The marine biome is considered the largest environment and one of the most important for biodiversity. In this blog, you will find an introduction to the marine environment and its different ecosystems.
What is the marine biome like?
The marine environment is the largest in the world and covers three-quarters of the Earth’s surface. The types of ecosystems found in this environment are seas, coral reefs, and estuaries, all of which are saltwater environments. The marine environment has five major oceans: the Atlantic, Pacific, Indian, Arctic, and Southern Oceans. The marine environment also includes many bays.
The marine environment supports various organisms, and healthy oceans are essential for life on Earth. Marine algae provide much oxygen and absorb much atmospheric carbon dioxide.
The average temperature of seawater is about 39 degrees Fahrenheit (4 degrees Celsius), but it can be colder or warmer depending on some criteria, such as location and depth. The coldest ocean is the Arctic Ocean, which has an average temperature of 28°F (-2.22°C).
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The ocean is divided into three vertical zones based on depth: the luminous zone, the non-luminous zone, and the subluminous zone.
The luminous zone is where light can penetrate, and most photosynthesis occurs. This zone is about 656 feet (200 m) deep.
The middle layer is the auroral or mesopelagic zone, the ocean’s “twilight zone.” Because less light reaches this zone, it appears dark blue to black.
The third layer is called the completely dark twilight zone. It is also extremely cold and has little to no life. This zone makes up about 80% of the ocean.
The deepest part of the ocean is the Mariana Trench, which is 36,200 feet (10,000 m) deep, deeper than the height of Mount Everest!
The marine environment has three main ecosystems: oceans, coral reefs, and estuaries. Each has many habitats that support different marine life and have very different characteristics.
Marine Coral Reef Ecosystems
Coral reef ecosystems are diverse and can be found worldwide, from tropical to polar regions.
Coral polyps are the animals primarily responsible for building coral reefs. Thousands of species of coral have been discovered, and they can take many forms, some forming large, colorful colonies while others are more solitary and smaller.
Coral reefs form when corals grow close to the coast. Most coral reefs are called fringing reefs because they surround the coast of a continent or island.
Corals grow slowly, so a reef takes a long time to form. The fastest-growing corals grow six inches (15 centimeters) annually, but most grow less than an inch in 12 months.
The largest coral reef is the Great Barrier Reef, located off the east coast of Australia. It began growing 20,000 years ago and now stretches 1,600 miles (2,600 km). It’s so big it can be seen from space!
Great Barrier Reef
Australia’s Great Barrier Reef is the largest coral reef in the world. Although coral reefs cover less than 2% of the ocean floor, it is estimated that about 25% of marine species depend on reefs for food and shelter. Many species also use reefs as places to raise their young.
Marine Ecosystems
The marine ecosystem is the largest ecosystem found in the marine environment. It is divided into four horizontal zones: tidal, pelagic, benthic, and bathypelagic.
The intertidal zone is where the ocean meets the land, and its appearance changes depending on its location and the time of day. The area is sometimes submerged and exposed as waves and tides move in and out.
In some areas, the intertidal zone is rocky. At the edge of the zone, the rocks are often exposed and are home to a few species of algae and mollusks. On the flooded rocks, life forms became more diverse and abundant.
In some areas, the intertidal zone is rocky. The rocks are often exposed at the edge of this zone, with only a few algae and mollusks surviving. In general, life forms become more diverse and abundant in the underwater rocks. This rocky area is home to algae and small animals, including snails, crabs, starfish, and small fish.
The lower part of the intertidal zone, which is exposed only at low tide, is home to large fish, algae, and invertebrates. Sandy shores are less diverse than rocky shores. The waves keep mud and sand moving, making it difficult for plants and algae to grow. This area is mainly home to worms, shellfish, crustaceans, crabs, and shorebirds.
The pelagic zone is farthest from land and is home to many fish species and some mammals, such as whales and dolphins.
This zone is cooler than the intertidal zone and has different temperatures at different depths due to thermal stratification and mixing of warm and cold currents. Vegetation in this area is usually composed of aquatic algae.
Below the surface is the benthic zone, which includes the seafloor. The bottom of this zone is composed of sand, silt, and dead organisms. The temperature here is very cold and decreases as the depth increases towards the abyssal zone (the deepest part of the ocean).
The benthic zone is rich in nutrients and, therefore, can support a wide variety of animals, including bacteria, fungi, starfish, sea worms, anemones, and fish. The main plant in this area is seaweed.
The abyssal zone is the deepest and usually dark because light cannot penetrate that deep. Therefore, the water here is very cold. They are also high in oxygen but low in nutrients.
Hydrothermal springs are found in the abyssal zone. These vents release large amounts of hydrogen sulfide and other minerals supporting various chemosynthetic bacteria. This, in turn, provides food for invertebrates and fish.
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Estuarine ecosystems
Estuarine ecosystems are formed when salt water from the ocean mixes with fresh water from the land. Other names for estuaries include bays, lakes, inlets, harbors, wetlands, fjords, and swamps, and they vary in size.
Estuaries are tidal, and their changes are related to mixing fresh and saltwater and the ebb and flow of the tides. Therefore, the plants and animals that live here have to adapt to cope with challenges associated with physical changes (such as the rise and fall of tides) and changes in water chemistry (such as salinity).
Despite these challenges, estuaries are one of the most productive ecosystems on Earth. It is home to various plants and animals, including fish, shellfish, crustaceans, marine worms, seaweed, algae, plankton, and mangroves.
Many animals rely on estuaries as nesting and breeding grounds. Many species of sharks use estuaries as areas for spawning. The young can use estuaries for food and shelter until they are ready to swim out to the open ocean.
The marine biome includes a variety of habitats, so it is no surprise that it is home to a wide variety of plants and animals.
The marine food chain begins with tiny phytoplankton, single-celled organisms, such as algae, that make food through photosynthesis.
Zooplankton, shrimp, and other small animals consume the phytoplankton. Next in the food chain are larger animals, including sedentary species such as corals and mollusks.
Above them are more mobile animals such as crustaceans, squids, jellyfish, eels, and mollusks. At the top of the marine food chain are predators, which include killer whales and great white sharks.
Most life forms in the marine biome exist within the first 200 meters. Less light can penetrate at greater depths, and population density drops rapidly. However, some organisms, including shellfish and marine worms, are found at greater depths.
The ocean is home to nearly 200,000 identified species. Still, since most of the world’s oceans remain unexplored, the number of organisms living in the oceans is likely in the millions.
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Climate change and pollution are two of the biggest marine environmental threats. Climate change is changing many characteristics of marine habitats through rising temperatures and acidification.
Rising temperatures affect species on multiple levels, changing their distribution and the distribution of their prey or the plants they feed on. Temperature fluctuations can also have adverse effects on reproduction and growth. Some species disappear completely, for example certain types of corals bleach rapidly as temperatures rise, eventually leading to death.
Pollution also harms marine ecosystems. Plastic is a source of pollution: 8 million tons of plastic end up in the ocean yearly. To put it in context, plastic pollution accounts for 80% of all marine debris found throughout the water. Many problems arise when species ingest or become entangled in this debris, which can result in serious injury or death.
Plastic pollution not only causes problems for marine life but also affects humans. Microplastics, invisible to the naked eye, are found in tap water, beer, salt, and all water samples collected from the ocean.
The chemicals used in the production of plastics interfere with various processes in humans and wildlife and have also been shown to be carcinogenic.
Other impacts on the marine environment include overfishing, agricultural and industrial wastewater pollution and habitat destruction.
Many people rely on the ocean for food, income, and recreation. Conservation and management plans must address these issues so that we can ensure the long-term sustainability of our practices while minimizing impacts on nature.
