Transcript Presentation

Aquatic Ecosystems
 Nearly 75 % of the planet is covered with
water. It only makes sense that most life may
be found in water.
 Aquatic ecosystems are determined primarily
by the depth, flow, temperature, and
chemistry of the overlying water.
 The depth of the water determines the
amount of light that the area receives.
 The chemistry refers primarily to the amount
of dissolved chemicals --- salts, nutrients, and
oxygen -- on which life depends.
 Only 3% of the water on earth is fresh water.
 Freshwater systems are divided into two main
types: flowing and standing ecosystems.
Flowing ecosystems
 Rivers, streams, creeks, and brooks.
 insect larvae, catfish, trout
 origin in mountains or hills
 plants usually establish further downstream
where the flow is slower.
 turtles, beavers, otters downstream creatures
Standing Water
 Lakes and ponds
 Water usually circulates heat, oxygen, and
nutrients
 Plankton are usually found in lakes and
ponds
 Plankton is a general term for the tiny, free
floating organisms that live in both freshwater
and saltwater environments.
Freshwater Wetlands
 An ecosystem in which water either covers
the soil or is present at or near the surface of
the soil for at least part of the year.
 Water may be flowing or standing, fresh,
salty, or brackish.
 Brackish is a mixture of fresh and salt water.
 Wetlands serve as breeding grounds for
insects, birds, fish, and amphibians.
Wetlands
 The three main types of freshwater wetlands
are bogs, marshes, and swamps.
 Bogs form in depressions called kettle holes
left by ice sheets that melted thousands of
years ago. Sphagnum moss may be found
here.
 Marshes are shallow wetlands along rivers.
Cattails, rushes, tall grasslike plants
 Swamps – slow flowing water, trees, shrubs
Estuaries
 Wetlands that form where rivers meet the
sea.
 Contain fresh and saltwater….affected by the
rise and fall of ocean tides.
 Shallow, so light hits bottom for
photosynthesis to occur.
 plantlife, algae, photosynthetic and
chemosynthetic bacteria
 Most production is not consumed by
herbivores……clams, worms, sponges,
shrimp, crab, birds.
Estuaries continued
 Much organic material enters as detritus
 Detritus is made up of tiny pieces of organic
material.
 Salt Marshes – temperate zone estuaries
dominated by salt tolerant grasses above the low
tide line, and by seagrasses under water.
 Mangrove swamps – coastal wetlands that are
widespread across tropical regions (southern
florida) salt tolerant trees (mangroves)
seagrasses, nurseries for fish and shellfish.
 Largest mangrove area is in Florida’s Everglades
Marine Ecosystems
 Sunlight only penetrates a short distance.
 Photosynthesis is limited to the photic
zone….depth of 200 meters.
 Below the photic zone is the aphotic zone
….it is permanently dark.
 Chemosynthetic autotrophs are the only
producers that can survive in the aphotic
zone.
Classification Systems for Marine
Ecosystems
 Intertidal zone, coastal ocean, open ocean,
benthic zone.
Intertidal Zone
 Organisms exposed to extreme changes.
 Submerged in sea water, exposed to air,
temperature changes, and sunlight.
 Battered by strong currents.
 barnacles, seaweed, snails, sea urchins, sea
stars
 Competition results in zonation.
 Zonation - the prominent horizontal banding
of organisms that live in a particular habitat.
Coastal Ocean
 Extends from the low tide mark to the outer
edge of the continental shelf.
 Mostly photic
 rich in plankton and other organisms
 kelp forests
 snails, sea urchins, sea otters, fishes, seals,
and whales.
Coral Reefs
 Warm shallow water of coastal, tropical
oceans.
 Named for the coral animals whose hard,
calcium carbonate skeletons make up their
structure.
 jellyfish, fish, microscopic animals.
Open Ocean
 The largest marine zone.
 500 meters to 11,000 meters
 High pressure, frigid temperatures, total
darkness.
 Very low levels of nutrients.
 Swordfish, octopus, dolphins, whales
Benthic Zone
 The ocean floor contains organisms that live
attached to or near the bottom.
 sea stars, anemones, marine worms
 Depend on food from organisms that grow in
the photic zone.
 mostly attached to the bottom and do not
move around much.
 clams, sea cucumbers
Populations
 Three important characteristics of a
population are its geographic distribution,
density, and growth rate.
 Geographic distribution - range
 Population density – the number of
individuals per unit area.
Population Growth
 Three factors can affect population size: the
number of births, the number of deaths, and
the number of individuals tht enter or leave
the population.
 Immigration – the movement of individuals
into an area
 Emigration – the movement of individuals out
of a population
 Food shortages may result in emigration.
Exponential Growth
 Occurs when the individuals in a population
reproduce at a constant rate.
 Under ideal conditions with unlimited
resources, a population will grow
exponentially.
Logistic Growth
 As resources become less available, the
growth of a population slows or stops.
 Logistic growth occurs when a population’s
growth slows or stops following a period of
exponential growth.
Carrying capacity
 the largest number of individuals that an
environment can support.
 Limiting Factors – competition, predation,
parasitism, disease, drought, human
disturbances, limited nutrients.
Density Dependent Factors
 A limiting factor that depends on population
size is called a density dependent limiting
factor.
 Include competition, predation, parasitism,
and disease.
 The best method of population control is the
predator-prey relationship. The predator-prey
relationship follows a cycle of increasing and
decreasing numbers.
Density Independent Factors
 Unusual weather, natural disasters, seasonal
cycles, human activities.
 Extreme cold can wipe out many plant and
insect species.
Human Activities
 Hunting, gathering, agriculture, industry, and urban
development have transformed the biosphere.
 1950’s -- fast growing global human population forced
agriculture to increase production…this era is now known
as the green revolution.
 monoculture – the planting of large crops year after
year….the advantage….lots of the same food….the
disadvantage…increased use of water, increase in certain
insect populations….heavy use of pesticides…chemicals
can be harmful to environment, other species, and
humans.
The tragedy of the Commons
 When a resource is open to everyone, no one is
responsible for preserving it, so we eventually
destroy it.
 Environmental Resources can be classified into
two types: renewable and nonrenewable.
 Renewable resources can be replenished but
they are now LIMITED due to our population.
 Nonrenewable resources cannot be replenished
naturally but may be replenished in the lab.
Synthetic oil
Sustainable Use
 A way of using natural resources at a rate
that does not deplete them.
 Soil is renewable but can be damaged
beyond use.
 Problems with overfishing -- no one country
can control fishing in open ocean waters.
 Aquaculture -- farming of aquatic organisms
is part of the solution.
Air resources
 Smog, acid rain
 WATER RESOURCES
 wastes, sewage, chemicals, oil spills
Biodiversity
 The sum total of the genetically based variety
of all organisms in the environment.
 Extinction occurs when a species disappears
from all or part of its range.
 Endangered species…..a species whose
population size decreases in such a way to
place it in danger of extinction.
Habitat Fragmentation
 The dividing of a habitat by human activity.
 The smaller the area, the fewer species that
may be maintained there.
Invasive Species
 Apparently harmless plants and animals that
we transport from one place to another. The
new area lacks the parasites and predators
that control the population and their numbers
increase beyond control. Native species may
be brought to extinction or endangered.