Aquatic Biomes: Freshwater

What are the factors affecting aquatic ecosystems?

• water depth

• Temperature

• Current

• Nutrient availability

• pH, Salinity and dissolved oxygen

What are the components of water depth?

• photic zone

• Aphotic zone

• Benthic zone

• the sunlit region near the surface in which photosynthesis can occur

• Photosynthetic organisms live in this zone

Photic zone

• at depths greater than 200 m where light cannot penetrate

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

Aphotic zone

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

• Benthos are organisms living in this zone

Benthic zone

Water depth (ocean) zones

• Euphotic zone

• Disphotic zone

• Aphotic zone

• the sunlit zone where algae and phytoplankton are abundant

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

Euphotic 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

Disphotic zone

• the deepest layer also known as midnight zone where temperature is low and pressure is high

• Bioluminescent organisms are thriving in this layer

Aphotic zone

Temperature in aquatic habitats also often varies with?

• temperature in aquatic habitats also often varies with depth

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

• 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

Currents

Organisms need certain substances to live such as?

• such as oxygen, nitrogen, potassium, and phosphorus

• The type of availability of these dissolved substances vary within and between bodies of water, greatly affecting the types of organisms that can survive there

Why is pH an issue with corals and coral reefs?

pH is now an issue with corals and coral reefs as lower pH decreases coral’s ability to form structure

• Freshwater intrusion in clam beds can stress the organisms leading to disease and mortality

• Low DO influenced by eutrophication and low flushing rates have caused massive fish kills

Coral reefs could be in an irreversible decline by 2040 due to?

Ocean acidification

What are the aquatic ecosystems

• freshwater

• Marine

What are the components of freshwater

• ice sheets

• Ice caps

• Glaciers

• Bogs

• Ponds

• Lakes

• Rivers

• Streams

• Groundwater (aquifer and underground streams)

What are the of marine ecosystems

• coral reefs

• Estuaries

• Open ocean

• Mangrove

• Swamps

• Seagrass meadows

What are the types of freshwater habitat

• lentic habitat

• lotic habitat

• calm freshwater habitat or standing water

Lentic habitat

Washed or the running water

Lotic habitat

• large and open

• Deeper with photic and aphotic zones

• Sunlight doesn’t reach the bottom, temperature is not uniform

Freshwater ecosystems: Lakes

• small and enfolded

• Shallow, photic zone only

• Sunlight reaches bottom temperature is uniform

Freshwater ecosystems: pond

• The surface layer of water that is constantly mixed by wind and waves and is warmed by the sun, from late spring to late fall

Epilimnion

The middle layer characterized by a steep gradient in temperature and demarcated by the regions above (epilimnion) and below (hypolimnion)

Metalimnion

What is the function of Metalimnion?

The Metalimnion is the barrier that prevents mixing and heat exchange between the epilimnion and hypolimnion

The deepest layer of uniformly cold water that does not mix with the upper layers and has low circulation. The colder water within the hypolimnion is at its maximum density at a temperature of 39.2 F (4C)

Hypolimnion

Is a seasonal phenomenon that occurs from late spring to late fall in temperate regions.

Thermal stratification

• in the summer, the upper layer of water in the Great Lakes (epilimnion) is warmed significantly by the sun. Cooler water separates, forming two additional layers (Metalimnion and hypolimnion) that are heavier or denser. During the winter, there is no stratification as the lake cools, and the overall temperature of the lake is more uniform

What are the lake tropic classifications?

• oligotrophic lakes

• Eutrophication lakes

are generally deep and clear with little aquatic plant growth. These lakes maintain sufficient dissolved oxygen in the cool, deep bottom waters during late summer to support cold water fish such as trout and whitefish

Oligotrophic lakes

Lakes that fall between the two extremes of oligotrophic and eutrophication are called?

Mesotrophic lakes

Lakes have poor clarity, and support abundant aquatic plant growth. In deep eutrophication lakes, the cool bottom waters usually contain little or no dissolved oxygen. Therefore, these lakes can only support warm water fish such as bass and pike

Eutrophication lakes

What are characteristics of Oligotrophic lake?

• low nutrient levels

• Good light penetration

• High dissolved oxygen

• Deep waters

• Low algal growth

• Small mouth bass, lake trout, pike, sturgeon, whitefish

What are the characteristics of eutrophication lake

• high nutrient levels

• Poor light penetration

• Low dissolved oxygen

• Shallow waters

• High algal growth

• Carp, bullhead, catfish

Oligotrophic

• clear water, low productivity

• Very desirable fishery of large game fish

Mesotrophic

• increased production

• Accumulated organic matter

• Occasional algal bloom

• Good fishery

Eutrophic

• very productive

• May experience oxygen depletion

• Rough fish common

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

Streams

flow all year long while seasonal streams are only seen at certain times of year, usually in wet season or as a result of snow or ice melting

Perennial streams

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

continuous streams

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

Interrupted steams

a ribbon-like body of water that flows downhill due to the force of gravity. This is a larger stream

Rivers

mountain headwater streams flow swiftly down steep slopes and cut a deep V-shaped valley. Rapids and waterfalls are common

Zone 1: Headwaters

low elevation streams merge and flow down gentler slopes. The valley broadens and the river begins to meander

Zone 2: Transfer zone

• at even lower elevation a river wanders and meanders slowly across a broad, nearly flat valley

• At its mouth it may divide into many separate channels as it flows across a delta built up of riverborne sediment and into the sea

Zone 3: Depositional Zone

an area of land that is covered by water or saturated with water. It is entirely covered by water at least part of the year. This is a transition zone

wetlands

what are the three major kinds of wetlands?

swamps, marshes and bogs

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

swamps

freshwater marshes are dominated by grasses and aquatic plants. These marshes often develop around lakes and streams

Marshes

swamps and marshes are generally found where?

swamps and marshes are generally found in warm climates

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

• They often begin in glacial depression called kettle lakes, which are deeper than prairie potholes. this commonly is found in cold or even artic areas in north america, europe and asia

bogs

• this is an area where freshwater river or streams meet in the ocean

• the salty ocean mixes with a freshwater river resulting in BRACKISH WATER

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

Estuaries

what are the four major types of estuaries?

The four major types of estuaries classified by their geology are:

• drowned river valley

• bar-built tectonic

• fjords