Experiments with Zebra Fish show that if their embryo’s develop in warmer water, they not only are able to swim faster but they cope better in both warmer and colder water. (How catastrophic can that be, I ask you?)
ScienceDaily (Aug. 14, 2012) — New research by McMaster University biologist Graham Scott suggests that growing up at warmer temperatures helps some aquatic animals cope with climate change, raising questions about the limits of adaptation.
Scott and Johnston found that when embryos raised in warm water experienced temperature variation as adults, they could swim faster, their muscle was better suited for aerobic exercise, and they expressed at higher levels many of the genes that contribute to exercise performance.
The improvements were true for the adult fish in warmer and colder water alike — a finding that surprised the researchers.
“We thought that they might do better under warmer conditions because they grew up in warmer conditions. We didn’t think they’d also do better under colder conditions, but they did.
Their research shows the fish are hardier after being raised in a warm-water nursery, and raises the question of how far the temperature can rise before the advantage becomes a liability, as inevitably it will, Scott says.
The question then for Zebra Fish lovers is to ask what we are doing to stop the world cooling? Clearly a cooler ocean is a threat to their health and welfare. We simply can’t allow those baby fish to develop in water that is not warm enough for them to reach their full potential.
Global warming is intensifying interest in the mechanisms enabling ectothermic animals to adjust physiological performance and cope with temperature change. Here we show that embryonic temperature can have dramatic and persistent effects on thermal acclimation capacity at multiple levels of biological organization. Zebrafish embryos were incubated until hatching at control temperature (TE = 27 °C) or near the extremes for normal development (TE = 22 °C or 32 °C) and were then raised to adulthood under common conditions at 27 °C. Short-term temperature challenge affected aerobic exercise performance (Ucrit), but each TE group had reduced thermal sensitivity at its respective TE. In contrast, unexpected differences arose after long-term acclimation to 16 °C, when performance in the cold was ∼20% higher in both 32 °C and 22 °C TE groups compared with 27 °C TE controls. Differences in performance after acclimation to cold or warm (34 °C) temperatures were partially explained by variation in fiber type composition in the swimming muscle. Cold acclimation changed the abundance of 3,452 of 19,712 unique and unambiguously identified transcripts detected in the fast muscle using RNA-Seq. Principal components analysis differentiated the general transcriptional responses to cold of the 27 °C and 32 °C TE groups. Differences in expression were observed for individual genes involved in energy metabolism, angiogenesis, cell stress, muscle contraction and remodeling, and apoptosis. Therefore, thermal acclimation capacity is not fixed and can be modified by temperature during early development. Developmental plasticity may thus help some ectothermic organisms cope with the more variable temperatures that are expected under future climate-change scenarios.