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.