Oceans Ecology

Ocean Ecology

The Earth's oceans cover over 70% of its surface, playing a vital role in the global ecosystem.

Ocean ecology, a scientific discipline, delves into the intricate relationships and processes within these vast aquatic realms. It studies how marine organisms interact with their environment and the complex ecological dynamics shaping marine ecosystems, from surface waters to deep zones.

Ocean ecology encompasses fields like marine biology, oceanography, marine chemistry, and marine geology, collectively aiming to decipher the workings of ocean life. The oceans significantly influence Earth's climate, weather patterns, and support diverse, often undiscovered life forms. Ocean ecology now holds heightened importance in addressing modern challenges like climate change, overfishing, pollution, and habitat loss.

Oceans on the Earth
The oceans cover approximately 71% of the Earth's surface and play an important role in the planet's ecosystem and climate regulation. 

On Earth, there are five major oceans:

  • Pacific Ocean: It is the world's largest and deepest ocean, stretching from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded on the east by Asia, Australia, North and South America. 

  • The Atlantic Ocean, the world's second-largest ocean, is situated between Europe and Africa to the east and the Americas to the west. It stretches all the way from the Southern Ocean in the south to the Arctic Ocean in the north.

  • Indian Ocean: This ocean has coastlines on Africa, Asia, Australia, and the Indian subcontinent. The third-largest ocean is the Southern Ocean, which connects to the Atlantic Ocean.

  • Southern Ocean: It is sometimes thought of as the southernmost extension of the Atlantic, Pacific, and Indian Oceans because it surrounds Antarctica. It is distinguished by the chilly waters and distinctive marine ecosystems.

  • Arctic Ocean: It is situated near the North Pole and is the shallowest and smallest ocean in the world. The majority of it is covered in ice. Through the Greenland Sea and Norwegian Sea, it is connected to the Atlantic Ocean.

The Oceanic Cycle

The oceanic cycle, also known as the oceanic circulation or the global conveyor belt, refers to the continuous movement of ocean water around the Earth. It's a vital part of the Earth's climate system, playing a crucial role in distributing heat, nutrients, and energy across the planet.

Here's how the oceanic cycle works:

1. Surface Currents: Surface currents are like rivers of ocean water flowing across the surface. These currents are primarily driven by winds, the Earth's rotation, and differences in temperature and salinity. For instance, warm currents flow from the equator towards the poles, and cold currents move from the poles towards the equator.

2. Deep Ocean Currents: As surface currents move, they gradually transfer heat from the equator to the poles, helping regulate global temperatures. Once the surface currents reach the colder regions, they become denser due to cooling. This denser, colder water sinks and forms deep ocean currents. These currents can take centuries to circulate the entire ocean.

3. Thermohaline Circulation: The movement of ocean water due to differences in temperature (thermo) and salinity (haline) is known as thermohaline circulation. It's like a conveyor belt that carries warm surface water to colder depths and brings cold, dense water back up to the surface in other areas.

4. Impact on Climate: The oceanic cycle has a significant impact on the Earth's climate. Warm ocean currents transport heat from the equator to higher latitudes, influencing regional climates. Cold currents have a cooling effect on nearby land areas. Additionally, the ocean's ability to absorb and store heat helps moderate temperature extremes on land.

5. Nutrient Distribution: Ocean currents also play a vital role in distributing nutrients. As surface currents move, they bring nutrients from deeper layers to the surface, where they support marine life. Upwelling, which is the rising of cold, nutrient-rich water from the deep ocean to the surface, is a crucial process for marine ecosystems.

6.Effect on Marine Life: The oceanic cycle affects marine life by shaping the distribution of species and the availability of food. Nutrient-rich currents support productive fisheries, while changes in currents can impact the migration patterns of marine animals.

Diversity of Oceans

The oceans are home to an incredible diversity of flora and fauna, collectively forming some of the most complex and vibrant ecosystems on Earth.

Flora (Plants):

  • Phytoplankton: These are tiny algae that float in the ocean's upper layers. They serve as the foundation of the marine food web and produce a sizable portion of the oxygen on Earth through photosynthesis. 

  • Seaweeds and Algae: Many marine organisms rely on larger forms of marine algae, such as kelp and other types of seaweeds, for habitat and food.They also help coastal ecosystems.

Fauna (Animals):

  • Fish: Oceans are home to a diverse range of fish species, from small anchovies to large predators like sharks and tuna.  

  • Coral reefs are among the most biologically diverse and alive marine ecosystems. Numerous species of fish, invertebrates, and other marine organisms find habitat on coral reefs.

  • Marine Mammals: Oceans all over the world are home to whales, dolphins, seals, sea lions, and other marine mammals. They are essential to preserving the harmony of marine ecosystems.

  • Invertebrates: A variety of invertebrates, including mollusks (such as clams, mussels, and squid), crustaceans (such as crabs and lobsters), and echinoderms (such as starfish and sea urchins), can be found in the ocean.

  • Throughout the oceans, you can find jellyfish and comb jellies, which have a variety of functions in the marine food chain.

  • Deep-Sea Creatures: Anglerfish, giant squid, and hydrothermal vent communities are just a few of the strange and unusual organisms that can be found in the deep ocean.

  • Sharks and rays: By controlling prey populations, these apex predators are crucial for preserving the wellbeing of marine ecosystems. They come in a variety of sizes and behave in different ways.

  • Marine Birds: Fish and other marine organisms are the main sources of food for seabirds like albatrosses, penguins, and gulls, which are dependent on the oceans for survival.

  • Turtles: Oceans all over the world are home to marine turtles like the loggerhead and green sea turtles. Both coral reefs and seagrass beds depend on them for continued health. 

Changing Colour of Oceans : a concern

In the News?

A recent study found that the colour of Earth's oceans has changed significantly over the past 20 years, most likely due to increase in phytoplankton and marine life.

Key Takeaways of the Study

  • Ocean colour changes do not directly affect marine life. 
  • The changing productivity of ecosystem can affect the amount of carbon the ocean stores and the amount of food supply there is for fisheries.

What makes the oceans colourful in the first place?

The oceans' appearance of being blue or navy blue in most parts of the world is not accidental. According to a NASA report, this happens as a result of "the absorption and scattering of light." Longer wavelength colours like red, yellow, and green are absorbed by the water molecules when sunlight strikes deep, clear water, while shorter wavelength colours like blue and violet are reflected back.

However, if the water is not clear or deep, an ocean may appear to be a different colour. For example, along Argentina's coastline, where major rivers meet the Atlantic Ocean, the ocean has a brown tint due to dead leaves and sediments emitted by the rivers

Due to the presence of phytoplankton on the water's upper surface, the oceans in other parts of the world appear green (The green pigment chlorophyll is found in phytoplankton, which are microscopic marine algae). So, depending on the type and density of the phytoplankton population, the ocean over regions with high concentrations of phytoplankton will appear in various shades ranging from blue-green to green. 

Why is the colour of the oceans changing?

According to the research, colour changes are observed in areas where oceans are becoming more stratified. 

  • Due to climate change, the amount of carbon dioxide that oceans can absorb from the atmosphere has decreased, and the oxygen absorbed has failed to properly mix with the cooler ocean waters below, endangering the survival of marine life. 
  • In addition, nutrients from below the ocean's surface cannot reach the surface. Phytoplankton, which thrives on the ocean's upper surface, is directly impacted by this.
  • This would lead to changes in the plankton community's composition of small plankton, which leave a mark on the water's colour. 

Importance of Ocean Protection

  1. Livelihood Support: The livelihoods of 3 billion people are intertwined with ocean ecosystems, ensuring their food and economic security. Protecting oceans safeguards these communities.
  1. Climate Resilience: Oceans mitigate climate change impacts by absorbing 93% of trapped heat and around 30% of released CO2 from fossil fuels. This pivotal role aids in reducing climate change rates.
  1. Carbon Cycle Preservation: A healthy ocean ecosystem significantly impacts the carbon cycle, vital for oxygen production and carbon sequestration. Marine biodiversity thrives in such an ecosystem.
  1. Economic Value: Oceans contribute to the global economy by providing resources like food, energy, and more. The fishing industry alone employs over 50 million people and supports billions through food supply. Shipbuilding, tourism, and renewable energy industries are also growing.
  1. Biodiversity Support: A thriving ocean ecosystem sustains diverse marine life, contributing to global biodiversity. Protection efforts ensure the survival of countless species and maintain ecosystem health.

Challenges in Ocean Protection

  1. IUU Fishing: Overfishing poses a significant threat to oceans. Depleted fish stocks and disrupted marine ecosystems are major concerns. About 33% of fish stocks are overfished, and 60% are fully exploited. Illegal fishing costs the global economy up to $23.5 billion annually.

  2. Climate Change: Rising ocean temperatures and acidity due to climate change harm coral reefs and marine life. Habitat loss and altered ocean currents are potential outcomes. Oceans absorbed 90% of excess heat since the 1970s, elevating temperatures. Acidification is linked to absorbing 30% of atmospheric carbon dioxide.

  3. Pollution: Pollution from plastics, oil spills, agriculture, and chemicals jeopardizes oceans. Polluted water can create dead zones, harming marine life.

  4. Unsustainable Tourism: High-demand tourism, like snorkeling and diving, can harm oceans. Mismanaged tourism leads to pollution, habitat destruction, and overfishing. Coastal and marine tourism impacted 1.4 billion travelers in 2018, according to UNWTO.

  5. Invasive Species: Invasive species disrupt marine ecosystems and harm native species. Accidental releases from aquaculture and ballast water introduce them. Invasive species contribute to 18% of global fish extinctions.

  6. Governance Gap: Inadequate governance and international cooperation hamper ocean protection. With much of the ocean considered international waters, enacting and enforcing laws is complex. Only 16% of oceans are protected by marine protected areas, and the high seas lack effective coordination.

Indian Initiatives to Protect Oceans

India has undertaken a range of initiatives to safeguard its oceans and marine ecosystems, reflecting its commitment to ocean conservation:

  1. National Marine Turtle Action Plan (2007): This plan focuses on safeguarding marine turtles and their habitats, advocating measures like habitat protection, conservation education, and promoting sustainable fishing practices.
  1. Integrated Coastal Zone Management (ICZM) Project (2010): The ICZM project promotes sustainable coastal development by integrating land-use planning, biodiversity conservation, disaster management, and livelihood enhancement.
  1. Blue Flag Certification Programme (2018): Through this initiative, India encourages responsible coastal tourism and cleanliness by awarding the Blue Flag certification to environmentally conscious beaches.
  1. National Mission for Clean Ganga (NMCG): While primarily centered on the Ganges River, NMCG indirectly contributes to ocean protection by tackling pollution at its source, which impacts marine ecosystems downstream.
  1. Project Dolphin (2020): Aiming to preserve dolphins and their habitats, this project targets both river and marine dolphins, addressing pollution, habitat degradation, and bycatch.
  1. Mangroves for the Future (MFF): India's participation in MFF contributes to the conservation and sustainable management of mangrove ecosystems, critical for coastline protection and marine life support.
  1. National Marine Spatial Planning (MSP) Framework: India is developing an MSP framework to balance marine development and conservation by zoning various activities in its marine areas.
  1. Indian Marine Fisheries Code: Proposed to regulate fisheries in its Exclusive Economic Zone, this code strives for sustainable fisheries management, preventing overfishing and minimizing bycatch.
  1. Coral Reef Conservation Programme: With a focus on protecting and restoring coral reefs, especially in the Gulf of Mannar, Lakshadweep, and Andaman and Nicobar Islands, India is actively engaged in coral reef conservation.
  1. Marine Pollution Control and Coastal Management Programme: Managed through the Ministry of Environment, Forest and Climate Change, this program tackles marine pollution, advocates sustainable coastal management, and protects marine ecosystems.

These initiatives collectively highlight India's holistic approach to ocean conservation, incorporating policies, actions, and collaborations to ensure the health and vitality of its marine environments.

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