The Three Aquatic Ecosystems

Digging deeper to find more info on aquatic ecosystems


Freshwater is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and other total dissolved solids. The term "sweet water" has been used to describe freshwater in contrast to salt water.

Freshwater Plants

Freshwater Animals



Brackish water is water that has more salty than freshwater, but not as much as saltwater. It may result from mixing of seawater with fresh water, or may occur in brackish fossil aquifers. Certain human activities can produce brackish water, in particular certain civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment. Examples of Brackish water include esturaries, mangroves, brackish seas and lakes, and brackish marshes.

Brackish Water Plants

Brackish Water Animals



Salt water is water from a sea or ocean. Seawater is denser than both fresh water because the dissolved salts add mass without contributing significantly to the volume. Seawater contains more dissolved ions than all types of freshwater. However, the ratios of solutes differ dramatically. For instance, although seawater contains about 2.8 times more bicarbonate than river water based on molarity, the percentage of bicarbonate in seawater as a ratio of all dissolved ions is far lower than in river water. Bicarbonate ions also constitute 48% of river water solutes but only 0.14% of all seawater ions. Differences like these are due to the varying residence times of seawater solutes; sodium and chlorine have very long residence times, while calcium (vital for carbonate formation) tends to precipitate much more quickly. The most abundant dissolved ions in seawater are sodium, chloride, magnesium, and calcium.

Saltwater Plants

Saltwater Animals

Cassie Holloway

3rd period