Aquatic Biomes
Introduced| English |
|---|
| aquatic/əˈkwætɪk/ |
| salinity/seɪˈlɪnɪti/ |
| freshwater/ˈfreʃwɔːtə/ |
| marine/məˈriːn/ |
| estuary/ˈestjuːəri/ |
The water worlds
- Most of Earth's surface is water, and it teems with life.
- Aquatic biomes range from a tiny pond to the vast open ocean.
- What separates them is not temperature but salt.
- The amount of salt decides which creatures can live there.
Salinity divides the waters
- Aquatic 水生的 biomes are sorted mainly by their salinity 盐度 — how salty the water is.
- Freshwater 淡水 biomes, like lakes and rivers, have very little salt.
- Marine 海洋的 biomes, like the ocean and reefs, are salty.
- Most organisms are adapted to one or the other, not both.
Aquatic biomes are mainly divided by their salinity, which means…
Salinity is the amount of dissolved salt; it separates freshwater from marine biomes.
Where waters mix
- An estuary 河口 is where a river meets the sea.
- Its water is brackish — a mix of fresh and salt.
- Estuaries are among the richest, most productive places on Earth.
- They act as nurseries for fish and feeding grounds for birds.
Which is a marine biome?
A coral reef is marine (salt water); lakes, rivers and ponds are freshwater.
The brackish place where a river meets the sea is called an ____.
An estuary is where fresh and salt water mix; it is very rich in life.
Sunlight and life
- Sunlight only reaches the shallow, upper layer of water.
- Producers like algae need that light to photosynthesise.
- So most aquatic life is packed into the sunlit surface waters.
- The deep, dark ocean holds far fewer living things.
Freshwater, marine, or in-between?
Sort each aquatic biome by its salinity - fresh, salty, or the brackish mix where they meet.
Most aquatic life is found in shallow, sunlit water where photosynthesis can happen.
Sunlight only reaches shallow water, so the sunlit zone supports the most producers and life.
Select all true statements about aquatic biomes.
Many aquatic biomes are marine (salt water), not freshwater. The other three are correct.
Do not sort aquatic biomes by temperature — sort them by salinity. Fresh versus salt water is the key divide, because most organisms can survive in only one. A fish from a river would die in the sea, and vice versa.
An estuary at work:
- A river carries fresh water and nutrients down to the coast.
- Where it meets the salty sea, the two mix into brackish water.
- The rich mix of nutrients feeds huge amounts of life — which is why estuaries are vital nurseries for fish.
Aquatic biomes are divided mainly by salinity: freshwater (lakes, rivers) has little salt, marine (ocean, reefs) is salty, and an estuary is the brackish mix where a river meets the sea. Because sunlight reaches only shallow water, most life is found near the surface.