Ecosystem

Ecosystem:~

☆An ecosystem is a natural unit consisting of all plants, animals and micro-organisms (biotic factors) in an area functioning together with all of the non-living physical (abiotic) factors of the environment.

★An ecosystem is a completely independent unit of interdependent organisms which share the same habitat.

☆Ecosystems usually form a number of food webs which show the interdependence of the organisms within the ecosystem.

★ The physical environment consists of water, air, soil, sunlight, minerals and temparature that make up the non-living part of the ecosystem.



Ocean ecosystem:

Perch in giant kelp forest
Click on image for full size (425 Kb)
Courtesy of NOAA

The ocean holds the largest of all biomes on Earth. It covers 70% of the planet’s surface.

Life in the ocean is diverse. The smallest creatures that call the ocean home are microscopic and made of a single cell( algae).The largest creatures are blue whales, which can be as much as 34 meters (110 feet) long. There are many different ways to live in the ocean too. Some animals travel thousands of miles through ocean water while others stay in the same place on the ocean floor for their entire lives. Some burrow beneath the sand while others float near the water surface.

The ocean is not uniform, nor is the marine life within it. While life in the ocean is often described as one biome, there are actually many specific ecosystems within the ocean that are characterized by physical conditions such as water temperature, the amount of sunlight that penetrates through the water, and the amount of nutrients.

Sunlight penetrates the top layer of ocean water, as much as 200 meters (656 feet) deep. This allows phytoplankton, algae, and plants like seagrass to make their own food through the process of photosynthesis. Almost all marine life (about 90%) lives within this top, sunlit layer of the ocean. Photosynthesizing organisms are the start of most marine food chains except for those in the deep ocean where there is no sunlight.

The temperature of ocean water varies depending on its location. Closer to the Earth’s polar regions, ocean water is colder. Closer to the equator, ocean water is warmer. Water that is deep in the ocean is colder than water that is near the ocean surface. Many animals can only survive at certain temperatures. Other animals in the ocean are able to survive at a range of temperatures and can live in more places in the world’s ocean basins.



═☆　The underwater observatory gives scientists the ability to observe and begin to unravel all the factors that combine to sustain the oceanic ecosystem—how fresh water, plant detritus, sediments, chemical, and other materials run off the coasts; how they mix into the sea, increase turbidity, change the penetration of light, and add nutrients; how all these influence marine life, from microscoic plants to corals and fish; and how these change after storms and over seasons.




═☆　This graphic shows a simplified version of how carbon and phosphorus cycle through the upper ocean ecosystem before settling to the bottom. The two subclassifications of phosphorus shown are phosphate (H2PO4) and dissolved organic phosphorus (DOP).




═☆　Ocean ecosystems are increasingly threatened by overfishing, pollution, habitat loss, climate change and coastal development. Understanding why some ecosystems resist these shocks, and continue to deliver benefits such as plentiful fish and pristine beaches, and how others collapse is the subject of resilience science.




Ψ Most of the remaining population of critically endangered Hawaiian monk seals lives in the Northwestern Hawaiian Islands.