Marine Biology - Ecosystems

Here's an overview of each of these important coastal ecosystems, including their locations, characteristics, typical organisms, and human impacts.

1. Mangrove Forests

Location:
Mangrove forests are found in tropical and subtropical regions worldwide, along coastlines in Asia, Africa, the Americas, and Australia. Major areas include Southeast Asia, the Caribbean, Central America, West Africa, and northern Australia.

Depth:
Mangrove forests are typically found in shallow coastal areas, at depths of up to 1-2 meters (3-6 feet), where tidal waters can flood the land.

Water Temperature:
Mangroves thrive in warm tropical and subtropical waters, with temperatures ranging between 22°C and 30°C (72°F - 86°F).

Light Levels:
Moderate light levels as mangroves grow in intertidal zones, where they receive sunlight at low tide and are submerged at high tide.

Types of Organisms:

• Algae & Plants:

  • Mangrove trees (e.g., Rhizophora, Avicennia, and Laguncularia) that have specialized adaptations to survive saltwater (e.g., salt excretion, aerial roots).

  • Various epiphytic algae grow on mangrove trunks and roots.

• Animals:

  • Fish: Mangrove snapper, grouper, juvenile fish such as snappers and barracuda, mudskippers.

  • Invertebrates: Mangrove crabs (e.g., Sesarma, U. mjoebergi), snails, oysters, and shrimp.

  • Other animals: Birds such as herons, egrets, and migratory wading birds, as well as mammals like monkeys, bats, and, occasionally, large marine mammals (e.g., manatees).

Survival Strategies:

• Mangrove Trees: Adapt to saltwater by filtering salt through their roots and excreting it through specialized glands. They also have pneumatophores (aerial roots) to access oxygen in waterlogged soils.

• Fish and Crustaceans: Adapt to varying salinities by regulating their internal salt balance through osmoregulation. Juvenile fish use mangrove forests as nursery habitats, taking advantage of abundant shelter and food.

Food Web:

• Producers: Mangrove trees, algae, and seagrasses.

• Primary Consumers: Herbivores like snails, crabs, and small fish.

• Secondary Consumers: Predatory fish, larger crabs, and birds.

• Tertiary Consumers: Larger predators like sharks, eagles, or large fish.

• Decomposers: Bacteria, fungi, and detritivores.

Human Impacts:

• Deforestation: Mangroves are often cleared for coastal development, agriculture, and aquaculture.

• Pollution: Mangroves are affected by oil spills, plastic waste, and agricultural runoff, leading to habitat degradation.

• Climate Change: Rising sea levels and increased storm intensity threaten mangrove survival.

2. Seagrass Meadows

Location:
Seagrass meadows are typically found in temperate and tropical coastal regions. Notable locations include the Gulf of Mexico, Australia’s Great Barrier Reef, the Mediterranean Sea, and parts of Southeast Asia.

Depth:
Seagrasses grow in shallow coastal waters, usually from 1 meter (3 feet) to depths of 30 meters (100 feet) in clear waters.

Water Temperature:
Seagrasses prefer warmer waters (15°C to 30°C or 59°F - 86°F), but some species can tolerate cooler temperatures.

Light Levels:
Seagrasses need clear water and adequate sunlight for photosynthesis. They thrive in areas with good light penetration (low turbidity).

Types of Organisms:

• Plants:

  • Seagrasses like Zostera, Posidonia, Thalassia, and Halodule.

• Animals:

  • Fish: Juvenile fish (e.g., parrotfish, snapper), seahorses, rays.

  • Invertebrates: Sea urchins, crabs, polychaete worms, mollusks (e.g., clams), and shrimp.

  • Other animals: Turtles (e.g., green sea turtles), dugongs (in some regions), and manatees.

Survival Strategies:

• Seagrasses: Have adapted to live in saline, submerged environments by storing nutrients in rhizomes and using oxygen-storing tissues.

• Fish and Turtles: Many species use seagrass meadows as nurseries, while herbivores graze on the plants. Sea turtles and dugongs have specialized adaptations to feed on seagrasses.

Food Web:

• Producers: Seagrasses and algae.

• Primary Consumers: Herbivores like sea turtles, dugongs, and certain fish species.

• Secondary Consumers: Small predatory fish, crabs, and other invertebrates.

• Tertiary Consumers: Larger fish, sharks, and marine birds.

• Decomposers: Bacteria and fungi, along with detritivores that break down plant matter.

Human Impacts:

• Coastal Development: Pollution, boat propellers, and sedimentation damage seagrass beds.

• Overgrazing: Overfishing and grazing by herbivores can deplete seagrass beds.

• Climate Change: Ocean acidification and warming waters threaten seagrass health.

3. Kelp Forests

Location:
Kelp forests thrive in nutrient-rich, temperate waters, mostly in the Northern Hemisphere along coasts of North America, Europe, and parts of Asia and Oceania.

Depth:
Kelp forests are typically found at depths ranging from 5 meters to 40 meters (16-130 feet), although they need clear, shallow waters to thrive.

Water Temperature:
Kelp forests prefer cooler waters, typically between 5°C and 20°C (41°F - 68°F).

Light Levels:
Kelp requires strong light to grow, but it can only thrive in clear water, as light can penetrate to depths of about 30 meters in pristine conditions.

Types of Organisms:

• Algae:

  • Brown algae species like Laminaria, Macrocystis, and Nereocystis.

• Animals:

  • Fish: Rockfish, kelp bass, cod, and sea otters.

  • Invertebrates: Sea urchins, abalone, crabs, sea stars, and snails.

  • Other animals: Sea otters, which help control sea urchin populations, sea lions, and various marine birds.

Survival Strategies:

• Kelp: Adapt to strong wave action with a flexible, tough structure; can grow rapidly in nutrient-rich waters.

• Fish & Invertebrates: Many organisms use kelp forests for shelter, camouflage, and breeding grounds. Herbivores feed on kelp, while predators use them for hunting.

Food Web:

• Producers: Kelp and other macroalgae.

• Primary Consumers: Herbivorous fish, sea urchins, and snails.

• Secondary Consumers: Predatory fish, sea otters, and crabs.

• Tertiary Consumers: Larger predators like sharks, larger fish, and sea birds.

• Decomposers: Bacteria and detritivores.

Human Impacts:

• Pollution: Agricultural runoff and oil spills can damage kelp forests.

• Overfishing: Overfishing of herbivores like sea urchins can disrupt the balance of the ecosystem.

• Climate Change: Warming seas threaten kelp growth, while ocean acidification impacts the survival of some species.

4. Wetlands & Estuaries

Location:
Wetlands and estuaries are found in coastal regions, rivers, and inland areas. Examples include the Mississippi Delta, Everglades, Thames Estuary, and the Sundarbans.

Depth:
Estuaries can vary from shallow (0.5-1 meter deep) to deeper regions in the case of tidal flats.

Water Temperature:
Estuarine waters have variable temperatures, ranging from temperate to tropical conditions (10°C to 30°C or 50°F - 86°F).

Light Levels:
Light availability varies with depth and turbidity but is generally moderate to low due to suspended sediments.

Types of Organisms:

• Plants:

  • Salt-tolerant plants like cordgrass (Spartina), mangroves, and bulrushes.

• Animals:

  • Fish: Bass, flounder, eels, and many species of juvenile fish.

  • Invertebrates: Clams, mussels, crabs, and shrimp.

  • Other animals: Birds (waders, ducks, and shorebirds), otters, and various amphibians.

Survival Strategies:

• Plants: Adapt to brackish water with specialized salt-excreting mechanisms.

• Animals: Adapt to fluctuating salinities, with many species having the ability to tolerate both fresh and saltwater (euryhaline).

Food Web:

• Producers: Marsh grasses, mangroves, algae, and phytoplankton.

• Primary Consumers: Invertebrates, small fish, and herbivorous waterfowl.

• Secondary Consumers: Larger fish, crabs, and shorebirds.

• Tertiary Consumers: Predators like eagles, larger fish, and w

ading birds.

• Decomposers: Bacteria, fungi, and detritivores.

Human Impacts:

• Habitat Loss: Urbanization, agriculture, and industry threaten wetland and estuarine habitats.

• Pollution: Runoff and chemical pollution impact water quality and organisms.

• Sea-Level Rise: Climate change increases flooding, threatening wetlands and estuaries.

5. Rocky Shores

Location:
Rocky shores are found worldwide, typically along high-energy coasts with strong wave action. Examples include the Pacific Northwest of the U.S., the shores of the British Isles, and parts of Australia.

Depth:
Rocky shores are primarily intertidal zones, ranging from high-tide areas to low-tide zones (intertidal zone).

Water Temperature:
Varies widely depending on location, from cold waters in northern latitudes to warm temperate regions.

Light Levels:
Moderate light availability, with exposure to full sunlight at low tide, while submerged at high tide.

Types of Organisms:

• Plants & Algae:

  • Coastal algae like Fucus (rockweed), kelp, and green algae.

• Animals:

  • Fish: Gobies, blennies, and wrasse.

  • Invertebrates: Barnacles, limpets, mussels, crabs, sea urchins, and snails.

  • Other animals: Seabirds, crabs, and sea stars.

Survival Strategies:

• Algae: Adapted to high wave action, they have strong holdfasts to anchor them to rocks.

• Animals: Many animals have shells (e.g., mollusks) for protection, and others are adapted to cope with desiccation at low tide (e.g., barnacles).

Food Web:

• Producers: Algae and seaweed.

• Primary Consumers: Herbivores like limpets, sea urchins, and snails.

• Secondary Consumers: Crabs, sea stars, and predatory fish.

• Tertiary Consumers: Larger predators like seabirds and larger fish.

• Decomposers: Bacteria and detritivores.

Human Impacts:

• Pollution: Oil spills, plastics, and chemicals affect rocky shore ecosystems.

• Overharvesting: Shellfish and marine invertebrates are overharvested for food.

• Coastal Development: Development and infrastructure disrupt rocky shore habitats.

These ecosystems play crucial roles in maintaining biodiversity, protecting coastlines, and supporting various species. However, they are all threatened by human activities like pollution, habitat destruction, and climate change.