Presentation: Lesson 5

The lower part of a river where it flows into the sea is called the estuary or the mouth of the river. An estuary is a transitional zone between fresh water and the open sea. In the estuary, warm shallow water, tides, currents, and wind carry rich organic nutrients from the bottom of the estuary to the water’s surface. With every tide these nutrients are carried from the estuary to the sea. This exchange of organic material between the estuary and the ocean creates a very productive habitat for many plants and animals.

Bradán is introduced in this lesson as a creature undergoing great body changes (a teenager).

She learns to “osmoregulate”, which means to regulate the salt and water in her body. She must guard against the loss of water and be capable of secreting excess salt from her body fluids.

Pupils already know from the last lesson that Bradán has already reached smolt stage (6-8 weeks before migrating to sea) and has made her way down the river to spend a number of years at sea. By now she will have changed to a silver colour.

As salmon travel down the estuary area, there are increased challenges due to infrastructure expansion, car parks, bridges, pollution, effluent from factories, oil spills and port activity.

The river estuary is introduced as a busy place, which usually bares the brunt of human waste and pollution.

Any substance that has entered the river upstream such as waste from agricultural works, industries and towns affects the entire river downstream, including the estuary.

The environment is threatened by oil from ships and boats, and by industrial and domestic waste from heavily populated areas. There must be strict monitoring and control to ensure that water quality is maintained. Any change to an estuary can have considerable effects on the ecosystem in the coastal zone.

To test childrens observation skills and prompt oral work, show an image of Ballypolluted and ask pupils to point activities that might cause impact on life in the estuary and on the coast. Ask pupils "How will the local tourism and fishing industry will fare if this situation continues?" and "What ways can the people of the area might improve the water quality and ensure fish stocks for the future

The concept of an estuary food web is introduced as a continual reminder of the interdependence of creatures.

An experiment may be done to investigate deposition in an estuary.

Lastly, habitats need to be managed and protected so that enough salmon can survive to eventually revisit the spawning grounds. This means that we must look after the environment itself, protecting it from pollution while at the same time conserving stocks of fish.

Follow Up Work
Freshwater Aquarium

Set up a freshwater aquarium in class. A video link below illustrates the steps that need to be taken

Revision

Two different types of revision material accompany this lesson; activity cards and whiteboard material.
The activity card is a 3 page document that is filled out by the pupils to test their knowledge of the lesson taught. The teacher can decide if the activity card is filled out individually or in teams

The whiteboard resource tests the pupils knowledge of the lesson taught. Pupils are encouraged to actively engage in answering questions relating to challenges faced by life in the river estuary, the ecosystem of the costal zone and management of water quality.

At the end of the lesson, Pupils should know