Estuaries are one of the coastal areas most at risk from human activities. Developments in and around estuaries and the increasing population growth affect these special places.
Some of the threats to the estuary biome are:
- Urban development: Housing development, recreational activities and fishing will change the environment and have an impact on estuaries.
- Agricultural activities: Runoff water and chemicals from agricultural land can affect the health of estuaries and the organisms living in and around it. An example would be the use of the chemical superphosphate which could lead to the increase in nutrient levels and fuel the growth of algae in estuaries.
- Industries like fishing and oyster farming can impact the water quality and also the movement of water in estuaries. Over-fishing and habitat loss reduces the amount of fish in the ocean and disrupts the food chain. If there are less fish in the ocean there will be more in estuaries trying to reproduce so there are more of their species.
- Boating can damage seagrass, reducing or degrading habitat and disrupting the food chain. This can happen due to boat propellers, anchoring in seagrass beds and also the wakes of boats.
- Structures such as sea walls, bridges, drains, jetties, marinas, levy banks, rock walls and breakwaters can all affect the passage of water and can change the conditions in an estuary. The structures aren’t just bad. They can have an immense amount of marine life that have made themselves at home on the pillars.
- Erosion and the build-up of sediments and pollutants can cover seagrass and other vegetation. This reduces the amount of food sources and the available habitats for marine life and wildlife to live in.
- Dams and power stations can change the water temperature in estuaries, as well as affecting aquatic ecosystems. Cold water from dams and warm water from power stations are types of thermal pollution that affect water ways.
- Litter on our beaches and floating in the salt and fresh water pollutes estuaries. In particular, non-biodegradable litter. It tangles up marine life and they can also swallow it. It is also a harm to divers, fishers and anyone who uses beaches.