Marine Ecosystems

Coverage: More than 70% of Earth is covered by oceans.
Function in Climate: Oceans help maintain Earth's global temperature.
Biodiversity & Food Source: Serves as habitat for hundreds of thousands of species and provides food for billions of people.

Five Major Oceans: Interconnected to form the World Ocean:
- Pacific Ocean: Largest, covers 33% of Earth's surface; contains the Mariana Trench (11,034m deep).
- Atlantic Ocean: Second largest, covers 20% of Earth's surface, divided by equatorial currents.
- Indian Ocean: Third largest.
- Southern Ocean: Surrounds Antarctica, responsible for southern circulation.
- Arctic Ocean: Smallest, located around the North Pole.

Division Based on Light Penetration:
- Benthic Zone: Ocean floor, always dark.
- Epipelagic Zone: Surface, high light and nutrient levels; high productivity.
- Mesopelagic Zone: 200m-1000m deep; light is present but insufficient for photosynthesis, specialized organisms.
- Bathypelagic Zone: 1000m-4000m deep; complete darkness, organisms feed on detritus and marine snow; bioluminescence is common.
- Abyssopelagic Zone: 4000m+; dark, extremely cold waters, species are blind and colorless.

Ecosystem Services:
- Food production
- Maintaining biodiversity
- Recreational uses
- Carbon sink (major carbon storage)
- Source of oxygen (via phytoplankton)
- Temperature regulation (high heat capacity)
- Global climate control.

Life Stage: Corals exist as polyps, which capture food using cnidocytes (stinging cells).
Structure:
- Cylindrical, made of epidermal tissue.
- Tentacles surrounding a mouth lined with cnidocytes that contain nematocysts (toxin-laden harpoons).
- Simple stomach (gastrovascular cavity) secreted digestive enzymes.
- Attach to rocky surfaces using a basal plate.

Ahermatypic Corals:
- Do not build reefs, soft and flexible; examples include sea whips and gorgonians.
Hermatypic Corals:
- Build reefs, depend on symbiosis with zooxanthellae.
- Begin as larvae that settle on hard substrate; reproduce asexually through budding.

Feeding: Mostly get nutrients from zooxanthellae; can also capture through cnidocytes and absorb organic matter via diffusion.

Temperature: Optimal between 23°C-25°C (ideal range 16°C-35°C).
Water Depth: Fast growth occurs within 20m; light is critical for zooxanthellae.
Water Clarity: Essential for sunlight penetration.
Substrate: Requires rocky surfaces.
Salinity and pH Levels: Not adapted to fresh or brackish water; prefers slightly basic pH.

Fringing Reef: Near shore, susceptible to pollution.
Barrier Reef: Separate from land by a lagoon; Great Barrier Reef as an example.
Patch Reef: Small reefs within lagoons of barrier reefs.
Atolls: Ring-shaped reefs around lagoons, typically found far from land.

Ecological Role: Protect shorelines, habitat for marine organisms, and sources for food and tourism.
Threats: Reef erosion due to ocean acidification, rising sea temperatures, and predation (e.g., by parrotfish and crown-of-thorns starfish).

Environmental Challenges: Fluctuating temperatures, wave action, exposure to air.
Biodiversity: High due to various niches available for organisms to attach.
Zonation: Species distribution is affected by tolerance to desiccation and competition.

Splash Zone: Alternates between wet and dry; organisms here survive dry spells.
Upper Shore: Only submerged during high tides; organisms have adaptations for long dry periods.
Middle Shore: Exposed less frequently; organisms facing both heavy waves and desiccation.
Lower Shore: More stable conditions; supports greater biodiversity.

Dynamic Environment: Constantly shifting, porous substrate, limited attachment points for organisms.
Adaptations: Species like ghost crabs and razor clams burrow to evade predation.

Characteristics: Coastal ecosystems with high biodiversity due to saline habitats; vital for coral reef health.
Conditions for Growth: Require specific climatic conditions and protection from strong wave actions.
Ecological Importance: Provide nurseries for fish, protect shorelines, carbon sinks, and mitigate climate change effects.
Threats: Climate change and overharvesting of mangroves lead to habitat loss, impacting biodiversity.

Open Ocean
- What percentage of Earth is covered by oceans?
- Describe the main functions of oceans in climate regulation.
- Name three major goods provided by the ocean that contribute to human life.
Oceans Overview
- List the five major oceans and provide a unique feature of each.
- Which ocean is the largest, and what is a significant geological feature it contains?
Zones of the Open Ocean
- What determines the division of the open ocean into various zones?
- Describe the characteristics of the mesopelagic zone.
- How do organisms in the abyssopelagic zone adapt to their environment?
Importance of Oceans
- What are the ecosystem services provided by oceans?
- Explain the role of phytoplankton in ocean ecosystems.
Tropical Coral Reef
- What are the fundamental characteristics of corals?
- Differentiate between hermatypic and ahermatypic corals.
- Describe the conditions necessary for coral growth.
Types of Coral Reefs
- Identify and explain the differences between fringing reefs, barrier reefs, patch reefs, and atolls.
Rocky Shore
- What environmental challenges do organisms on rocky shores face?
- Define the zones of intertidal environments.
Sandy Shore
- What adaptations do organisms living in sandy shore environments have to avoid predation?
Mangrove Forest
- Explain the importance of mangrove forests to marine ecosystems.
- What threats do mangrove forests currently face?