Analysis of the ear bones of the River Murray estuarine fish black bream has revealed how these fish ‘hedge their bets’ for population survival.
Published in the journal Biology Letters, University of Adelaide research has shown that within this single species of fish there are some individuals which migrate to different parts of the Coorong in South Australia, and some that generally stay in the one location. Black bream are important for recreational and commercial fishing.
“When we consider animal migration, we tend to think of large seasonal migrations of species like the humpback whale or the Arctic tern. We don’t often think of migratory behaviour that varies within populations,” says Professor Bronwyn Gillanders, from the University’s School of Biological Sciences and Environment Institute.
“But it appears that within the black bream Coorong population there is a ‘bet-hedging strategy’ that allows the fish to survive and persist in the Coorong over good times and bad.
“Migration to another area may be more favourable under drought conditions when the water becomes more saline and, conversely, when there is lots of fresh water coming in and there is lots of food readily available, it would be more beneficial for the fish to stay in the location. This probably helps to make the species more resistant to both climate and human-related change.”
The researchers used the ear bones of fish collected throughout the estuary to construct their findings. Fish ear bones provide much information through analysis of the trace elements they contain and the width of their growth rings.
“Like tree growth rings, the ear bones reveal the age of the fish and growth periods which correlate with the growth of the fish itself,” says Professor Gillanders. “When we measure the width of the growth increments, we can trace back to see how fast the fish was growing at a particular time and year.
“The bones can also tell us whether the fish is migratory or ‘resident’ by mapping the ratios of barium against calcium. The higher levels of barium indicate when the fish was in fresher water.”
Professor Gillanders found that 62% of the fish were resident and 38% were migratory. Models were used to investigate differences in annual growth between the two groups and construct a growth time series.
“Throughout the late 1990s and early 2000s resident fish had increased growth compared with migrant fish but this changed around 2005 when growth of migrant fish increases,” says Professor Gillanders. “This is likely to be a result of the deteriorating conditions in the Coorong and reflects the ability of the migratory fish to find more favourable conditions and source more food.”
This research was in collaboration with the South Australian Research and Development Institute (SARDI.
Professor Bronwyn Gillanders
Southern Seas Ecology Laboratories
School of Biological Sciences and Environment Institute
The University of Adelaide
Phone: +61 8 8313 6235
Mobile: +61 417 036 235
Media and Communications Officer
The University of Adelaide
Phone: +61 8 8313 6341
Mobile: +61 410 689 084
Robyn Mills | newswise
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering