Marine life

Into the Storm


Earlier this year I presented some of my findings at the 2016 Australasian Society for the Study of Animal Behaviour Conference in Katoomba. These findinges were based on data collected over the last 2 years during which my field sites have been impacted by 2 cyclones. Below is an adaptation of the talk from the conference.

The Importance of Sociality

slide2There are lots of examples in nature of animals that form social groups. These species gain advantages and incur disadvantages from their social behaviour. For example an advantage might be better predator detection while foraging (known as the “many eyes” hypothesis) while a disadvantage could include higher rates of disease transmission. Studies suggest that the evolution and maintenance of sociality is likely to be influenced by environmental factors. Changes in the environment, like those caused by extreme weather events, are therefore likely to impact upon the social organisation of social species.

For social species, the balance between the advantages and disadvantages of sociality are vitally important in determining reproductive output, competitive ability, foraging success and survival, factors which can ultimately impact on a species’ ability to recover from a major impact.

The Study System

slide3My research focuses on the coral gobies at Lizard Island, Queensland. Coral gobies are small fish, approximately three to four centimeters in length and they spend their entire adult lives within the branches Acroporid corals (corals of the genus Acropora). They suffer high mortality outside of their corals, and as such rarely move between corals once they have established themselves. I have observed up to 16 species of coral goby at Lizard Island which range in social organisation from strictly pair-forming species (which I will refer to as ‘Asocial’ species) to highly social species which can be found in groups of 12 or more (the largest group I’ve found was over 20 individuals).

slide4During my studies, two cyclones have impacted my sites at Lizard Island which has been quite disruptive to my research, but has also presented a rare opportunity to gain an insight into the rarely studied effects of cyclones on social organisation. There is no doubt (unless you’re a cyclone skeptic) that cyclones cause severe damage to the physical structure of the reef. This destruction obviously has impacts on the abundance, diversity and distribution of reef species following the event. For example, obligate reef-dwelling species (species which depend on the structure of coral reefs for protection and food) tend to decrease in abundance while algal grazers tend to increase in abundance. However we know relatively little about how these events affect social structures of reef inhabitants which is a potential driver of the diversity and abundance patterns we observe. As I previously mentioned, social organisation is important in determining factors such as reproduction, foraging success and survival, all of which are critical for a species’ recovery from a major disturbance.

Methods and Results


We have been surveying sites around Lizard Island since 2014. During these surveys we search each Acroporid coral on our transects for coral gobies. We identify the gobies to species and count the number of individuals living within each coral head (which constitutes a group). We also identify the coral to species and measure it along three axes to estimate an average diameter. I’ve used average diameter in my research so that my findings are directly comparable to previous work which has used this measurement.

The next few slides show some graphs and conceptual diagrams in which I’ve tried to use consistent symbols which I’ll briefly explain. The yellow fish represent ‘asocial’ species (they’re actually pictures of Gobiodon axillaris, a strictly pair-forming species). The green fish represent the social species (these are pictures of G. erythrospilus which is often founds in groups of 3 or 4). I’ve used a little cyclone symbol with an arrow on the graphs to indicate when a cyclone affected the field sites.

slide6We found that social species decreased in group size following each cyclone while asocial species group size remained the same. This indicates that group size decreases observed in social species were unlikely due to direct mortality from the cyclones (otherwise we would have seen a corresponding drop in average group size in the asocial species as well). A year after the first cyclone, the social species had returned to their pre-cyclone group sizes (keep this point in mind as I’ll return to this in a minute). However, a year after the second cyclone the social species had not returned to pre-cyclone group sizes. This may indicate that multiple impacts have longer lasting effects on social organisation.


Unsurprisingly, we found that coral size had decreased significantly throughout the study. This was the case for for both social and asocial species. The last set of bars on this graph shows the corals that were uninhabited. I’ve included this to illustrate that corals that were uninhabited at the beginning of the study (darkest bar) were of a similar size to the corals that the gobies were inhabiting at the end of the study. This means that at the end of the study, gobies were cramming into small corals that they previously wouldn’t have inhabited.

Let’s return now to that point I made about the social species returning to pre-cyclone group sizes a year after the first cyclone. From the coral size graphs we can see that these larger groups were cramming into smaller corals than before the cyclone.


I might pause here for a second to explain the underlying mechanism of the hypotheses of social evolution which I have looked at in this study, the ‘ecological constraints’ and ‘benefits of philopatry’ hypotheses. For both of these hypotheses we need to consider the proposition that social groups arise because subordinate individuals make the decision to delay their dispersal (often at a considerable cost to their own reproductive opportunities). The question of why some individuals will delay or forgo their own reproductive opportunities in order to remain within a group is one of the fundamental questions of evolutionary ecology. There are of course other ideas about why social groups arise, but this idea of delayed dispersal is what I will focus on for this study. It is also important to note that these hypotheses are not mutually exclusive and often act together.  So why separate them out? Well, because each hypothesis contains its own set of testable parameters. These parameters can be used to create a statistical model which we test against the real data and we can determine which hypotheses best describe the observed social structure.

Ecological Constraints

slide8This hypothesis looks at ecological factors which might constrain dispersal from a territory such as a lack of available habitat or high predation pressure. In relation to my work, one of the reasons that the social gobies might have re-formed their large social groups in smaller corals could be that they were constrained by a lack of available habitat. i.e. Gobies displaced by the cyclone might have had no choice, but to move into a coral which already had a small group of fish living in it. In this case, we would expect to see that most of the corals would be inhabited because vacant corals would be quickly taken up by gobies dispersing from crowded corals.

Benefits of Philopatry

slide9This hypothesis looks at the idea that animals gain some benefit of remaining on a site that outweighs the benefits of dispersing. For example, the site might be of a high quality which improves the animal’s fitness to survive and reproduce. Dispersing from this site risks, losing this benefit, unless it can find a site which confers the same or better benefits. In my project, it is likely that there was a lot of variation in coral quality following the cyclone. While fish might have quickly moved into whatever shelter they could find, they might have realised later on that their coral was not very good (indicated by the green, algae covered coral in the diagram), and decided that it was more beneficial to vacate their low quality coral and move into a high quality coral (white coral in the diagram) with an existing group of fish. In this scenario, we would expect to find a lower proportion of inhabited corals than we would under the ecological constraints scenario as fish would have vacated low quality corals in favour of high quality corals.

slide10What we found was that after the cyclone, there was indeed a substantial drop in the proportion of inhabited corals. While this doesn’t definitively prove that benefits of philopatry are causing the observed social patterns, it does lend some support to the idea. There was also a drop in the proportion of inhabited corals for the asocial species, but it was not as substantial as that observed for social species. This likely due to a methodological ‘artefact’ which I won’t get into, but suffice to say, for social species, there is some support for benefits of philopatry playing a role in the observed social pattern following the first cyclone. Stay tuned for a more in-depth analysis of this data.

slide11So, in summary, the major findings of this study were that after a cyclone, social species reduced in group size but asocial species did not. A year later social species had returned to their pre-cyclone group sizes, but in smaller corals. There is some evidence that benefits of philopatry are contributing to this pattern. The fact that asocial species did not alter their social organisation could indicate that the asocial strategy is either more robust to such an impact or that it is less flexible. Unfortunately, my surveys were not designed to examine patterns in abundance and I can’t really say whether either strategy is better or worse for recovery following a cyclone. This would be an interesting avenue for further research. Following a second cyclone, social species again decreased in group size, but did not return to pre-cyclone levels another year down the track. This might be because multiple impacts have longer lasting effects on social structure or because corals had reduced to such a small size that they were not capable of supporting larger groups.

Social organisation in social species is influential  in determining survival. The effects of cyclones on social structures has received little attention thus far in the scientific literature. While my research raises many questions, I hope that it can provide a foundation to build upon and move toward  a better understanding of how severe weather events might impact upon social organisation.

I would like to thank my supervisors and field assistants who have contributed to this work. Also a shout out to the Hermon Slade Foundation for funding this research and  the Lizard Island Research Station for accommodating us.

State of fear: what should we do about sharks in New South Wales?

Jane Williamson

Sharks have long been a symbol of the terror of the deep seas and a source of trepidation among Australian beachgoers. But a recent cluster of dangerous encounters with sharks in New South Wales has raised new concerns among the public and sparked fresh calls for culls.

Fears of more casualties are also changing the way our beaches are being used. Some high schools have reportedly cancelled their surf programs, and several surf lifesaving clubs recently announced that they will seek other venues for “Little Nipper” training.

So what’s actually happening with the sharks?

Shark attacks or shark bites?

Negative interactions between sharks and people can range from light (small lacerations and stitches required) to severe (large pieces of flesh removed, including limbs).

All are routinely termed “attacks”, but as this emotive word conjures up a perception of maliciousness on the shark’s behalf it is not a very useful description. There is a recent move to rename shark attacks as “shark bites”, in the same way that injuries from aggressive dogs on humans are documented, thus lessening the incorrect perception that all interactions with sharks are fatal.

Due to their public interest, there are good data sets on negative interactions with sharks in both Australia and globally that span centuries. Comprehensive data on shark bites, including those in NSW, are collected and compiled in the publicly available Australian Shark Attack File (ASAF), which was established in 1984 and is held at Taronga Zoo.

ASAF data and associated publications do show that shark bites have increased over the past couple of decades, from an average of 6.5 incidents annually from 1990 to 2000, to 15 incidents per year since 2000.

Interestingly, however, while the number of shark bites has recently increased, the number of deaths resulting from the bites remains consistently low (an average of 1.1 people per year over the past 20 years).

Why are fatalities from sharks not increasing in proportion with the increase in shark bites? If sharks were the premeditated killing machines portrayed by the media and entertainment industries, why do most negative shark-human interactions involve only one bite and not the victim being consumed?

Feeding habits

Answers lie in the way that sharks feed. Sharks are apex predators that actively hunt their prey, which can include fish, seals and whales. But they are also opportunistic scavengers that feed on dying or dead organisms, as do terrestrial predators such as bears and lions.

It is important to understand this because it means that sharks are not always the hunters they are painted as. A surfer in a wetsuit paddling on a board could be mistaken for sick or dead prey, floating on the water. The shark may give an exploratory bite to assess. Unfortunately such exploratory bites can remove substantial tissue and even limbs in humans, particularly if the shark is over two metres in length, and may thus be fatal.

Data from ASAF support the concept that sharks are not actively hunting humans as prey, and that a bite is more often a “mistake” by the shark. The vast majority of bites occur on a victim’s extremities (legs, arms), consistent with exploratory bites by scavenging sharks. The shark usually disappears after the initial bite. There are no accounts of a person also being bitten when coming to the aid of a bitten victim in the water.

More people, more encounters

While the number of negative interactions with sharks has risen this year, there have been previous clusters of interactions in ASAF data. A peak of 74 incidents was documented in the 1930s. Considering the method of reporting at the time, it is highly likely that this number was greater.

While it is easy to assume that today’s increase in negative shark-human interactions is directly related to an increase in the number of aggressive sharks in the vicinity, there are other hypotheses that can explain this pattern. John West, the curator of ASAF explains that more contact between sharks and people has also resulted from an increase in the number of people and how they use the beach.

The number of incidents and their locations coincide with an increase in the number of people residing in rural coastal areas, particularly in northern NSW. There has also been a steady increase in the use of beaches and water activities over past decades, which has resulted in more people being in the water.

People have also extended their time in the water, with an increase in the use of wetsuits. Methods for reporting negative shark interactions have also improved. All such reported interactions attract substantial media attention in recent times, leading to the perception of proportionally more interactions than actually occur.

It is also highly probable that the behaviour of the sharks may have changed and not the number of sharks in the water. Sharks are known to come into shore to follow baitfish, which have been prevalent in the shallow waters of beaches this year. It is difficult to know the probability of this without rigorous scientific data that track the patterns of movements of the sharks.

To kill, or not to kill

Following the recent spate of bites this year, controversy exists as to whether beaches in northern NSW should be meshed – which has been known to indiscriminately kill sharks. However, negative shark interactions continue to occur in beaches from Newcastle to Wollongong that are periodically meshed by the Shark Meshing (Bather Protection) Program.

Since 2005, shark bites have occurred at 13 of the 51 meshed beaches. This should not be too surprising because the nets are only 150 m long and 6 m high, allowing marine organisms to swim over, under and around them. Shark nets are not continuous curtains of net that completely enclose areas for swimming, as in the case of the stinger nets found in northern Queensland. Moreover, they are deployed for only part of the year.

But experience from Western Australia shows that shark culls also do not work. Instead, NSW Premier Mike Baird has announced an A$250,000 shark tagging and surveillance program alongside an international “shark summit” to be held this month.

Baird’s more measured and rational approach to beach safety should be welcomed as a valuable addition to a debate so often driven by fear.

Jane Williamson, Associate Professor in Marine Ecology

This article was originally published on The Conversation. Read the original article.


Did that get your attention?

There has been a lot of media attention surrounding sharks recently, starting with that terrifying footage of Mick Fanning and a number of incidents on the NSW north coast. Following on from these incidents there have been calls from a very vocal minority of ocean users to ramp up efforts in shark control measures. It should come as no surprise that I don’t support lethal methods of shark control. As far as I’m concerned there are much bigger risks in life than the threat of being bitten by a shark. If we wish to enjoy the ocean we should know the risks and accept that we share this wonderful environment with these apex predators. However, with all of the media hype, it’s easy to forget that we also share the ocean with some other amazing animals, which is what I though I’d share today.

The beauty of the ocean never ceases to amaze me.

A picture tells a thousand words Jan – Feb Lizard Island trip

I was joined by my sister, Kaz (author of the Madagascan Adventure series) on my latest field trip to Lizard Island. We repeated the surveys that Kylie, Grant and I had conducted last time and ran an experiment to investigate whether a subordinate fish would decide to move out when exposed to an adjacent coral of varying size and with different numbers of fish already residing in it.  I hope you enjoy this visual expose of our time there.

Life at Lizard

The Experiment

For a brief description of the experiment we ran see here.

Day Reef trip

We were honoured to be invited by Anne, Lyle and Alex for a trip out to Day Reef on our day off. It was meant to be a dry day for us, but we were willing to make the sacrifice!

Interesting inkings

downloadBefore we delve into a couple of fascinating media reports which I’d like to share, allow me to apologise for the long interval between posts. There will be a report on my latest round of field work coming shortly. But in the mean time, please enjoy these marine media clippings:

Squid recode their genetic make-up on-the-fly to adjust to their surroundings

Meet Ruby, Australia’s newly discovered seadragon

A small win for the PhD!

I had a small win this afternoon!

I’m back on Lizard Island at the moment and over the last few days I’ve been setting up an experiment.


This experiment is to try to determine what factors might influence a subordinate individual’s decision to either stay within a group or to move out. I am testing habitat size and habitat saturation. To test these factors I have created groups of three fish (two adults and a subordinate) in medium sized corals. These groups of three are then presented with either a small, medium or large coral containing either 0, 1, 2 or 3 other fish.

Wow! that’s confusing when I write it all out. Here’s a diagram of my experimental design.

Experimental design

Over the last 48 hours Kaz and I have had the first trial running. In trial 1 the group of three fish were presented with an empty coral which was smaller in size. Last night the subordinate actually moved into this smaller coral. I can’t really draw any conclusions from this one trial, but if we keep seeing this happen, it could indicate that the degree of habitat saturation is more critical than the size of the habitat in determining whether a subordinate will stay or leave a group. In terms of group formation, it could indicate that groups are more likely to form when the habitat is highly saturated (i.e. when there are not many vacant corals). That’s exciting for me and my thesis 🙂

More info on my research

My research

Initial project report

Lizard Log series starting here

Lizard pics

Fish tattooing

Fish tattooing

Capturing the fishies

Capturing the fishies

Goby hunting.

Goby hunting.

Kaz shopping for corals

Kaz shopping for corals

Kaz measuring

Kaz measuring

It's not paradise every day...

It’s not paradise every day…


Part 3: Conservation and the Vezo

I promised to talk more about the Vezo people, whom I lived amongst for three months, in my last post, so here we go…

The Vezo are known to be the best fishermen in Madagascar. The name ‘Vezo’ translates to, ‘ROW!’ (Literally the imperative form of the infinitive verb ‘mive’, so it’s the command ‘ROW!’), which is apt, as they may well be the best seafarers in Madagascar as well!

Readying the pirogue

Readying the pirogue

Local fisherman. Photo by Sandy Maksimowska.

Local fisherman. Photo by Sandy Maksimowska.

(See more of Sandy’s beautiful photos here)

Living a hand to mouth existence as they do in Andavadoake, is a hard life. It begins before sunrise and ends when you have enough fish to feed your family, and on a good day you might have a little left over to sell as well.

The ocean and the seafood it provides is vital to the Vezo as the main source of protein in their diet and a crucial source of income. The sandy soil that surrounds their homelands make agriculture near impossible, so the sea really is their food bowl and therefore, needs to be managed in a sustainable way. Not to mention the inherent cultural value that the ocean represents for the Vezo.

Who are we, coming from rich, developed countries, to tell these subsistence fishermen what they can and can’t fish and what sizes they should be? The people of Andava (and beyond) don’t have the luxury of being choosy when it comes to their catch. They don’t have the luxury to be able to afford to throw things back if they don’t meet our conservation standards.

However, with a booming population (the village of Andava doubles in size every 10-15 yrs) comes increasing pressure on the once abundant food bowl; the sea. And what about the national and international (Europe and Asia) fleets that fish these waters as well? This has amounted to huge pressures on the inshore reefs and eco-systems that feed so many.

Blue Ventures (BV) recognized the challenge facing the reef and its people and seeks to engage and educate the community not only on the issues of overfishing and destructive fishing practices, but also to assist in developing strategies that will help fishers fish more sustainably (BV’s efforts are not solely focused on the marine environment. Take a look at their website to learn more about their integrated approach to conservation, incorporating community health and education programs! I simply cannot cover it all here). This has seen the adoption of temporary and permanent Locally Managed Marine Areas (LMMA’s) and the development of aquaculture projects such as sea cumber and seaweed farming. Aquaculture is growing rapidly, generating alternate incomes for families and also getting women more involved in income generation and importantly, management of these industries.

Seaweed farming in Tampolove

Seaweed farming in Tampolove

Seacucumber pens in Tampolove

Seacucumber pens in Tampolove

BV’s establishment in the area came via an unlikely hero… Octopus! They’ve had incredible success with this lucrative fishery, which I believe, cemented the relationship between BV and the wider community. After the first temporary closure of the octopus fishery on one small section of reef in 2004, the community saw amazing results with unprecedented catches, and an increase in number and size of individuals. This strategy has been reproduced up and down the coast over the following years, and has now gone countrywide with communities in the northwest and northeast of the country using the same model, and Madagascar’s government establishing an annual national closure!

On the back of this success, many of the fishing communities saw the benefits of marine reserves and created their own network of reserves called the Velondriake (means ‘to live with the sea’ in local Vezo language) which comprise 640 sq km of protected area. It encompasses 25 villages and representatives from these villages establish and protect their marine reserves under the LMMA structure. BV volunteers collect data on both reserve and non reserve locations to help with the decision making and build a stronger case for the implementation of marine reserves.

Sustainability is key to the Vezo’s survival – what more of an incentive does one need to protect the Great Reef? And coupled with the adoption of aquaculture projects and other alternative income activities, such as eco-tourism, are showing this community that there is hope for their future.

President of the Velondriake stating the rules on opening day

President of the Velondriake stating the rules on opening day

Octopus reserve opening day on Nosy Fasy

Octopus reserve opening day on Nosy Fasy

My experience in Andavadoake told me that yes, conservation is a luxury, and yet it is necessary for the survival of fishing communities, not only in Madagascar. It was amazing to see so many people in this community willing to make sacrifices in order to mitigate the challenges they face with food and income security. It’s inspiring to see a community so focused on a common goal, which will not only benefit them as a people in the long term, but the environment upon which they rely, as well. Win, win!

So what did I learn/what have I taken away from the experience?

I’ve learnt to appreciate living a day-to-day existence, rather than always looking to the future for the next big thing – though whether I can maintain this back in the fast paced, developed world, remains to be seen. I’ve learnt to be more mindful of our oceans, what we’re taking from it and what we’re doing to protect it. I was inspired by many of the staff and volunteers I met along the way and am grateful for having made some great connections with people I know will be my friends for many years to come.

People always ask me, “what was your favourite part?” This is such a difficult question, but I guess my answer would be: Having the opportunity to live with the people of Andavadoake. Learning (sort of!) their language, listening to their stories, meeting their families, observing and participating in their way of life. Having that sort of context overlaid on the volunteer work we were doing, was for me, the best part. I wasn’t just counting fish, I was contributing to building a sustainable future for the people I met along the way.

On the whole, it was eye opening, enriching, challenging at times and a whole lot of fun. It gave me an appreciation for what it is to live in a remote community and the challenges they face each day and it gave me perspective on my own life.

Beautiful Andava Rock

Beautiful Andava Rock

And I saw the boababs and lemurs that had lured me here in the first place!



Brown Lemur in Parc National de I'Isalo

Brown Lemur in Parc National de I’Isalo

Ringtail lemurs in Réserve Park

Ringtail lemurs in Réserve Anja

Magical Indri in Parc National Andasibe

Magical Indri in Parc National Andasibe

Simporna (Silky Sifaka) in Parc National de Marojejy

Simporna (Silky Sifaka) in Parc National de Marojejy

Misaotra Bevata!

A Madagascan Adventure: Part 2

Part 2: Life as a volunteer

Picking up from where I left off in the last post, after our sojourn through the Madagascan countryside, our initial culture shock somewhat subsided; my fellow volunteers and I were finally in Andavadoake – our home for the next 6 weeks (for some of us, the next 12 weeks). Following that first hypnotic sunset, it was time to get stuck into life on site. Our living conditions were basic but comfortable, with huts situated right above a small cove called half moon beach. We’d wake to the sound of the waves and passing pirogues (wooden sail boats) heading out for the day’s fishing.

Beach Huts

Home in Andava

Our diet consisted of mainly fish, beans and rice, with a few variations on the theme from time to time, including the delicious Malagasy beef equivalent – zebu; The mighty zebu is also used to draw carts, plough fields and buy wives and is a precious commodity for many tribes in Madagascar. I couldn’t get enough of the fresh seafood, though we did miss the abundance of fresh fruit and veg we’re used to back home.

But basically, we were living in paradise!


The mighty zebu


Freshly caught lunch

A typical day consisted of 2 dives in the morning, many with whale sightings on our ride out to site, a stroll to the village for a cup (or five!) of peanuts, study/hammock time followed by duties, lectures, presentations or language lessons then dinner and ‘tantara’. Tantara roughly translates to ‘story’ in English, and we all took turns to tell a story, run an activity or game, show some pictures etc. for our evening entertainments

A typical week was diving Monday-Friday, Saturday land based activities like visiting mangroves or learning to cook samosas and boko boko (deepfried dough filled with chocolate – yum!), followed by a night of shaking our butts Vezo style in the local bar, Dada’s… the Malagasy’s put us Westerners to shame! Those guys can seriously move. Sunday was our day off where we got to go exploring! We embarked on baobab walks, whale watching, spear and lobster fishing, island picnics, snorkeling trips and even an overnight camping trip on a nearby island. One of the highlights of the trip!

making samosas

Making Samosas. Photo by JD Toppin

(for more adventures, check out JD’s travel blog here)


Camping at Nosy Ve

We were assigned English partners and spent three sessions a week imparting our knowledge of the English language onto them with varying degrees of success. During the expedition my English lessons consisted of the pleasure and delight of trying to decipher then reinterpret the PADI divemaster manual for one of our boat drivers and dive master in training, Patty. Challenging? Yes. Poor Patty. I think I successfully confused him rather than enlightening him! If you’ve ever read a PADI manual, you may understand my struggle.

But back to my reason for travelling to Madagascar – the marine environment. I was here to count fish! As a volunteer, I had to learn 150 fish species along with 36 benthic and invertebrate species. Thank goodness our coral ID was limited to 11 hard coral formations and simply, soft coral. We didn’t have to be species specific. Those scientific names may have killed me! As it was, when I closed my eyes at night, I would see fish and corals flying at me and I’d be chanting names over and over in my head!

Luckily for me, I’ve been plaguing my brother with fish questions over the years of diving together, so I had a basic knowledge of some fish families before we even started, which was an advantage. But when it came down to species level, I still needed work, especially as not all the names were the same – moon wrasse became crescent wrasse, leather jackets became filefish, bullseyes – sweepers, flutemouth – trumpetfish…

Benthic on the other hand, was a bit of a struggle. I’ve never been overly enamored with benthic life, accepting kelp and sea grass, sponges, and corals as an important part of the ecosystem, but indifferent to their actual role and avoiding invertebrates such as sea cucumbers like the plague (ick!). However, our passionate field scientists were somehow able to convince me that benthic was cool and I subsequently looked forward to a bit of benthic surveying.


My fav coral species, Goniopora; despite it’s appearance, this is a hard coral! Image from Wikimedia Commons

I even overcame my fear of sea cucumbers one spring tide, when we helped the aquaculture farmers with their data collection. I opted to be the weigh-er, thinking it would be the best job to avoid handling any squishy, slimy, boneless creatures. Turned out, I had to pick up every. Single. One. Not once, but twice! After a few girly squeals, I managed to get into the swing of things. I can’t say I love them as a result, but I don’t have that fleeting moment of panic when I see them now.


Zanga! (Seacucumbers)

The sites we dived ranged from healthy to pretty destroyed. The ones that didn’t look so great were affected by a combination of cyclone and storm damage plus destructive fishing practices and overfishing. Education and subsequent dinas (local laws) are in place, to outlaw destructive fishing methods such as poison fishing and beach seining. This has improved the health of the reefs in many areas, which is encouraging to see. Most sites were populated with small to medium reef fishes such as schools of snapper, fusilier, parrotfish and many species of wrasse. But the best part was diving in the protected areas and seeing HUGE fish, such as blue spined unicorns, often in schools, which seemed to be a sign that the protection zones were working! Win!


School of snapper. Photo by Niki Boyer

Diving with species knowledge really made it such a rewarding experience. It was always exciting identifying something you hadn’t seen in the water before, or something you struggled with! And I had some really special encounters including seeing a turtle – turtles are rare as they’re hunted as a coming of age ritual – hearing humpback whales sing quite regularly, a myriad of new nudis (colourful seaslugs), schooling, yes schooling Moorish idols, and even a sailfish!!


Some kind of Halgerda Nudibranch. Photo by Niki Boyer

Expedition life was an incredible existence for me. So far removed from my everyday reality in Australia. It was refreshing to be learning again and to be immersed in a culture and way of life I never knew existed. I will talk more about the people of Andava in my next post…


Being in or on the water every single day!

The infinite stars at night

Watching pirogues sail by

Constant sound of the ocean

The pace of life

The vazah and vezo friends I made

My hammock

Kids yelling ‘Salama’ everywhere you go

The dancing!



Sand in my bed


hammock day

View from my hammock

hammock sunset

Sunset from my hammock


Stars! Photo by Ben Large

Initial Project Report


Last week I presented at the University of Wollongong Post-Graduate Conference. I have adapted my presentation below as it was a good overview of my project to date. By way of some background, each year the biology post-graduate students are set a challenge to incorporate an object or personality into their presentations. This year it was Leonardo Dicaprio, so keep an eye out for some celebrity cameos.

So without further ado, let’s start this talk by having a quick think about why animals form groups. We might imagine that in a perfect world, the ideal way to ensure that you maximise your genetic contribution would be to breed as soon as possible and as many times as possible. This would involve leaving the natal territory as soon as possible to pursue individual breeding opportunities.


So why then do we see so many examples in nature of reproductively mature animals which routinely delay or (in extreme cases) completely forgo their own reproductive opportunities in order to join and remain within a group as a subordinate non-breeding member?

The answer is that we don’t really know. We have a few ideas and theories about the costs and benefits of group living, but a general explanation has remained elusive. A major obstacle standing in the way of achieving a general explanation is that there are a lack of studies on marine organisms, which is what my study will focus on.

One of the most promising frameworks with which to study this behaviour is the cooperative breeding framework. This framework contains several hypotheses. I’ll go through just a few which I would like to test and which I will refer to throughout the presentation.

1) Ecological constraints – EC looks at a situation where ecological factors force animals into groups. eg. high predator abundance might cause animals to group in order to obtain a protective benefit through the dilution effect or by making use of discrete habitat patches which provide defence.

2) Life-history – LH hypothesis and EC are closely linked. LH hypothesis looks at inherent life-history traits of animals which might lead to a situation where group formation if more beneficial. For example, animals with long life-spans might cause a breeding habitat to become ‘saturated’. i.e. no vacant breeding ground for new recruits to make use of. In this case it might be more beneficial for the next generation of reproductively mature individuals to join a group and wait for the breeding habitat to become available (avoids conflict).

Most of these studies on birds, insects and mammals to date have either been broad phylogenetic comparisons or fine scale experimental manipulations. Both methods have merit and have in fact been responsible for the huge advances in this field, but there are few studies combining the two approaches. It is important to combine these methods as the broad scale studies can draw correlative conclusions across multiple taxa, but they don’t offer causative explanations. Which is where the experimentation becomes important. However, fine scale experimentation can only focus on a few taxa so the results are often difficult to apply generally across multiple taxa.

So how am I going to approach this question?

I will use a genus of coral reef fishes which show considerable variation in social organisation as a model. Gobiodon species are found in high abundance on tropical reefs. There are over 20 known species.


I will start by conducting a broad phylogenetic comparison of the Lizard island population of Gobiodon. This will involve making a genetic phylogeny of the species at Lizard Island (the above picture shows the phylogeny of the Red Sea population). Phylogenies show how closely related species are to each other. Species radiating from a common node are more closely related to each other, than to species originating from other nodes. The nodes represent some common ancestor. Looking at where sociality occurs on this phylogeny is important as we can see whether the behaviour arose at a single evolutionary point or whether it has evolved multiple times. Looking at the tree above, social behaviour does appear to have evolved multiple times.

Using this phylogeny as a base, I can map ecological and life history traits of each species. This will show which traits the social species share and which the asocial species have in common with each other. I will use this information to identify traits to manipulate experimentally to try to induce social behaviour in an asocial species or vice-versa.

I have chosen these fishes because they show great variation in social structure. for example G. histrio is stubbornly pair forming like Romeo and Juliet. While G. rivulatus forms large social groups more akin to the Great Gatsby, although I suspect that there might be some reproductive shares going to subordinate individuals in the Great Gatsby…


But back to Gobiodon; they are also highly site attached, which makes observing and cataloguing their social systems, ecological traits and life history traits far simpler and experimenting logistically easier with them. Once they have chosen a coral to settle in, that is where they stay. Even when the water level drops below their corals during extreme low tides, they will hunker down and remain within the coral, exposed to air for a couple of hours. They have a high hypoxia tolerance and air breathing ability which enables them to do this.


I have chosen Lizard Island in far north queensland as my study site because:


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a) it has an exclusive resort where celebs like leo can be found. Unfortunately, they don’t let the researchers stay here. They tuck us around the corner in this photo.





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b) most of the species of gobiodon are known to occur here (and possibly a new species). It’s also worth noting the size of these fishes in the picture below. The fish in the second and fourth pictures on the top row are actually sitting on my gloved hand.




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c) There is a well established research station here run by the Australian Museum which makes field work and experiments much easier.



We started this work by finding Gobiodon colonies around lizard island and capturing, counting and identifying the species. To capture the fish we use a mixture of clove oil and ethanol which anesthetises the fish and then we ‘waft’ them out of the coral. Once we capture the fish we hold them in plastic bags until the end of the dive and then take them to a boat to be processed.


To build the genetic phylogeny we need to obtain genetic material. I’ve been taking fin clips from the fish for this. We just snip off about 1/8th of the caudal (tail) fin area while the fish are anesthetised. It’s not uncommon to see these fish with much larger chunks taken out of their fins, usually from conspecific disputes. The fins do grow back quickly so we’re not doing any permanent damage to the fish.

While we have the fish on board and anesthetised, we measure their SL and TL and we give them little tattoos. These are a flourescent elastomer tag inserted under the skin so that we can identify the fish again when we come back in order to determine some life-history traits like dominant turn over rates or growth rates or mortality.

To collect the information about the ecological traits to map onto my phylogeny, I have been seeking out Gobiodon colonies and taking Coral measurements.


To measure habitat saturation we have been using x-transects centred on a colony of Gobiodon. We move along each axis of the transect and catalogue all of the corals known to be inhabited by Gobiodon species. We record whether they were inhabited or not, what they were inhabited by, how many individuals are in each coral, the size and species of each coral.

This gives us an indication of how many and what types of colonies are surrounding the focal colony and how much available habitat there is in the immediate area.

I need to complete the phylogeny now to map these LH and ecological traits and see if there is any correlation between sociality and these traits.


The downside to working in beautiful tropical locations is that they are prone to cyclone activity.

Cyclone Ita came right over Lizard Island in April this year. The photos below are taken from the same sites (left to right) before and after the cyclone. In February, my assistants, and I had tagged about 600 individual fish with a plan to come back in 6 months to re-capture and re-measure these individuals and determine growth rates and dominant turn over rates. I returned in August and found 8 of the original 600 tagged fish.


But moving on, I am still interested in the evolution of social behaviour in these fish, but I will focus more on the evolutionary advantages of sociality or asociality in re-colonising a reef after a disturbance. And I’m hoping that I’ll be able to see that recovery in the data coming out of the x-transects that we’re using to measure habitat saturation.

Anecdotally, there appeared to be more uninhabited corals than there were in February, though I can’t verify this statistically because I used different methods (we were looking at a different question in February). There also appeared to be more juveniles present in August than in February.


Moving on to some preliminary results, these tables show the results from a statistical method called a Generalized Linear Model or GLM for short. Don’t worry about that or all of the technical looking numbers, all you need to know is that a significant result is indicated in red or a highly significant result in yellow. For most of the species above, there is a significant result for average diameter of the coral. That just means that there was a strong relationship between the size of the coral (the predictor) and the number of individuals living within the coral (the response). i.e. the size of the coral could be used to predict the number of fish living within it for those species with a significant result.

I’ve found that the group size of some of the social Gobiodon species is related to the coral size, but not to the size of the largest individual (alpha), which is interesting as Marian Wong and Pete Buston (who presented at UoW a couple of weeks ago) had found that there was a relationship between both coral size and the size of the alpha with the group size in the anemone fish Amphiprion percula. G. oculolineatus does appear to follow this pattern. What I can take away from this is that the determinant of group size is probably species specific and will therefore be more difficult for me to make general conclusions about.

Looking at some of the before-after cyclone data that was comparable, the corals that did survive the cyclone showed positive growth. However when we looked at the site as a whole, the average size of the corals had decreased. This was to be expected since, as you can imagine, a major disturbance like a cyclone would smash up the larger corals into smaller corals. The smaller corals also have less surface area so are more likely to survive a cyclone.


I’ve also found that, as you would expect there was a decline in the coral goby abundance. However, the second graph is more interesting. Some species, like G. erythrospilus, G. rivulatus and G. unicolor appear to be occurring in larger groups post-cyclone. This is possibly an indication that they are in a phase of recruitment.


This will require further exploration so I have another trip planned for January. During this trip I will be re-conducting the x-transects in order to examine this trend across multiple sites. What I will be looking for is whether there is a detectable shift in the goby community. There might be a higher proportion of social species present which could indicate that social species have some kind of advantage in recolonising a reef after a disturbance (or vice-versa).


I will now need to finish the genetic phylogeny and map on the ecological traits that I have collected so far. I have another round of field work booked in for January. I will be conducting more of the cross transects to see if there has been a detectable community shift since my last visit. I also want to set up a pilot experiment looking at the effects of habitat quality and habitat saturation on a subordinate individual’s decision to move or not.

I would also like to set up and run the life history traits work again. i.e. the capturing and tagging component, as this is a really important part of the cooperative breeding framework which I’d like to explore.

To finish up I’d like to say a final thank you to my assistants for their help in the field. It really is a big commitment for them to come and help me out for weeks at a time. Thank you very much! My work could not happen without your help.


If anyone has any questions about my project, please leave a comment below. Thank you!

GobyPro issue 2

Welcome to the second edition of Gobypro!

It’s been quite a while since the previous post of GobyPro and we’ve been out in the field collecting more photos.

As promised in the last issue of GobyPro, Oranges are up first. We called these guys ‘Oranges’ because their species name is citrinus, which kind of sounds like citrus. G. citrinus is found mostly in big bunches of staghorn corals like A. intermedia. We usually saw them in large groups with two dominant breeders. These are the giants of the Gobiodon world, reaching sizes of up to 6.5 cm! Despite their massive size they were extremely difficult to capture as they would retreat right down into the coral. I really want to capture a few groups of these ones to see if they have a distinct size based hierarchy, but no luck so far. While I was diving in Indonesia recently, we found a group of G. citrinus which were black in colour.

G. citrinus

G. citrinus

G. citrinus black variant

G. citrinus black variant

Next we have the lemons, G. okinawae. These gobies are a very distinct bright yellow – hence the nickname “lemons”. We also called them lemons because we often found them living with a G. citrinus colony, forming a pretty little underwater orchid. Unlike most other species of Gobiodon, the lemons are the only species in this genus which like to hang out at the branch tips of the corals and often hover above and even move between corals. We found individuals ranging from 1.0 cm to 3.5 cm.

G. okinawae

G. okinawae

Goby Trivia

Some species have a high hypoxia tolerance and air breathing ability, meaning that they can stay in their corals even if the coral becomes exposed at extreme low tides.

Nilsson et al. 2004. Coward or braveheart: extreme habitat fidelity through hypoxia tolerance in a coral-dwelling goby

We saw this incredible ability on the last field trip during a king tide.

A G. erythrospilus, high and dry

A G. erythrospilus, high and dry

In the next issue of GobyPro:

An unidentified species of goby that we found on our last field trip.

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