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Terrestrial invertebrate ecology

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Dr Gollan is a terrestrial invertebrate ecologist. Insects make up 99% of Earth’s biodiversity and are an important part of our environment, one being to decompose organic material. Anyone scraping back compost will see the amphipods (sometimes called land shrimps), springtails and isopods that live there and which break down the leaf litter layer.

Invertebrate ecology often requires you to be up-close-and-personal with study subjects. Here, Dr John Gollan is extracting a trap door spider from its underground burrow in the Pilbara, WA. The Pilbara has great economic value due to the presence of minerals such as iron ore, but it is important to remember that conservation of all animals – even the ‘creepy crawlies’– need to be considered. 
Insect research is not easy. A field study could potentially collect many thousands of insect specimens which would then take months to sort through and analyse.

Citizen science may well be the answer here as was some citizen science research into spider webs. Spider species often spin their own distinct kind of web so for this project a web identification guide was developed so that people could measure spider web diversity in their environment. The guide worked like a dichotomous key (think choose your own adventure story) which led participants to one of 32 web types. Some questions to be considered when identifying webs were based on web decorations like crosses, radial supports or open centres while other decorations use leaves that are curled into the web which the spider uses to hide in.

Other webs are called lace webs for obvious reasons and there are also ladder webs and platform sheet webs that spiders use when they emerge from their burrowed funnels. Not all spiders make webs.
The micro world of invertebrates is largely forgotten when it comes to species conservation and the scale of some insect communities is very small, some always living in mere metres of space their whole lives. Development and environmental changes for those insects are far more damaging but insects have yet to be placed in high regard as are mammals
or birds.
Field work in remote locations is rewarding, but also has its challenges. Here, Dr John Gollan and colleagues are exploring an isolated ridge for the presence of short-range endemic (SREs) invertebrates. SREs are ones that have a restricted distribution, reliant on particular habitat types and have limited ability to move around the landscape. These characteristics put them at high risk of extinction from large scale developments such as open cut mines.

Ants, for instance, provide the ecosystem service of seed dispersal. Many acacia species (often called 'wattles' or 'mallee') have seeds with small external glands which ants can use to latch onto and haul underground where the seeds can then germinate. Of all the invertebrates, bees are perhaps the most important as they are the pollinators on which many plants rely.

Dr John Gollan extracting a trap door spider from its underground burrow in the Pilbara region, Western Australia. A steady hand with forceps is required to catch the spider. This type of work is not for the arachnophobes!
Invertebrates are also important for removing waste - if invertebrates were not there, we'd be up to our knees in it! In a recent study, the effect of dung beetles on manure was studied in plots that had been replanted with native species. Both numbers of beetles and speed of decay were studied, the result showing a direct and close relationship.

Monitoring rates of dung decay as an indicator of an ecosystem service are the kinds of tools that allow citizens to be involved in invertebrate ecology. More importantly, they are tools that leave the invertebrates in the environment and not in glass jars on the shelves of scientists! Citizen science may well be a way of putting invertebrates under the microscope.


St Andrew's Cross spider in web.

The guide to identifying web types is located at: 

A guide to the spiders that make different web types can be found at:

Dr John Gollan was interviewed for A Question of Balance by Ruby Vincent.
All images provided by Dr Gollan.
Summary text initially prepared by Victor Barry, December 2012 and re edited April 2015 and November 2016.

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