Aquatic Biomes: Marine Freshwater Freshwater

Freshwater Regions Freshwater is defined as having a low salt concentration—usually less than 1%. Plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (ocean). Types of Freshwater Regions: Ponds Streams Lakes Wetlands Rivers

Ponds and Lakes These regions range in size from just a few square meters to thousands of square kilometers. Many ponds are seasonal, lasting just a couple of months Vernal Pools Great Lakes (such as Superior, shown here) are 10,000 years old, forming at the end of the last glacial period. They contain 21% of earth’s surface freshwater. while some lakes may exist for hundreds, to thousands of years.

Freshwater Zones 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 different “zones” which are usually determined by distance from shore, and depth Profundal Littoral Euphotic Limnetic Aphotic Benthic

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 like the bluegill sunfish, and amphibians.

A variety of freshwater fish also occupy this zone. 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. A variety of freshwater fish also occupy this zone.

Colder Denser Less light ONLY heterotrophs Plankton have short life spans—when they die, they fall into the deep-water part of the lake/pond, the profundal zone. Colder Denser Less light ONLY heterotrophs Vertically, there are also other zones within lakes. Euphotic Aphotic Euphotic: With light Aphotic: Without light Benthic The bottom sediment, known as the benthic zone has a surface layer abundant with organisms. Profundal Zone

What two zones are measured by distance from shore? What types of organisms might you find in the littoral freshwater zone? What types of organisms might you find in the limnetic freshwater zone? What is the difference between phytoplankton and zooplankton? What zones in a body of freshwater are measured by depth? Littoral; Limnetic Amphibians, snails, sunfish, sun-loving aquatic plants Zooplankton and phytoplankton, as well as many larger fish Phytoplankton: autotrophs; Zooplankton: Heterotrophs Euphotic (light); Aphotic: No light; Benthic: bottom sediment

Rivers and Streams Headwaters Mouths These are bodies of flowing water moving in one direction. Headwaters Mouths Source of Colorado River The characteristics of a river or stream change during the journey from the source to the mouth. 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. Source: Water is colder, and highly oxygenated (usually) Freshwater fish such as trout and other heterotrophs that rely upon high dissolved oxygen 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 the water slows down, and the channel widens, resulting in Increasing turbidity Resulting in Decreasing light Resulting in…? Mid-Hudson River Valley Muddy Mississippi What do you suppose all this mud, and decreasing light means to the relative number of autotrophs and heterotrophs? More sediment in the water Less light penetrates the water, low floral diversity, lower animal diversity due to less dissolved oxygen (which the plants produce) Because of the lower oxygen levels, only species who can survive in those conditions do well, like catfish and carp. The water generally moves at such a slow pace as it nears the ocean, and the sediments begin to “fall out”, producing a delta.

Where do rivers begin? Where do rivers end? How do the conditions of the river change throughout its long journey? Headwaters Middle Mouth How do organisms that live at the headwaters and the mouth of a river differ? Give examples

Wetlands Marshes Swamps Bogs Wetlands are areas of standing water that support aquatic plants. Marshes Swamps Bogs Wetland soil is special because it is often soaked with water. The water fills up the spaces between the soil so no oxygen can fit. This swamp gas smell is produced by the element sulfur, NOT methane like many people suspect. Methane is odorless and colorless. This is called anaerobic soil. Anaerobic bacteria live in wetland soil to decompose plants without the use of oxygen.  This process causes the “swamp gas” smell that is characteristic of wetlands.

Why do you suppose that’s true? Plant species adapted to the very moist and humid conditions are called hydrophytes. Wetlands have the highest species diversity of all aquatic ecosystems. Many species of amphibians, reptiles, birds (such as ducks and waders), and mammals can be found in the wetlands. Wetlands are among the most endangered of all biomes. Wetlands exist where humans want to live, and we alter the biome greatly to suit us. Why do you suppose that’s true?

Marshes Marshes predominantly contain plants without strong woody stems and branches, called herbaceous plants. Plants that flourish in marshes can grow in the varying water levels of the marsh, with their stems partly immersed in the water and partly above it. Marshes may be either freshwater or saltwater, depending on the type of water they contain. Freshwater Marshes: cattails, water lilies, and arrowheads, ducks, geese, waterfowl including snowy egrets and great blue herons, raptors such as hawks and bald eagles, and mammals including raccoons, minks, and beavers. Freshwater marshes constitute 90 percent of America's wetlands.

Swamps Swamps start out as lakes, ponds or other shallow bodies of water. Over time, trees and shrubs begin to fill in the land. Plants die and decay and the level of the water gets lower and lower. Succession Eventually, the original body of water becomes a swamp.

Swamps are wetlands whose dominant vegetation is comprised of woody plants such as trees and shrubs. The water may be anywhere from a few inches to over a foot deep. Though swamps are usually saturated with water during the growing season, they may dry out in the heat of a long summer. Pneumatophores The soil saturation and diversity of vegetation in swamps lures a wide variety of animal life into their murky environments. Alligators and cottonmouths are the more famous swamp inhabitants. Because of the ever present water, insects abound in the swamp. Pneumatophores- plant adaptations (roots that enable the plant to gather oxygen in very wet ecosystems, required for cellular respiration by the plant)

Bogs Bogs are freshwater wetlands found in cold regions. In North America, many bogs were formed over 10,000 years ago when the last of the glaciers departed, leaving lakes called kettle holes. In some instances, the retreating ice left shallow basins where rain collected and formed the wetland.

A variety of wildlife including moose, bear, and deer often find food, water, and shelter in bogs throughout the year. The bottom layer of a bog consists of peat. Peat is an organically rich material that forms when plants die, fall into the water, and are compressed over time, forming a thick layer. What resource got it’s start as peat? This layer of peat can be up to forty feet deep. Bogs are sometimes called "peatlands." Among the more interesting and unique plants of bogs are bladderworts, pitcher plants, and sundews that trap and digest insects and tiny animals.

___Wetlands_________ as ____________________ Aquatic biomes Terrestrial biomes Wetlands include… What are plants adapted to wetlands known as? Why are wetlands so endangered? How do plants from marshes differ from plants in swamps? What ecological process helps to form swamps? What plant root type is well adapted to a water-logged existence? What is peat, and why are bogs sometimes called “peatlands”? Marshes, swamps and bogs; hydrophytes; highest aquatic biome diversity; because people want to live there; herbaceous vs. woody stems; succession; pheumatophores; decomposing plant material which builds up thickly, exists in bogs…will go on to form coal. Peat is the first form of coal.

Nepenthes Dionaea muscipula While carnivorous plants are autotrophs...They are also: “facultative heterotrophs” They are able to gather some of their nutrients (primarily nitrogen) through digesting organisms. The tropical rainforest. This becomes extremely important in biomes that have poor soil nutrient value. What other biomes with notoriously poor soil (low in nitrogen) might you also find facultative heterotrophs in?