Wednesday, January 27, 2010

Aquatic Ecosystem


Edited by:Ummu Syauqina Nurharyati Husna

An aquatic ecosystem is an ecosystem located in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.

Main article: Marine ecosystem

Marine ecosystems cover approximately 71% of the Earth's surface and contain approximately 97% of the planet's water. They generate 32% of the world's net primary production.

They are distinguished from freshwater ecosystems by the presence of dissolved compounds, especially salts, in the water. Approximately 85% of the dissolved materials in seawater are sodium and chlorine. Seawater has an average salinity of 35 parts per thousand (ppt) of water. Actual salinity varies among different marine ecosystems.

Marine ecosystems can be divided into the following zones: oceanic (the relatively shallow part of the ocean that lies over the continental shelf); profundal (bottom or deep water); benthic (bottom substrates); intertidal (the area between high and low tides); estuaries; salt marshes; coral reefs; and hydrothermal vents (where chemosynthetic sulfur bacteria form the food base).

Classes of organisms found in marine ecosystems include brown algae, dinoflagellates, corals, cephalopods, echinoderms, and sharks. Fish caught in marine ecosystems are the biggest source of commercial foods obtained from wild populations.

Environmental problems concerning marine ecosystems include unsustainable exploitation of marine resources (for example overfishing of certain species), marine pollution, climate change, and building on coastal areas.


Main article: Freshwater ecosystem

Freshwater ecosystems cover 0.8% of the Earth's surface and contain 0.009% of its total water. They generate nearly 3% of its net primary production.

Freshwater ecosystems contain 41% of the world's known fish species.

There are three basic types of freshwater ecosystems:

Lentic: slow-moving water, including pools, ponds, and lakes.

Lotic: rapidly-moving water, for example streams and rivers.

Wetlands: areas where the soil is saturated or inundated for at least part of the time.

Lake ecosystems can be divided into zones: pelagic (open offshore waters); profundal; littoral (nearshore shallow waters); and riparian (the area of land bordering a body of water).

Two important subclasses of lakes are ponds, which typically are small lakes that intergrade with wetlands, and water reservoirs. Many lakes, or bays within them, gradually become enriched by nutrients and fill in with organic sediments, a process called eutrophication. Eutrophication is accelerated by human activity within the water catchment area of the lake.

Freshwater ecosystem.

The major zones in river ecosystems are determined by the river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen, which supports greater biodiversity than the slow moving water of pools.

These distinctions forms the basis for the division of rivers into upland and lowland rivers. The food base of streams within riparian forests is mostly derived from the trees, but wider streams and those that lack a canopy derive the majority of their food base from algae. Anadromous fish are also an important source of nutrients. Environmental threats to rivers include loss of water, dams, chemical pollution and introduced species.

Wetlands are dominated by vascular plants that have adapted to saturated soil. Wetlands are the most productive natural ecosystems because of the proximity of water and soil. Due to their productivity, wetlands are often converted into dry land with dykes and drains and used for agricultural purposes. Their closeness to lakes and rivers means that they are often developed for human settlement.

Main article: Pond

These are a specific type of freshwater ecosystems that are largely based on the autotroph algae which provide the base trophic level for all life in the area. The largest predator in a pond ecosystem will normally be a fish and in-between range smaller insects and microorganisms. It may have a scale of organisms from small bacteria to big creatures like water snakes, beetles, water bugs, frogs, tadpoles, and turtles. This is important for the environment.

Aquatic ecosystems perform many important environmental functions. For example, they recycle nutrients, purify water, attenuate floods, recharge ground water and provide habitats for wildlife.

Aquatic ecosystems are also used for human recreation, and are very important to the tourism industry, especially in coastal regions.

The health of an aquatic ecosystem is degraded when the ecosystem's ability to absorb a stress has been exceeded. A stress on an aquatic ecosystem can be a result of physical, chemical or biological aterations of the environment. Physical alterations include changes in water temperature, water flow and light availability. Chemical alterations include changes in the loading rates of biostimulatory nutrients, oxygen consuming materials, and toxins. Biological alterations include the introduction of exotic species. Human populations can impose excessive stresses on aquatic ecosystems.

Abiotic characteristics

An ecosystem is composed of biotic communities and abiotic environmental factors, which form a self-regulating and self-sustaining unit. Abiotic environmental factors of aquatic ecosystems include temperature, salinity, and flow.

The amount of dissolved oxygen in a water body is frequently the key substance in determining the extent and kinds of organic life in the water body. Fish need dissolved oxygen to survive. Conversely, oxygen is fatal to many kinds of anaerobic bacteria.

The salinity of the water body is also a determining factor in the kinds of species found in the water body. Organisms in marine ecosystems tolerate salinity, while many freshwater organisms are intolerant of salt. Freshwater used for irrigation purposes often absorb levels of salt that are harmful to freshwater organisms.Though some salt can be good for organisms.

Biotic characteristics

The organisms (also called biota) found in aquatic ecosystems are either autotrophic or heterotrophic.

Autotrophic organisms

Autotrophic organisms are producers that generate organic compounds from inorganic material. Algae use solar energy to generate biomass from carbon dioxide and are the most important autotrophic organisms in aquatic environments.

Chemosynthetic bacteria are found in benthic marine ecosystems. These organisms are able to feed on hydrogen sulfide in water that comes from volcanic vents. Great concentrations of animals that feed on this bacteria are found around volcanic vents. For example, there are giant tube worms (Riftia pachyptila) 1.5m in length and clams (Calyptogena magnifica) 30cm long.

Heterotrophic organisms

Heterotrophic organisms consume autotrophic organisms and use the organic compounds in their bodies as energy sources and as raw materials to create their own biomass.

Euryhaline organisms are salt tolerant and can survive in marine ecosystems, while stenohaline or salt intolerant species can only live in freshwater environments.

Sunday, January 10, 2010

Ecology Report,Durian Valley of USM

Report by,
Nurharyati Husna Bt Mohd Khalid(102144)
BST 203-Population and Community Ecology
Explorations to Durian Valley in USM and introduced to Eco-Hub USM.
1.To observe the green parts of trees and organism living in the Durian Valley of USM.
2.To learn how to reuse the unuseful area into conserved area for our sustainable ecosystem.
Populations are members of a species interact in group in a specific area.Community is a populations of different species living and interacting in an area.Ecosystem is a community interacting with its physical environment of matter and energy.
In most natural populations individuals vary slightly in their genetic make-up,thus they do not all look or act alike.This is known as genetic diversity.Habitat is where these populations lives.
Having many different species appears to increase the sustainability of many communities.Communities with more species tend to have a higher net primary production(NPP) and can be more resilient than simpler ones.
Human activities are disrupting ecosystem services that support and sustain all life and economies.Ecologist says that undisturbed systems are not always in equilibrium or balance does not always mean they are unimportant parts of the earth’s natural capital that help promote ecosystem sustainability.Therefore,scientist have developed a number of ways to rehabilitate and restore degraded ecosystems and created artificial ecosystem.
Ecological restorations is the process of repairing damage caused by human to the biodiversity and dynamics of ecosystems.Restoration trying to return a particular degraded habitat or ecosystem to a condition as similar as possible to its natural state.Rehabilitation is attempting to turn a degrade habitat or ecosystem back into a functional or useful ecosystem without trying to restore it to its original condition.Creating artificial ecosystems is an examples is the creation of artificial wetlands to help reduce flooding and to treat sewage.
We went into Durian Valley,to see the green parts of the USM that is build to conserved the ecosystem and becoming habitats for flora and fauna.Amazingly,before Durian Valley is build the land is unused.Thus,this unsused land is rehabilitation into Durian Valley that conserved many biodiversity of organisms,and also there are species that are introduced in this Durian Valley.Our Cancellor(USM Cancellor),Prof Dzulkifli ambition he says,
USM will set its vision of a sustainable tomorrow while keenly promoting values such as equity, accessibility, availability, affordability and quality as the optimal endpoints.Concomitantly, USM will embrace the protection of the ecosystem,the conservation and restoration of resources as well as the development of human and intellectual capitals for this purpose. USM will position itself to facilitate in meeting existing (e.g., Millennium Development Goals) andother future global aspirations towards the upliftment of the billions trapped at the bottom of the socioeconomic pyramid
We gather at Eco-Hub to hear briefing about the importance of Durian Valley and to conserved our ecosystem,certainly,Our Durian Valley is helping the birds populations to grow and we diversity of birds can be found in USM as we conserved the ecosystems.It is greatful to see the pictures of birds that were captured in the USM area.
Ecologist develop mathematical and other models to stimulate the behavior of ecosystems.First,ecologist need baseline data on the ecosystem to see how the ecosystem change and develop effective strategies for preventing or slowing their degradation.We need system measurement to define objectives,identify and inventory variables.Then,obtain baseline data on variables.
Data analysis is done to make statistical analysis of relationships among variables.We are able to determine significant interactions.System modeling by constructing mathematical model describing interactions among variables.
Durian Valley is one of the method to conserved our ecosystem,and USM will conserved living organism from extinction.This is a very good planning for sustainable development.