Marine Communities - PowerPoint Presentation

Slide1

Marine CommunitiesSlide2

Basics

Community: Organisms in a specific group of interacting producers, consumers, and recyclers that share a common living space.

Population: A group of organisms of the same species that occupy a specific area. Slide3

Organisms Within Communities

Dependent on the availability of energy

Habitat: an organisms “address” within a community. Its physical location.

Niche: An organisms “occupation” or “job”. Its relationship to its food and predators.

Example: Small fish in a coral reef share the same habitat, but each species has a different niche. Each population has a different “job” based on its shape, size, color, behavior, and feeding habits. Slide4

Influence of Physical and Biological Factors

Physical Factors include:

Temperature

Pressure

Salinity

Biological Factors include:

Crowding

Predation

Grazing

Parasitism

Lack of sunlight

Generation of wastes

Competition for oxygenSlide5

Limiting Factors

A a factor that limits and organisms success in a community.

Prevents organism from feeding, growing, reproducing, defending itself, or sensing danger.

Stenothermal Species: Affected greatly by temperature

Eurythermal

Species: Not affected by temperature

Stenohaline

: Affected greatly by change in salinity

Euryhaline

: Not affected by changes in salinity

What does

Stenobaric

mean?

Eurybaric

?Slide6

Competition

Availability of resources such as a food and light determine the number and composition of populations within a community.

In a stable population, two species cannot occupy the same niche for long. One will outcompete the other and force one to extinction or to leave.

Sometimes this is very simple: Fore example, in a rocky intertidal community, one species of barnacle lives on the upper portion of rocks and the other lives on the lower portion of rocks. Slide7

Growth Rate and Carrying Capacity

If there were no competitors for food or space, then growth rate is exponential or J-Shaped curve (i.e. humans, bacteria).

But most species have limiting factors which leads to environmental resistance (the sum of all limiting factors).

This creates an S-shaped curve where a species grows until it reaches its carrying capacity and then levels out.

Carrying Capacity: Population size of a species that a community can support indefinitely under a stable set of environmental conditions.Slide8
Slide9

Distribution of Organisms

Population Density: The number of individuals per unit area or volume.

Higher in places like coral reefs and forests than in tougher conditions like polar regions or deserts.

Random Distribution: Position of one organism in no way influences positions of others in the same community. Very rare. Abyssal Plains.

Clumped Distribution: Conditions for growth are optimal in small areas (like cracks in rocks) or if there is nutrient concentration. Most common type.

Uniform Distribution: Rarest type. Equal space between each individual (like arrangement of trees in orchards). Slide10

Distribution Types

Random

Uniform

ClumpedSlide11

Change in Marine Communities

Occur slower in marine communities than on land.

However, natural catastrophes and human influence can rapidly change communities.

Climax Community: Stable, long established community.

Succession: Orderly changes of a community’s species composition from temporary inhabitants to long-term inhabitants.Slide12

Examples of Marine Communities

Rocky Intertidal

Seaweed

Sand Beach and Cobble Beach

Salt Marshes and Estuaries

Coral Reefs

Open Ocean

Deep-Sea Floor

Deep Rock

Hydrothermal Vent and Cold Seep