How many of the ten typical marine ecosystems do you know?

Students who have been paying attention to us should be impressed by this sentence:

"Mangroves, coral reefs and seagrass beds are three typical marine natural ecosystems."

However, typical marine ecosystems are not limited to mangroves, coral reefs and seagrass beds. There are also seven other categories, including oyster reefs, seaweed beds, salt marshes, muddy coasts, sandy coasts, estuaries and bays, for a total of 10 categories.

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Let's briefly introduce

Not yet on stage

7 types of typical marine life systems!

(Highlight the key points)

Here is a piece of knowledge:

What are marine ecosystems?

To understand this question, we must first know what an ecosystem is?

The ecosystem is like an automatic machine that does not require human control. It has its own structure and functions. In this huge machine, there is the circulation of matter and the flow of energy, which can operate naturally.

In 1935, British ecologist Arthur George Tansley, influenced by Danish botanist Eugenius Warming, clearly put forward the concept of ecosystem.

Arthur George Tansley

He argues: "The fundamental concept is that of a whole system (in the physical sense), including the complex composition of organisms and the complex composition of physical elements we call the environment, together forming a physical system...We can call these ecosystems, and these ecosystems come in the greatest variety and size. They form one type of the great variety of physical systems in the universe, ranging from the universe as a whole to the atomic scale."

Very good. At this point, some students may not understand.

Therefore, today we simplify the concept of ecosystem to:

A unified whole formed by the interaction between a biological community and its inorganic environment (People's Education Press high school biology textbook).

It can be deduced that the marine ecosystem is a diverse natural system in the ocean composed of the interaction between biological communities and their environment (Research on the Diversity of Marine Ecosystems, Wang Youshao, 2011). For the marine ecosystem, the interconnected animals, plants and microorganisms constitute the biological community, and the marine environment includes sunlight, air, seawater, etc. It can be as small as a clump of seaweed or as large as a bay.

Let’s get to the point——

1. Oyster Reef

Speaking of oysters, I believe many people have tasted their deliciousness. This ancient creature has lived on Earth for about 15 million years. They like to live a "settled and happy" life very much. Once they find a place to settle down, they will hardly move for the rest of their lives. This filter-feeding shellfish feeds on phytoplankton in the water.

Oyster reef is a kind of biological reef formed by a large number of oysters growing on the surface of hard substrate. It is widely distributed in temperate and subtropical estuaries and coastal areas. In addition to providing food for humans, it also has many important ecological functions and service values, including purifying water, providing habitats, and preventing shoreline erosion (Jackson et al., 2001; Quan Weimin et al., 2006).

Whenever extreme weather such as hurricanes come, the layers of oyster reefs under the water become an important barrier to protect the coastal zone, which can effectively reduce the impact of waves on the coastal zone. Of course, oyster reefs are not only useful when disasters occur, but they can also provide habitats for a variety of organisms and improve biodiversity on weekdays.

Tips:

Tianjin Binhai National Marine Park, formerly the Tianjin Dashendang Oyster Reef National Marine Special Protection Area, is the only oyster habitat in the Bohai Bay. The existing oyster reefs in the area are the highest modern living oyster reefs discovered in northern my country to date.

2. Seaweed Field

Although seaweed and seaweed are both floating in the sea water, smart students must be able to distinguish them clearly.

Seaweed is generally considered to be a simple plant, without true differentiation of roots, stems, and leaves, without flowers, fruits, or seeds.

In comparison, seaweed is much more advanced. It is the only type of higher angiosperm on Earth that can live entirely in seawater. It has differentiated roots, stems, and leaves, and can bloom and produce seeds.

Seaweed fields refer to a typical nearshore marine ecosystem composed of large benthic algae and other marine biological communities in the lower intertidal zone and shallow hard bottom area within 30m of the subtidal zone. They are widely distributed in cold temperate zones and some tropical and subtropical coasts. The large algae that form seaweed fields mainly include Sargassum, Macroalgae, Laminaria, Undaria, Laminaria and Staghorn algae (Technical Guidelines for Marine Ecological Restoration (Trial), Ministry of Natural Resources, 2021).

Seaweed fields are mostly composed of 1-2 large brown algae communities, and are named after the dominant seaweed. In other words, whoever has the most power will have the name of the territory. For example, red algae communities constitute the support system of red algae forests, giant algae communities constitute the support system of giant algae fields, and sargassum communities constitute the support system of sargassum fields.

Seaweed beds are one of the most biodiverse ecosystems in the Earth's biosphere and play an important role in maintaining the system's productivity, stability, and resource flow.

3. Salt marsh

Salt marsh refers to tidal flats in coastal or island edge areas covered with herbaceous plants that are affected by periodic tidal movements (Technical Guidelines for Marine Ecological Restoration (Trial), Ministry of Natural Resources, 2021). It is widely found in mid- and high-latitude regions around the world, and in low-latitude regions it is often replaced by its tropical analogue, mangroves, or forms a mangrove-coastal salt marsh ecotone.

Salt marshes at low tide, mean low tide, high tide and highest tide

Coastal salt marsh is a wetland ecosystem located in the transitional area between the marine and terrestrial ecosystems. It is regularly or irregularly flooded by ocean tides and has a high coverage of herbaceous or low shrub vegetation (Distribution and Diversity of Coastal Salt Marshes and Their Plant Communities, He Qiang et al., 2010).

In my country, salt marshes are widely distributed in the northern coastal areas north of Hangzhou Bay, including the Yangtze River Delta, the Yellow Sea coast and the Bohai Sea coast from south to north. At present, relatively intact salt marshes exist in nature reserves in areas such as the Yangtze River Estuary, the Yellow River Estuary and the Shuangtaizi River Estuary.

Coastal salt marshes are the main primary producers in intertidal ecosystems and have important functions such as purifying seawater, promoting siltation and protecting banks, resisting storm surges, and providing suitable habitats for wildlife. In recent years, due to their high primary productivity and slow organic matter degradation rate, they have become an effective blue carbon sink to mitigate global warming, attracting keen attention worldwide.

4. Muddy Coast & Sandy Coast

The topography of the coastal zone is the result of the interaction between land and sea. According to its material composition, it can be divided into bedrock coast, gravel coast and mud coast.

In terms of origin, muddy coasts are formed by the sedimentation of silt carried by plain rivers. The sediment particles are relatively fine, the coast is wide, the slope is small, and the coastline is straight ("South China Sea Geography", Bi Hua et al., 2011). Most silt beaches have fertile soil and can be used for tidal flat aquaculture. The large lowland mud beaches on the coast are convenient for the introduction of seawater and difficult for brine to seep in, making them a good place to develop salt fields. Gravel coasts are formed by the accumulation of gravel and sand. The sediment particles are relatively coarse, and the beach is wide and flat ("South China Sea Geography", Bi Hua et al., 2011). Gravel coasts are mostly gentle in slope and clear in water, and can be developed into seaside bathing beaches, which can best meet people's needs to get close to the sea.

In terms of distribution, China's muddy coast is 4,000 kilometers long, accounting for about 23% of the land coastline, distributed in the top of Liaodong Bay, the west coast of Bohai Bay, the south coast of Laizhou Bay, northern Jiangsu and the Yangtze River Estuary. The rest are gravel coasts, formed in areas with abundant supply of debris and strong wave action, and are distributed from south to north. The coast of central and southern Jiangsu is a world-famous (silt) muddy coast, and it still retains a long and continuous natural muddy coastline with a total length of more than 300 kilometers.

5. Estuary

An estuary is a semi-enclosed coastal water area that extends inland to the upper limit of the influence of tidal water level changes, with one or more channels connecting to the open sea or other salty coastal waters (Technical Guidelines for Marine Ecological Restoration (Trial Implementation), Ministry of Natural Resources, 2021).

The interaction between land and sea gives estuarine ecosystems unique ecological and environmental characteristics. An important feature that distinguishes them from other ecosystems is the mixing of runoff and tides. The biological communities in the water are in a transitional state between terrestrial and marine ecosystems.

How complex is it?

It integrates freshwater ecosystems, seawater ecosystems, mixed fresh and brackish water ecosystems, tidal flat wetland ecosystems, estuarine islands and sandbar wetland ecosystems, and is an important gathering and dispersion area where the four major spheres of the earth converge, and energy and logistics flow.

How important is it?

As a highly productive ecosystem, it can provide humans with a large amount of food, raw materials and water resources; maintain biodiversity and rare species resources; regulate material circulation and maintain regional ecological balance; purify the environment; regulate the atmosphere; and build land...

How disturbing is it?

The special geographical location enables humans to frequently move around in the estuary area, carrying out transportation, trade, aquatic activities, etc., which affects the ecology of the estuary; and the river water flowing through people’s living areas gathers a large amount of land-based pollutants, threatening the survival and reproduction of estuary organisms.

6. The Bay

A bay is a sea area surrounded by land and with an area no less than a semicircle with the width of the mouth as its diameter (Technical Guidelines for Marine Ecological Restoration (Trial Implementation), Ministry of Natural Resources, 2021).

The more famous bays in my country include Bohai Bay, Laizhou Bay, Liaodong Bay, Jiaozhou Bay, Hangzhou Bay, Beibu Gulf, etc.

Long ago, people settled near the bay to obtain fish and other biological resources in the bay. Later, people developed trade, built ports, and carried out marine aquaculture activities here. Therefore, the bay is the area in the ocean that is most affected by human activities and is also one of the core areas for the development of the marine economy. The size of the bay represents the amount of resources, including spatial resources, landscape resources, biological resources, etc.

Why are the Yangtze River Delta and the Pearl River Delta the key areas for economic development? To a large extent, it is because they are connected to the bay where they are located, Hangzhou Bay. The water area of ​​Hangzhou Bay reaches more than 3,000 square kilometers. The combination of vast land and large bay naturally creates a superior Greater Bay Area environment.

On the other hand, the impact of human activities on the Gulf ecosystem is enormous, and its resilience is constantly being compromised under multiple stresses, often exacerbated by climate change.

How important is the health of the Gulf ecosystem?

To put it bluntly, the degradation of the bay's ecosystem will have a significant negative impact on the bay's economic development. This is one of the reasons why my country has always attached great importance to the improvement of the bay's environment and ecological restoration.

The above is a brief introduction to the ten typical marine ecosystems in this issue. Take a break and don’t go away. We will continue to update detailed knowledge about them. Stay tuned for the next content!

Written by: Yu Tingwei

Art Editor: Shi Yuqing

Review: Xiang Siyuan Jinxi

Source: Ocean World Communications