Sheepshead minnows. Photo courtesy of Stony Brook University. |
If you want young fish fry to grow quickly, the answer is to keep them in water at the same temperature as that of their parents, according to the latest research. This is because adult fish are able to pre-condition their offspring to grow most rapidly in such surroundings. Pre-conditioning of this type, known as transgenerational plasticity (TGP), occurs whenever environmental cues experienced by either parent prior to fertilization changes how their offspring respond to the environment.
Dr. Stephan B. Munch, an adjunct associate professor at the School of Marine and Atmospheric Sciences (SoMAS) at Stony Brook University and a member of the Early Life History Team at the Southwest Fisheries Science Center of the National Oceanic and Atmospheric Administration (NOAA), along with Santiago Salinas, a Ph.D candidate from Stony Brook University, have found what they believe to be the first evidence for thermal TGP in a vertebrate.
How the discovery was made
For the experiment, the team collected several hundred adult sheepshead minnows (Cyprinodon variegatus), a killifish from the Gulf Islands National Seashore in Gulf Breeze, Florida, and brought them to the fish facility at Stony Brook University. To test for thermal TGP in growth, parents were held at several different temperatures and growth of their offspring was subsequently measured.
After seven days of parental temperature exposure, offspring growth was the same for all parents. However, after 30 days of temperature exposure, offspring grew best at their parents' temperature. The experiment was fully replicated and repeated, each time revealing the same result that offspring from high (34°C) and low (24°C) temperature parents grew best at high and low temperatures, respectively. "The differences in growth of the offspring, based on whether the parents had experienced that same temperature, were significant," noted Salinas.
Survival benefits
"There is very little known about transgenerational effects on physiology," said Dr. Munch. "I think the most exciting part about the research is that, although there has been a lot of work on transgenerational effects on fish, this is the first demonstration of a transgenerational effect of temperature.
"From a practical point of view, if such effects occur in other species, aquaculture programs could potentially make large gains by manipulating the parental environment before breeding. There are good reasons to believe that these effects will occur in many species, but we've only just started looking."
Munch and Salinas also highlight TGP as another potential mechanism for rapid responses to climate shifts. "In light of global climate change, transgenerational effects of temperature may be incredibly important mechanisms for coping with altered thermal regimes," said Dr. Munch.
Reference: Santiago Salinas, Stephan B. Munch. Thermal legacies: transgenerational effects of temperature on growth in a vertebrate. Ecology Letters, 2012; 15 (2): 159 DOI: 10.1111/j.1461-0248.2011.01721.x.