Perhaps the greater visibility of the vertebrates is a reason for their dominanant conservation focus. However, as we re-focus on ecological processes, which a large landscape scale project like Gondwana Link must do, then invertebrates start to get much more of the limelight. Some of the processes that depend on insects, spiders, crustaceans and the rest of the invertebrates are:
- Pollination. With so much diversity and with plants of the same species often far apart, most Australian plants don’t rely on wind pollination but on animals – birds, bats, small mammals like Honey possums and insects. About 15% of the south-western wildflowers are pollinated by vertebrates, notably the larger flowered plants like Banksias which are pollinated by both birds and small mammals like Honey Possums, but smaller flowered species such as Verticordia and Chamelaucium rely on insect pollinators. Some orchids look like the insects they need to attract to their flowers for pollination.
- Seed dispersal. Seeds of some species need to be tough to survive drought and fire, and need to be dispersed away from their parent plants. Ants are the ideal vector and are essential for the dispersal of seed of many species, especially woody ones like Acacias.
- Fragmentation of detritus. Both on land and in fresh and salt water, the sclerophyllous (leathery) leaves of Australian plants would be extremely slow to break down if not for the diverse insects that break them down, thus allowing the nutrients they contain to be recycled through the food chain.
- Nutrient retention and recycling. As well as the nutrients that are in short supply, invertebrates are a key part of the cycling of organic carbon. Isopods, land snails and worms are among those that help to break down organic material and make it available to other organisms.
- Soil structure and aeration. Many Australian soils are non-wetting, and the presence of soil fauna, including worms and the burrowing insects, is one way that soils are aerated and can retain more water.
- Food. Invertebrates are a major part of the food chain for many of Australia’s birds, reptiles and small mammals. Even Honeyeaters, for example, which feed on the nectar and pollen from eucalypts and proteaceous plants, depend on invertebrates for protein at certain times of the year.
- Regulating populations. Predators within the invertebrate world, such as the spiders, regulate other invertebrate populations, while parasites such as wasps can reduce pest species.
- Bioindicators. Aquatic macroinvertebrates are a reliable indicator of aquatic health as they respond quickly and predictably to changes in salinity, nutrients and pollutants. Terrestrial invertebrates, including butterflies and spiders, are potential bioindicators for the health of ecosystems.
In Western Australia, quite a lot of the invertebrate research that has taken place has been associated with post-mining and post-forestry activity. Within the Gondwana Link area there are a few studies and projects that have produced valuable knowledge of the forgotten fauna – but more is needed.