fish

Into the Storm

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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

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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.

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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.

Why?

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.

A plea to new spearo’s

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A great weekend diving with friends was somewhat tarnished by the actions of a naive spearfisher. We were unfortunate to witness a spearo enter the water in a sanctuary zone (no-take zone) and spear a blue wrasse, a protected species in NSW.

Spearfishing is a great way to get some fish into your diet. It can be a great challenge learning to freedive and learning to observe fish behaviour. That being said, there are no throw backs with spearfishing. Which is why I implore people new to the sport to know where you can fish and what species are ok to target. Do not pull that trigger unless you are 100% certain that the fish is of legal size and not protected. The fisheries rules are in place to help sustain our fish populations so that everyone can continue to enjoy our oceans.

Getting started can be daunting. It might seem like there are a lot of species to learn and there are. I would recommend tagging along with someone more experienced until you get to know your local fish. Join a spearfishing forum – there are often people looking for buddies. Failing that, get out and go freediving without the spear and look up the fish you see. In only a few dives you will quickly learn the common fish at your local sites. If you really want to get straight into it, consider deciding on a specific species to target before you even get in the water. Failing all of this, you can follow 1 simple rule: If you don’t know what it is, don’t shoot it. 

Some useful websites:

DPI Fishing rules – http://www.dpi.nsw.gov.au/fishing/recreational/fishing-rules-and-regs/saltwater-bag-and-size-limits

Marine protected areas – http://www.dpi.nsw.gov.au/fishing/marine-protected-areas

Spearfishing forum – http://www.spearfishing.com.au/sf-forum/

Shark!

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!

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.

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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…

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!

Zebu

The mighty zebu

mackerel

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

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.

Goniopora

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.

seacucumbers

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!

snapper

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!!

nudibranch

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…

THINGS I MISS…

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!

 

THINGS I DON’T MISS…

Sand in my bed

 

hammock day

View from my hammock

hammock sunset

Sunset from my hammock

stars

Stars! Photo by Ben Large

Initial Project Report

Slide1

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.

Slide2

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.

Slide3

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…

Slide4

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.

Slide5.1

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

Slide5.2

Click to enlarge

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.

 

 

 

Slide5.3

Click to enlarge

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.

 

 

Slide5.4

Click to enlarge

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.

Slide7

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.

Slide8

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.

Slide9.1

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.

Slide9.2

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.

Slide10

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.

Slide11

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.

Slide12

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).

Slide13

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.

Slide14

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

For Fish Sake!

If you love seafood, as I do (or know people who love it), I would highly recommend watching “What’s the Catch” which aired on SBS last night. If you missed it you can catch up on it here.

What's the Catch

The three part series follows Matthew Evans (of Gourmet Farmer), former chef and restaurant critic, on his mission to raise awareness and start a conversation about the origin, practices and sustainability of the seafood that we eat. Last night’s episode focussed mostly on prawns and seafood labelling.

In the spirit of starting a conversation about sustainable seafood, I’d like to talk about one of the most staggering statistics mentioned in last nights episode, which was that in Australia, we import 70% of our seafood! I think that figure is worth repeating here and it’s a figure that I would like to encourage my friends to pass on to their friends.

70% is massive! In the 2008/09 financial year that figure equated to 193 000 tonnes of imported seafood (Fisheries Research and Development Corporation). That’s 1 930 000 000 standard servings of fish in a country of just over 23 000 000 people – about 1.5 standard servings per week per person. The NSW Food Authority recommends eating 2-3 serves of fish per week. That means that half of our recommended maximum weekly fish consumption is coming from overseas (assuming that every single person in Australia eats seafood and sticks to the NSW recommendations, which they clearly don’t, but I think my point still stands). I see this as an issue, as it indicates that we’re not supporting our local fisheries.

OLYMPUS DIGITAL CAMERA

Some people tend to think of commercial fishers as indiscriminate pillagers of the sea. However, In Australia, most commercial fishing is highly targeted and must conform to strict environmental regulation. I can’t deny that there are bad apples (or should I say smelly prawns?) amongst the bunch, but overall, the fishers themselves know the importance of fishing sustainably. It is their business and livelihood after all. My experience of Australian fisheries is that they are generally supportive of sustainable practices. We need to get behind these fisheries which have strict environmental regulation and good practices rather than continuing to buy cheap imported seafood, of which we have absolutely no control over how it is produced  (not to mention the carbon footprint involved in importing 193 000 tonnes of seafood).

In my opinion (having worked in fisheries organisations in Tonga and Australia), Australia does have some of the best managed fisheries in the world, despite what some conservation groups might say. I’m not suggesting that Australia’s fisheries are perfect, I know we still have a long way to go, and I think that the consumer has a big part to play on that journey. Keeping our fisheries sustainable requires solid governance, research, extension and compliance (to name but a few components) which all costs money.

Australia’s Northern Prawn Fishery (NPF) is held up as somewhat of a gold standard in industry best practice (for the prawn trawling industry). Whilst acknowledging that there is still a large amount of bycatch produced in this fishery, the NPF really has done an outstanding job of improving their practices. They have been able to research and implement technologies to reduce bycatch (over 50% reduction in bycatch), develop management plans and conduct continual stock assessment modelling and ecological risk assessments because they are one of Australia’s largest and most profitable fisheries.

trawlers

Which brings me to my point; If we, as consumers want premium quality management of our fisheries we need to start supporting our fisheries and be willing to pay a premium for the seafood produced. Supporting our fisheries means that the individual fisheries industries will have more money to put toward sustainable management and implementing good environmental practice.

That starts with knowing where our seafood comes from (seafood labelling has a big role to play here) and choosing the sustainable options. That’s not always easy to do, but I think that keeping our fisheries sustainable is worth hunting around for that option. To help you to make those choices, I’ll put a few links at the bottom of this post. I highly recommend watching the rest of “What’s the Catch” and please engage in the discussion on sustainable seafood!

Links:

If you have any other resources that you’d like to suggest, please leave me a comment and I’ll add it to the list.

Guides and Recipes

Good Fish Bad Fish – A page dedicated to sustainable seafood with an excellent seafood guide including a seafood converter to convert less sustainable choices to more sustainable ones. Contains good summaries of ratings given by other organisations.

The Australian Marine Conservation Society’s (AMCS) Sustainable Seafood Guide – A simple “traffic light” system for seafood. An easy to use and understand tool but keep in mind that the simplicity of this system may miss some of the subtleties of choosing sustainably and may conflict with other agencies. For example Banana Prawns are categorised as yellow or “eat less” whereas the Marine Stewardship Council (MSC) has certified the NPF, where the majority of banana prawns are caught, as sustainable.

Sustainable Table’s Seafood page – Sustainable Table advocates sustainable food choices from all sources, not just seafood. But this is their seafood page with some excellent information.

The Good Fish Project – An AMCS initiative. Good summary of fishing and harvesting methods here.

Sustainable seafood restaurants

Fish & Co. – Fully MSC certified Sydney restaurant, meaning that if you wanted to, you could trace the fish on your plate all the way back to the vessel it was caught from.

Love.Fish – Though not MSC certified, they obviously care about where their fish comes from and support local fisheries. Sydney based.

Swampdog – Sustainably sourced fish and chips in Brisbane

Certification agencies and Non-Government Organisations

Marine Stewardship Council – The most rigorous international certification scheme available for seafood. See here for an interactive map of the certified fisheries.

Aquaculture Stewardship Council

International Union for Conservation of Nature – For threatened species lists. Keep in mind that these lists are based on international data and may not accurately represent local populations. This works both ways; just because one species is sustainable in Australia doesn’t mean that it’s sustainable on a global scale.

Government organisations

Australian Government Department of the Environment – Australia’s export fisheries which have been assessed against the Australian Government’s Guidelines for the Ecologically Sustainable Management of Fisheries.

Fisheries Research and Development Corporation – A good resource for fisheries statistics and information on fisheries research.

Australian Fisheries Management Authority – For information on the management of Australia’s Commonwealth managed fisheries. i.e. fisheries operating within 3 – 200 nm of the coastline. For state managed fisheries (within 0-3 nm of the coastline) see the individual state fishery pages.

Australian Bureau of Agricultural and Resource Economics and Sciences Fishery Status Reports – Status reports on Commonwealth managed fisheries.

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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Lizard Log 31/8/14 – 4/9/14

Apologies for the slight delay in getting this post up. We’ve been hanging out with a good mate in Townsville for the last few days. Whilst there we did a dive on the SS. Yongala.

Diving the SS. Yongala off Townsville.

Diving the SS. Yongala off Townsville.

Without further ado, the final Lizard Log for this field trip.

Day 30 31/8/14

The wind had dropped quite a bit today which was a great relief. We were able to get out to the Palfrey reef system, near Horseshoe reef today. It was shallow, but clear and the sun was shining so it was quite pleasant. We got heaps of transects done on our first dive.

On our second dive we moved to Big Vickey’s reef where we came across three of my tagged corals. Unfortunately one of them was completely dead and covered in algae. The other two were intact and even contained the same tagged fish from last time. Great news, but sadly, still not enough to run any meaningful analysis.

We removed the old tags once we'd made our measurements.

We removed the old tags once we’d made our measurements.

In the evening, Kylie and I packed a picnic box and wandered up the beach for sunset. One of the resident seagulls waddled after us and kept us company. I quite like this particular seagull as it keeps all the other gulls away. We enjoyed a couple of sunset beers and a whole heap of chips and dips.

 Day 31 1/9/14

First day of Spring! We dived another part of the Palfrey reef system today. It was much shallower than our dives yesterday, so it was difficult to spot the gobies. We went over to Palfrey Island for our surface interval. As we were walking in over the sand bar, we saw a little black tip reef shark cruising the shoreline. It disappeared pretty quickly when it saw us though.

We had the Bshari lab group over tonight for a pizza night. I really enjoy their company. I had a good chat to one of the researchers about my PhD. It was really reassuring to hear his perspective, looking back at their own experience.

Day 32 2/9/14

Last day of work diving today. I was pretty happy to be finishing up honestly. It’s nice diving in warm water, but the surface conditions have been pretty tough this time around. We dived at Loomis reef today, which I’ve never been to before. It was in really good condition with huge heads of acroporid corals scattered throughout the reef. I was expecting to see some big groups of gobies in these corals, but most of the gobies were still only in pairs. When we did our surveys in February, we found that the group sizes for the social species, were related to the coral size. This doesn’t seem to be the case this time. I suspect that the population is in recovery after the cyclone, but only time will tell.

We went to, the station managers house for dinner tonight. It was a lovely evening with lots of laughs. They cooked up a blue fin trevalley that they caught yesterday. When he caught the fish though, he spiked himself on the lure and had to go to the clinic over at the resort to get it removed!

Day 33 3/9/14

Kylie and I went out for a fun dive this morning. We fly out tomorrow afternoon so we decided to squeeze in a dive before our 24 hour no-fly limit kicks in. The wind was really low today and Lyle said that we might be able to dive at Coconut Beach. We went out around Lizard Head to check out the conditions. It would have been fine for a dive, but the regulations prohibit us from diving without a boat watch person if the swell is over half a metre. It was definitely getting close to that limit and the conditions were predicted to deteriorate in the afternoon, so we decided to play it safe and head back to Big Vickey’s for a dive. We anchored up on the western side of the reef and jumped in. It was lovely to be diving deeper the two metres. We saw quite a few nudibranchs and flatworms, but not many fish. We were just happy to be in the water diving without having to record anything.

Nudibranch

Nudibranch

We’re winding up now, just going through all the cleaning and finalising paperwork etc. It’s always a little sad to be leaving this place. I love meeting all the researchers here and the social scene is great. But I am ready to go home.

Day 34 4/9/14

It was our last day on the Island today. We decided to kick it off by climbing Cook’s Look, the highest peak on Lizard Island. We set out early from the station and made it to the top in about an hour. We stopped several time to admire the views as we climbed higher and higher. The walk heads out along the ridge to the north of Watson’s Bay and then turns back towards and up the main peak. It was quite steep in places, but the view from the top was beautiful! It would be interesting to do the walk again but later in the day as the sun in the morning reflects off the water in the east and you can’t see the ribbon reefs. It would make for a really hot climb though.

Kylie admiring the view

Kylie admiring the view

After getting back to the station we finished our clean up duties including pulling the boat out and giving it a wash down. We found out that our plane was actually scheduled 2 hours earlier than we’d thought, but that was fine as we’d done most of our cleaning the previous afternoon.

We made our way around the station in the afternoon to say our farewells and then got picked up and taken to the airport. Unfortunately, some of the workmen from the resort were held up and our plane was delayed by about an hour. We were entertained a couple of times by Bruce driving past on the station tractor and blowing kisses at us! We finally boarded the plane and lifted off, passing over the blue waters and patch reefs of Lizard Island.

Flying out

Flying out

It has been a rough (weather wise) trip but reasonably successful. We didn’t get the information we wanted, but I was expecting that. Our plan B worked well though. I now just need to sit down and analyse the data. Thank you to everyone on Lizard Island for making our trip not only successful, but, just as importantly, FUN! A special thank you to Anne and Lyle, the station directors, and Maryanne, Lance, Cassie and Bruce. You guys do a fantastic job of keeping the station operational and creating a great atmosphere there. And you make it look easy! We look forward to seeing you all next trip!