the water and trigger short-lived blooms. Tropical lakes also support frequent blooms, but they stay warm year-round and respond strongly to rainfall, especially when nitrogen-fixing cyanobacteria grow.

Lakes also vary in nutrient level. Oligotrophic lakes are nutrient-poor and usually stay oxygenated throughout the year. Eutrophic lakes are nutrient-rich and can support large cyanobacterial populations. These microbes do well in warm, alkaline water and may outcompete eukaryotic algae. Some can also produce toxins and change water quality.

Microbes in Streams, Lakes, and Rivers

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

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methods to assess microbial populations

Measuring Microbes in Samples

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methods to assess microbial communities

Measuring Microbial Diversity and Activity

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the winogradsky column

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microenvironments

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microbial mats

Microbial Mats and Oxygen Gradients

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microbial interactions: mutualism

Mutualistic Partnerships in Nature

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microbial interactions: cooperation

Microbial Cooperation in Soil and Hosts

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microbial interactions: predation

How Microbes Hunt and Defend

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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

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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

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microbes and other elemental cycles

Microbes Driving Iron and Manganese Cycles

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marine microbial ecology

Microbial Life in the Ocean

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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

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

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key terms and concepts

Explore how water flow, depth, nutrients, and pollution shape freshwater microbes in streams, rivers, lakes, and cyanobacteria blooms.

Microbes in Streams, Lakes, and Rivers | JoVE K12

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Microbes in Streams, Lakes, and Rivers

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