A warming planet is influencing the sex ratio of sea turtles, but could industrial pollution also be playing a part?
It might be one of the most exciting moments of a person’s life. A baby is born and, after months of anticipation, the great question is answered. Is it a girl or a boy? But for many expectant reptile mums (except snakes and some lizards) this question can be answered before the eggs begin to hatch.
All that’s needed is to take a measure of the average temperature surrounding the eggs. Below a certain temperature and the majority of the youngsters will be born male. Above a certain temperature and the majority will be of the fairer sex.
When the world’s climate is in balance this doesn’t really alter things too much. Some years might see more little boy crocodiles born on one river bank, some years it’s more little girl crocodiles.
Related articles
- Green turtle population recovery in Seychelles
- Great Barrier Reef coral recovery pauses
- UK turtle strandings on the rise this winter
- Spring jellyfish blooms bring turtles to UK shores
But, that equilibrium is changing now thanks to climate change. Take sea turtles for example. From Australia to Florida, researchers are recording ever higher percentages of female turtles being born than male. This is because when the sand the turtle eggs are being laid in is warmer than normal then the majority of eggs hatch as females. The worry is that as worldwide temperatures continue to climb then so an ever-higher percentage of turtles will be born female.
Some estimates say that come 2100 up to 94 per cent of green sea turtles born worldwide could be born female. Indeed, already in the northern part of Australia’s Great Barrier Reef as many as 99 per cent of green turtles hatching out are female.
But now, another human-caused obstacle has been thrown at turtles. Industrial pollution. A team from the Griffith University in Australia has found that industrial beach pollution may also be leading to a sex bias in green sea turtles. The team monitored the sex ratio from 16 clutches of eggs and discovered that 11 clutches contained more females than predicted.
When the team examined the livers of the baby turtles, they discovered that the turtles originating from clutches containing more females contained higher levels of industrial waste products such as cobalt, lead and antimony. It’s thought that these heavy metals can bind to oestrogen receptors, which may lead to the development of more female hatchlings.
The research is not yet conclusive, but even so, team leader Arthur Barraza hopes that these early-stage discoveries can be used to shape conservation efforts.
The study ‘Exploring contaminants as a disruptor of temperature-dependent sex determination in sea turtle hatchlings’ by Arthur D Barzza et al is published in the open access Frontiers in Marine Science
- Half of all mangrove forests at risk of collapse - 14 July 2024
- Fibreglass particles discovered in oysters and mussels - 4 July 2024
- Grey whales in the northeastern Pacific are shrinking - 19 June 2024
