SCIENCE 1.12 Investigate the biological impact of an event on a New Zealand ecosystem. Internal – 4 credits

What are we thinking about? There are numerous events which affect New Zealand’s ecosystem, from short storms to long-term climate fluctuations, from slow erosion to sudden landslides, from creeping evolution to the sudden introduction of foreign species. You will study one event and the biological impact that event has had on an ecosystem

Ecosystem Definition: All the organisms living in an area and all the environmental factors that affect them. This means that an ecosystem can be a tiny piece of decaying fruit or as large as the Southern Ocean. What are some examples of Ecosystems that you can think of?

Some examples of ecosystems A mountain

Alpine tussock grassland Lammermoor range, Otago

Kaimanawa ranges ecosystem

Ocean

Pasture ecosystem

Some others Sand dunes Native forest grasslands Tidal areas such as mangroves, mud flats, rocky shores

Environmental factors The event (introduction of horses) will have caused a change in environmental factors. You will need to identify what environmental factors have changed and are causing the change in organisms. Ecosystems are often controlled by one factor in particular, such as the length of time spent in sea water on a rocky shore. But there are also many other interactions happening in an ecosystem.

Abiotic and biotic Biotic factors – living factors, including interactions between organisms, such as competitions, predation, parasitism and disease. Abiotic factors – non living, physical factors such as moisture levels, wind speed, wave action, temperature, oxygen levels and light intensity.

A biological impact A biological impact could be a change in the number (density) or range (diversity) of organisms. This change could have an impact on the ecosystem as a whole, effecting food chains and food webs, etc. When you consider a impact, you don’t make a judgement whether it is good or bad, you just consider data, evidence and known facts.

Combined effects Within an ecosystem if one factor is changed, it can have an effect on other factors.

Mangrove ecosystem The removal of mangroves growing on a tidal mudflat may increase the effect of waves, leading to greater erosion of the coastline, which may lead to the death of more mangroves.

Human effects on ecosystems Humans can have a direct or indirect effect on an ecosystem. For example, humans can spill oil which may cover a shoreline with thick, black crude oil. The fact that humans did it, makes it a biotic effect, but the effect on the shore will be due to abiotic factors such as reduced oxygen levels, lower light levels or an increase in the levels of toxic chemicals.

Communities Ecosystems are made of the habitat (non-living) and communities within it (living organisms). Defined as all the organisms living in an area and the relationship between them. All the plants and animals living in an area, being part of a complex food web are all heavily reliant on each other. Relationships can be so strong that the presence or absence of one key species can change a whole community.

Communities in ecosystems Mountain ecosystem Alpine rock and snow Alpine tussock Steep mountain streams Isolated forests Native and introduced grasses

Alpine tussock grassland ecosystem Alpine rock and snow Large rivers Tussock grasslands Rock outcrops

Indicator species Organisms have preferences and limits for environmental factors and where they want to live. An indicator species is one whose numbers are sensitive to environmental threat, and which can be used to indicate the state of health of that environment. When we know what effects a species, we can use their number, health and distribution to identify issues in an ecosystem.

Plant indicators Because plants can’t move, they are good indicators. They are affected by the nutrients and water their roots can obtain. Plants will then show the effects of ground disturbance, like that caused by being trod on all the time. (especially from above)

Insect indicators Insects are widespread and involved in nearly every community relationship including decomposition of forest litter, pollination, parasitism and predation. Also important food sources for birds, lizards, tuatara and freshwater fish. Insect larvae are often found in streams, their abundance indicates a lack of pollutants and good oxygen levels.

Some examples of indicator species Woodrose – a parasitic flowering plant Forest health in parts of the North Island If there is lack of woodrose, it indicates presence of browsers, native pollinators, seed dispersers and host trees. Kiwi lack of kiwi indicates an abundance of mammalian predators

Most destructive species in NZ What do you think is the most destructive species in NZ?

Probably humans! Why? We have altered nearly every Ecosystem in New Zealand. We have introduced over 32 mammals, 33 birds, 3 amphibians, 18 fish, 33 reptiles, thousands of species of invertebrates, plants and micro-organisms into New Zealand who have all had an affect on Ecosystems, eg, rat, possum, goat and wild horses.

Introduced species Of all of the species introduced, many didn’t survive, thankfully! Eg, Zebra, camel, squirrels. Of those that survived, many became major pests within a few years. To exterminate little ones such as rabbits and hares their natural predators were introduced – weasels, ferrets and stoats. Larger pests such as deer and pigs were shot as their natural predators (wolves, tigers, lions) were too dangerous! Really? Didn’t work well – what do you think was the consequence? One of the worst is the possum along with many plants

1. Environmental Factors Describe how the event changed environmental factors in the ecosystem you are investigating. You need to find information on at least two factors. Eg, In the stream that ran through native bush, average water temp was 15C during the sampling period. In the stream in the industrial area, average water temp was 17C Organisms need to be adapted to environmental factors to survive, so if they change, an organism may be affected. see hand out.

2. Changes Explain how the event changed a characteristic of, or process within, the environment. Eg, the suspended particles in the water in the stream in the industrialised area contributed to heating the water as the particles warmed up. There is less dissolved oxygen in warm water than in cold. The warmth of the water in the stream in the industrialised area meant there could be little dissolved oxygen in that part of the stream.

3. Impact Explain how these changes have had an impact on the organisms in the ecosystem. You can discuss diversity and density of species, plants or animals that have been effected here.

4. Implications The implications that the changes have for the ecosystem as a whole can be discussed here. You need to link your findings and biological ideas into a comprehensive discussion of the biological impact of the event on the ecosystem. Make causal links – constantly explaining how or why one change caused another change. Also discuss the implications of these changes for the organisms and the ecosystem.