I have been writing blog posts about my research for over a year now, talking about how interesting my research is. But there is a lot of interesting marine research happening besides mine. So I will now try to get friends and colleagues to write guestblogs about their research, giving you the chance to have an even better insight in what happens in the world of marine biology.

The person to kick off this new section of the blog is Dr. Joseph DiBattista, a geneticist at Curtin University. If you have been following the Critters Research Instagram account, you might have noticed I was up in Shark Bay last week. I was there to help Joey with his research on “vagrants” in the waters of Western Australia. His blog explains more about these vagrants and what they have to do with climate change…

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The age of climate change is upon us. This reality can no longer be denied given that the scientific evidence is overwhelming. One of the areas hardest hit by this human-influenced phenomena is our oceans, and the result for our precious coral reefs is often bleaching, bleaching, and more bleaching. Just ask those that study our beloved Great Barrier Reef, a UNSECO world heritage site where only 7% of its corals escaped nature’s wrath in early 2016.

At the same time that corals were suffering in Australia, so were mangrove forests that border the Cape York Peninsula in the Gulf of Carpentaria, which experienced a die-off like scientists worldwide have never seen before (i.e. 7,000 hectares of mangroves left dead or dying…). The recent temperature fluctuations are attributed to this year’s particularly strong El Niño–Southern Oscillation (ENSO), and have now caused bleaching at Indian Ocean coral reefs in the Maldives and at Christmas Island for example, and are imminently predicted for tropical sites further north in the Pacific Ocean (e.g. Okinawa).

It may seem like temperate ecosystems are protected from these warming effects, but no more are we feeling the heat than in the coastal waters off of South-Western Australia (WA). Near the end of the summer of 2011 we suffered through what was aptly coined a “marine heat wave”. Sea surface temperatures from Ningaloo reef to the southern tip of the continent at Cape Leeuwin, a distance of more than 1,500 km, crept up to over 5° C above the seasonal average. This affront was both broad and sustained, extending out more than 200 km from shore and lasting more than 10 weeks. The heat wave killed off more than 100 km of economically important kelp forests (often teeming with their own rich and unique fauna), that have to this day not recovered, but instead may slowly be replaced by corals, a process known in the science world as tropicalisation.

This heat wave in 2011 overlays on top of an already warming trend in WA, which itself has been flagged as a global climate change hotspot. Climate change not only affects the kelps and the corals, but appears to be resulting in tropical and subtropical fish species rapidly moving towards the poles. Indeed, in addition to WA, tropicalisation has caused important changes to temperate ecosystems by introducing tropical fishes to sites in western Japan and off the coast of New South Wales, all themselves bathed in warm water currents that act as vehicles for this fresh “flow” of fish larvae.

Normally the water temperatures cool over winter months and these juvenile tropical “vagrants” die off, never to reproduce themselves (…sniff, sniff, shed a tear…), but not for some species. In rare cases, enough individuals survived and have now taken up permanent residence in their new southerly (or northerly for Japan!) home. I have a keen interest in these survivors along the coast of WA, where I have started to use next generation sequencing technology to track the movement and diet of these vagrants. This technology is capable of simultaneously sequencing millions of copies of DNA from complex samples, at a not so nominal cost of course. This innovative work is only possible because of a close collaboration with the Trace and Environmental DNA (TrEnD) laboratory at Curtin University in Western Australia. Particularly Professor Michael Bunce, who has extensive experience in isolating DNA from a variety of substrates including bulk bone, faecal material, and, more recently, samples sourced from the marine sector such as filtered water and fish stomach contents. This project remains in its infancy, but with the Department of Fisheries WA supplementing samples and the TrEnD Lab supporting my experimental work, I am confident that we will soon know exactly where these vagrants are coming from and what they are doing once they get here.

Dr. Joseph DiBattista

Early Career Postdoctoral Research Fellow

Department of Environment and Agriculture

Curtin University

E-mail: josephdibattista@gmail.com

Note: For those keen recreational fisherman or scuba divers in WA, there is a website dedicated to tropical fish species that seem “out of place” in their new temperate environment (click here for site). I encourage anyone that spots vagrant fish to take photos and register their important find on this regularly updated website.