With 75% of New Zealanders living within 10 km of the coast, many students will be familiar with estuaries. In scientific terms, estuaries are the interface between the land and the sea – the intersection of water, plants and animals.
Historically, estuaries have been either highly valued – as food baskets for mana whenua – or viewed as unproductive wastelands to be filled or reclaimed. However, as our understanding of ecosystems grows, the wider New Zealand population now understands the ecological, economic and cultural value of estuaries.
Estuaries – a realistic context for learning
As a topic, estuaries have the potential to combine conceptual scientific understanding, cultural awareness and thinking about socio-scientific issues. This article uses Hub resources to suggest four planning pathways as starting points for contextual-based learning.
Biological and ecological functions of estuaries
New Zealand has approximately 300 estuaries made up of a diverse range of subtidal and intertidal habitats. Estuaries are typically nutrient-rich, productive areas because of their proximity to land. As a biological learning context, estuaries cover four key science concepts: ecosystems, habitat, biodiversity and food webs.
The article Ecosystems explains basic ecosystem factors and interactions. The Life in an estuary article explains estuary ecosystems. The Marine ecosystem and Auckland Islands marine ecosystem interactives explore marine ecosystems in greater detail.
The estuarine habitat and its diverse range of life forms are described in the articles Marine habitats and Life in the estuary. The student activities delve into the importance of estuarine habitats. Estuary metaphors uses everyday objects as metaphors for estuary functions, and Bird hotel is an active game that demonstrates the importance of estuaries for bird migration.
The concepts of biodiversity and biodiversity loss are introduced in the article Biodiversity. Students can explore these concepts both in the classroom and in the field. Introducing biodiversity brings together the concepts of biodiversity, ecosystems and habitat in a literacy-based activity. Threats to biodiversity is another literacy activity and utilises online research. Making and using a quadrat gets students outside to observe local biodiversity. Watch a demonstration of the sampling technique in the video Using a quadrat.
The article Marine food webs explains the complex link between what eats what in a marine habitat. Read how Dr Stephen Wing is actively working to understand Food webs in Fiordland. Students can use image cards to build a marine food web.
Cultural and economic aspects of estuaries
In addition to their biological importance, estuaries also have significant cultural and economic values. Māori have always valued estuaries as sources of food and other commodities. We now know that estuaries have commercial value to the fishing industry as spawning grounds. Estuaries also perform ecosystem services such as maintaining water quality and providing flood protection. Read about these services in Valuing estuaries and Mussels and ecosystem services. Use the student activity Estuaries – a Māori perspective for insights into kaitiakitanga and common estuary terms in te reo and read an associated Māori legend.
Geological and geographic features of estuaries
Estuaries have many shapes and sizes. There are four main types of estuaries based on how they were formed. Estuary formation explains the geology of estuaries using diagrams and specific New Zealand locations. Estuaries have a life cycle – they are formed and change over time. Tectonic activity can bring an estuary to a sudden end. However, sedimentation is the more common cause, as explained below.
Human impacts on estuaries
Presently, the two main impacts affecting estuaries are sedimentation and pollution from run-off. These issues are explained in the articles Human impacts on estuaries and Estuaries and farmland run-off. Protecting estuaries explains land management and traditional Māori practices that are effective in maintaining estuarine functions.
Scientists are a key part of finding solutions and strategies for estuarine protection. Marine ecologist Dr Candida Savage investigates human impacts on coastal ecosystems. View some of her work in the interactive Environmental forensics. Dr Andrew Swales is a coastal and estuarine physical processes scientist. Andrew discusses his work in the video Estuary issues and protection.
Students can use the Hubbub Estuary activity to identify estuarine impacts and protection actions. The accompanying diagram is ideal for the capability Interpret representations. Constructing an aquifer model, Groundwater contamination and the Nutrient impact experiment are simple but effective hands-on models demonstrating the land and water interface and potential impacts.
Nature of science
Many of New Zealand’s towns and cities are built around estuaries. Students can use their knowledge of estuaries to explore local impacts and make decisions about actions to protect their local waterways as part of the ‘Participating and contributing’ strand.
Use literacy resources from the School Journal and Connected to support science understanding:
The secret life of estuaries Connected Number 3 2006
Estuary health check Part 4 Number 3 2008
Learning from the Tangata Whenua Connected Level 2 Part 3 2015