Revealing microscopic details using a Scanning Electron Microscope (SEM)

Using the SEM in bryozoan research

While the coral reefs of the Great Barrier Reef (GBR) receive a lot of attention, much less is known about the areas between the reefs. These “inter-reefal” areas comprise 93% of the GBR Marine Park. Here, animals called bryozoans can dominate the seafloor and create reef habitat that sustains a high diversity of mobile and attached animals, in the same way that corals create habitat on shallow coral reefs.

Queensland Museum Tropics (Queensland Museum Tropics) holds the world’s leading collection of tropical Australian bryozoans, currently ~28,000 specimens. Project DIG has supported acquisition of a scanning electron microscope (SEM), transforming the way we conduct our research on specimens from the Great Barrier Reef.

Bryozoan animals are tiny, usually less than 1 mm in length (like corals, colonies contain 100s or 1000s of individuals). Taxonomy and ecology involve inspecting and measuring tiny features of their skeletons just a fraction of a millimetre long, and this requires high magnification imagery only achievable by SEM.

Why is this research so important?

Bryozoans may act as ecological refugia for shallow coral reef species affected by storms or coral bleaching, and they could be sites of special conservation significance if they harbour species that are rare or have small geographic ranges. Additionally, bryozoans are a source of biologically active compounds for biomedical research – an area of active research in Australasia.

There is an urgency to develop greater understanding of these sites because the delicate calcium carbonate skeletons of bryozoans are susceptible to ocean acidification caused by rising carbon dioxide levels. Rising temperature may also affect bryozoan growth; in Europe, bryozoans are currently used as indicators of environmental change. Queensland’s bryozoans may well prove to be useful indicators of environmental change in the tropics.

Using the SEM in coral research

One of the challenges of identifying corals is that some species can vary their morphology considerably depending on where they live to the point that they can look like totally different species, and transplanting experiments show that even genetically identical individuals can be very inflexible in their appearance. Molecular phylogenetic data is helping us solve these issues, but the hunt is now on for features that allow us to delineate coral species.

Genetic studies have shown that fine-scale features of the coral skeleton are very useful for delineating the groups identified based on genetics. These ‘micromorphological’ characters can therefore be used to identify species, but many of these features can only be examined using a scanning electron microscope (SEM). Having this equipment at Queensland Museum Tropics (Queensland Museum Tropics) assists our researchers to accurately re-identify specimens in the collection and helps them to identify new species.

Our researchers are using a combination of SEM insights and genetic data to develop an image library and provide accurate names for the specimens in our collection, creating a foundation for crucial research that will inform our understanding and conservation efforts of the Great Barrier Reef.

Using the SEM in palaeontology

Our palaeontologists are using the Scanning Electron Microscope (SEM) to uncover new information about our fossil collection, helping us to build a more detailed picture of Queensland’s ancient past.

The incredible magnification of the SEM allows our researchers to investigate minute details of fossil specimens, such as 100 million-year-old fish teeth. In addition to producing high definition images, the SEM’s Energy Dispersive Spectrometer (EDS) can analyse the elemental composition of a fossil. This step is integral to streamlining the research process as it determines whether bones or teeth have been altered or replaced with other minerals during the fossilisation process. These insights confirm if our researchers are actually analysing bone material before moving onto more costly analytical techniques which look at trace elements to determine the habitat, diet and fossilisation history of the animal.

By combining SEM imaging and photogrammetry, we can also produce highly detailed 3D models of microscopic objects. This allows us to enlarge the size of an otherwise tiny object to more easily study it in three dimensions and share our collection and research online with communities worldwide.