Terrestrial Biomes
BIOME
1. Tropical
Rainforest
2. Deciduous
Forest
3. Taiga
4. Savanna
5.Grasslands
6. Desert
7. Tundra
CLIMATE/ABIOTIC
FACTORS
BIOTIC FACTORS/PLANTS
& ANIMALS
THREATS
Aquatic Biomes
BIOME
FRESHWATER
CLIMATE/ABIOTIC
FACTORS
BIOTIC FACTORS/PLANTS
& ANIMALS
THREATS
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Streams/Rivers
Lakes/Ponds
Wetlands
MARINE
Oceans
Coral Reefs
Estuaries
(1.________________________________ 2____________________________________3_____________________________________)
1. Streams and Rivers
These are bodies of flowing water moving in one direction. Streams and rivers can be found everywhere—they get their starts at headwaters, which may be
springs, snowmelt or even lakes, and then travel all the way to their mouths, usually another water channel or the ocean. The characteristics of a river or stream
change during the journey from the source to the mouth. The temperature is cooler at the source than it is at the mouth. The water is also clearer, has higher
oxygen levels, and freshwater fish such as trout and heterotrophs can be found there. Towards the middle part of the stream/river, the width increases, as does
species diversity—numerous aquatic green plants and algae can be found. Toward the mouth of the river/stream, the water becomes murky from all the
sediments that it has picked up upstream, decreasing the amount of light that can penetrate through the water. Since there is less light, there is less diversity of
flora, and because of the lower oxygen levels, fish that require less oxygen, such as catfish and carp, can be found.
Lakes and Ponds (NO VIDEO)
These regions range in size from just a few square meters to thousands of square kilometers. Scattered throughout the earth, several are remnants from the
Pleistocene glaciation. Many ponds are seasonal, lasting just a couple of months (such as sessile pools) while lakes may exist for hundreds of years or more.
Ponds and lakes may have limited species diversity since they are often isolated from one another and from other water sources like rivers and oceans. Lakes
and ponds are divided into three different “zones” which are usually determined by depth and distance from the shoreline.
The topmost zone near the shore of a lake or pond is the littoral zone. This zone is the warmest since it is shallow and can absorb more of the Sun’s heat. It
sustains a fairly diverse community, which can include several species of algae (like diatoms), rooted and floating aquatic plants, grazing snails, clams, insects,
crustaceans, fishes, and amphibians. In the case of the insects, such as dragonflies and midges, only the egg and larvae stages are found in this zone. The
vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks.
The near-surface open water surrounded by the littoral zone is the limnetic zone. The limnetic zone is well-lighted (like the littoral zone) and is dominated by
plankton, both phytoplankton and zooplankton. Plankton are small organisms that play a crucial role in the food chain. Without aquatic plankton, there would
be few living organisms in the world, and certainly no humans. A variety of freshwater fish also occupy this zone.
Plankton have short life spans—when they die, they fall into the deep-water part of the lake/pond, the profundal zone. This zone is much colder and denser than
the other two. Little light penetrates all the way through the limnetic zone into the profundal zone. The fauna are heterotrophs, meaning that they eat dead
organisms and use oxygen for cellular respiration.
Temperature varies in ponds and lakes seasonally. During the summer, the temperature can range from 4° C near the bottom to 22° C at the top. During the
winter, the temperature at the bottom can be 4° C while the top is 0° C (ice). In between the two layers, there is a narrow zone called the thermocline where the
temperature of the water changes rapidly. During the spring and fall seasons, there is a mixing of the top and bottom layers, usually due to winds, which results
in a uniform water temperature of around 4° C. This mixing also circulates oxygen throughout the lake. Of course there are many lakes and ponds that do not
freeze during the winter, thus the top layer would be a little warmer.
Wetlands (NO VIDEO)
Wetlands are areas of standing water that support aquatic plants. Marshes, swamps, and bogs are all considered wetlands. Plant species adapted to the very
moist and humid conditions are called hydrophytes. These include pond lilies, cattails, sedges, tamarack, and black spruce. Marsh flora also include such species
as cypress and gum. Wetlands have the highest species diversity of all ecosystems. Many species of amphibians, reptiles, birds (such as ducks and waders), and
furbearers can be found in the wetlands. Wetlands are not considered freshwater ecosystems as there are some, such as salt marshes, that have high salt
concentrations—these support different species of animals, such as shrimp, shellfish, and various grasses.
Estuary (NO VIDEO)
An estuary is a partially enclosed body of water formed where freshwater from rivers and streams flows into the ocean, mixing with the salty sea water.
Estuaries and the lands surrounding them are places of transition from land to sea, and from fresh to salt water. Although influenced by the tides, estuaries are
protected from the full force of ocean waves, winds, and storms by the reefs, barrier islands, or fingers of land, mud, or sand that define an estuary's seaward
boundary.
Intertidal Zone
The intertidal zone, also known as the littoral zone, in marine aquatic environments is the area of the foreshore and seabed that is exposed to the air at low tide
and submerged at high tide, ie the area between tide marks.
In the intertidal zone the most common organisms are small and most are relatively uncomplicated organisms. This is for a variety of reasons; firstly the supply
of water which marine organisms require to survive is intermittent. Secondly, the wave action around the shore can wash away or dislodge poorly suited or
adapted organisms. Thirdly, because of the intertidal zone's high exposure to the sun the temperature range can be extreme from very hot to near freezing in
frigid climates (with cold seas). Lastly, the salinity is much higher in the intertidal zone because salt water trapped in rock pools evaporates leaving behind salt
deposits. These four factors make the intertidal zone an extreme environment in which to live.
A typical rocky shore can be divided into a spray zone (also known as the Supratidal Zone, which is above the spring high-tide line and is covered by water only
during storms, and an intertidal zone, which lies between the high and low tidal extremes. Along most shores, the intertidal zone can be clearly separated into
the following subzones: high tide zone, middle tide zone, and low tide zone.
High tide zone (upper mid-littoral)-The high tide zone is flooded during high tide only, and is a highly saline environment. The abundancy of water is not high
enough to sustain large amounts of vegetation, although some do survive in the high tide zone. The predominant organisms in this subregion are anemones,
barnacles, brittle stars, chitons, crabs, green algae, isopods, limpets, mussels, sea stars, snails, whelks and some marine vegetation. The high tide zone can also
contain rock pools inhabited by small fish and larger seaweeds. Another organism found here is the hermit crab, which because of its portable home in the form
of a shell does extremely well as it is sheltered from the high temperature range to an extent and can also carry water with it in its shell. Consequently there is
generally a higher population of hermit crabs to common crabs in the high tide zone. Life is much more abundant here than in the spray
Middle tide zone (lower mid-littoral)-The middle tide zone is submerged and flooded for approximately equal periods of time per tide cycle. Consequently
temperatures are less extreme due to shorter direct exposure to the sun, and therefore salinity is only marginally higher than ocean levels. However wave action
is generally more extreme than the high tide and spray zones. The middle tide zone also has much higher population of marine vegetation, specifically seaweeds.
Organisms are also more complex and often larger in size than those found in the high tide and splash zones. Organisms in this area include anemones,
barnacles, chitons, crabs, green algae, isopods, limpets, mussels, sea lettuce, sea palms, sea stars, snails, sponges, and whelks. Again rock pools can also provide
a habitat for small fish, shrimps, krill, sea urchins and zooplankton. Apart from being more populated, life in the middle tide zone is more diversified than the
high tide and splash zones.
Low tide zone (lower littoral)
This subregion is mostly submerged - it is only exposed at the point of low tide and for a longer period of time during extremely low tides. This area is teeming
with life; the most notable difference with this subregion to the other three is that there is much more marine vegetation, especially seaweeds. There is also a
great biodiversity. Organisms in this zone generally are not well adapted to periods of dryness and temperature extremes. Some of the organisms in this area are
abalone, anemones, brown seaweed, chitons, crabs, green algae, hydroids, isopods, limpets, mussels, nudibranchs, sculpin, sea cucumber, sea lettuce, sea
palms, sea stars, sea urchins, shrimp, snails, sponges, surf grass, tube worms, and whelks. Creatures in this area can grow to larger sizes because there is more
energy in the localised ecosystem and because marine vegetation can grow to much greater sizes than in the other three intertidal subregions due to the better
water coverage: the water is shallow enough to allow plenty of light to reach the vegetation to allow substantial photosynthetic activity, and the salinity is at
almost normal levels. This area is also protected from large predators such as large fish because of the wave action and the water still being relatively shallow.
Coastal
The coastal oceans of the world, while amazingly diverse, are also fairly similar. Because these zones are close to land, there are certain related plants and
animals that have adapted to these conditions, and are likely to be found around the globe.
This zone is also one of the most important for humans. While they cover only a very small percentage of total ocean body, they harbor most of the seafood
caught for human consumption.
Coastal Oceans include many other habitat types not covered in this "temperate" ocean video. These include waters around coral reefs, and mangrove habitats both found only in tropical waters. Kelp forests are another major habitat type found in coastal oceans.
In this video we highlighted three species found in swedish temperate coastal oceans. However, it is important to realize there are many different types of
animals in coastal oceans around the world. To expand on this point here are the current estimates for but a few of the species found in the coastal oceans.
Fish species worldwide: 28,000
Cnidarians (seapens/Jellyfish/corals) worldwide: 11,000
Crustaceans worldwide: 52,000
Coral Reefs
If you're looking for the most biodiverse habitats, forget the rainforests. Many biologists consider coral reefs to be more diverse and productive than their land
equivalents. Corals are the only animals other than humans that are capable of building structures that can be seen by space. The Great Barrier Reef for instance
is constructed from small coral polyps that together form a nearly 2000 mile long barrier reef.
Where are coral reefs found?
Coral reefs are found around the globe in warm waters. Corals can not stand temperatures that drop much below an average temperature of 18°C. This limits
their habitat to waters between 23°N and 23°S latitude. But, while latitude is important, so too is the current.
For instance, in Florida the last real reefs end around Miami even though certain coral species can be found up through the Carolinas. The same is true in
Australia where the last reefs are just north of Fraser Island while a few scattered coral species can be found south in Sydney.
Taxonomy of Corals
Corals are members of the phylum Cnidaria, which they share with jellyfish, comb jellies and sea anemones. Class Anthozoa denotes soft and hard corals (6,000
species total). Reef building corals (hermatypic corals) belong to the order Scleractinia. To date there are no freshwater corals.
Biogeography
Coral reefs are more diverse on the east coasts of continents. Thus, corals are found primarily in the Caribbean, Florida and Brazil in the Americas while there is
very little coral development in California, Chile or any American Pacific coast. This may not seem logical until you think about the way ocean currents work.
Ocean currents move clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. This causes cold water currents to flow along
coastlines towards the equator on the eastern sides of oceans.
Biodiversity centers
One interesting biogeographical phenomena is the presence of a central biologically diverse region of the world for coral reefs. The indo-pacific ocean,
particularly around the waters of Indonesia has the most diverse coral reef ecosystems in the world. Diversity drops as you leave this epicenter. Coral reefs in the
western Pacific have 75% more genera and 85% more species of corals than coral reefs in the Caribbean.
Physiology - Plants or animals?
The essence of what makes the coral reef work is the presence of of a unique symbiosis with unicellular algae called zooxanthellae. These zooxanthellae help the
coral by giving the coral the by-products of their photosynthetic activity. Corals help the zooxanthellae by providing them with an environment to live.
Zooxanthellae provide the corals with their diverse colors. Without them the corals are white. During bleaching events (conditions that stress corals such as high
temperatures), corals release their zooxanthellae and become completely white.
While zooxanthellae allow corals to use the energy from the sun, corals themselves are not autotrophic. Corals are made up of individual coral polyps whom are
carnivorous. Each has a small mouth and stinging tentacles. However, coral reefs are often found in clear blue water. This water is nutrient poor and thus corals
are able to thrive because a large portion of their energy is actually acquired from their symbiosis with these small algae.
Reproduction
Corals can reproduce both sexually and asexually. Asexual reproduction occurs when fragments of a coral break off and start a new colony. Certain corals like
staghorn coral rely on this method heavily.
Sexual reproduction in corals is a unique event that is often synchronous. On a few nights every year corals will have a mass spawning event. The most amazing
thing about mass spawning events is the ability of coral species to synchronize to a given hour. In Australia, on the great barrier reef spawnings occur in
November. During this event spawn are released and cover the surface of the water. When diving in an event like this it feels like it is snowing upside down!