Aquatic Ecosystems

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

Ponds & Lakes Streams & Rivers Wetlands Freshwater

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."

Ponds and Lakes

Fig. 7-21 p. 158 Types of Lakes: Oligotrophic – nutrient poor

Fig. 7-21 p. 158 Types of Lakes: Eutrophic – nutrient rich

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

Streams & Rivers

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

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

Coastal Wetlands • Land areas covered with H2O all or part of the year • Include: mouths of rivers, bays, sounds, mangrove forest swamps in tropical waters • Temperature & salinity vary widely with tidal, seasonal & weather changes

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

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

Human Impact on Freshwater Inland Wetlands • Fragmentation by dams, diversions or canals  wildlife habitat destruction • Flood control dikes & levees  habitat damage, disconnect rivers from floodplains, eliminate important spawning grounds • Drainage or filling of wetlands for agriculture

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

Oceans

Ocean Zones Fig. 7-7 p. 148 Refer to Figs. 7-11 & 7-12 p. 151 & 152

Euphotic Zone • Upper layer • Photosynthesis can occur here because sunlight can penetrate • Algal blooms may cause a decrease in euphotic zone

A note or two about Dissolved Oxygen (DO)… • High at surface – b/c of diffusion from atmosphere & photosynthesis • Lower at depths – b/c of use by consumers during respiration • Warm water holds more DO than cold water • Remember that CO2 is the reverse!

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

ctenophore – related to jellyfish Big Scale - ambush predator cilia can be illuminated Firefly squid three kinds of photophores Hatchet Fish only a few inches long Viperfish specially adapted hinged skull Dragonfish - stomachs hold big meals Snipeel up to 1.2m Siphonophores are colonies of animals related to jellyfish best known is Portugese Man of War http://oceanlink.island.net/oinfo/deepsea/meso.html

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

Narcomedusa Vampire Squid Snake Dragon Angler Fish Amphi - crustacean Ctenophore – voracious predator Deepstaria very slow swimmers, no tentacles, close flexible bells (up to a meter across) around their prey Big Red grows to over a meter across

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

Deep Water Squid Basketstar Sea Pig Sea Spider Shrimp Winged Sea Cucumber Medussa Deep Sea Smoker - 648°F Deep-sea AnemoneHydrothermal Vent

The Coral Reef Biome A Look at a Marine Biome

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.

= 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

Aquatic Ecosystems