The University of Newcastle, Australia

Seagrasses and marine environments - an immersive project

Amanda Clarke can always remember liking the environment, though it wasn’t until she started UON Open Foundation that she realised her love for science.

“It’s one of those things, I’ve just always been a bit of a tree-hugger. And once I started doing my Open Foundation science classes, I sat back and realised, ‘Wait a moment, I like this!’”

Nutrient transfer in marine habitats

During her Honours project, Amanda looked at trophic subsidies and the outwelling process. Outwelling occurs when an excess of nutrients in one catchment flows out and subsidises another; a process which can be both beneficial or detrimental when it comes to overall ecosystem health.

“I wanted to then look not just at outwelling but behind it, where it starts. Seagrasses are a great example to study because there is just so much happening in them.”

Amanda is particularly interested on the impact of human settlement and estuary development on ecosystem health.

“I’ve got a project looking at the influences of storm water after extreme weather events. Often these events can cause sewage overflow – while some nutrient transfer isn’t always a bad thing, if seagrass is exposed to lots of raw effluent, it takes it up, absorbing the effluent and that can be detrimental to the fish and other marine wildlife.

“Then if we then go on to catch and eat the fish then there is potential for all sorts of problems.”

Amanda conducts her research at Lake Macquarie, with support from Hunter Water and Lake Macquarie Council.

“The supporting bodies wanted to know whether their facilities were having a negative impact on the marine environment- and if they were, where the target areas were which needed to be fixed.”

Trigger levels at Hunter Water let Amanda know when their treatment ponds have overflown and this marks the beginning of a sample collection phase.

“You can do all the collection sites in one day, but it’s a pretty long day!”

Amanda collects seagrass (along with its associated algae, or ‘epiphytes’) and common fish species from each site, and then performs stable isotope analysis on the various samples. This analytic technique is commonly used while investigating marine ecosystems as it can tell us about food web interactions and potential detrimental impacts to the ecosystem.

Artificial seagrass: an adequate replacement?

Both natural and man-made disturbances can significantly disrupt seagrass growth, and this has been shown to intensify habitat change, and sometimes even lead to habitat loss. Dredging, destructive fishing, pollution and anchoring have all been shown to disturb local seagrass species. For this reason, artificial seagrass units (ASU) are commonly used in an attempt to compensate for this disruption.

“A lot of people use ASU methods because it is non-invasive,” Amanda confirms.

In another of Amanda’s projects, based in Brisbane Water, she is performing research on ASUs in order to assess just how effective it is as a replacement, in particular in the context of mooring scars. This ‘scarring’ of the sea bed occurs when moored boats drift with the currents, dragging their heavy chain across the seafloor, often creating huge areas completely devoid of these vital seagrass species.

“We want to know whether ASU functions just as efficiently as a nutrient source and habitat. Does it facilitate growth? Does it buffer the water in the same way as real species and aid seed distribution? What sort of organisms colonise there?”

Leading up to collection of her ASU for stable isotope analysis, Amanda monitors her ASU by remote underwater video systems. In doing so, she is able to visualise diversity and abundance of mobile fauna associated with the ASU.

A passion for science communication

Prompted by the mass coral bleaching in the Great Barrier Reef, ‘Real Scientists’, a rotational curated Twitter account, ran ‘Coral Week’, wherein marine biologists were recruited to live tweet their research. Amanda Clarke put her name forward for the task of being a featured curator (following some gentle prodding from her supportive colleagues), and the experience sparked Amanda’s passion for science communication.

“We covered a great deal of diverse research that week because we all came from different backgrounds. It blended together really well though, and I am still in contact with the three curators that I shared the time with.”

Following that experience, Amanda is now a blogger for Scientista, a site dedicated to supporting and reporting women’s careers in science. On the site, Amanda writes about her experiences as a PhD student, from juggling parenting and studying to tips on how to throw a great science themed party.