Freshwater biomes include lakes and ponds (standing water) as well as rivers and streams (flowing water). They also include wetlands, which will be discussed later.

Humans rely on freshwater biomes to provide aquatic resources for drinking water, crop irrigation, sanitation, and industry.

various roles and human benefits are referred to as ecosystem services.

Estuaries are aquatic biomes that occur where a source of fresh water, such as a river, meets the ocean.

both fresh water and salt water are found in the same vicinity; mixing results in a diluted (brackish) saltwater.

Estuaries form protected areas where many of the young offspring of crustaceans, mollusks, and fish begin their lives.

Coral reefs are ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone of the ocean.

found within 30˚ north and south of the equator.

Other coral reef systems are fringing islands, which are directly adjacent to land, or atolls, which are circular reef systems surrounding a former landmass that is now underwater.

the ocean is categorized into different zones based on how far light reaches into the water.

All of the ocean’s open water is referred to as the pelagic realm (or zone).

benthic realm (or zone) extends along the ocean bottom from the shoreline to the deepest parts of the ocean floor.

Aquatic ecosystems are divided into marine and freshwater biomes.

As one descends into a deep body of water, there will eventually be a depth which the sunlight cannot reach. While there are some abiotic and biotic factors in a terrestrial ecosystem that might obscure light (like fog, dust, or insect swarms), usually these are not permanent features of the environment.

importance of light in aquatic biomes is central to the communities of organisms found in both freshwater and marine ecosystems.

Biomes are characterized by general climate conditions, such as average temperatures and precipitation.

the geology and quantity and quality of abiotic factors—such as sunlight, water, and soil fertility—are also unique to each biome.

hot desert ecosystems generally experience fewer than 12 cm of rain per year, and rainfall is unpredictable.

Biomes are based on general climate and biological characteristics that describe a large geographical area.

Ecosystems are more specific and found within different biomes.

are based on the specific characteristics found in a specific area and can be described, in part, using a classification of a biome.

Forming relationships with others is a necessity for social beings.

We expect reciprocity and self-disclosure in our relationships.

Physical attractiveness is usually the first thing we notice about a person.

Voluntary behavior with the intent to help other people is called prosocial behavior.

Altruism is a pure form of helping others out of empathy, which can be contrasted with egoistic motivations for helping.

Empathy is the capacity to understand another person’s perspective, to feel what he or she feels.

Altruism is people’s desire to help others even if the costs outweigh the benefits of helping.