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