Author: martyhing

Octlantis

Below the clear blue waters of Jervis Bay, a gloomy octopus creeps along the sand foraging on the abundant scallops and hunting crabs when she can locate them. Her soft body is vulnerable to all sorts of predators, but she is a master of disguise, and can jet away in an inky instant as a last resort if she needs to. She is a long way from the safety of her den, but these are good hunting grounds and the risk is usually worth the reward. Today however, she spies a large shadow cruising along in the distance. Her skin morphs to resemble the colour and texture of seaweed as she attempts to creep away. The shadow approaches. A wobbegong shark – homing in on the minute electrical signals given off by the involuntary beating of the octopuses’ heart. No matter how good her camouflage is, the shark knows she is here somewhere and circles closer. Too close for comfort now, the octopus flees using her siphon to jet away. The shark, reacting to the sudden movement, gives chase. The octopus knows that she can’t outrun the shark. She must find cover. She ejects a cloud of ink into the water to cover her next dash. This buys her a second but the shark, highly alert now, knows she is here. She inks again and makes another panicked dash. She sees an irregularity in the otherwise ubiquitously sandy bottom and jets toward it. A small rocky outcrop with some kelp growing on it. Shelter. As she dives for cover under the kelp fronds, she sees a crack between the two boulders that make up this tiny oasis. The crack is only a few centimetres wide, but her body is soft and malleable and she knows that the shark will not be able to get to her in there. The shark soars over the rocks. It knows there is food down there, but it can’t get to it right now. Better to continue its hunting elsewhere, it cruises off into the distance. After a while, sensing that it is safe to emerge, the octopus crawls out of the crevice. Having fled in such a hurry, she has no idea where her old den is and having expended so much energy, she needs to feed. The rocky outcrop is surrounded by scallops and mud arks. Hardly even moving from the safety of the crevice, she reaches out a tentacle and plucks a large scallop from the sand. She deftly pries the shell apart and feasts on the meat within. She drops the shell and reaches for another scallop…

Why is Octlantis special?

The gloomy octopus, Octopus tetricus, is usually thought of as a solitary animal. Two sites have now been discovered in Jervis Bay, Australia, where O. tetricus gathers in groups of up to 15 animals which are challenging that perception and revealing some interesting and previously unobserved behaviours.

The second site, dubbed ‘Octlantis’ was discovered last year and consists of three rocky outcrops around which the octopuses have built up an extensive bed of discarded shells and human garbage. The discarded shells have provided material for more octopuses to dig their burrows in the sand which they then stabilise using the shells.

Doughboy scallops, a favourite food for the resident octopuses.

This second site is centred around natural objects whereas the first site (known as ‘Octopolis’) reported in 2012, was formed around an unknown man-made object. The discovery of the second ‘natural’ site shows that the nature of the object around which the octopuses can make their dens is not as important as other factors (e.g. access to an unlimited food source) for the formation of a large group of octopuses. Social interactions (e.g. mating, attempted mating, reaching, eviction, displays and signals) observed at both sites also points to the ability of these octopuses to change their social behaviour from solitary to group living when conditions allow.

Misinterpretation of the report

We published a site description and some behavioural observations earlier this year. Since publishing this article, both sites have been the subject of a number of news reports. The early reports were accurate accounts of our report and welcome coverage of these unique sites. However many later news articles have exaggerated what we reported with the word ‘city’ appearing in a number of headlines (a word not used anywhere in our report). We did not find (nor did we report) octopus cities. The journalistic flare no doubt stems from the nick-names given to the sites (Octopolis and Octlantis), but we did not report these names. The use of the term ‘ecosystem engineering’ from an earlier paper has also likely led to the claim of ‘engineering underwater cities’, though the authors (of the scientific report) used the term in the sense that the piles of discarded shells created by the resident octopuses had significantly altered the habitat.

Ecosystem engineering and ‘intent’

Ecosystem engineering benefited the octopuses, but has also increased the abundance of some fish species, compared to the nearby sandy areas.

While the octopuses have modified their environment by ‘constructing’ the extensive shell-bed in which other octopuses have dug their dens, it is not clear whether this ‘construction’ is intentional or not. A city on the other hand is constructed cooperatively with the intent to provide a centre for living, business and entertainment, among other things. It is very likely that the ‘construction’ of the octopuses’ shell-bed is simply the result of individual octopuses bringing food back to their dens (a safe place to eat) and discarding the shells just outside. That is, it is the shell bed is likely the unintended result of individual behaviour. This idea of intent will be explored further in a new paper currently in press.

What’s next?

As previously mentioned, the complex social behaviour observed at both sites is unusual for this species, at least as far as we know. The costs and benefits (e.g. energy expenditure vs access to food) of these interactions is yet to be investigated and may help us to understand why the octopuses at these two sites choose to tolerate each other, rather than conforming to the solitary strategy employed by the majority of individuals of the species.

The hard substrate in the middle of the shell-bed, whether it be of man-made or natural origin, appears to have provided a nucleus for the initial settlement of octopuses who have then created an extended shell-bed. Why then do we not observe large groups of O. tetricus in other areas where a solid object has been placed in seemingly ecologically similar areas?

These questions and many others are of great interest to us and are currently being investigated. Watch this space.

 

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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/

The Rapture of the Deep

DCIM100GOPRODeep diving is something that I am passionate about – especially if it involves a shipwreck. It is a chance for me to push my skills, training and equipment and to explore some of the lesser dived or known sites. However this comes at a considerably higher risk which involves specialised training and equipment to manage safely. One of these risks is Nitrogen Narcosis – aka “the rapture of the deep”. Not a lot is known about the causes of nitrogen narcosis, but it is a narcotic effect brought on by the increased partial pressure of nitrogen in the breathing gas at depth. The threshold for nitrogen narcosis is different for each diver and can even vary dive-to-dive within a diver, depending on many factors. I usually enjoy getting a little “narc’d”. It can be quite euphoric and enjoyable if managed well. Nitrogen narcosis itself is not dangerous, unlike decompression illness, and there are no long lasting effects – no nasty hangovers. What can be dangerous though is the impaired actions of the diver experiencing euphoria. It’s essentially diving drunk. Nitrogen narcosis, like other narcotics can also present as paranoia and confusion which can lead to panic. Bad news in any depth of water. Thinking about these effects, I thought I’d share a story I wrote about a dive many years ago where I was overcome by narcosis paranoia in the hope that others can learn from my bad experience. This dive was a huge learning experience for me and still serves as a source of healthy anxiety before a deep dive. Nitrogen narcosis is not something that can be (nor should be) avoided, but it is certainly something to be aware of.

Before I get into the story, I should also make a quick note about solo diving. This practice is often frowned upon in diving circles and I do agree that diving with a buddy significantly reduces many risks associated with diving. However, I also believe that with proper training and additional equipment, many of these risks can be minimised and solo diving can be conducted reasonably safely. The training that I have done to enable me to dive outside the recreational limits had a special focus on redundant equipment and self reliance in emergency situations. I personally find solo diving to be quite relaxing and enjoyable, but only because I take the necessary precautions when I do it (which isn’t often).

When 3 things go wrong…

“If you turn right when you get to the anchor you’ll see the boiler. Then if you go left from there, you’ll get to the stern section” said my buddy.

“No worries. Too easy”. I think to my self.

There are some days when you really should just stay in bed. I was gearing up to dive a wreck off Sydney. It was one of those magic days on the water, with the sun newly risen and barely a whisper of a breeze to ruffle the smooth surface of the ocean. Unfortunately this magic had been marred by the realisation on the trip out that I’d left the undergarment for my dry suit laying on the back seat of my car. Idiot! This was to be the least of my troubles on this dive. As I was gearing up, to my horror I discovered that my fins were no where to be seen. They too were laying in the boot of the car along with my ankle weights. The ankle weights didn’t really concern me, but without my fins I was resigned to being the boat boy. Shit! how could I forget my fins! The undergarment and ankle weights were no big deal, I could get by without them, but my fins! You Idiot! I cursed my self again.

My buddy has said on many occasions “when you have 3 things go wrong on a dive, any 3 things at all, call it off”. Hmmmm, fins, ankle wights, undergarment…. I should have taken that advice.

The two others on board rolled over the side and descended onto the wreck 50 m below. I watched them disappear into the inky blue depths. 20 minutes later my buddy reappeared on the surface. He was diving in a wetsuit and was getting cold so had called his dive short. He climbed back on board raving about the excellent visibility and the fish life. He suggested I take his fins and go check out the wreck. It didn’t take much to talk me into it, although I could hear his words (spoken to me so many times) going through my head “when 3 things go wrong….”. But I couldn’t resist. I had gotten up early and made the trip out here and I was grateful to him for the offer of his fins, giving me the opportunity to explore this wreck that I’d heard so much about.

So I turned on the air for my two back mounted tanks, checked my gauges and climbed into my harness. As I was attaching my stage tank (a 3rd tank containing a Nitrox mix to reduce the ascent time) my buddy described the layout of the wreck to me.

“If you turn right when you get to the anchor you’ll see the boiler. Then if you go left from there, you’ll get to the stern section”.

I was so excited by this stage as this was my first time on this wreck and the conditions couldn’t have been better.

“What bottom time are you going to do?” He asked me.

“I’ll just do 10 minutes” I replied, feeling safe in the knowledge that I’d previously planned a 20 minute bottom time with breathing gas to spare.

I donned my buddies fins, went through my final checks, rolled over the side and kicked below the surface to the anchor line.

Breathe in breathe out…. slow, even breaths. Equalize. The particles suspended in the water whiz past me as I descend. I’m dropping fast. Breathe in, breathe out, equalize. Check instruments: depth – 12 m, dive time – 0:00, air – 223 bar. Every thing looks good. I feel great! I love this part. There is nothing around me. The only reference is the anchor line in front of me, disappearing into oblivion. I feel like I’m in free fall.

The visibility at this depth is only 5 m at best. My descent continues. 15 m… 22 m… 25 m… The visibility opens up. I can just make out the wreck below me sitting in 50 m of water. The gunk in the water above me partially blocks out the sunlight. I turn on my torch, more for comfort than anything else. I’m breathing a little harder now with the increased pressure so I adjust the resistance on my reg and add some more air to my dry suit to slow my descent. as I pass through 30 m depth I’m still dropping fast so I add some air to my BC to slow my descent.

Instrument check: depth – 48m, dive time – 0:02, air – 204 bar. As I arrive at the bottom, I try to unclip my reel from my harness. My fingers are clumsy, I must be narc’d but I still feel fine. I get my reel free and manage to tie onto the anchor line. I take a couple of seconds to catch my breath and gather my senses. Breathe in… breathe out… Wow! I am narc’d! I can’t concentrate…. better check my gauges: 0:05 dive time. What happened to those 3 minutes! This is fantastic! The vis is at least 30 m! 3 huge trevally cruise past me glinting bronze in my torch light. I watch them disappear into the distance. I’m surrounded by wreckage covered with tiny pink, purple and white bryozoans. Orange and yellow sponges fight for space with iridescent algaes. A school of pomfret, glowing golden in my torch light, cascade over parts of the wreck. I’m loving it!

Ok, what was I doing?…. Turn right from the anchor…. Right or left? No it was definitely right…. Which way is that? Ok concentrate now… this is my right hand… turn that way. I see the edge of the debris field and sand…. Where is the boiler? I keep turning. There’s the anchor…. Ok, I’ve turned right around. maybe it was left…. Ok turn left…. Wreckage… Sand… Anchor. I’ve turned around again…. where is that boiler? it was definately “turn right from the anchor”…. Ok, calm down, breathe. Should I bail out? I’m really really narc’d and I feel like I’m really pushing my abilities. No I’m ok, I’m well trained, I’m using familiar equipment (apart from the fins), my skills are up to scratch and I have heaps of air… I can handle this situation. Stop, breathe, think and act. Breathe in….breathe out. Think: “turn right from the anchor…” Act. Ok…. turn right. Ok I see a shadow out on the sand…. Is that the boiler? All the way out there? Ok… Start swimming…. It’s hard work…. Bugger that. I’m not swimming out there. Turn around… Which way?… Oh yeah, that’s right, it won’t matter.

I turn around and reel my way back to the anchor. I’m so narc’d. I can’t think. Calm down…. Breathe…. Check instruments: dive time 0:08 minutes. damn! I’ve wasted most of my bottom time. Air – 182 bar. I can’t think straight.

I close my eyes to try to gather my thoughts. Breathe in… Breathe out… Ok…. I’m on the edge of the debris field. I’ll just follow the sand line for a little bit. Which way? There’s a slight current… I’ll just drift along with that…. No wait!… I tell my students not to do that in the open water course… But I only have 2 minutes left. I’ll just drift a little way, then turn around. It’ll be fine.

I move along the wreck with the current. There are some beautiful little gorgonian fans, and some little pink bryozoans. Three juvenile blue wrass scull along beside me…. This isn’t so bad… A little leather jacket moves out of my way. Wow! this is a beautiful wreck! There are scattered deck plates and beams all around me. I wish I could have found that boiler or the stern section. Ah well next time… Oh shit! what’s my bottom time? 0:10! Shit! Turn around. I swim into the current. It’s not strong, but I have to work harder. I can feel my breathing rate increase with the extra effort. I reel in my line as I swim back to the anchor.

Back at the anchor. Instrument check: dive time – 0:11 minutes, air – 156 bar. My computer tells me that I require a 4 minute stop at 6 m with a total ascent time of 13 minutes. It’s ok, I have plenty of air and a 40% nitrox mix in my stage tank. Ok… relax… I try to detatch my line from the anchor chain, but my fingers just won’t work the way I tell them to. Finally the line comes free (I was so close to cutting it). I secure the reel to my harness and begin my ascent. Dive time – 0:14. Shit! I stayed way too long. I’m ok, I’ve got plenty of air left. I make my way up the anchor line. not too fast….dump air….breathe in breathe out. Up I go… at 25 m (the safe operating depth for a 40% nitrox mix) I reach for the reg on my stage tank but unbeknownst to me, the hose is caught on the buckle. I pull at the reg, but it wont come free. I’m still going up… dump air…. breathe…. I’m thinking more clearly now. Ok stop… Breathe… Think: “why won’t the reg come free?…. It’s caught on something”… Act: follow the hose with my hand. Ok, it’s caught under the buckle here. Ok, there it goes. I pull the reg free and start to breathe my nitrox mix. Instrument check: Dive time – 0:18 minutes, gas – 200 bar, 10 minute stop now required at 6 m. I make the gas switch on my computer. it re-calculates my ascent profile taking into account the new gas mixture I’m now breathing. Dive computers are such wonderful things! 1 minute of decompression now required at 6 m, total ascent time, 7 minutes. I slowly make my way to my 6 m stop and wait for 1 minute. Up to 3 m for just 5 minutes (oh how I love nitrox).

Hanging on the anchor line at 3 m I have time to contemplate the dive. I was out of my depth (excuse the pun). It all started out wrong. I feel lucky to be back near the surface. Things could have really gone wrong down there. Well, actually, maybe I’m not lucky, per se. When I knew I was getting into trouble, my training kicked in: Stop, breathe, think and act. And I was able to gather my self sufficiently to be able to get back safely. Nevertheless, I’ve learnt some valuable lessons from this dive. I should have bailed out when I felt the narcosis become overwhelming. Always start the dive swimming into the current. Practice practice practice with your equipment so that muscle memory can relieve some of the task loading on your brain at depth. And especially “When 3 things go wrong…”

Make your assignment marker happy

The dreaded red pen.

The dreaded red pen. An example of a very frustrated marker. I hope my feedback was a little less personal (this is NOT a picture of my marking). 

Recently I’ve been marking for some second and third year biology classes. I’ve been a little shocked at the quality of the work the students have been presenting. I found myself wondering whether I was marking them too hard? However, I soon came to the conclusion that this was not the case.

One of the classes is a third year class and some of these students are on the cusp of completing a Bachelor of Science without knowing whether to use “two”, “to” or “too”. It’s a scary thought. I would like to think that these students wouldn’t be able to complete their degrees with such appalling spelling and grammar, but let’s face it, they’ve made it through to the final semester of their undergraduate degrees in this fashion. As a marker of a third year subject, I should be committing my time to marking the content and assessing a student’s understanding of the subject matter rather than correcting basic spelling mistakes.

As scientists, good writing skills are essential. It’s what we do. When all is said and done, the time spent writing vastly outweighs the time spent on experimental design and data collection. Writing is how we convey our research (with the odd presentation thrown in for good measure) to the scientific community, decision makers and the broader public. Unfortunately, most of us (myself included) are not born writers. It is a skill that is developed through reading and especially through writing.

Good writing starts with the basics (spelling, grammar, presentation) and this is where I am finding that a lot of students are falling short. As a marker, I’ve found myself writing the same comments on these basic concepts over and over and over and over again, which makes me miserable.

It is such a delight to find that one paper among it all that just nails the basics. These few papers are the ones that stand out to markers and (somewhat unfairly) receive disproportionately higher marks. i.e. if I mark two papers with essentially the same content, the one with the good spelling, grammar and presentation is going to get the higher marks every time.

These small things matter. Not only for undergraduate assignments, but for report writing, grant applications and manuscripts for peer reviewed journals, which these students will face in the workforce. Then it is not just the grumpy marker that they’ll have to face. It will be the supervisor, the reviewer, and the question of continued employment that they will be contending with.

This being the case, I’ve started developing a report writing guide for my students. It is still very much a work in progress but I would welcome any feedback on it. It is aimed at science students, so some of the sections on presentation may not be applicable in other disciplines.

If you are a teacher, examiner or marker and you find this guide helpful, please feel free to share it with your students/friends in the interest of promoting good writing skills. If you are a science student, I hope this guide helps to boost your marks and improve the mood of your marker. Please let me know if there are things that you struggle with that are not included in the guide. If you are one of my students I hope you read this guide and apply it to your next assignment. I look forward to reading them and awarding some much higher marks for your hard work.

Report writing tips (download)

 

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.

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!

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.

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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…