Aquatic Ecosystems

Freshwater Ponds & Lakes Streams & Rivers Wetlands Marine Oceans Coral Reefs Estuaries Aquatic Ecosystems

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 (i.e, ocean) Freshwater

Ponds and Lakes • range in size from just a few square meters to thousands of square kilometers • ponds may be seasonal, lasting just a couple of months (such as sessile pools) • lakes may exist for hundreds of years or more • may have limited species diversity since they are often isolated from one another and from other water sources like rivers and oceans

Ponds and Lakes • divided into three different “zones” determined by depth and distance from the shoreline • littoral zone • limnetic zone • profundal zone

Littoral Zone • warmest since it is shallow and can absorb more of the Sun’s heat • 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, and amphibians • the egg and larvae stages of some insects are found in this zone • vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks

Limnetic Zone • near-surface open water surrounded by the littoral zone • 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 – most life would not be possible without them • variety of freshwater fish also occupy this zone

Profundal Zone • Plankton have short life spans—when they die, they fall into the deep-water part of the lake/pond • much colder and denser than the other two • little light penetrates all the way through the limnetic zone into the profundal zone • animals are decomposers

Ponds and Lakes Temperature • varies seasonally. • Summer • from 4° C near the bottom to 22° C at the top • Winter • from 4° C while the top is 0° C (ice) • between the two layers is a narrow zone called the thermocline where the temperature of the water changes rapidly with depth

Ponds and Lakes • during the spring and fall seasons is a mixing of the top and bottom layers resulting in a uniform water temperature of around 4° C • mixing also circulates oxygen throughout the lake • many lakes and ponds do not freeze during the winter resulting in the top layer being a little warmer

Ponds and Lakes • ice can develop on the top of lakes during winter • blocks out sunlight and can prevent photosynthesis • oxygen levels drop and some plants and animals may die • called "winterkill."

Streams & Rivers • bodies of flowing water moving in one direction • found everywhere—they get their start at headwaters, which may be springs, snowmelt or even lakes • travel all the way to their mouths, usually another water channel or the ocean

Watershed • describes an area of land that contains a common set of streams and rivers • drains into a single larger body of water, such as a larger river, a lake or an ocean

Streams & Rivers • characteristics change during the journey from the source to the mouth • temperature is cooler at the source than it is at the mouth • water is also clearer, has higher oxygen levels, and freshwater fish such as trout and heterotrophs can be found there

Streams & Rivers • Towards the middle part of the stream/river, the width increases, as does species diversity—numerous aquatic green plants and algae can be found

Streams & Rivers • toward the mouth the water becomes murky from all the sediments that it has picked up upstream • decreasing the amount of light that can penetrate through the water • less light • less diversity of flora • lower oxygen levels • fish that require less oxygen, such as catfish and carp, can be found

Wetlands • Wetlands are areas of standing water that support aquatic plants • Marshes, swamps, and bogs are all considered wetlands

Wetlands Plants • adapted to the very moist and humid conditions are called hydrophytes Pond lilies Cattails Sedges Tamarack Black Spruce Gum Cypress

Wetlands • highest species diversity of all ecosystems • many species of amphibians, reptiles, birds (such as ducks and waders), and furbearers can be found in the wetlands • not considered freshwater ecosystems as there are some, such as salt marshes, that have high salt concentrations—these support different species of animals, such as shrimp, shellfish, and various grasses

Wetlands River Otter Damselfly Dragonfly Mayfly Crayfish Snails Leech Bluegill Bass Catfish Sculpin Minnow Snakes Frog Turtle Great Blue Heron Canadian Goose

Marine Oceans Coral Reefs Estuaries Aquatic Ecosystems

Marine • cover about three-fourths of the Earth’s surface and include oceans, coral reefs, and estuaries • algae supply much of the world’s oxygen supply and take in a huge amount of atmospheric carbon dioxide • evaporation of the seawater provides rainwater for the land

Oceans • largest of all the ecosystems • dominate the Earth’s surface • separate zones • Intertidal • Pelagic • Abyssal • Benthic • great diversity of species • richest diversity of species even though it contains fewer species than there are on land

Intertidal Zone • where the ocean meets the land • sometimes submerged and at other times exposed • waves and tides come in and out • communities are constantly changing

Pelagic – Open Ocean • waters further from the land, basically the open ocean • generally cold though it is hard to give a general temperature range since, just like ponds and lakes, there is thermal stratification with a constant mixing of warm and cold ocean currents

Mesopelagic Zone http://oceanlink.island.net/oinfo/deepsea/meso.html • "twilight zone" of the ocean • photic zone above • darkness below • food becomes scarce – some animals • migrate up to the surface at night to feed • rely on food that falls down from above • eat each other • sometimes the only things to eat may be bigger than the hunter • developed long sharp teeth, • expandable jaws and stomachs

Bathypelagic Zone • extends down from 1000 to 4000m • only light is from bioluminescent organisms • only food is what trickles down from above, or from eating other animals • water pressure at this depth is considerable (~100 – 400 atmospheres) • most animals are either black or red in color • very little blue/green light penetrates this deep – red is not reflected and looks black

Abyssopelagic Zone - the Abyss • 4000m to the sea floor • only zone deeper than this is the hadal zone • areas found in deep sea trenches and canyons • home to pretty inhospitable living conditions • near- freezing temperatures • crushing pressures

The Coral Reef Biome A Look at a Marine Biome Created by Terri Street

What Is a Coral Reef? • A structure formed by coral polyps, tiny animals that live in colonies. • Coral polyps form a hard, stony, branching structure made of limestone. • New polyps attach to old coral and gradually build the reef.

Types of Coral Reefs • Fringing reefs • Submerged platforms of living coral extending from the shore into the sea • Barrier reefs • Follow the shore but are separated from it by water • Great Barrier Reef is world’s largest

Types of Coral Reefs • Atolls • Ring-shaped islands of coral in open sea • Form on submerged mud banks or volcano craters • Surround a seawater lagoon • Channels connect lagoon to the sea

= Coral Reef A World of Coral Reefs

Coral Reef Climate • Usually found near land in shallow, warm salt water • Lots of light • Tropical temperatures, averaging 70°-85° F • Most coral cannot survive below 65° F

Coral Reef Plants • Phytoplankton • Microscopic • Basis for all ocean food chains

Coral Reef Plants • Algae • Green • Red • Brown algaetakes many forms

Coral Reef Plants • Seaweed and Sea grasses • Brown seaweed • Sea grass • Shoal grass • Turtle grass

Fascinating Fact: The Great Barrier Reef • World’s largest coral reef • Over 1257 mileslong • Off the northeast coast of Australia • Only grows about one inch per year

The Great Barrier Reef: Home to… • 1500 species of fish • 400 different types of coral • 4,000 mollusks • 500 species of seaweed • 215 species of birds • 16 species of sea snake • 6 species of sea turtle • Whales visit during winter

Endangered Coral Reefs • Major threats to coral reefs include: • Ocean pollution • Dredging off the coast

Endangered Coral Reefs • Other dangers: • Careless collection of coral specimens • Sedimentation • Inhibits growth of coral polyps • Inhibits algae growth • Upsets balance of the biome

Estuaries http://www.epa.gov/owow/estuaries/about1.htm • enclosed body of water formed where freshwater from rivers and streams flows into the ocean, mixing with the salty sea water • estuaries and the lands surrounding them are places of transition from land to sea, and from fresh to salt water • although influenced by the tides, estuaries are protected from the full force of ocean waves, winds, and storms by the reefs, barrier islands, or fingers of land, mud, or sand that define an estuary's seaward boundary

Estuaries are semi-enclosed bodies of water where fresh water from the land mixes with sea water. • Estuaries originate as: drowned river valleys, fjords, bar-built estuaries, and tectonic estuaries. • Salinity typically grades from normal marine salinity at the tidal inlet to fresh water at the mouth of the river.

Estuaries can be subdivided into three types based upon the relative importance of river inflow and tidal mixing. • Salt-wedge estuaries are dominated by the outflow from rivers. • Partially-mixed estuaries are dominated by neither river inflow nor tidal mixing. • In well-mixed estuaries tidal turbulence destroys the halocline and water stratification. • Because river discharge and tidal flow vary, conditions within an estuary can also change, being well-mixed when river flow decreases relative to tidal mixing, to becoming a salt-wedge estuary at times of maximum river discharge.

The widely fluctuating environmental conditions in estuaries make life stressful for organisms. • Estuaries are extremely fertile because nutrients are brought in by rivers and recycled from the bottom because of the turbulence. • Stressful conditions and abundant nutrients result in low species diversity, but great abundance of the species present. • Despite abundance of nutrients, phytoplankton blooms are irregular and the base of the food chain is detritus washed in from adjacent salt marshes. • The benthonic fauna strongly reflects the nature of the substrate and most fishes are juvenile forms living within the estuary until they mature and migrate to the ocean.

Estuaries http://www.epa.gov/owow/estuaries/about1.htm • Estuaries are sometimes called “marine nurseries” • habitats for many juvenile organisms, especially for fishes • many fish are born and grow up in estuaries • migrate to the open ocean

Lagoons are isolated to semi-enclosed, shallow, coastal bodies of water that receive little if any fresh water inflow. • Lagoons can occur at any latitude and their salinities vary from brackish to hypersaline depending upon climate and local hydrology. • Bottom sediments are usually sand or mud eroded which was from the shoreline or swept in through the tidal inlet. • In the tropics, the water column is typically isothermal. • In the subtropics, salinity generally increases away from the inlet and the lagoon may display inverse flow.

Salt marshes are intertidal flats covered by grassy vegetation. • Marshes are most commonly found in protected areas with a moderate tidal range, such as the landward side of barrier islands. • Marshes flood daily at high tide and then drain through a series of channels with the ebb tide. • They are one of the most productive environments. • Marshes can be divided into two parts: Low salt marshes and High salt marshes. • Distribution and density of organisms in salt marshes strongly reflects availability of food, need for protection, and frequency of flooding.

Mangroves are large woody trees with a dense, complex root system that grows downward from the branches • Mangroves are the dominant plant of the tropical and subtropical intertidal area • Distribution of the trees is largely controlled by air temperature, exposure to wave and current attack, tidal range, substrate and sea water chemistry • Detritus from the mangrove forms the base of the food chain

Aquatic Ecosystems