Global warming impacts sex-ratio of reef fishes Coral reefs are biological hotspots, harbouring thou

Global warming impacts sex-ratio of reef fishesCoral reefs are biological hotspots, harbouring thousands of different marine species. Excessive carbon emissions are changing climate all over the globe, making the oceans warmer and more acidic (see, http://tmblr.co/Zyv2Js1pjC6Q0 ocean acidification results in coral bleaching which adversely affects and endangers marine lives. Some fish species are unable to cope with rising ocean temperatures and are forced to seek newer habitats near the cooler poles (link: http://bitly.com/1KCZVeJ), thereby changing marine food webs. However, instead of moving away a few fish species are adjusting to the prevailing environmental conditions.Researchers from the University of Technology (UTS), Sydney in Australia recently conducted a study on how reef fishes are adapting to warmer temperatures. These fish and reptile species are known for their temperature-dependent sex determination (TSD) as the fertilized eggs may develop into either male or female depending on the environmental temperature. The team found that the sex-ratio of the fish species was affected by minute temperature changes; even 1.5°C rise in temperature increases the proportion of male offspring by more than 30 percent. Global warming can “potentially skew the sex-ratio of their [fish] offspring and, consequently, affect breeding individuals in a population,” (sic) according to lead author and UTS marine biologist Jennifer Donelson. It may not be mandatory to have 1:1 gender ratio to sustain the population, but if offspring are mostly males it will create a problem as population growth becomes contingent on female fertility.Although TSD is common in some reef fish, the researchers found one species, the Spiny Chromis, that was particularly resistant to the climate changes. They studied multiple generations of the Spiny Chromis, (Acanthochromis polyacanthus, photographed below), a resident of the coral reefs in and around the western Pacific Ocean. In this case, they found that sex of the offspring is dependent on the temperature conditions prevalent in the parent generations rather than the conditions experienced by the eggs, a phenomenon they called transgenerational plasticity. When parent generations were reared at a higher temperature than usual, the offspring are also able to tolerate the high temperature and sex-ratio is not skewed.The researchers also found that the adaptability in the fish species is not without limitation; when the temperature is increased by 3°C the fish species show only partial improvement. Donelson believed this proves that there is “a limitation to transgenerational plasticity when the developmental temperature is too hot,” among the Spiny Chromis species.The fortitude shown by the Spiny Chromis fish species brings hope for the fishing industry as it helps in the survival of the future generations in the face of the harsh climate changes. Donelson believes the ability of the Spiny Chromis fish species to adapt “is showing the importance of transgenerational plasticity in reducing the negative impacts of climate change on species with TSD.” Although Donelson’s team studied the trait in Spiny Chromis only, they are hoping to find the same in other reef species as well. If more fish species can cope with climate change through transgenerational plasticity like the Spiny Chromis, then at least some reef species will have resilience against the impacts of global warming.–RB.Further information: http://bit.ly/1Ts2hPmhttp://bit.ly/1CxlESthttp://bit.ly/1MOAFjdhttp://bit.ly/1dSnstKImage: Wikimedia commons (http://bit.ly/1CSJt7q)http://bit.ly/1MhEKzuReference: Donelson, J. M. and Munday, P. L. (2015). Transgenerational plasticity mitigates the impact of global warming to offspring sex ratios. Global Change Biology, 2015; DOI: 10.1111/gcb.12912On climate change: http://bit.ly/1pqz22HImportance of sex-ratio in aquaculture: http://bit.ly/1HVs3rb -- source link

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