Climate vagrants: Guestblog by Joey DiBattista

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…


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.

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Bleached coral at the Great Barrier Reef. Photo: XL Catlin Seaview Survey

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.

Chaetodon lunula

Tropical species like this Racoon Butterflyfish (Chaetodon lunula) are increasingly found in Western Australia’s temperate waters. Source: www.redmap.org.au

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.

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Joey filtering water in Shark Bay to extract eDNA

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.

 

 

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New publication: Fluo frogfish lures

After a weekend looking for vagrant fish in the cold waters of Shark Bay (more about that later this week), I came home to find a pleasant email in my inbox. A new publication has been published online last week. This one is in the journal “Coral Reefs” and is about biofluorescence in the Striated Frogfish (Antennarius striatus), more commonly known as the Hairy Frogfish. The article can be found here, but is restricted access. For those of you who cannot access it, here is what it is about.

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Hairy Frogfish by day. Photo: Luke Gordon

 

As I have written previously, I have been doing a fair bit of work looking at biofluorescence in fishes. During these surveys i had noticed something strange going on with the Hairy Frogfish: their bodies are not fluorescent, but their lure is (very strongly). As you might know, frogfish use their lure as a fishing rod, attracting small fish closer, which are then eaten whole. The fact that the Hairy Frogfish’s lure alone is fluorescent but their bodies are not, hints at the possibility that this fluorescence could be used in what is called “aggressive mimicry”. Aggressive mimicry is the term used for animals who pretend to be something harmless (the “model”) and use that to get close enough to eat their prey.

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Hairy Frogfish (Antennarius striatus) with fluorescent orange lure

But the question was, what would it be trying to mimic? Are there animals out there that resemble this fluorescent lure? Cue my last Philippines trip. During a nightdive with the unparalleled science hobbit, we found three more Hairy Frogfish (with fluo orange lures). More importantly, we also found a lot of freeswimming worms near them. Most of them a similar size as the lure of the frogfish, AND the same colour fluorescence as those lures. The resemblance between the lures and the worms went further than just size, shape and movement, but also the fluorescence is imitated. We found our model species!

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Fluorescent worm (top orange squiggle) and fluorescent lure (bottom orange squiggle)

This is very exciting, as it is the first time anyone found strong indications that biofluorescence might be used to help fish catch prey. To prove whether it is really used to hunt, lab experiments or extensive observations would need to be done to check if this fluorescence really makes a difference. So while this is a very exciting glimpse into an unexplored part of hunting strategies in the ocean, much more work needs to be done to understand all the details.

If you can’t access the article but want to read it, or you just want to know more, send me an email or ask in comments and I can send the publication to you.

Critters in the cold

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Squid during nightdive in Camp Cove (Photo: Greg Lecoeur)

I have been back in Perth for well over a month now and it had been close to two months without diving, so I was starting to get anxious to get back in the water. I don’t really have the time to go abroad at the moment, so I jumped on the opportunity to do a short trip to Sydney. A good friend (Greg Lecoeur) had an extended stopover before flying to Europe and asked me if I wanted to join him to find and photograph the elusive Weedy Seadragon (Phyllopteryx taeniolatus). Not only would it mean interesting dives, it also gave me the opportunity to catch up with another friend (the amazing Emma Camp) who does some great research at the University of Technology Sydney. The departure of the trip was a bit rushed but I managed to bring everything, except for my actual camera. Luckily both Emma and Greg are great underwater photographers, so I could enjoy the dives and get better pictures than I could ever take of them, win-win!

The waters around Sydney might be a lot colder than what I am used to, but they do offer some sweet diving and a lot of really interesting critters. The best known and most sought after critters in temperate waters in Australia are without a doubt the Seadragons. Seadragons are endemic to Australia (=found nowhere else) and only live in its southern, colder waters. Two species exist within reach of divers: The Weedy Seadragon (Phyllopteryx taeniolatus) and the Leafy Seadragon (Phycodurus eques). We went looking for the Weedy Seadragon, as the leafy variety is only found further south. I had been told where to look and that there were a lot more interesting critters to find, but when looking for critters it’s always a good idea to have a local guide. Through a friend I got in touch with a very keen local diver who knows the waters around Sydney better than anyone. Andrew (check his site here) kindly offered to take us diving and promised us dragons and much more.

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Checking out a gorgeous Weedy Seadragon (Photo: Greg Lecoeur)

Our first dives were in the southern part of Botany Bay, Kurnell is known as one of the most reliable spots for seadragons. After the shock of hopping in 16 degrees cold water (I’m used to nearly double!) I managed to have a look around and appreciate the site. Descent visibility, kelp, rocks, sand and critters, what more do you need? After a mere 15 minutes Andrew delivered on his promise and showed us a beautiful seadragon. We would find a total of 7 that day! They really are amazing and stunningly beautiful animals. While they are related to seahorses and pipefishes, they are still very different. They are quite a bit larger and seem to be the result of a crazy drunk night between pipefishes, seahorses and some strands of kelp. Our presence did not seem to bother them at all, most of the ones we saw were happily pretending to be kelp and didn’t even stop feeding when we came in close for a good look.

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Find the critter, a Sydney Pygmy Pipehorse (Photo: Greg Lecoeur)

We found some other members of the seahorse/pipefish family that day. Besides a Potbelly Seahorse (Hippocampus abdominalis), Andrew also showed us some Sydney Pygmy Pipehorses (Idiotropiscis lumnitzeri). I was under the impression Pipehorses were a tropics only kind of family, but was happy to be proven wrong. This particular species is only found in the greater Sydney area, but is closely related to the ones I was observing in Dauin and Lembeh. They are at least as beautiful as their tropical cousins and in my opinion a lot braver for spending their days in the cold water. That cold water made Emma and me cut the second dive a bit short, diving in Sydney is all fun and games until someone gets hypothermia.

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The beautiful Pyjama Squid (Photo: Greg Lecoeur)

Our second dive day started at Bare Island. I only went for a short dive, but saw 3 juvenile frogfish! What’s more, they were Painted Frogfish (Antennarius pictus), which I also (wrongfully) assumed to be found in the tropics only. It’s funny how after nearly two years of studying critters there is still a LOT I can learn about them. That evening Greg and me went for a night dive at Camp Cove to find a little guy I had been dying to see for years, the Pyjama Squid (Sepioloidea lineolata). The site is a pure muckdive: a calm bay, no structures to speak of, just sand with a smattering of seagrass and some bits and pieces of debris. Needless to say I had a great time in that kind of environment, as would any other diver who likes critters. We found nearly a dozen Pyjama Squid, the first one about 20 seconds after we put our heads down! They are the cutest little things and pretty much nothing is known about them, I might have to consider them for my next project 🙂  We also found a lot of other critters: Bobtail Squid, a juvenile Hairy Frogfish, Toadfish, Bottletail Squid,… Basically everything a muckdiver could want.

Conclusion: Sydney is a sweet place to dive, both for muck and other kinds of diving. But beware of the very real risk of hypothermia (as Emma can attest to), especially if you are doing long dives and not moving much. So bring your warmest wetsuit, tea/coffee for surface intervals and most importantly, don’t forget your camera!

 

Critters Research on Instagram!

It’s been a busy few weeks for me the last few week, which is why it has been quiet for a while on this blog. That will hopefully change in the near future, more critter posts coming up and a trip to Sydney to look for seadragons as well!

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Coming up: looking for more of these guys! (Phyllopteryx taeniolatus)

InstagramLogoIf you are stuck for critter updates in the mean time, here’s the solution for you. Critters Research is now also active on Instagram. Mostly focused on nice pictures and short updates of what is happening at the moment. Check it out at “crittersresearch”  Instagram