Question

1. what is the average salinity of seawater?
2. name the layer of the ocean that is warmed by the sun.
3. what causes ocean tides?
4. define ocean currents.
5. what happens to corals when ocean temperatures rise too much?
6. how does salinity affect the density of seawater?
7. what is the primary effect of ocean acidification on marine organisms?
8. what two factors drive ocean circulation?
9. describe what a thermocline is in simple terms.
10. why are coral reefs important to marine ecosystems?

Explanation:

1. The average salinity of seawater is about 3.5% or 35 parts per thousand. This is due to the presence of various dissolved salts like sodium chloride.
2. The sun - warmed layer of the ocean is the epipelagic zone or the photic zone. It receives sunlight for photosynthesis.
3. Ocean tides are caused by the gravitational pull of the moon and the sun on the Earth's oceans.
4. Ocean currents are the continuous, directed movement of seawater. They can be surface - or deep - water currents driven by factors like wind, temperature, and salinity.
5. When ocean temperatures rise too much, corals expel the symbiotic algae (zooxanthellae) living in their tissues, a process called coral bleaching.
6. An increase in salinity increases the density of seawater. This is because more dissolved salts add mass to a given volume of water.
7. The primary effect of ocean acidification on marine organisms is the interference with the formation of calcium - carbonate shells and skeletons, as the more acidic water makes it harder for them to extract the necessary carbonate ions.
8. The two main factors driving ocean circulation are wind and differences in water density (thermohaline circulation), which is related to temperature and salinity.
9. A thermocline is a layer in the ocean where there is a rapid change in temperature with depth. The upper layer is warmer and the lower layer is colder.
10. Coral reefs are important to marine ecosystems as they provide habitat for a vast number of marine species, protect coastlines from erosion, and are a source of food and income for many human communities.

Answer:

1. About 3.5% or 35 parts per thousand.
2. Epipelagic zone/Photic zone.
3. Gravitational pull of the moon and the sun.
4. Continuous, directed movement of seawater.
5. Coral bleaching (expulsion of zooxanthellae).
6. Increase in salinity increases density.
7. Interference with calcium - carbonate shell/skeleton formation.
8. Wind and differences in water density (thermohaline circulation).
9. Layer with rapid temperature change with depth.
10. Provide habitat, protect coastlines, source of food and income.