Marine Ecosystem Overview Quiz

Marine Ecosystem Overview

• Marine ecosystems encompass all aquatic ecosystems with high salt content, comprising nearly half the Earth's oxygen supply.
• These ecosystems are incredibly diverse, with a wide array of species inhabiting them.

Intertidal Zone

• The intertidal zone, also known as the foreshore or seashore and sometimes the littoral zone, is the area between high and low tide marks.
• This area experiences exposure to air at low tide and submersion during high tide.

Pelagic Zone

• The pelagic zone comprises the water column of the open ocean, extending from the surface to the ocean floor.
• It's divided into distinct subzones based on depth (epipelagic, mesopelagic, bathypelagic, abyssopelagic), each with specific characteristics.

Abyssal Zone

• The abyssal zone lies within the pelagic zone, at great depths in the ocean; it's characterized by extreme pressure and cold temperatures, low nutrient levels, and high levels of oxygen.
• Many invertebrate and fish species inhabit this zone; bacteria thrive in the abyssal zone due to the presence of hydrogen sulfide.

Benthic Zone

• The benthic zone represents the ecological region at the bottom of the sea, encompassing the sediment surface and some subsurface layers.
• This zone contains various organisms adapted to the low-light, high-pressure, and often-variable conditions of the seafloor.

Corals

• Corals are marine invertebrates belonging to the class Anthozoa within the phylum Cnidaria.
• They exist in colonies of interconnected polyps and play a crucial role in building coral reefs, crucial in many tropical ocean ecosystems.
• Corals secrete calcium carbonate to create the hard skeleton of the reef.

Coral Reef Formation

• Coral reefs originate when free-swimming coral larvae attach to submerged rocks or hard surfaces near continents.
• Fringing reefs are the most common type, projecting seaward from the shore.
• Barrier reefs are distinguished from fringing reefs by deeper lagoons near the shore.
• Atolls are ring-shaped reefs surrounding a lagoon.

Symbiotic Relationship of Corals and Zooxanthellae

• Reef-building corals host photosynthetic algae called zooxanthellae within their tissues.
• This relationship is mutualistic, benefiting both corals and algae.

Coral Bleaching

• Coral bleaching occurs when corals expel zooxanthellae from their tissues due to stressful environmental factors.
• Stressors implicated in coral bleaching events typically include temperature fluctuations, solar irradiance changes, subaerial exposure, changes in freshwater dilution, inorganic nutrient increases, and xenobiotics or epizootics.

Mangroves

• Mangroves are salt-tolerant trees, known as halophytes.
• They are adapted to harsh coastal conditions, with specialized adaptations such as salt-excreting glands and breathing roots (pneumatophores) to cope with salt and oxygen-poor conditions.
• Varieties of mangroves include black mangrove, red mangrove, and white mangrove.

Mangrove Reproductive Strategies

• Mangroves have unique reproductive strategies, dispersing propagules (seeds or seedlings) via water with varying degrees of embryonic development while still attached to the parent trees.

Mangrove Adaptations

• Mangrove adaptations enable these plants to thrive in harsh coastal environments.
• Specialized features like salt excretion and breathing roots assist in dealing with salinity and oxygen uptake in highly saturated, waterlogged soils.

People and Ocean

• The ocean covers a significant portion (approximatley 72 per cent) of the Earth's surface and is vital for billions of people.
• 600 million populate coastal areas within 10 meters of sea level and nearly 2.4 billion (~40% of the world's population) live within 100 km (~60 miles) of the coast.
• Fisheries and aquaculture contribute substantially to both employment and the global economy, estimated to generate billions of USD per year.
• Shipping accounts for a large percentage (~90%) of global trade, passing through the ocean.

Problems of Marine Ecosystems

• Siltation/siltification, a pollution of water by particulate terrestrial clastic material, is a major concern.
• Trawling, a fishing method using large nets, destroys seabed habitats, including corals and seagrass.
• Purse seining, a fishing method involving use of large nets, can damage and endanger marine mammals such as dolphins.
• Red tides are large algal blooms that deplete oxygen and release harmful toxins into the water.

Other Problems in Marine Ecosystems

• Climate change impacts include coral bleaching, rising sea levels, and shifting species distributions.
• Pollution from various sources (oil spills, untreated sewage, fertilizers, pesticides, industrial chemicals, plastics) pollute the ocean and harm the entire marine food chain.

Test your knowledge on marine ecosystems, including the intertidal, pelagic, and abyssal zones. Understand the unique characteristics and biodiversity found within these aquatic environments. Challenge yourself with questions that cover various aspects of marine life and ecology.