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Unlock This CourseCoastal ecosystems are some of the most productive and diverse environments on Earth. From rocky shores to salt marshes, these areas support complex networks of living organisms that depend on each other for survival. Understanding how energy flows through these systems helps us protect these vital habitats.
Key Definitions:
Energy enters coastal food webs through sunlight, which producers use for photosynthesis. This energy then flows up through the food chain, with only about 10% passing from one level to the next. The rest is lost as heat or used for life processes.
Coastal food webs contain several key groups of organisms, each playing a crucial role in maintaining the ecosystem's balance. Let's explore how these different levels interact.
In coastal ecosystems, producers form the base of all food webs. These organisms convert sunlight into chemical energy through photosynthesis, providing food for all other life forms.
Seaweeds, kelp forests and seagrass beds provide shelter and food. Kelp can grow up to 60cm per day, creating underwater forests that support hundreds of species.
Microscopic floating plants that form the base of marine food chains. Despite their tiny size, they produce over 50% of the world's oxygen.
Specially adapted plants like cordgrass that can survive in salty conditions. They trap sediment and provide nursery areas for young fish.
Primary consumers feed directly on producers and play a vital role in transferring energy up the food web. These herbivores have special adaptations to help them survive in harsh coastal conditions.
Limpets scrape algae from rocks with their radula (rasping tongue). Sea urchins use their spines for protection whilst feeding on kelp. Periwinkles can seal their shells to survive when the tide goes out.
These predators control population sizes and maintain ecosystem balance. They show remarkable adaptations for hunting in coastal environments.
Coastal predators range from small crabs to large marine mammals. Each has evolved specific hunting strategies and plays a unique role in the ecosystem.
In the 1960s, overfishing of herring in the North Sea caused a cascade effect. With fewer herring to eat zooplankton, jellyfish populations exploded. This disrupted the entire food web, affecting seabirds, marine mammals and commercial fisheries. Recovery took decades and required strict fishing quotas.
Food web diagrams use arrows to show energy flow between organisms. The arrow always points from the organism being eaten to the one doing the eating. Understanding these diagrams helps us predict what happens when species are removed or added.
Each arrow represents energy transfer. Multiple arrows from one organism show it has several predators. Multiple arrows to one organism show it eats various prey. The more connections, the more stable the ecosystem.
Human activities significantly affect coastal ecosystems through pollution, overfishing, coastal development and climate change. Understanding these impacts helps us make better conservation decisions.
Coastal ecosystems face multiple pressures from human activities. These threats often work together, making their combined impact much worse than individual effects.
Plastic waste, chemical runoff and oil spills poison marine life. Microplastics enter food chains at the bottom and concentrate as they move up, affecting top predators most severely.
Removing too many fish disrupts food webs. When large predators disappear, their prey populations explode, overgrazing producers and destabilising the entire system.
Rising sea temperatures and ocean acidification affect all levels of food webs. Coral bleaching destroys habitat whilst changing currents alter nutrient distribution.
Climate change and pollution have severely damaged the Great Barrier Reef's food webs. Coral bleaching has removed primary habitat, whilst crown-of-thorns starfish outbreaks (caused by agricultural runoff) have destroyed remaining coral. Fish populations have crashed, affecting tourism and local communities. Conservation efforts now focus on reducing pollution and creating marine protected areas.
Protecting coastal food webs requires understanding their complexity and the multiple threats they face. Successful conservation combines scientific research with community action and government policy.
Creating no-fishing zones allows ecosystems to recover. Studies show that fish populations inside protected areas can be 5-10 times larger than in unprotected waters, with benefits spreading to surrounding areas.
Many coastal ecosystems have been successfully restored through careful management and community involvement.
Overhunting of sea otters led to sea urchin population explosions that destroyed California's kelp forests. When sea otters were reintroduced and protected, they controlled urchin numbers, allowing kelp forests to regrow. This restored the entire food web, supporting fish, seabirds and marine mammals whilst boosting local tourism.
Stable food webs have many connections between species, providing alternative pathways for energy flow. When one species declines, others can fill its role, maintaining ecosystem function.
Some species have disproportionately large effects on their ecosystems. Removing a keystone species causes dramatic changes throughout the food web, often leading to ecosystem collapse.
Coastal food webs face increasing pressure from human activities and climate change. However, growing awareness and improved technology offer hope for better protection and management.
New technologies and approaches are helping scientists better understand and protect coastal ecosystems.
Satellite monitoring, underwater drones and genetic analysis help track ecosystem health and species populations in real-time.
Local communities play crucial roles in conservation through beach cleanups, sustainable fishing practices and citizen science projects.
International agreements and shared research help coordinate conservation efforts across national boundaries.