Aquatic Science: Types of Aquatic Environments

Freshwater Bodies

• Tasik Chini is an example of a freshwater body in Malaysia.

Brackish-Water Bodies

• Estuaries and brackish seas are characterized by a mix of freshwater and seawater.
• The Danga Bay is an example of a brackish-water body in Malaysia.

Watersheds

• Watersheds encompass entire land areas, including rivers, streams, and lakes.
• Watersheds can be as large as entire continents.

Aquatic Environments

• Icebergs and snows can be found in polar regions.
• Estuaries, brackish seas, and mangrove swamps are characterized by mix of freshwater and seawater.
• Deep ocean currents are created by thermohaline circulation.

Properties of Seawater

• Seawater has a higher freezing point than freshwater (−1.8°C compared to 0°C).
• The main difference between seawater and freshwater is the presence of high concentrations of dissolved salts.
• Seawater has a pH level around 8.1, slightly higher than freshwater.
• Salinity is measured in units of parts per thousand (ppt).
• The proportion of salt content in all oceans is around 3.5%.

Nutrient Cycle

• Oxygen is involved in the nutrient cycle of the oceans.

Ocean Currents

• Densest water is found at the bottom of the ocean.
• Deep ocean currents are driven by changes in temperature and salinity.

Aquatic Life

• Deep-sea fish are adapted to deep-water pressure and cannot survive in the upper parts of the water column.
• Zooplankton feeds on phytoplankton.
• Nekton is characterized by its ability to move freely through the water column.
• Phytoplankton and zooplankton are both small and floating.
• Benthos obtains energy from detritus and organic matter.
• Phytoplankton appears as a green discoloration of the water due to the presence of chlorophyll.

Primary Productivity

• Phytoplankton is the primary source of Earth's oceans' primary productivity.
• High levels of nutrients and abundant plant growth characterize eutrophic marine environments.
• Eutrophic marine environments have a high level of organic matter, while oligotrophic environments have a low level.
• Algal density affects the heating of lakes.
• Fish predation helps cool lakes by controlling algal growth.
• Global warming affects lakes by increasing water temperatures and reducing oxygen levels.

Fish Behavior

• Fish schooling is a behavior that provides protection and increases foraging success.
• Anadromous fish migrate from saltwater to freshwater to breed.

Dead Zones

• Dead zones are areas where oxygen levels are too low to support most life.

Producers

• The two principal categories of producers in marine environments are phytoplankton and benthic algae.