PRINCIPLES OF ECOLOGY

ECOLOGISTS STUDY ENVIRONMENTS AT DIFFERENT LEVELS OF ORGANIZATION

Over their life cycle, Pacific salmon are the main food source for more than 140 species of wildlife, including grizzly bears. If they are not eaten (most are not

consumed completely), their bodies return vital nutrients back to the river system, some of which are used by plants to grow.

Pacific salmon are threatened with extinction due to competition from hatchery fish, blocked river paths, and loss of spawning grounds. As salmon populations decline, how

are other species affected? What effect would the loss of salmon have on a local and a global scale?

WHAT IS ECOLOGY?

Ecology is the study of the interactions among living things, and between living things and their surroundings.

RELATIONSHIPS

The relationships between organisms is sometimes very difficult to decipher.

THE POLAR BEAR AND THE SLED DOGS

THE POLAR BEAR AND THE SLED DOGS

THE POLAR BEAR AND THE SLED DOGS

THE POLAR BEAR AND THE SLED DOGS

THE POLAR BEAR AND THE SLED DOG

THE LIONESS AND THE BABY ORYX

THE LIONESS AND THE BABY ONYX

THE LIONESS AND THE BABY ONYX

THE LIONESS AND THE BABY ONYX

THE LIONESS AND THE BABY ONYX

WAR!

WAR!

WAR!

WAR!

LEVELS OF ORGANIZATION Ecologists study nature on different levels, from a local to a

global scale. These levels reveal the complex relationships found in nature.

Organism An organism is an individual living thing, such as an alligator.

Population A population is a group of the same species that lives in an area,

such as all the alligators that live in a swamp. Community

A community is a group of different species that live together in one area, such as groups of alligators, turtles, birds, fish, and plants that live together in the Florida Everglades.

Ecosystem An ecosystem includes all of the organisms as well as the

climate, soil, water, rocks, and other nonliving things in a given area. Ecosystems can vary in size. An entire ecosystem may live within a decaying log, which in turn may be part of a larger wetland ecosystem.

Biome A biome is a major regional or global community of organisms.

Biomes are usually characterized by the climate conditions and plant communities that thrive there.

ECOLOGICAL RESEARCH METHODS Observation

Observation is the act of carefully watching something over time. Long-term studies are a key part of ecology because most

environmental changes happen over a long period of time. Surveys

Direct surveys – for easy to follow organisms. Scientist can watch animals with the naked eye or with binoculars or scopes.

Indirect surveys—for difficult to track organisms. Scientists search for signs of its presence, such as feces or a recent kill.

Radio telemetry— for organisms with broad ranges. Radio collars are fitted onto an animal, and scientists are able to track its movements.

Mark recapture—to estimate population size. Scientists will tag a sample size of animals and calculate size of population by counting the ratio of tagged animals to untagged animals.

Quadrat sampling—to monitor plant populations. Several rectangular frames are randomly placed in a study site. Scientists identify and count plants within those frames and estimate total population.

Long-eared Jerboa

ECOLOGICAL RESEARCH METHODS Experimentation

Experiments may be performed in the lab or in the field.

In the lab Conducted in a controlled, indoor

experiment. Allows a focus on a specific part of an

ecosystem, like a single organism. Does not reflect the complex interactions

that occur in nature. In the field

Performed where the organism lives, have controls and manipulated variables.

More accurate picture of how organisms interact in a natural setting, more difficult to determine cause and effect due to a large number of factors at work.

This study focuses on small ecosystems. Moss provides structure and ultimately detritus that feeds bacteria, fungus, and other microorganisms at the base of a complex food-web including mites and microarthropods. This has been used as a successful model system to study questions relating to habitat fragmentation and patterns of biodiversity.

ECOLOGICAL RESEARCH METHODS Modeling

Using computer and mathematical models to describe and model nature.

Used to test hypothetical situations with the use of real data.

Example: In the US, scientists developed a computer software program to create a virtual model of the Greater Yellowstone ecosystem. They used data including:

The movement of elk, bison, bear, and wolf populations.

The location of different vegetation. The amount of precipitation. The activities of geysers and other

geothermal landforms. From this, they created a virtual

ecosystem, where they can model how one variable affects another.

Yellowstone Falls

BIOTIC AND ABIOTIC FACTORS

AN ECOSYSTEM INCLUDES BOTH BIOTIC AND ABIOTIC FACTORS.

Biotic Factors that are living things, such

as plants, animals, fungi, and bacteria.

Abiotic Factors that are non-living things

such as moisture, temperature, wind, sunlight, and soil. The balance of these factors determines which living things can survive in a particular environment.

ABIOTIC OR BIOTIC?

Biotic

BIOTIC OR ABIOTIC?

Abiotic

BIOTIC OR ABIOTIC?

Biotic

BIOTIC OR ABIOTIC?

Biotic

BIOTIC OR ABIOTIC?

Abiotic

BIOTIC OR ABIOTIC?

Abiotic

CHANGING ONE FACTOR IN AN ECOSYSTEM CAN AFFECT MANY OTHER FACTORS. An ecosystem is a complex web

of connected biotic and abiotic factors. You may not always think of yourself as part of the ecosystem, but humans, like other species, rely on the environment for survival.

All species are affected by changes to the biotic and abiotic factors in an ecosystem.

BP oil spill--Cormorant clean up

THE HARBOR SEALS OF CALIFORNIA

This is a red tide. Red tides are algal blooms that cause toxins to accumulate in the water. The occurrence of algal blooms (red tides) have increased since 1991, caused by the run off of fertilizers, human sewage, and other chemicals into the ocean, as well as rising ocean temperatures.

Shellfish will eat the algal blooms. One side effect of consuming these blooms is the accumulation of domoic acid in the shell fish.

THE HARBOR SEALS OF CALIFORNIA

Harbor seals live along the coast of California (among other places). They eat many types of fish, including shell fish.

THE HARBOR SEALS OF CALIFORNIA

As harbor seals eat shell fish that have accumulated toxins, they get domoic acid poisoning. The domoic acid causes severe neurological deterioration. Seals will have nausea, vomiting, abdominal cramps, dizziness, confusion, disorientations, memory loss, motor weakness, seizures, respiratory secretions, cardiac arrhythmia, coma, and death if untreated.

Demoic Acid Poisoning The Marine Mammal Center in southern

California has a success rate of 65% in rehabilitating Harbor Seals.

BIODIVERSITY Biodiversity is the assortment, or

variety, of living things in an ecosystem. An area with a high level of biodiversity,

such as a rain forest, has a large assortment of different species living near one another.

The amount of biodiversity found in an area depends on many factors, including moisture and temperature. Tropical rain forests, which are moist and

warm environments, cover less than 7% of Earth’s ground surface, but account for over 50% of the planet’s plant and animal species.

Tropical rain forests are known as “hot spots”.

Hot spots are areas that are rich in biodiversity, but threatened by human activities.

KEYSTONE SPECIES

The complex relationship in ecosystems mean that a change in a single biotic or abiotic factor, can have a variety of effects. The change may be barely noticed, or it

may have a deep impact. In some cases, the loss of a single

species may cause a ripple effect felt across an entire ecosystem. These organisms are called keystone species. Keystone species have an unusually large

effect on its ecosystem. Prairie dogs are keystone species. They are an important prey item for many predators, and their expansive homes provide shelter for many different organisms.

THE INCREDIBLE SEA OTTER

Sea otters are native to the coasts of the northern and eastern North Pacific Ocean. They are the largest member of the weasel family at 30-100 lbs.

Their fur is the densest in the animal kingdom.

Sea otters prey mostly on marine invertebrates, like sea urchins, mollusks, and crustaceans.

THE INCREDIBLE SEA OTTER Sea urchins graze on the lower stems of kelp,

causing the kelp to drift away and die. Loss of the habitat and nutrients provided

by kelp forests lead to profound cascade effects on the marine ecosystem.

Between 1741 and 1911, sea otter were hunted for their fur. Their population dropped from around

150,000-300,000 individuals to 1,000-2,000 individuals.

North Pacific areas that lost sea otters turned into urchin barrens, with abundant sea urchins and no kelp forest.

Sea Otters Eat Urchins

THE INCREDIBLE SEA OTTER The hunting of sea otters was

banned in 1911, and extensive conservation efforts have seen the Sea Otter return to two-thirds of its original habitat and population. With their re-introduction, the

health of coastal ecosystem rebounded.

Aside from helping kelp forests, and the organisms that rely on them thrive, sea otters also remove mussels from rocks, liberating space for competitive species, thereby increasing the diversity of species in the area.

Sea Otters