Small aquarium... wide research niche

The Shark Lab and Research Aquarium initially functioned as both a public aquarium and a unique research facility, offering South African and International students alike the opportunity to advance their academic careers. Most recently, this facility has realigned its focus and functions primarily as a research unit.

In a world where human pressure is threatening entire ecosystems, the need to understand the individual elements that make up such systems becomes progressively more urgent and the research required to achieve these goals, become paramount. Research projects conducted at the Shark Lab and Research Aquarium therefore are of great value to and dovetail with conservation efforts on an international scale.

A number of honours and masters projects have been completed at the Shark Lab and Research Aquarium. A project titled “Temperature Niche of Four Benthic Shark Species”, conducted by honours student R. Lombard, from the Department of Zoology and Entomology, University of Pretoria, aimed to show how benthic sharks react physiologically to ambient temperature changes in their environment by assessing respiration rates as an indicator of abiotic tolerance. An additional aim of this project was to ascertain if dissolved oxygen is the major driver of respiration as opposed to temperature, as well as to assess if any variations in responses occur amongst the three species used in the experiment. The species used, being the leopard cat shark (Poroderma pantherinum), pyjama cat shark (Poroderma africanum) and the puff adder shy shark (Haploblepharus edwardsii).

A second honours project, conducted by honours student, Monica Betts, also from the Department of Zoology and Entomology, University of Pretoria, was titled, “Intraspecific and Interspecific Interactions of Benthic Sharks”.

This study aimed to determine the interspecific and intraspecific interactions of benthic sharks through a series of manipulative laboratory experiments. These insights into how three otherwise similar benthic species interact in a captive setting under the same controlled environmental conditions, will hopefully inform on their inter-relationships in nature.

Questions posed for this project, considered the response of different individuals of conspecific sharks to the tank environment, the responses compared amongst the three species of benthic shark, the response of an individual shark in the tank environment to the presence of one, or more conspecifics, the response of an individual shark in the tank environment to the presence of one or more heterospecifics and how the findings of this study reflect on the likely interspecific relationships of the three benthic sharks in the wild

Current research projects at the Lab include amongst others, a Cognition experiment and a Tonic Immobilization study, as well as a project to determine the growth rates of select benthic shark embryos and a project looking at stress in select pelagic shark species. These species being the leopard cat shark (Poroderma pantherinum), pyjama cat shark (Poroderma africanum) and the puff adder shy shark (Haploblepharus edwardsii).

The tonic immobilization study examines various factors which may affect TI behaviour of three species of scyliorhindae. The aims of this study are to investigate differences in TI behaviour between dependant variables, such as success rate, time in tonic, time taken to go into tonic, and the tenseness or calmness of the individual specimens. These factors are then compared between various independent factors, which include species, gender, and size and respiration rate. Variation in responses is then used to critically compare and interpret the potential biological significance of this behaviour.

The Cognition project aims to assess the relative learning capabilities of the three benthic shark species already mentioned, using an open plan choice-based maze. These sharks are conditioned to distinguish a visually distinct colour, using food as a reward. Furthermore, the different species will be used to ascertain if differences in learning behaviour exists between benthic species.

Questions that were asked during this project included the following: Can these species of benthic shark be conditioned to associate a visually distinct colour by using food as a reward?  Is the ability to condition sharks to associate a visually distinct colour with food independent of shark species and is the duration that the conditioned response persists independent of shark species?

The aim of a very recent egg project is to gauge the growth rates of the embryos of select benthic shark species in different temperatures as well as the growth rate between these species. A minilogger is used to obtain the average temperature of ocean water in Mossel Bay to most accurately duplicate this temperature in the research tanks.

Over the previous two years, two masters projects have also been completed at the Shark Lab and Research Aquarium.

One of these projects, titled “Occupational patterns of sharks in Mossel Bay as a function of air and hydrostatic pressure”, looked at understanding the functional behavioral responses of the three previously mentioned benthic shark species as a result of the environmental factors. The researcher, Tristan Scott from the Department of Zoology and Entomology, University of Pretoria, wanted to demonstrate that movements in these species may be related to atmospheric pressure declines associated with approaching storms.

Dylan Irion from the University of Cape Town, also completed his masters titled “Identification of the Swimming Behavior of the common smooth hound shark (Mustelus mustelus) based on TriAxial Accelerometer Data”, at the Shark Lab and Research Aquarium.

Alan Jardine - Aquarium manager

Under pressure

In the United States on Februaury 2^nd every year, if a groundhog sees its shadow then there will be 30 more days of winter, if not then spring follows immediately. Folklore in relation to atmospheric conditions has been common place for centuries and in times before accurate weather prediction could be made, people had a need to find ways of figuring out what was going to happen to their crop or what the conditions at sea would be like. Although most of those early ideas and myths are just fairy tales, like the groundhog story, many are steeped in truth as they were based on multiple observations over time. For example, “ no weather is ill, if the wind be still,” when there is a high pressure system, there is cooling air moving towards the earth’s surface, cool subsiding air is then warmed which may cause evaporation of clouds and often results fair weather.

Similarly, there have been stories over the centuries of animals being able to “predict” conditions such as violent storms and earth quakes. Dogs howling incessantly, caged birds becoming restless, the sound of insects disappearing as they had all left to find safety elsewhere. These are anecdotal stories but scientists are starting to research the validity of such claims. 

Here at Oceans Research it was observed on our regular chumming trips (where our interns get the opportunity to come face to face with white sharks as they help us collect essential data on population dynamics of this apex predator), that on the days after heavy storms, there seemed to be less sharks in the bay. And here at Oceans Research we are all about the research and not the anecdotes.  With a little searching we came across a paper that was published about juvenile blacktip sharks, who left their sheltered nursery grounds for deeper water before the tropical storm Gabriel made landfall, and all the sharks returned after the storm was over. It was concluded after looking at all possible environmental variables that the sharks were responding (perhaps innately) to a drop in atmospheric pressure. The only other paper published in relation to sharks and pressure showed that vestibular hair cells in dogfish are responsible for detecting changes in pressure and that these sharks can detect pressure changes as low as 5 millibars.

We have extensive data sets on the movements of white sharks in Mossel Bay, with more data coming in everyday using more and more sophisticated methods for tracking sharks such as acoustic telemetry, where sharks are tagged and are detected when moving past receivers in the bay (part of the Ocean Tracking Network- OTN), or by satellite tracking devices (part of the Ocearch expedition). The goal of this part of the project is to compare the movements of the white sharks in relation to changing atmospheric pressure systems. This is the meat of my MSc project and hopefully the results will yield some exiting information about these majestic creatures.

Another observation was made by an aquarist who worked at the Shark Lab and aquarium of Mossel Bay (more info can be found on this blog about the Shark Lab and its workings). He noticed that during storms the three species of benthic (or bottom dwelling) sharks that are on display seemed to group together more than usual when there was a storm outside. So sticking with the shark/pressure topic we decided to test this.

When it comes to scientific experimental design there can be a lot of ups and downs. What was supposed to be a simple experiment turned out to be one of the most difficult of the Master projects, with the irony being when you finally get it right you end up moving back to the simple instead of the complicated, after having discarded all the other parameters.

When looking at the grouping behaviour of sharks in a public aquarium, you have to take into account the aesthetics of whatever you are doing. You have a small sample size of sharks to work with at any time, the roof is low and the tank is wide, so photographic or video footage has to be taken with a wide angle lens. Can we correct for the fish eyes effect of that lens? 

    Figure 1: Using software we can remove the fisheye effect and measure accurate distances between         sharks.

How often are you going to record behaviours. We started at three times a week, for three hours spread over a day. But what about behaviour at night? It is presumed that some of these species are nocturnal.  Do we really need behaviour metrics such as swimming patterns when these sharks spend most of their time resting in one place? Do we somehow divide the tank into quadrants and see which are more favourable?

    Figure 2: An early experimental design

There is a skylight and the sharks tend to be on the opposite end of the tank to the skylight. Are they moving away from the light or is it because the tanks water inflow pipe happens to be on the same side as the skylight? Do we take readings on all days to encompass a more “natural” behaviour or do we avoid the three days a week that the sharks are fed and become most active? Do we need to identify individual sharks by using some sort of marking method or do we look at what they are doing as a collective bunch? The three benthic species we have in Mossel Bay (in captivity and on the reefs) tend to group and lie on top of each other as if they didn’t know they are separate species. With each answer comes a new idea or question and it compounds so much in trying to design the perfect experiment where all variables needed are accounted for and those that are not are discarded. 

    Figure 3: Redesigning

In the end Occam’s Razor often proves to be the way to go.  It basically states that among competing hypotheses, the one that makes the fewest assumptions should be selected. And when designing an experiment, a similar idea can come through, where after removing all that is unnecessary in what is needed in finding the answer to the question, we are left with a simple experiment that has all the scientific power necessary to get the research question answered. It also helps when going through the literature that you find an experiment that someone else has done which answers even more of the methodological questions you were struggling with and helps make things even simpler.

So in the end we are looking at the distances between the sharks at half hour intervals over a 24 hour period once a week to ascertain how they are grouping, and then comparing that grouping with how much they congregate during low pressure systems. We are currently in the control phase and are eagerly awaiting the stormy season to see what results we get.  

    Figure 4: Almost there

It is also  important to realize for young budding shark scientists and prospective interns which no doubt will read this blog when looking into coming to Oceans Research to learn about sharks, that their dream job isn’t just about being on a boat all day and playing with sharks. Research can be tedious and monotonous with many hours spent off the water problem solving and conducting experiments which seem extremely boring, but it all adds up to the great database of life, where scientists publish their findings and contribute to the global knowledge and ultimately the protection of the planet and the organisms which inhabit it.

Tristan Scott

MSc candidate. University of Pretoria/Oceans Research

 

Tag and Release

After a short recess, the benthic catshark tag and release program is up and running again! This year we have added an additional two sites to the sampling protocol, namely: Santos and Darwin.

Since August 2012 we have tagged a total of 17 catsharks: Leopard = 1, Pyjama Jacket = 3 and Puffadder = 13. Unfortunately, with no recaptures yet, however, there are possible reasons for this. Negatives: (i) the tag may have fallen off – any scars would likely have healed as sharks have incredible regenerative capabilities, (ii) tagged sharks have died due to natural predation, or alternatively have been caught by fishermen and killed - as they are considered a pest species. Positives: (i) these sharks are abundant and there is a low probability of capturing the same individual more than once. Let’s hope it’s the latter!

Although most species of catshark occurring in Mossel Bay are endemic to South Africa, despite their relative abundance – information is still limited. This tag and release project therefore represents an effective, low cost tool to obtain vital information on these little studied species.

This research project aims to investigate the following key questions relating to the biology and ecology of these endemic sharks:

              i.        Diversity of benthic catsharks in Mossel Bay reef systems

            ii.        Degree of spatial variation in benthic catshark composition between Mossel Bay reef systems

           iii.        Population composition and abundance of benthic catsharks sampled in Mossel Bay

The insight gained from this study will contribute to a more comprehensive understanding about the role these catsharks play in community dynamics. These benthic sharks likely represent predators within their micro-scale habitats and are thus considered to have top-down predatory effects at the community level at which they occur.

Furthermore, most of these catsharks are listed as Near Threatened on the IUCN Red List of Threatened Species – prioritising them as species of conservation concern!!

Shark Chronicles 085 - Passion, inspiration and determination

I never knew it was possible for one single experience to define your life until now. I have only had the pleasure of being an Oceans intern for a week now but this week has been so unbelievable that every time I try to explain it to anyone, nothing can even do it justice. From helping out at the aquarium to going out chumming for white sharks, I have learned more and experienced more in this last week than I ever thought was possible. Everything that I have done here so far has completely touched my heart in ways that are indescribable.

Even the most mundane tasks like cleaning out the turtle area gives me the greatest pleasure because I know what I am doing is making a difference. The aquarium is such a quaint and wonderful place to be. The personal atmosphere allows me to talk with interested visitors and witness their curiosity first hand. Because of the wonderful mentors and leaders of Oceans and the aquarium, I am able to answer their questions with great confidence. As we are feeding the sharks, you get to spend time with the graceful creatures where they are most comfortable and just watch in awe as they dominate their own world. Then there is doing Tonic on the small sharks. Nothing has ever made me feel so alive in my life than taking these powerful, beautiful creatures and holding them as they are completely relaxed. By grabbing the sharks and flipping them upside down, the sharks become immobilized for a brief period. This can be used for reproductive reasons mostly in sharks and humans can use it to better study the sharks. Handling each shark was so unforgettable. Each sharks seemed to have its own personality, from really chill to super active and feisty, that made me fall in love with them even more. Not only do the smaller sharks have unique personalities, but the bigger, better known ones do as well.

The first time I looked into the eyes of a great white shark here in Mossel Bay, I knew I made the right decision in what I want to study throughout my life and on coming to intern at Oceans. It is by far the most ingrained memory I will ever have in my mind. As we came across more and more of these graceful giants, I realized that they also all have personalities that make them stand out in your mind. Some are playful and will stay around for hours going for the bait line, and others will curiously come to the boat for just an once-over and then go on their way. Each time another shark came to the boat, my heart skipped a beat. Every job on the boat is a treat. Even chumming, which is as wonderful as it sounds, is rewarding. Throwing fish juice and guts overboard may not sound enjoyable to some, but as soon as the sharks arrive, you know that they are there just because of your efforts. The pay-offs are more obvious when it comes to data and photography of shark identification. The idea of being able to take observations of sharks and their dorsal fins to identify and track sharks is simplistic yet so imaginative at the same time. When everyone comes together at one time on the boat for the common goal of studying and understanding the beautiful predators that populate the area, it is truly a heartwarming occurrence. The simple observations we make can help understand the underwater world that we know so little about.

Other projects that we interns get the pleasure of working on include seal dolphin survey. Just sitting and observing the awe-inspiring animals is treat enough without even considering what scientific advances you are helping with. We all enjoy sitting on the beach, a boat, a harbor, or anywhere else and watching how animals naturally act. So doing so with the purpose of understanding them and their behaviors more not only feed your curiosity but also your sense of well-being. The main purpose of the surveys is to monitor their behaviors while in the harbor but a fortunate side affect is putting a smile on your face. Thinking about the activities I have participated in during the last week seems so very surreal to me.
One such activity was helping to transport a dead ragged-toothed shark off the beach. While my whole body felt heavy with grief when I saw it at first was overwhelming but I knew that we had to help. The shark had been caught by a fisherman, released and washed up on shore shortly afterwards. To see the impact that humans are having on these animals first hand is rather unnerving. I felt that I already was inspired to help these creatures before helping with the washed up shark, but somehow, that experience brought up a stronger passion that I didn’t even know existed. It’s as if that fisherman brought up the desire to help in any way possible as it brought up the ragged-toothed shark from the deep. What better place to have these feelings than at Oceans.

I have never felt like people have understood me or my passions for marine life as much as I did when I came to Oceans. The people are so very helpful and informative in every possible aspect imaginable. Not only are they nice to have around while doing research, but also just to hang around with in our spare time. When people with similar desires to help something come together, it becomes impossible for them not to enjoy each other’s company. I am definitely going to miss each and every person I have met here while interning and will hopefully continue these relationships built on common goals and wishes for years and years to come.

Needless to say, my experience here with Oceans Research has been one of inspiration. Like adding wood to a fire, my admiration of the ocean and all its creatures, especially sharks, has grown tremendously. I have not had one bad experience while in Mossel Bay and have experienced more than I ever thought I would. I came into this internship with high aspirations, and every single one of them has been blown away and replaced with experiences that would be impossible to get anywhere else. If in the future, anyone asks me what is the one experience that has made my life more magnificent, without hesitation, I would say interning for Oceans Research.

Kayla Melton - Oceans Reseach intern

Shark Chronicles 083 - Not only chumming

As with any research project, there are factors that cannot be controlled. Midway through this month we had trouble finding white sharks. Due to big swells and high winds we were unable to stay out for long, if we made it out at all. Instead of chumming we put in some extra hours at the office, entering tracking data from previous years and writing articles for Beyond Blue. Beyond Blue is an online magazine founded by Oceans Community. The magazine is for everyone and focuses on marine research, conservation, and exploration.

We also had a presentation by Enrico about the Great White shark research projects going on at Oceans, their findings, and the importance of those findings. He stressed the value of communicating the results to the general public and explaining how those results affect their life. Fellow conservationists and researchers make an effort to know the current issues. However, the majority of people in the world are either unaware of current issues or believe they don’t concern them. The research going on at Oceans has helped keep swimmers and surfers safe by alerting the public to where the white sharks are and when they are in the area. As disappointing as it can be not to see our beloved Great Whites, it was good to see how the work we do furthers the research that goes on to affect the community.

On the third week of our internship month we finally had a chance to do some shark tagging as well we started seeing white sharks again during our chumming trips! After a successful shark collection at Mitch’s Reef for our benthic shark aquarium in the Shark Lab, it was finally time for us to release the old sharks. The benthic sharks are kept for four months at the aquarium and then tagged and released when we collect new ones. This is part of an ongoing project to measure the population of the benthic shark species in Mossel Bay. Two of the species, the Pyjama Jacket and Leopard sharks are priority because we think their population may be threatened.

Each shark was weighed and measured and photos of their total length, mouth, and defining features were taken. Every tag that we fitted on the shark had an identification number and mailing address for ORI’s tag and release database. The tag was fitted by making a small incision anterior to the dorsal fin of the shark. For female species we always make the incision on the right side of the dorsal fin and left side of the dorsal fin for male species. It was difficult to penetrate the tough skin of the sharks, which are composed of small denticles, or teeth like scales. One through it is fairly easy to insert the tag into the thick wall of muscle that forms the sharks back.

Two Pyjama-jacket sharks and one Leopard shark were being tagged that day. One of the Pyjama-jacket was male and two other sharks were female. As the Pyjama-jacket sharks that we have were quite feisty, it took a couple of intern to hold the shark while the incision was being made. One intern took pictures of the shark during the whole process while another intern made the incision for the shark tag. We try our best to put the least amount of stress on the shark while we fitted the tag.

After all the sharks were tagged we loaded them on to the boat and took them back to the waters off Mitch reef. We are hopeful that the catch, tag and release study will provide us information on the population of benthic sharks on Mitch’s Reef, Mossel Bay.

Rachael Cashman and Karina Harum - Oceans Research interns

Shark Chronicles 073 - First Shark Lab's experiments

It’s been an active week at the aquarium. We wrapped the preliminary trials for the shark metabolic studies. The study was truly a group effort with all of the interns spending many a midnight hour camped out in the aquarium’s wet lab anxiously attempting to count gill movement on a swimming shark with a solitary red headlamp.

For the initial protocol, one male and one female shark were kept in isolation for several weeks, and after feeding to satiation, we monitored gill movement rates and time until feeding response to establish baseline metabolic rates for the sharks over a range of different temperatures. Preliminary results were as expected, with both sharks showing faster feeding response times in warmer temperatures. While there are still all the standard little glitches to be ironed out, the trials themselves were a great success as they should provide valuable insight into the set up and operation of future wet lab studies.

This week also saw the official beginning of the Shark Labs’ participation in the national Oceanographic Research Institutes’ tag and release program. After taking measurements and collecting a photographic record of the sharks we were prepping for release: each shark was fitted with a plastic tag with an individual identification number and mailing address for ORI’s tag and release database. Then the two pyjama sharks, two puffadder shysharks, and two smooth hound sharks were loaded on to the boat and taken back to the waters off Mitch reef, where they were returned to their natural environment. While we were sad to see them go, we are excited and looking forward to the possibility of collecting important information about their population size, habitat use, and growth rate in the future.

Since an empty aquarium is never good, Saturday was spent on a collection run. A team of two snorkelers and two divers worked to collect new sharks using chum bags to draw them in, while hoping the scent didn’t attract anything too big to the location. Seal Island was only a few hundred meters away after all! Luckily the trip was a success, with three leopard catsharks, two puffadder shysharks, and one new pyjama shark added to the Shark Lab’s guests. After spending the evening acclimating to their new residence our guests were catalogued, measured and ready to begin work! Their first assignment – a new study comparing the ease of induction and total duration of tonic among the different species found locally, and the potential for using tonic induction as a tool for handling and working with the sharks in the Lab.