Of the entire land surface, 70.8% (equivalent to 362 million km2), corresponds to oceans and seas. These marine systems are very dynamic environments and they are connected to each other by networks of surface currents. The variation of temperatures and salinity levels in these environments defines different zones occupied by different organisms.
In this AgroCorrn article we talk about what are the saltwater aquatic ecosystems and their characteristics .
Seas and oceans are the main saltwater ecosystems
The oceans are large masses of salty water that separate the continents. There are three major oceans (Atlantic, Indian and Pacific) and two smaller (Arctic and Antarctic). While the seas are also masses of salt water, but smaller than the oceans. There are many seas around the world such as the Caribbean Sea, the North Sea or the Ross Sea.
In this type of environment, it is aspects such as tides, waves, cold and warm currents, salinity, temperature or light intensity, which determine life. These factors influence the availability of nutrients, behavior, development and interrelationships between living beings.
Several areas within these ecosystems can be differentiated according to different criteria such as proximity to the coasts, depth or depth according to the presence of light. Taking into account the depth according to the light , we differentiate:
Photic zone of seas and oceans
It is an illuminated oceanic area and covers up to 200 meters deep. Divided in turn into:
- Euphotic region: most illuminated area. Photosynthetic organisms inhabit this area of this type of saltwater aquatic ecosystems .
- Dysphotic region : less illuminated region of the photic zone. In this region live certain algae that can carry out photosynthesis.
Aphotic zone of the seas and oceans
Dark area located at a depth greater than 200 meters. In turn, it is divided into:
- Bathyal region: an area between 200 and 4,000 meters deep. In this area inhabits what we know as marine nekton, which includes fish, squid, sea turtles, seals or whales.
- Abyssal region: located between 4,000 and 6,000 meters deep. In this region the light is non-existent. In this area inhabits what we know as marine benthos, formed by starfish, sponges and other animals. It is a very rich region in terms of species biodeversity, with organisms that are not found in any other geographic region on the planet.
- Hadal zone: located between 6,000 and more than 10,000 meters deep. This region includes the seabed, the great ocean trenches and the hydrothermal vents. In this region, we can find some of the most extreme microorganisms on the planet.
In this other article we will tell you all about the biodiversity of the oceans .
Mangroves, marine and coastal ecosystems
Mangroves are marine-coastal ecosystems that we can find in the tropics and subtropics of the planet. We can find mangroves, for example, on the coasts of Latin America, from Mexico to Peru. In certain areas of the planet, they are also called salty forests , referring to the fact that it is an environment dominated by halophilic species (plant species with a preference for salty environments).
Mangroves are very important ecosystems for the maintenance of the natural balance wherever they are present. These tasks include:
- They help control floods.
- They help stabilize the shoreline and control erosion.
- They retain sediments and toxic substances.
- They are a source of organic matter.
In this other AgroCorrn article you will be able to learn more about what a mangrove is and its characteristics .
Coral reefs are very special saltwater ecosystems
These types of saltwater aquatic ecosystems develop in tropical waters such as the Pacific and Indian Oceans and the Caribbean Sea. They are made up of coral skeletons that grow year after year due to the deposit of new structures. Due to their location, they serve as important protective barriers for mangroves and seagrass beds.
These structures are constantly exposed to the beating of the waves. One of the organisms most responsible for the growth of this type of coral is a species of red algae, the calcareous algae. In this way, a symbiotic relationship is established, where corals provide protection and algae provide nutrients through photosynthesis. Two types of coral are distinguished : soft corals and hard or stony corals.
For the growth of a coral reef , it is essential that the water temperature is between 20ºC and 28ºC, something that occurs in tropical waters. These structures grow only in the photic zone, where sunlight offers them the necessary energy. Because of this, reefs grow best in crystal clear waters.
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