Pengantar Oseanografi - Marine Ecosystem (part 1)

Summary

This lecture delves into marine ecosystems, exploring the two primary ocean zones: neritic (shallow, coastal areas) and pelagic (deeper regions). It covers the unique adaptations of marine organisms to different depths, including the photic and aphotic zones. Key topics include ocean circulation, thermohaline currents, and nutrient distribution, with a focus on how deep-sea organisms rely on chemosynthesis for energy. The lecture also highlights the importance of hydrothermal vents, where rich ecosystems thrive due to symbiotic relationships with bacteria. Understanding these processes is crucial for appreciating the delicate balance and diversity of life in our oceans.

Takeaways

• 😀 There are two main types of ocean zones: benthic and pelagic, which are further subdivided based on depth.
• 😀 The neritic zone has a depth of up to 200 meters and is located near the coast, while the oceanic zone extends beyond 200 meters deep.
• 😀 Light availability in the ocean creates two primary zones: the photic zone, where light penetrates, and the aphotic zone, where no light reaches.
• 😀 Marine life decreases as you go deeper into the ocean, especially below the aphotic zone, due to a lack of food and light.
• 😀 Thermohaline circulation, or the movement of water masses, plays a critical role in transporting oxygen and nutrients throughout the ocean.
• 😀 The Great Ocean Conveyor Belt is a global term used to describe thermohaline circulation, originating in the North Atlantic and affecting global climates.
• 😀 Deep-sea organisms depend on surface-derived food and oxygen, and many deep-sea predators exhibit gigantism, such as larger squid and starfish.
• 😀 Organisms in the deep ocean have slow growth rates and long lifespans due to food scarcity, low temperatures, and high pressure.
• 😀 Deep-sea animals are often hermaphroditic and use chemical signaling to find mates in the dark depths.
• 😀 Unique ecosystems like hydrothermal vent communities exist in deep ocean areas, with some organisms relying on chemosynthesis rather than photosynthesis for energy.
• 😀 Hydrothermal vents provide rich sources of nutrients for specialized deep-sea organisms, including bacteria that form symbiotic relationships with animals to create an organic food base.

Q & A

What are the two main types of oceanic zones discussed in the lecture?

The two main types of oceanic zones are the benthic zone and the pelagic zone. The pelagic zone is further divided into sub-zones based on depth.

What is the primary distinction between the neritic zone and the oceanic zone?

The neritic zone has a depth of up to 200 meters and is located close to the coast, while the oceanic zone extends deeper than 200 meters.

How is ocean life distribution affected by the depth and light availability?

Ocean life distribution depends on light and depth. In areas where light is available, such as the photic zone, life is abundant. However, in deeper, darker regions like the aphotic zone, life becomes sparse, and food availability decreases.

What role does thermohaline circulation play in the ocean ecosystem?

Thermohaline circulation moves water and oxygen throughout the ocean. It begins in the North Atlantic near Norway and circulates through the world's oceans, affecting global climate and nutrient distribution.

How does the deep-sea food web function in comparison to surface-level ecosystems?

Deep-sea organisms rely on food that falls from the surface, such as organic particles, since there is no photosynthesis at these depths. Many deep-sea creatures experience gigantism due to limited food supply.

What is the phenomenon of gigantism in deep-sea organisms?

Gigantism in deep-sea organisms refers to the unusually large size of certain species, like deep-sea squid and starfish, which is thought to be an adaptation to the harsh, low-food environment.

Why do deep-sea organisms generally have slow growth and long lifespans?

Deep-sea organisms grow slowly and live longer because of the cold temperatures, high pressure, and limited food availability. These factors slow metabolic processes and require longer lifespans to gather enough energy for reproduction.

What is the importance of symbiotic bacteria in deep-sea ecosystems?

Symbiotic bacteria play a crucial role in deep-sea ecosystems by providing nutrients to organisms. These bacteria use hydrogen sulfide from hydrothermal vents to create organic compounds, which form the base of the food web.

What is kemosynthesis, and how does it differ from photosynthesis?

Kemosynthesis is the process by which certain organisms synthesize organic compounds using chemicals like hydrogen sulfide, rather than sunlight. This is the primary source of energy in deep-sea environments where light does not reach.

How do deep-sea organisms adapt to avoid predators?

Deep-sea organisms use various adaptations to avoid predators, such as counter-illumination, where they create light patterns to blend in with their environment, and reducing their silhouette to make them less visible.