Aquatic Biomes PDF

AQUATIC ECOSYSTEMS OR BIOMES Aquatic ecosystems are classified primarily on abiotic factors such as salinity that help determine an aquatic life zone’s boundaries. Salinity – the concentration of dissolved salts, such as sodium chloride in a body of water affects the kinds of organisms present...

AQUATIC ECOSYSTEMS OR BIOMES Aquatic ecosystems are classified primarily on abiotic factors such as salinity that help determine an aquatic life zone’s boundaries. Salinity – the concentration of dissolved salts, such as sodium chloride in a body of water affects the kinds of organisms present in aquatic ecosystems, as does the amount of dissolved oxygen. Water greatly interferes with the penetration of light, so floating aquatic organisms that photosynthesize remain near the water’s surface and vegetation attached to the bottom grows only in shallow water. Other determinants of species composition in aquatic ecosystems include depth of water, temperature, pH, and the presence or absence of waves and currents.  Three Main Ecological Categories of Organisms in Aquatic Ecosystems 1. Free floating plankton Plankton – are usually small or microscopic organisms that are relatively feeble swimmers. They are carried about by currents and waves. Planktons are generally subdivided into two major categories: phytoplankton and zooplankton Phytoplankton (photosynthetic cyanobacteria and free – floating algae) are producers that form the base of most aquatic food webs. Zooplankton – are nonphotosynthetic organisms that include protozoa, tiny crustaceans, and the larval stages of many  Three Main Ecological Categories of Organisms in Aquatic Ecosystems 2. Swimming Nekton Nekton – are larger, strong swimming organisms such as fishes, turtle and whales 3. Bottom –dwelling Benthos Benthos – are bottom dwelling organisms that fix themselves to one spot (sponges, oysters, and barnacles), those that burrow into sand (many worms and echinoderms), or simply walk or swim about on the bottom (crayfish, and brittle stars)  Freshwater Ecosystem Each type of freshwater ecosystem has its own abiotic conditions and characteristic organisms. Although occupying a small portion (about 2%) of the Earth’s surface, the freshwater ecosystem is important in the hydrologic cycle. They assist in recycling precipitation that flows as surface runoff to the ocean. Bodies of freshwater also moderate daily and seasonal temperature fluctuations on nearby land. It also provide homes for large number of species.  Freshwater Ecosystem Streams and Rivers  Are flowing – water ecosystems that changes its source to its mouth (where it empties into another body of water). Headwater streams (small stream that are sources of a river) are usually shallow, clear, cold, swiftly flowing and highly oxygenated.  In contrast, rivers downstream from the headwaters are wider and deep and contain suspended particulates. It is less cold, slower in flow and less oxygenated. Freshwater Ecosystem  Freshwater Ecosystem Streams and Rivers  Along the length of a stream or river, groundwater wells up through sediments on the bottoms. This local input of water moderates the water temperature so that summer temperatures are cooler and winter temperatures are warmer than in adjacent parts of the flowing – water ecosystem.  Human activities have adverse impacts on rivers and streams. This include water pollution and the effects of dams constructed to contain water or rivers or streams. Dams change the nature of flowing – water ecosystems both upstream and down stream from the dam location. Dams causes water to back – up, flooding large areas of land and Freshwater Ecosystem  Freshwater Ecosystem Lakes and Ponds  Are standing – water ecosystems. Large lakes has three basic zones based on penetration of light. A. Littoral zone – a shallow water area along the shore or a lake or pond. It includes rooted vegetation and several deep – dwelling aquatic plants and algae. This zone is the most productive zone of the lake. Photosynthesis is greatest in this zone because light is abundant and it receives nutrient inputs from the surrounding land that stimulate the growth of plants and algae. The animals in the littoral zone are frogs, turtles, worms, crayfish and other crustaceans, insect larvae, and many fishes such as carp.  Freshwater Ecosystem Lakes and Ponds B. Limnetic zone – the open water beyond the littoral zone., away from the shore. It extends down as sunlight penetrates to permit photosynthesis. The main organisms of the limnetic zone are microscopic phytoplankton and zooplankton. Larger fishes also spend some of their time in this zone, but they may also visit the littoral zone to feed and reproduce. Due to its depth, less vegetation grows in the limnetic zone.  Freshwater Ecosystem Lakes and Ponds C. Profundal (Aphotic) zone - light does not penetrate effectively to this depth so that plants and algae do not exist in this zone. Food drifts into the profundal zone from the littoral and limnetic zones. Bacteria decompose dead plants and animals that reach profundal zone, thus liberating nutrient minerals. Freshwater Ecosystem Freshwater Ecosystem  Freshwater Ecosystem Freshwater Wetlands  Freshwater wetland are transitional between aquatic and terrestrial ecosystems. Shallow water usually covers for at least part of the year, have characteristic soils, and water – tolerant vegetation. They include marshes in which grasslike plants dominate, and swamps in which woody trees and shrubs dominate.  Wetland plants which are highly productive provide enough food to support a wide variety of organisms. It serves as wildlife habitat for migratory waterfowls and other bird species.  Wetlands are holding areas for excess water when rivers flood their banks. The floodwater stored in wetlands then Freshwater Ecosystem  Freshwater Ecosystem Estuaries  An estuary is a coastal body of water partly surrounded by land with access to open ocean and large supply of freshwater from rivers.  It occurs where fresh water and salt water meet. The kind of water in estuaries is Brackish Water which is a mixture of fresh and salt water.  The water level in estuaries rise and fall with the tides and its salinity fluctuates with tidal cycles, with the time of the year, and with precipitation.  Freshwater Ecosystem Estuaries  Salinity varies from usually freshwater at the river entrance to salty ocean water at the mouth of the estuary.  With the daily, seasonal, and annual variations in temperature, salinity, and other physical properties, organisms have a wide tolerance to such changes.  Estuaries cover areas where mangrove forests develop which provide stable environment for most aquatic organisms. Freshwater Ecosystem Freshwater Ecosystem  Marine Ecosystem  The large and complex marine environment is subdivided into several zones: The intertidal zone, the benthic environment (ocean floor), and the pelagic environment (ocean water)  Marine Ecosystem Intertidal zone  Is the shoreline area between low and high tide.  It is the transitional zone between land and ocean.  It has high levels of light and nutrients with abundance of oxygen.  Marine Ecosystem Benthic Environment  It is the ocean floor and is divided into zones based on distance from land, light availability, and depth.  It includes the following zones: Abyssal zone and Hadal zone  Marine Ecosystem Benthic Environment  Abyssal zone – extends to a depth of 4000 meters to 6000 meters.  Hadal zone – extends to a depth of more than 6000 meters  Marine Ecosystem Benthic Environment  Benthic communities in shallow ocean waters consists of the seagrass beds, the kelp forests, and the coral reefs.  Seagrass – are flowering plants that have adapted to complete submersion in ocean water.  Marine Ecosystem Benthic Environment  Kelps – reaches a length of 60 meters, are considered the largest brown algae. They are common in cooler temperate marine waters of the Northern and Southern Hemisphere  Marine Ecosystem Benthic Environment  Coral reefs – are built from accumulated layers of calcium carbonate (CaCO3 ) are found in warm (usually higher than 21OC), shallow seawater.  Marine Ecosystem Benthic Environment  The living portions of coral reefs grow in shallow waters where light penetrates.  Many coral reefs are composed principally of red coralline algae that require light for photosynthesis.  Coral reefs ecosystem are the most diverse of all marine environments and contains hundreds or thousands of species of fishes and invertebrates, such as giant clams, sea urchins, sea stars, sponges, sea fans, and shrimps  Marine Ecosystem Pelagic Zone (Open Ocean)  Neritic Province – an open ocean that overlies the continental shelves, the ocean floor from the shoreline to the depth of 200 m. Organisms that live in neritic province, are floaters or swimmers. The upper part of the neritic make up the Euphotic Zone which extends from the surface to a depth of about 100 m.  Phytoplankton, such as diatoms in cooler waters and dinoflagellates in warm water, produce food by photosynthesis and are the base of food webs.  Zooplankton such as tiny crustaceans, jellyfish, larvae or barnacles, sea urchins, worms, and crabs feed on phytoplankton  Marine Ecosystem Pelagic Zone (Open Ocean)  Neritic Province  Marine Ecosystem  Plankton – eating nekton such herring, sardines, squid, manta rays, and whales consume zooplankton. These in turn become prey for carnivorous nekton such as sharks, tuna, dolphins.  Nekton are mostly confined to the shallow neritic waters, less than 60 m deep.  Marine Ecosystem Pelagic Zone (Open Ocean)  Oceanic Province– is that part of the open ocean that covers the deep ocean basin that is the ocean floor at depths more than 200 m. It is the largest marine environment and contains about 75% of the ocean’s water. The cold temperature, high hydrostatic pressure, and the absence of sunlight characterize the oceanic province.  Ecotones  The transition zone where two communities or biomes meet and integrate is called an ecotone.  Ecotones vary in size from small, such s the area when an agricultural land or field meets a woodland or where a stream flows through a forest which covers several countries. Ex. The border between tundra and taiga  Ecotones are not permanent boundaries due to changes over time.