Biodiversity1 is short for biological diversity2. It refers to the number and variety of living things (animals, plants or microorganisms3) found within a particular area. There are complex relationships between this variety of life. Marine biodiversity specifically refers to the variety of life in coastal and ocean environments.
Biodiversity includes:
- genetic diversity – the different genetic4 make-up among individuals of one species5
- species diversity – the different species within a habitat6 such as the birds, worms, fish, bacteria7, insects and molluscs8 that live within an estuary9
- ecological diversity – the different ecosystem10 types (estuaries11, oceans, forests, wetlands12, grasslands, streams) and the communities within them.
Marine biodiversity
Marine species make up almost one-third of New Zealand’s total number of described native13 species. However, about seven new marine species are identified each fortnight – many more are yet to be discovered. Scientists estimate there could be as much as 80% of New Zealand’s biodiversity living in the sea.
A species inventory for New Zealand was developed over the last decade through a project called Species 2000: New Zealand. This project formally identified about 12,000 marine species in New Zealand’s waters, with another 3,550 known but not yet described. It is estimated that, at the present rate of description, it would take another 100 years to describe the remaining marine species.
Described species include:
- seabirds
- marine mammals
- fish
- molluscs (snails, shellfish and squid)
- sponges
- echinoderms (kina, sea stars (starfish))
- seaweeds (rimurimu)
- microalgae.
Examples of all of these are found in various Bay of Plenty habitats.
Life in the estuaries
The soft estuary bottom (consisting of sand and mud, including sediment14 carried down by rivers) supports a range of burrowing fauna15 such as worms, cockles and pipi. Most of these animals feed on accumulated debris and bacteria and algae16 films on the mud surface. Estuaries are ideal refuges for juvenile fish of many species and wading birds in search of fish and crustacea.
Life in the beach zone
Bay of Plenty beach zones support abundant species such as shellfish – pipi, tuatua, biscuit shell, dog cockle and triangle shell. Sandhoppers can often be found jumping around in the debris left by an outgoing tide, called the wrack line. Terns and gulls often pick through debris. Pieces of driftwood often contain oyster borers and other insects. Fragments of dead seaweed such as sea lettuce and kelp are also common in this area.
Life on the rocky shore
The rocky shores support a huge diversity of life. Life here is not easy. Salinity17, water, wave action, competition and predation18 are all factors affecting survival chances of life on the rocky shore. However, examples of many marine organism19 groups can be found there. Some examples are sea anemone, kina20, sea cucumber, sea slugs, sea stars, pāua21, crabs, chitons, sponges, worms, shrimp, barnacles, sea squirts, seaweeds, crayfish, octopus, fish, oysters and mussels.
Life around the offshore islands
These mostly volcanic rocky shores exposed to warm ocean currents support a unique diversity of subtropical marine life. In addition to species found on most New Zealand rocky shores, these habitats22 include long-finned boarfish, clown toado, crimson cleanerfish, the colourful splendid perch, Sandagers wrasse, copper23 moki and, in the summer, turtles.
The importance of biodiversity
New Zealand’s marine biodiversity is ecologically important because it is unique and of international importance – many of our species are not found anywhere else on Earth. Biodiversity also has intrinsic value – the value of the variety of life itself – and creates ecosystems24 that allow organisms to flourish in an interdependent25 web of life. Some of these species have commercial value to us as food and sources of potential medicines. Our relatively unspoiled marine environment also has economic value for tourism and our fishing industry. Finally, of cultural significance is that Māori have a special affinity with the oceans in a non-material way, and this is recognised in the Treaty of Waitangi.
Nature of science
Science knowledge changes over time. As science and technology allows greater exploration of the ocean, more species are being discovered. New species are being discovered and identified all the time. With new discoveries come new possibilities – discoveries of medicines and other valuable compounds (biodiscoveries).
Related content
Use these Building Science Concepts articles to explore the science concepts that underpin knowledge and understanding about:
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Biodiversity – estuaries and marine ecosystems is a collection of resources and notes for those teaching in primary school classrooms. You are welcome to copy the collection to your own profile, where you can edit and curate additional resources. Find out more about our easy to use collection tool.
These series of interactives features many of the Department of Conservation's marine infographics.
- Marine diversity in Aotearoa New Zealand
- New Zealand marine habitats
- Threats to marine habitats
- Areas of marine ecological importance
- Mussel reefs and biodiversity
Activity ideas
These two student activities explore the two key science concepts of habitat and biodiversity:
- Where do I live? looks at why and how marine animals and plants are best suited to particular habitats. The activity is ideal for rocky shore and estuary studies.
- With Introducing biodiversity, students make models of a marine ecosystem and then explore ways humans might impact on that ecosystem.
Useful link
The New Zealand Inventory of Biodiversity (in three volumes) is an inventory of biodiversity in New Zealand and it lists and describes all known species. Find out more on the Univeristy of Canterbury's website.
- biodiversity: The range of species found in a particular region. The more species that exist (the higher the biodiversity), the more likely it is that an ecosystem will survive episodes of change.
- biological diversity: The variety of species within a given ecosystem, biome or for the entire Earth.
- microorganism: A living organism which is too small to be seen with the naked eye and can only be observed using a microscope. Includes bacteria and most protists.
- genetic: Of, relating to, or determined by genes.
- species: (Abbreviation sp. or spp.) A division used in the Linnean system of classification or taxonomy. A group of living organisms that can interbreed to produce viable offspring.
- habitat: The natural environment in which an organism lives.
- bacteria: (Singular: bacterium) Single-celled microorganisms that have no nucleus.
- molluscs: A large division of invertebrate (without a backbone) animals. The best-known molluscs are snails, slugs, shellfish, octopuses and squids.
- estuary: A partially enclosed body of water where freshwater mixes with saltwater from the sea.
- ecosystem: An interacting system including the biological, physical, and chemical relationships between a community of organisms and the environment they live in.
- estuary: A partially enclosed body of water where freshwater mixes with saltwater from the sea.
- wetland: An area of land that is saturated with water, often referred to as a swamp or bog. Wetlands may be seasonally or permanently water-logged with vegetation adapted for life under those soil conditions. Wetlands are known as repo in te reo Māori.
- native: A species that lives naturally in a country, as opposed to species that have been introduced by the activity of humans.
- sediments: Material that settles to the bottom of a liquid. In geology, it describes the solid fragments of inorganic or organic material that come from the weathering of rock and are carried and deposited by wind, water or ice.
- fauna: Animals.
- algae: A large, diverse group of photosynthetic eukaryotic organisms. Algae have no stems or leaves and grow in water or on damp surfaces.
- salinity: The amount of chemicals dissolved in water. In seawater, the main chemical is sodium chloride (salt), but there are many others in smaller quantities.
- predates: To hunt or seek prey.
- organism: A living thing.
- kina: New Zealand endemic sea urchin.
- pāua: Large edible sea snails that are found around the coastline of New Zealand. They grow large shells that, when polished, have a blue, green and purple iridescent appearance.
- habitat: The natural environment in which an organism lives.
- copper: A transition metal in Group 11 of the periodic table – symbol Cu, atomic number 29.
- ecosystem: An interacting system including the biological, physical, and chemical relationships between a community of organisms and the environment they live in.
- interdependent: A relationship in which each member is mutually dependent on the others.
