Aquatic Biomes

Factors affecting Aquatic Biomes

Water Depth, Temperature, Current, Nutrient Availability, ph, Salinity and Dissolved Oxygen

Photic Zone

• sunlit region near the surface in which photosynthesis can occur

• Photosynthetic organisms lives in this zone

Aphotic Zone

• depths greater than 200 m where light can not penetrate

• Most organisms that live here are larger animals like sharks, squids etc.

Benthic Zone

• Bottom zone like the ocean floor or bottom of a lake

• Benthos are the organisms living in this zone

Euphotic Zone

• Sunlit zone where algae and phytoplankton are abundant

• Most life in the ocean is found in this layer due to abundant food source

Disphotic Zone

• Barely lit ocean layer (Twilight zone)

• This receives faint, and filtered sunlight during daytime which is not enough for photosynthesis to take place

• Food is not abundant

Aphotic Zone

• deepest layer AKA “Midnight Zone” where the temperature is low and pressure is high

• Bioluminescent organisms are thriving in this layer

Temperature

• often varies with depth.

• The deepest parts of lakes and oceans are often colder than surface waters

Current

can dramatically affect water temperature because they can carry water that is significantly warmer or cooler than would be typical for any given latitude, depth or distance from shore

oxygen, nitrogen, potassium and phosphorus.

Organisms need certain substances to live such as

low pH

decreases coral’s ability to form structure

Freshwater intrusion in clam beds

can stress the organism leading to disease and mortality

Low DO influenced by eutrophication and low flushing rates

causes massive fish kills

Freshwater

Ice sheets, Ice caps, Glaciers, Bogs, Ponds, Lakes, Rivers, Streams, Groundwater (aquifier and underground streams)

Marine

Coral reefs, Estuaries, Open ocean, Mangrove, Swamps, Seagrass meadows

Types of Freshwater Habitats

Lentic and Lotic

Lentic Habitat

Calm freshwater habitat or standing water

Lotic Habitat

Washed or running water

Epilimnion

Surface layer of water constantly mixed by wind and waves and is warmed by the sun, from late spring to fall

Metalimnion

• Barrier that prevents mixing and heat exchange between epilimnion and hypolimnion

• middle layer characterized by a steep gradient in temperature and demarcated by the regions above (Epilimnion) and below (Hypolimnion)

Thermal Stratification

• Seasonal phenomenon that occurs from late spring to late fall in temperate regions. In the summer, the upper layer of water in the Great Lakes (Epilimnion) is warmed significantly by the sun

• Cooler water separates, forming 2 additional layers (metalimnion and Hypolimnion) that are heavier and denser

Oligotrophic

• Lakes are generally deep and clear with little aquatic plant growth.

• maintain sufficient DO in the cool, deep bottom waters during late summer to support cold water fish such as trout and whitefish

Mesotrophic

Lakes that fall between two extremes of oligotrophic and eutrophic are called _________

Eutrophic

• have poor quality, and support abundant aquatic plant growth

• In these lakes, the cool bottom waters usually contain little or no DO. Therefore these lakes can only support warm water fish such as bass and pike

Streams

Small channels of freshwater that contains flowing water. They can be both natural and artificial

Perennial Streams

Flow all year long

Seasonal streams

only seen at certain times of year, usually in wet season or as a result of snow or ice melting

Continuous Streams

Flow without stopping until they reach an endpoint or another body of water

Interrupted Streams

have breaks or different reaches depending on seasonality, barriers, and other factors

Rivers

ribbon-like body of water that flows downhill due to the force of gravity. Larger stream

Wetlands

area of land that is covered by water or saturated with water. It is entirely covered by water atleast part of the year. Transition zone

Swamp, Marshes and Bogs

Three Major Kinds of Wetlands

Swamps

often form on flat land around lakes or streams, where the water table is high and runoff is slow.

Marshes

dominated by grasses and aquatic plants. often develop around lakes and streams

warm

Swamps and marshes are generally found in _______ climates.

Bogs

develop in areas where the water table, or the upper surface of underground water, is high.

Commonly found in cold / artic areas

Kettle lakes

= Bogs often begin in glacial depressions called ______, which are deeper than praire potholes

Estuaries

• Area where freshwater rivers or streams meet the ocean

• among the most productive ecosystems in the world. Many animals rely on this for food, places to breed, and migration stopovers

Drowned River Valley, Bar-built, tectonic and fjords

The four major types of estuaries classified by geology:

Headwater

• comes from rainfall or snowmelt in ocean or bubbles up from groundwater or form at edge of a lake or pond

• Swift, shallow, cold, O2 rich

• Bottom: Minimal accumulation

• Fast moving water inhibits phytoplanktons

Transfer Zone

• middle range of stream

• receives sediment from upstream

• Gradient decreases

• river widens as small streams merge

Depositional Zone

• Gradient flattens from sediment build-up

• river widens and meanders toward its mouth

• Current slows caused by gradient decrease

• More sedimentation

• Phytoplanktons can be suspended in slow-moving water

Coral Reefs

• Ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone of the ocean

• Foundation for marine species

• Grow in shallow clear water

Hermatypic Corals

• Possess zooxanthellae

• Reef builders

Ahermatypic Corals

• No zooxanthellae

• Rely on tentacular feeding

• Can live in aphotic zone

Types of Reef

Fringing, Barrier, Atoll, Drowned

Fringe Reef

• Growth on reefs often limited by tidal actions

Atoll reefs

Volcanic leftover

Environmental factors affecting corals

Water Motion. Depth, Sedimentation, Salinity, Temperature, Tidal Fluctuations, Nutrients

Open Ocean

• Largest marine biome with relatively uniform chemical composition

Continental Margin

Submerged area of continents.

Continental Shelf

flat gradually sloping seafloor) from shoreline to ~ 200m;

Shelf Break

End of shelf is called

Continental Slope

steeply sloping seafloor) seaward of shelf break

Continental Rise

(Moderately sloping seafloor) seaward of slope

Pelagic Zone

Water is referred to as

Nekton

Organisms that swim through the water column

Benthic Zone

The ocean floor is referred to as

Benthos

Organisms that lives in Benthic Zone

Saltwater Swamp

• regions dominated with trees, whereas salt marshes are covered with grasses.

• amphibians, reptiles, some migratory birds, shellfishes, reptiles, some migratory birds etc.

Saltwater Marsh

• coastal wetlands that are flooded and drained by saltwater brought by tides.

• the soil are composed of mud and peat

Peat

• made of decomposing plant matter that is often several feet thick.

• waterlogged, root-filled and very spongy

Mangroves

• Group of trees and shrubs that live in the coastal intertidal zone

• stabilize the coastline, reducing erosion from storm surges, currents, waves and tides.

The intricate root system of mangrove

makes these forests attractive and other organisms seeking food shelter from predators