Aquatic ecosystem An estuary mouth and coastal waters, part of an aquatic ecosystem. 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. What is an aquatic ecosystem? Aquatic systems are those that contain plants and animals that predominantly depend on a significant amount of water to be present for at least part of the year. But a perfect definition is tough to make.
How many weeks a year does an area need to show standing water in order to be a pond? How about a bird bath or dog water dish, as both can breed aquatic insects if left undisturbed for a few days? For our purposes, we have a number of aquatic systems that hold water all year (in most cases) and are impacted to different degrees by activities on the surrounding landscape. What are a few components of an aquatic ecosystem? pond layers – Like in a forest, the top, middle, and bottom of a pond can be vastly different from each other, and even the layers in between.
Under different temperature or light conditions the water in a pond can vary greatly in oxygen, clarity, and other factors that effect were plants and animals might live. The air above the pond and the land below the pond are important as well, as those provide space for animals to live, plants to root, and predators and prey to interact. diversity – while many people think of a pond as just a small lake with frogs and fish, there are thousands of differents species of plants and animals living together in a natural pond. The more diverse a pond is (more species that it has) the stronger and healthier it is. icro-organisms – some of the most imortant plants and animals in a pond are so small they are difficult to see without a microscope. They are called “micro-organisms” (micro=small, organism=life form) and while a few may cause disease, almost all are very beneficial and important to a pond ecosystem. While bigger animals may fly, walk, or swim away to other ponds, micro-organisms are always present in large numbers. macro-organisms – larger plants and animals that are easy to see on a pond are called “macro-organisms (macro=large).
They are the plants and animals that we often notice first, and can more easily spread from pond to pond. Types Marine 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. Freshwater 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. [pic] 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. Freshwater Ecosystems Only 3% of the world’s water is fresh. And 99% of this is either frozen in glaciers and pack ice or is buried in aquifers. The remainder is found in lakes, ponds, rivers, and streams. Lakes and Ponds Deep lakes contain three distinct zones, each with its characteristic community of organisms. Littoral zone The zone close to shore.
Here light reaches all the way to the bottom. The producers are plants rooted to the bottom and algae attached to the plants and to any other solid substrate. The consumers include • tiny crustaceans • flatworms • insect larvae • snails • frogs, fish, and turtles. Limnetic zone This is the layer of open water where photosynthesis can occur. As one descends deeper in the limnetic zone, the amount of light decreases until a depth is reached where the rate of photosynthesis becomes equal to the rate of respiration. At this level, net primary production no longer occurs.
The limnetic zone is shallower in turbid water than in clear and is a more prominent feature of lakes than of ponds. Life in the limnetic zone is dominated by • floating microorganisms – called plankton • actively swimming animals – called nekton. • The producers in this ecosystem are planktonic algae. • The primary consumers include such animals as microscopic crustaceans and rotifers – the so-called zooplankton. • The secondary (and higher) consumers are swimming insects and fish. These nekton usually move freely between the littoral and limnetic zones. Profundal zone
Many lakes (but few ponds) are so deep that not enough light reaches here to support net primary productivity. Therefore, this zone depends for its calories on the drifting down of organic matter from the littoral and limnetic zones. The profundal zone is chiefly inhabited by primary consumers that are either attached to or crawl along the sediments at the bottom of the lake. Such bottom-dwelling animals are called the benthos. The sediments underlying the profundal zone also support a large population of bacteria and fungi. These decomposers break down the organic matter reaching them, releasing inorganic nutrients for recycling.
Fall overturn Where there is a pronounced change of seasons, the warming of the surface of the lake in the summer prevents this water from mixing with deeper water. This is because warm water is less dense than cold. The surface water becomes enriched in oxygen • some from the air above it • the rest — because it is in the limnetic zone — from photosynthesis. But the water in the profundal zone — being removed from both these sources — becomes stagnant. In the fall, however, as the surface water cools, it becomes denser and sinks to the bottom — carrying oxygen with it. Spring overturn
A similar phenomenon occurs when the ice melts in the spring. Rivers and Streams The habitats available in rivers and streams differ in several ways from those in lakes and ponds. • Because of the current, the water is usually more oxygenated. • Photosynthesizers play a minor role in the food chains here; a large fraction of the energy available for consumers is brought from the land; e. g. , in falling leaves. Pollution in Freshwater Ecosystems – Freshwater Ecology As with all ecosystems, the existence and operations of human society inevitably have an effect on the way of life in a freshwater community.
Particularly in Western society, where a huge amount of resources are harnessed from the land to fund our lifestyle, there is a resulting effect on the ecosystems of our planet. For each action that man takes in this lifestyle, there is a resultant effect on the ecosystem, and the following looks at some scenarios where human action results in a response from the ecosystem, either physically or chemically, which in the long run affects the lives of organisms that live in these communities; • Hot water is used in many industries to cool machinery. This water is removed via a discharge pipe into the river.
This increase in temperature can affect the level of oxygen freely available to organisms, which, in turn affects respiration and essentially their way of life. Due to this temperature change, life in the ecosystem is affected. • Removal of foliage next to a freshwater ecosystem allows more running water to enter its capacity. In light of this, periods of heavy rainfall can result in the water levels fluctuating wildly, which in turn can also affect the temperature of the water quite considerably not to mention all the new chemical agents that would enter the stream from this extra water. Recreational use of water bodies such as canoeing also have their effect. Litter from these people can sit on the surface of water and block out sunlight required by the primary producers for photosynthesis. If these primary producers way of life is affected in such a way that their population level decreases, there is a knock on effect to all those organisms who rely on these primary producers for survival. • At a molecular level, chemicals discharged into the water, notably from industry or pesticides from farmland can affect the freshwater environment considerably.
Higher concentrations of particular chemicals (perhaps toxic) mean a lower concentration of essential chemicals required by the organisms of the ecosystem. If this is the case, these organisms cannot perform respiration and function at an optimum level, thus reducing overall biomass in the ecosystem. As you can see, there are many environmental factors that arise due to the usage of water in one way or another by our species.
The most important fact to take from this is that when we use water in the above examples, we are upsetting the fine balance of the ecosystem as a whole, which then has a knock on effect on other organisms living in that particular ecosystem. In light of this, and more consideration towards our environment, conservation measures are used to ensure that their is no detrimental damage caused to these environments, while at the same time man can continue to harness the water as a valuable resource. Ponds
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. What aquatic systems can be found at River Bend? Marsh – shallow water with non-woody plants growing above water level • Swamp – like a marsh but with bushes and trees growing from the water as well • Pond – a small and shallow body of water with plants growing above water level only on the edges; generally freezes solid during winter. • River – a moving body of water that flows from one place to another. • Stream – smaller than a river, may even dry up sometimes • Puddles – and body of water that lasts for a few days or more may attract aquatic life • Spring – area where underground water is discharged onto the land suface forming a pond or stream
What other types of aquatic systems can be found on Earth? You may research any of these they don’t seem familiar: |lake |sea |flood plain | |ocean |glacier |bog | |creek |tidal pool |estuary | |lagoon |geyser |aquifer | |bog |fen |salt lake |
What will we do at River Bend? You and your team will visit one of River Bend’s ponds and complete a series of tests and observations to get a “snapshot” assessment of that aquatic ecosystem. You will compare your results to those of other teams and in future years teams will make comparisons to yours. You and your team will: • Record date and the weather conditions at the time of your visit. • Draw a sky view map of the pond, including living and dead vegetation, various structures and visible features, and wildlife sighted at that time. • Test the various physical properties of the pond: Water depth o Water temperature • Perform several experiments to tell you more about the chemical properties of the water (detailed indicator sheet ): o Dissolved oxygen: Primarily absorbed from the air but also created by plants and used by animals. Also consumed by the decomposition of organic matter. o Nitrates: Excessive nitrogen from animal waste and fertilizers boosts plant growth o Phosphates: Excessive phosphorus from our detergents creates algae blooms that lead to water quality problems o pH: A measure of how acidic or basic the water is.
The pH is affected by geology of the area, plant growth, and pollutants. Water that is too acidic or too basic will cause a variety of problems for aquatic species. • Collect and identify insects and other creatures in and around the pond. They often are indicators of water quality as some insect prefer “dirty” water and others “clean” water. Download detailed indicator sheet. Your data will be compiled with data gathered by other teams to generate ranges and averages for future comparisons. What are some basic principles of a scientific investigation?
Science is often a process of performing scientific tests to investigate and learn things. For example, we can test a sample of water to see how much oxygen is present in a pond. In order for such tests to have any meaning, there are some rules (or “principles”) that we must remember: • Follow all directions and safety instructions for a test carefully. • Do each test the same way each time you do it. • When measuring something, be as exact as possible. • Doing the same test several times and taking an average can give you a better answer to a question than doing just one test.
What do we need to remember when we visit River Bend? 1. The quieter we are, the better. 2. Listen to your leader. 3. Be careful and safe with all tools and equipment 4. Raise your hand if you have something to say. 5. Do not pick anything unless given permission. 6. Stay where you leader asks you to be. 7. Be respectful of nature – and of each other! [pic] 2009 data reports |Amphitheater Spring Data – 2009 (Prairie Pond Dry again in 2009) | |Date | pic] |Turtle Pond Data – 2009 | |Date | Functions 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 alterations 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. 6] Euryhaline organisms are salt tolerant and can survive in marine ecosystems, while stenohaline or salt intolerant species can only live in freshwater environments. Introduction to Types of Aquatic ecosystems The word “Ecosystem” has a Greek origin that is oikos, meaning “home,” and systema, or “system. ” The word “Ecosystem” was proposed by British ecologist A. G. Tansley (1935) . Ecosystem is an biological community of an area, of interacting organisms and their physical and chemical environment. Earth’s surface can be described by a series of interconnected ecosystems.
Ecosystem can be classified into 2 main categories: • Terrestrial ecosystems: where organisms and their environment interacts on landmasses. • Aquatic ecosystems: where plants, animals and their physical environment interact in water. Types of Aquatic Ecosystems I. Fresh water: Very small proportion of earth’s area that is only 0. 8 percent of the earth’s surface is covered by them. Primary production in a fresh-water ecosystem is controlled by light and nutrient availability. Fresh water can be defined as the water that contains a relatively small amount of dissolved chemical compounds.
It includes :Standing Water- lakes & ponds and Moving Water- rivers & streams. • Standing Water- lakes & ponds: Standing water ecosystems are known as Lentic ecosystems such as lakes and ponds. The organisms in lentic ecosystem includs algae, rooted and floating-leaved plants, invertebrates such as crabs, shrimps, crayfish, clams etc, amphibians such as frogs and salamanders; and reptiles like alligators and water snakes. • Moving Water- rivers & streams: flowing-water ecosystems are known as Lotic ecosystems with water flowing in uniform direction and in a unidirectional way.
Examples are rivers and streams, which harbor several species of insects and fishes. Crustaceans like crayfish and crabs; and mollusks such as clams and limpets. II. Transitional Communities: • Estuaries: Areas where freshwater dumps into ocean. So the water is neither truly fresh water, since it has salt content, but it is also not consider salt water because it has a lower level of salt than the ocean. Estuaries are always productive and has rich biodiversity. Organisms are well adapted to varying levels of salinity. • Wetlands- bogs/fens, swamps, marshes: Here the water is completely or partially shallow.
Has a rich biodiversity because they receive plenty of sunlight which supports life. Plants include water lilies, mangrove, tamarack and sedges are commonly found in wetlands. Various species of reptiles and amphibians are also found in wetlands. III. Marine Ecosystem: About 71% of the earths surface is covered by marine ecosystem. Marine ecosystem involves: Shorelines, Coral Reefs, Open Ocean • Shorelines : are where oceans and seas meet land. Since its close to the sea its always prone to hurricanes and erosion. Habitat fo burrowing animals. • Coral Reefs: Cover less than 1% of the oceans. Also known as “Rainforests of sea”.
These are clear warm shallow sea’s. Made up of as a result of accumulation of calcium carbonate deposited by marine organisms like corals and shellfish. • Open Ocean: Oceans have a great impact on the biosphere. Its the source of rainfall. ocean temperatures determine climate and wind patterns. I. Fresh water: Very small proportion of earth’s area that is only 0. 8 percent of the earth’s surface is covered by them. Primary production in a fresh-water ecosystem is controlled by light and nutrient availability. Fresh water can be defined as the water that contains a relatively small amount of dissolved chemical compounds.
It includes :Standing Water- lakes & ponds and Moving Water- rivers & streams. • Standing Water- lakes & ponds: Standing water ecosystems are known as Lentic ecosystems such as lakes and ponds. The organisms in lentic ecosystem includs algae, rooted and floating-leaved plants, invertebrates such as crabs, shrimps, crayfish, clams etc, amphibians such as frogs and salamanders; and reptiles like alligators and water snakes. • Moving Water- rivers & streams: flowing-water ecosystems are known as Lotic ecosystems with water flowing in uniform direction and in a unidirectional way.
Examples are rivers and streams, which harbor several species of insects and fishes. Crustaceans like crayfish and crabs; and mollusks such as clams and limpets. II. Transitional Communities: • Estuaries: Areas where freshwater dumps into ocean. So the water is neither truly fresh water, since it has salt content, but it is also not consider salt water because it has a lower level of salt than the ocean. Estuaries are always productive and has rich biodiversity. Organisms are well adapted to varying levels of salinity. • Wetlands- bogs/fens, swamps, marshes: Here the water is completely or partially shallow.
Has a rich biodiversity because they receive plenty of sunlight which supports life. Plants include water lilies, mangrove, tamarack and sedges are commonly found in wetlands. Various species of reptiles and amphibians are also found in wetlands. III. Marine Ecosystem: About 71% of the earths surface is covered by marine ecosystem. Marine ecosystem involves: Shorelines, Coral Reefs, Open Ocean • Shorelines : are where oceans and seas meet land. Since its close to the sea its always prone to hurricanes and erosion. Habitat fo burrowing animals. • Coral Reefs: Cover less than 1% of the oceans.
Also known as “Rainforests of sea”. These are clear warm shallow sea’s. Made up of as a result of accumulation of calcium carbonate deposited by marine organisms like corals and shellfish. • Open Ocean: Oceans have a great impact on the biosphere. Its the source of rainfall. ocean temperatures determine climate and wind patterns. Significance of Different Types of Aquatic Ecosystems The study of aquatic ecosystem helps to understand the biodiversity (flora and fauna)of the aquatic ecosystem and their interaction with the physical and chemical environment .
Aquatic ecosystems are in danger mainly because of human activities like: Overfishing, Transportation, waste disposal , recreation and other activities which might harm the ecosystem. Marine Ecosystems [pic] Marine ecosystems are a part of the largest aquatic system on the planet, covering over 70% of the Earth’s surface. The habitats that make up this vast system range from the productive nearshore regions to the barren ocean floor. Some examples of important marine ecosystems are: • Oceans • Estuaries and Salt Marshes Coral Reefs and Other Tropical Communities (Mangrove Forests) • Coastal areas like Lagoons, Kelp and Seasgrass Beds and Intertidal systems (rocky, sandy, and muddy shores) Marine ecosystems are home to a host of different species ranging from tiny planktonic organisms that comprise the base of the marine food web (i. e. , phytoplankton and zooplankton) to large marine mammals like the whales, manatees, and seals. In addition, many fish species reside in marine ecosystems including flounder, scup, sea bass, monkfish, squid, mackerel, butterfish, and spiny dogfish.
Birds are also plentiful including shorebirds, gulls, wading birds, and terns. Some marine animals are also endangered including whales, turtles, etc. In summary, many animal species rely on marine ecosystems for both food and shelter from predators. [pic] Marine ecosystems contain several unique qualities that set them apart from other aquatic ecosystems, the key factor being the presence of dissolved compounds in seawater, particularly salts. This total gram weight of dissolved substances (salts) in one kg of seawater is referred to as salinity. In general 85% of the dissolved substances are Sodium (Na) and Chlorine (Cl) in seawater.
On average seawater has a salinity of 35 parts per thousand grams (ppt) of water. These dissolved compounds give seawater its distinctive “salty” taste, affect species composition of particular marine habitats, and prevent oceans from freezing during the winter. Daily changes in factors such as weather, currents, and seasons as well as variations in climate and location will cause salinity levels to vary among different marine ecosystems. In areas such as estuaries, tidal marshes, and mangrove forests, tidal and freshwater influences from river and streams makes it necessary for marine organisms to adapt to a wide range of salinity levels.
These organisms such as mussels, clams, and barnacles, are called euryhaline (salt tolerant) organisms. Other organisms, in particular finfish, are unable to tolerate such changes in salinity. These organisms are considered to be stenohaline (salt intolerant). These species require more constant levels of salinity, forcing them to either migrate to new areas when fluctuations in salinity levels occur or to seek out areas where salinity change is minimal (e. g. , the deep ocean). [pic] Like other aquatic ecosystems, marine ecosystems require nutrients and light to produce food and energy.
However, both nutrients and light are limiting factors in marine ecosystem productivity. Like many other aquatic plants, photosynthetic marine organisms (i. e. , phytoplankton) rely upon sunlight and chlorophyll a to absorb visible light from the sun as well as nitrogen (N), phosphorus (P), and silicon (Si) to generate food and promote growth and reproduction. However, the amount of light penetrating the ocean surface tends to decrease with increasing water depth, therefore photosynthesis can only take place within a small band near the surface of the water (called the photic zone).
In addition, nutrient availability often varies significantly from place to place. For example, in the open ocean, nutrient levels are often very poor causing primary production to be very low. In contrast, nearshore waters such as estuaries and marshes are often rich in nutrients, allowing primary production to be very high. In some instances, nearshore ecosystems have an excess of nutrients due to runoff and other terrestrial sources. Excess nutrients can cause an over-stimulation of primary production, depleting oxygen levels and causing eutrophic conditions to occur in coastal habitats.
Marine ecosystems are very important in to the overall health of both marine and terrestrial environments. According to the World Resources Center, coastal habitats alone account for approximately 1/3 of all marine biological productivity, and estuarine ecosystems (i. e. , salt marshes, seagrasses, mangrove forests) are among the most productive regions on the planet. In addition, other marine ecosystems such as coral reefs, provide food and shelter to the highest levels of marine diversity in the world. [pic]
The diversity and productivity of marine ecosystems are also important to human survival and well-being. These habitats provide us with a rich source of food and income, and support species that serve as animal feed, fertilizers for crops, additives in foods (i. e. , ice-cream) and cosmetics (i. e. , creams and lotions). Areas such as mangroves, reefs, and seagrass beds also provide protection to coastlines by reducing wave action, and helping to prevent erosion, while areas such as salt marshes and estuaries ave acted as sediment sinks, filtering runoff from the land. Despite the importance of marine ecosystems, increased human activities such as overfishing, coastal development, pollution, and the introduction of exotic species have caused significant damage and pose a serious threat to marine biodiversity. Please visit USEPA’s Web site for resources on Marine Ecosystems, Oceans, Coasts and Estuaries, and Marine Species at Risk. Also, read about EPA’s 2007 Report on the Environment Coastal Benthic Community indicator. CLASSIFIERS OR MODIFIERS FOR AQUATIC ECOSYSTEMS
Although the UNESCO classification system is usually considered to predominantly cover terrestrial formations, it does include vegetated aquatic ecosystems. Within formation classes I-VI terms such as “flooded,” “riparian,” and “waterlogged,” are used to describe ecosystems that are wet or covered with water on a periodic or temporary basis, or even constantly in the case of certain palustrine formations. These ecosystems include bogs, flushes, salt marshes, flood savannahs, sedge swamps, and numerous other water dominated ecosystems.
In addition, formation class VII, Aquatic Plant Formations, encompasses systems in which water covers the land constantly or most of the year. This formation class includes five formation subclasses. Each of these subclasses has a distinct assemblage or set of species that usually occupy different niches of an aquatic ecosystem depending on water clarity, depth, flow velocity, etc. Several formations may occur within a short distance of each other, and in many cases they are not mappable at a scale of 1:250,000 as used in Central America.
The Map of the Ecosystems of Central America project reviewed a variety of existing classification systems (including Salm and Clark 1984, Gomez 1984 1986c; Green et al. 2000) but finally they determined that the original UNESCO system categories were adequate to describe aquatic ecosystems with a distinguishable vegetation cover above or under the water surface. The recognised distinct vegetated aquatic classes all have distinct floristic species assemblages. The variation of differentiation of aquatic faunal assemblages may be more determined by some of the physical characteristics.
The USNVC and LCCS offer equally suitable options. Open Water Formations A considerable challenge is the classification of aquatic ecosystems. The botanists that thought out the physiologic ecological classification systems, primarily were terrestrial botanists, with great knowledge about terrestrial vegetation. Many parts of water bodies lack any vegetation at all while characterization and classification without protruding vegetation is severely hampered by the extremely limited reflection of sunlight of both water and submerged elements.
In order to reach analytical completeness to deal with all biodiversity the UNESCO classification system and their derived systems need an additional class to classify aquatic ecosystems with little or no vegetation cover: “Open Water “, which mapping team for Central America added as class VIII. These are predominantly covered by water and have less than 10 percent of their area covered by emergent or submerged vegetation. Such class is also needed for the USNVC. The LCCS has a few open water classes, but the system needs more subdivision.
The aquatic component of each system needs more elaboration, but with customised identification, sufficient distinction can be established to classify aquatic ecosystems with distinct species assemblages. One of the primary reasons why terrestrial ecosystems can be classified and mapped conveniently by using the vegetation as the main proxy for ecosystem characterization is that the largest biomass is accumulated in – sessile – plants. In aquatic ecosystems, the flora primarily consists of planktonic algae with a relatively low biomass but an extremely high turnover.
The largest biomass is primarily accumulated in planktonic and mobile fauna. None of these elements is sufficiently static to be observed as a group, the composition is often highly dynamic and there is no morphological structure. To add to this problem, remote sensors are very restricted in their underwater visibility. Data often must be acquired from direct measurement, underwater observation and sampling, all costly and slow methods. Moreover, it should be realised that aquatic ecosystems are often subject to considerably seasonal changes.
Their chemical composition and physical appearance vary over short periods and thanks to the mobility of many aquatic species, many aquatic ecosystems show a great seasonality in the species compositions. In order to determine how aquatic ecosystems can be distinguished in such a way that partially different species assemblies can be separated, one must analyse what the essential sets may look like and which classifiers or modifiers can tell them apart. When present, aquatic vegetation protruding through the water surface are distinctly determining classifiers or modifiers for the identification of aquatic ecosystems.
As the protruding part are directly exposed to the atmosphere, one may call these “atmospheric aquatic vegetations”. In this sense, floating vegetation should also be considered atmospheric aquatic vegetation. Rooted atmospheric aquatic vegetation may: indicate stagnant or relatively slowly flowing water. They provide distinct habitat for a variety of plant and animal species that without the vegetation structure would not be there. Many species use vegetation to hide from predators.
Surface water systems without atmospheric aquatic vegetation have been dubbed “Open Water Systems”. The other principle groups of organisms characteristic of aquatic ecosystems are: 1. plankton; 2. benthos; 3. mobility of organisms. Plankton The composition of plankton is highly volatile and may change in hours due to weather conditions, such as light exposure, wind, etc, as well as to changing currents. As such, plankton is not a good indicator of an ecosystem but a number of classifiers or modifiers are highly influential on plankton composition.
Usually they include a combination of physical and chemical modifiers of the water phase, such as: |[pic]|salinity; | |[pic]|nutrient levels of the water phase; | |[pic]|acidity; | |[pic]|hardness of the water or dissolved calcium carbonate; | |[pic]|current velocity; temperature; | |[pic]|transparency f the water column. | Many of these classifiers or modifiers are volatile in their consistency, sometimes difficult to assess, highly variable over short distances with continuously changing distribution. As a result, for classifying planktonic species assemblies, most physical and chemical conditions of the water phase should be used with great reservation. To further the division of open water systems for Central America, it was determined that salinity was the most important divisive characteristic.
Most marine species are separated from limnic (freshwater) species by higher concentrations of salt. Among them primary freshwater fish species are stenohaline, meaning that they have little tolerance for variations in salinity. Secondary freshwater fish species have a varying tolerance to salinity. Some may tolerate temporary exposure to undiluted seawater but it may not be their preference. Other species are adapted to switching back and forth between saline and freshwater systems and may do so with some frequency or during some phases of their life cycle.
Most marine species will never enter freshwaters and are also stenohaline. Species in brackish waters are euryhaline, meaning they are tolerant of significant fluctuations in variations in salinity. The ictiofaunal assemblages for limnic, brackish, and marine systems are partially distinct and the degree of salinity is considered the single most distinctive factor for aquatic ecosystems, which – besides differentiation in atmospheric vegetation components – is particularly clear in the composition of the partially different assemblages of fish species.
Primary indicators for biotic differentiation a new classification, the following division would be necessary from a point of view of protected areas informatics: |[pic]|Limnic (freshwater) ecosystems | |[pic]|Brackish ecosystems | |[pic]|Marine ecosystems | |[pic]|Saline lakes and closed seas | Limnic or freshwater systems
Like for terrestrial ecosystems, when present, vegetation is a determinative component for aquatic ecosystems, creating habitat for significant assemblages of species that could not be present without vegetation. Wooded swamps usually fall under Formations I, V, or VII. Lakes and rivers often have fringes of emerged vegetation that are classified under formations V or VII in the UNESCO system. Limnic open water systems lack major areas of aquatic vegetation that would allow their classification under the UNESCO system. Within freshwater ecosystems some useful modifiers are: Nutrient level: divided into eutrophic, mesotrophic and oligotrophic.
Usually oligotrophic systems are relatively poor in species which are highly specialised. The water may be dark due to colorants released from anaerobe decaying processes of plants. Transparency may nevertheless be reasonable. Mesotrophic ecosystems are the most species diverse freshwater systems. Transparency may be high, but this is not always the case. Eutrophic systems may occur under natural conditions, particularly in coastal lowlands where clayy soils abound, but increasingly eutrophic conditions are the result of pollution loads.
Natural eutrophic ecosystems have characteristic species, often resilient to temporary low oxygen contents and they have relatively low transparency during the growing season. Pollution related eutrophic conditions at moderate levels may be similar to those of natural eutrophic systems, but at high nutrient levels the species composition becomes very low, oxygen levels may approach zero and the water becomes very non-transparent and green from algae bloom. The pH level: Most water systems fluctuate close to neutral conditions.
Oligotrophic systems in areas with peat formation may have pH levels as low as less than 4. As pH values are easy to measure in the field, low pH values may be used to indicate oligotrophic water conditions. Some species need some dissolved calcium carbonate (Meyers 1966). The latter can be interpreted from the general characteristics of the soil if this is a calcareous region. Current velocity: Some species require rather quiet water with slow flowing to stagnant waters or “lentic” systems, while others require the conditions of strong currents, “lotic” systems.
Whether it is the current in itself or conditions that come along with them, like abundance of exposed rocks and/or gravel beds, high oxygenation, lower temperatures associated with streams in the upper watersheds in not clear. Current velocities may be deducted from terrain accidentation, drainage characteristics and the shapes of the water bodies. Wide rivers usually have at least some lentic systems, while lakes and ponds may have a current flowing through them. Geomorphological shapes and location of the water systems: The Map of the Ecosystems of Central America distinguishes a variety of lake types based on their geological origin.
There is no good evidence however, that the geological origin contributes much to the distinction of species assemblies, and from a protected areas informatics point of view the distinction is not required. Rivers can be devided up in upper stream, mid stream and low land river systems, although the whereabouts of this division is rather subjective. Upper and mid stream rivers are in principle freshwater systems – unless upstream highly saline waters or salt deposits exist – populated with primary and secondary freshwater fish species.
Mid stream rivers have the highest diversity in freshwater fish species. There is a rather steep decrease of fish species as elevation increases. Particularly along the Andes, this difference is dramatic. With an extraordinary diversity of fish species until about 600 masl, the diversity decreases rapidly and above about 1,000 masl only some 20 – 30 representatives can be found along the entire Andean region, all being members of just one single genus, Astroblepus spp. in Spanish know under the name “prenadillas”. These are abundant non-migratory fishes that live in highly turbulent waters. In Central America, the appears to be somewhat lower, at 300 and 600 m respectively or wherever the currents become too fast to allow for many species to survive. At least close to the coast, lowland rivers often have fluctuating levels of salinity and they may be predominantly populated with secondary freshwater, facultative freshwater and peripheral fish species.
Upper streams usually have rocky or gravely bottoms, while in lowland rivers the bottoms usually consist of sediments each with a distinct benthos. Geological barriers are important classifiers or modifiers for determining the composition of assemblages of fish species. Most endemic fish species are in geologically fully isolated locations, like remnant wells in deserts or small isolated watersheds. Probably all endemic freshwater fishes are known to science and their locations are known. There is no need to further identify them as isolated ecosystems, like endemic ichlids in the Fauna and Flora Reserve Cuatro Cienegas and Cyprinodon spp. in Death Valley National Monument. A divisive factor in assemblies of fish species are the water systems. While the ecological conditions may be the same, the species assemblies may vary among watersheds. In the watersheds of Central America, a gradual shift in species can be observed from North-west to South-east. A baseline would need to assess if watersheds with distinct fish populations are present and if the distinguishing fish species be represented.
The watersheds of large rivers like the Amazon and the Parana rivers need to split up as many species only occur in parts of the watersheds. The shapes of the water systems are probably irrelevant, but they may be proxys for certain conditions, like current velocity, salinity, composition of the water bottom, etc. Usually, it is not necessary to identify all upperstream creeks, as they will be automatically incorporated in any protected areas system covering all ecosystems and 10% of the territory of a country, while quite a few streams will originate in each protected area system.
Midstream and lowland rivers will usually merely pass through a protected areas. It is necessary to identify and map them as parts of the protected areas baseline. For most countries fairly detailed baselines exist for fish species, that allow the prediction of their occurrence in watersheds and for large rivers like the Amazon and Parana in parts of the watersheds. For many protected areas this may be rather indicative for the potential assemblage of fish species. Brackish systems
Estuarine open waters are very distinct from both marine and limnic water systems, as they are characterized by varying salinity and usually very high dynamics. Estuaries – the coastal waters (river mouths and deltas, lakes with permanent or temporary outlets to the sea, barrier enclosed coastal seas, etc. ) where fresh water and sea water mix – often have high sedimentation, low transparency, high algae content and low species diversity, but high organic productivity, highly specialized organisms and high fauna population densities.
In many tropical estuarine tidal zones, mangroves abound, while in all climates bare tidal mud flats and periodically inundated salt marshes may be found, all of which can be identified with the physiognomic ecological ecosystem classification systems. A distinction was made on the Map of the Ecosystems of Central America between semi-closed and open estuaries. In retrospect, however, there probably is no clear ecological reason for maintaining this distinction, as the probably all organisms that characterize those waters occur in both of them.
The primary distinctions from a protected areas informatics perspective are: |[pic]|Riverine: river courses where the riverine conditions still predominate but at least periodical brackish conditions | | |occur, usually with a lower saline water layer that may protrude many kilometers inland; | |[pic]|Brackish lakes: (semi) stagnant – at least periodically – brackish conditions that may be poorly or periodically | | |connected to or flooded by the sea. |[pic]|Tidal estuaries: river mouths and barrier enclosed coastal seas with somewhat lower than marine salinity – at least | | |during high river discharges. | Marine ecosystems Marine ecosystems are areas that are below the low tidal line and permanently under water.
Photosynthesis is one of the key factors determining the species composition of marine ecosystems, which among other things depends on: |[pic]|light penetration | |[pic]|temperature and | |[pic]|nutrients | Photosynthesis first increases with temperature, then reaches a maximum, above which it the photosynthesis starts to decrease again (Kondratyev et al 2004).
With regard to light penetration this varies greatly depending on the location of the earth. In the pelagic or open ocean realm, light may penetrate to a depth of 400 – 500 m but along the coasts this is much less depending on the abundance of turbidity caused by sediment particles and plankton. The crystal-clear waters allow sunlight to penetrate considerably deeper than around coral reefs, where the water is often teeming with plankton. In tropical coastal waters, photosynthesis may take place until around 150 m.
Coral reefs are built by stony corals that harbor in their tissues symbiotic algae called zooxanthellae. These algae need sunlight for photosynthesis, which they can only perform until about 60 m mentioned for the Pacific Ocean in Hawaii (Bishop Museum 2008) and 50 meters in the Atlantic ocean (Leite Prates et al 2003). Thus the reef-building stony corals dominate only those reefs shallower than 50 – 60 m. This depth is also the maximum depth to which scuba conventional scuba diving is possible. This zone is also referred to as the permanently submerged littoral zone.
Beyond that, our knowledge of the oceans is significantly less. In the zone between 50 and 150 m, light penetration is very limited, the water temperature is rather low and the composition of the species assemblages change, making way for soft-bodied marine organisms, such as sponges, soft-corals, tunicates, and other sessile invertebrates (Bishop Museum 2008). It therefore seems logical for the tropics to use the 50 or 60 m isobaths and the 150 m isobaths for separating the permanently submerged littoral ecosystem and a relatively shallow pelagic system and gradually less towards higher latitudes.
Another important zone is the tidal zone in which organisms live that can survive periodic exposure to the air and being submerged. Humby and Harborne (1999) provide a very detailed classification system for coral reefs in the Atlantic Ocean. This method however depends on mapping by scuba divers and it is too costly to produce maps at this level of detail. As one moves away from the equator, light penetration may decrease as light enters more under an angle. Thus the delimitation of the littoral marine zone is lower in depth, as may be the case in waters with permanently lower transparency.
For most coasts bathymetric maps exist, but they may not always coincide with the preferred isobats of separation. In absence of solid bathyometric models, it is preferable to use the nearest isobats on the map for ecosystem identification. As the term is traditionally used, littoral systems also encompass tidal zones, which may include beaches, salt marshes, and mangroves, and even coastal plains; all identifiable with physiognomic ecological classification systems. Within the permanently submerged littoral zone, sea floors may be rocky, silty, sandy, or gravely.
In particular, areas of sea grass can be classified as submerged vegetation classes. Sessile marine macro-algae often occur among corals (although in coverage, they usually are much less important than corals), and at times, may be important enough to be mapped as submerged marine fixed macro-algae. In coralline areas such cover often indicates disturbance. This may be of human or origin or caused by native conditions such as hurricanes (for example near Punto Allen in Sian Ka’an Biosphere Reserve, Mexico) or prolonged periods of excessive heat (Guzman, pers. com).
In general, marine ecosystems are much less varied than terrestrial ecosystems, which is particularly due to extremely good connectivity and much smaller climatic (smaller temperature variations and much more limited precipitation influence) variety in aquatic ecosystems. The greatest variability in marine ecosystems increases from deep to shallow and from soft versus hard substrates. Pelagic systems have not yet developed into a major issue in protected areas informatics, as thus far, protected areas have been bound within the 200 miles economical zones of nations.
Most pelagic systems within marine protected areas have been chosen for the protection of very specific fauna (particularly whales) and are within the 50 – 150 m isobats. Thus far, only 3 mappable classifiers have come to mind: depth, bottom accidentation (including ship wrecks) and hard versus soft substrate. These conditions can be identified systematically with ship-based sensors. The ARGO project has been measuring water seawater temperature and salinity between the surface and a depth of 2000 m in all oceans of the earth since 1990, using large numbers of “Argo floats” or buoys.
These measurements may be instrumental in helping determine more pelagic ecosystem differentiation over time. Mobile organisms In aquatic ecosystems, most lower organisms for their distribution primarily depend on their distribution on water currents. Many benthic species pass from a planktonic phase to a benthic phase in the course of their life cycles, in which they often can be distinctly observed during their benthic phase, while remaining rather elusive during their planktonic phase.
Also actively swimming organisms like crustaceans and a variety of fish species pass through a planktonic phase during their life cycles, while a variety of mobile species associate themselves with specific conditions of the water bottom (coral reef fish species, bottom feeding fish species, etc. ), making the bottom characteristics an important modifier for such species. Vreugdenhil et al 2002 suggests that fishes may be valuable indicators for distinguishing between some aquatic ecosystems.
After further consideration, this would not seem to be a good idea. Meyers 1966 describes how he sampled many water systems in Central America and often would not come up with more than 3 or 4 of the same fish species. Characterizing an aquatic ecosystem through such laborious sampling is too costly and too slow. The combination of a few physical classifiers or modifiers and salinity samples will be more efficient. A few words should be dedicated to water and shore birds and marine mammals and turtles.
These taxa are rather selective in their choice of habitat. While it is possible to assess their preferred habitats by a rather limited suite of physical, chemical and vegetation conditions, their actual presence is by no means guaranteed by seemingly suitable conditions like a tidal mud flat rich in benthos, waters rich in fish, etc. Other factors are involved, like disturbance and the simple habit of a species to go to a certain location of preference. Therefore, aquatic ecosystems must be overlaid with maps of congregations of fauna elements.
Benthic organisms The composition of bottom characteristics separates distinct species assemblages: Some benthic fauna and flora can only live in soft bottoms, while other species live on top of the bottom and require a hard substrate for their attachment (e. g. corals). Many mobile fauna species (e. g. Cod, coral fish species) prefer to stay near hard objects like boulders, submerged rockscapes, shipwrecks, etc. particularly if they provide hiding places for escape. Several Salmoids need gravel beds for spawning.
Salm and Clark (1984) provide several bottom modifiers that may be used to characterize open water formations and the composition of such formations can have very characteristic species assemblies (e. g. Corals, benthic communities on mud flats, benthic communities in gravel beds in creeks, etc. Mumby and Harborne (1999) provide detailed classes for coralline coasts, but at that level of detail, not all coralline classes reflect distinct assemblages of species (Guzman 1998). While bottom composition is extremely important, it is believed that a limited number of well-chosen For aquatic ecosystems distinctions should be made for: [pic]|Division marine, estuarine and fresh water systems; Non-marine saline and alkaline waters; | |[pic]|Distinction between different classes of fresh-water bodies (river, lake and lakes without outlet, swamps / marshes);| |[pic]|Distinction between waters in the Pacific versus the Atlantic drainage; | |[pic]|Subdivision of rivers in Upper, middle and lower stream; | |[pic]|Concentrations of gregarious faunal species of special concern, both permanent and seasonal; | |[pic]|Submerged vegetation if possible; | |[pic]|Coral reefs if possible. | ========================================================================== Types of Aquatic Ecosystems I want to do this! What’s This? 1. [pic] marine life image by pearlguy from Fotolia. com Marine ecosystem An aquatic ecosystem is any water-based environment in which plants and animals interact with the chemical and physical features of the environment. Aquatic ecosystems are generally divided into two types–the marine ecosystem and the freshwater ecosystem. Marine ecosystems cover over 70 percent of the earth’s surface. Oceans, estuaries, coral reefs and coastal ecosystems are the various kinds of marine ecosystems.
Freshwater ecosystems cover less than 1 percent of the earth and are subdivided into lotic, lentic and wetlands. Oceans 2. The earth has five major oceans: Pacific Ocean, Indian Ocean, Arctic Ocean, Atlantic Ocean and Southern (Antarctic) Ocean. Although the oceans are connected, each of them has unique species and features. According to Barbara A. Somerville (Earth’s Biomes: Oceans, Seas, and Reefs), the Pacific is the largest and deepest ocean and the Atlantic is second in size. Oceans are home to different species of life. The waters of the Arctic and Southern Oceans are very cold, yet filled with life. The largest population of krill (small, shrimp-like marine creatures) lies under the ice of the Southern Ocean. Estuaries 3.
Estuaries are places where rivers meet the sea and may be defined as areas where salt water is diluted with fresh water. River mouths, coastal bays, tidal marshes and water bodies behind barrier beaches are some examples of estuaries. They are biologically productive as they have a special kind of water circulation that traps plant nutrients and stimulates primary production. Coral Reefs 4. According to Environmental Protection Agency, coral reefs are the world’s second richest ecosystems and have a wide diversity of plants and animals. As a result, coral reefs often are referred to as the rain forest of the oceans. Coastal 5. Land and water join to create the coastal ecosystems.
These ecosystems have a distinct structure, diversity, and flow of energy. Plants and algae are found at the bottom of the coastal ecosystem. The fauna is diverse and consists of insects, snails, fish, crabs, shrimp, lobsters etc. Lotic 6. Lotic ecosystems are the systems with rapid flowing waters that move in a unidirectional way such as rivers and streams. These environments harbor numerous species of insects such as mayflies, stoneflies and beetles which have developed adapted features such as weighted cases to survive the environment . Several species of fishes such as eel, trout and minnow are found here. Various mammals such as beavers, otters and river dolphins inhabit lotic ecosystems. Lentic 7.
Lentic ecosystems include all standing water habitats such as lakes and ponds. These ecosystems are home to algae, rooted and floating-leaved plants and invertebrates such as crabs and shrimps. Amphibians such as frogs and salamanders and reptiles like alligators and water snakes are also found here. Wetlands 8. Wetlands are marshy areas and are sometimes covered in water which have a wide diversity of plants and animals. Swamps, marshes, and bogs are some examples in this regard. Plants such as black spruce and water lilies are commonly found in wetlands. The fauna consists of dragonflies and damselflies, birds such as Green Heron and fishes such as Northern Pike.
