Climate change and the Green Sea Turtle
The Great Barrier Reef is home to thousands of
species, including 1,500 fish species, sharks and rays, and hundreds of marine
mammals. One of the most endangered species residing here is the green sea
turtle. The issue however, is not about the number of turtles - the ratio of
male to female turtles is the main concern. Today the female green sea turtle
offspring makes up 99% of the green sea turtle population, leaving a mere 1%
for male juveniles.
Studies show that temperature determines the sex
of sea turtle offspring. On average, incubation periods surpassing 29o celsius (84.2o farenheit) result in
more female births.
The science behind it has to do with the enzyme
aromatase, which converts testosterone to estrogen, a key component of sex
determination. The blockage of aromatase with certain inhibitors drastically
reduces its activity and yields male offspring. At the female promoting
temperature of 29-30o celsius aromatase activity is very present, whereas at 25o celsius (the
male-promoting temperature) activity is low.
While this is not a good thing, it is not an
immediate danger. Green sea turtles practice polygyny, where one male will mate
with many females. More females results in a larger turnover of eggs, so this
can be looked at as a not all-bad type of situation for the overwhelming numbers
occurring lately.
However, due to rising average temperatures, the
future of the green sea turtle is in great danger. Increasing average
temperatures could result in skewed and lethal incubation periods. Scientists
are stepping in to help bring more male offspring to the population. There are
a few solutions that seem to offer hope for the future.
Natural shading from vegetation helps keep the
incubation temperatures down, so protecting beach vegetation and planting more
shady plants is an option. Relocating nest sites to areas of beach with more
natural shade, or to hatcheries is also suitable. Adding light colored sand on
top of the nesting sites can reduce the effects of solar radiation on the
incubation temperatures.
While they face an uncertain future, there is
hope for the green sea turtle. They have been around for over 200 million
years, surviving through the mass extinction that ended the era of the
dinosaurs and have lived through many trying climate changes. There is
potential for this species to adapt as well; whether it be migrating to places
of slightly cooler average temperatures, or by having nesting season be moved
to cooler times of year.
With endurance from the green sea turtle, the
help of scientists and some luck, the future of this species at the Great
Barrier Reef could be alright in the end.
Posted by Hannah Kullberg (2)
It’s unfortunate that a lot of animals are being affected by climate change. I learned about aromatase in my Behavioral Neuroendocrinology class, but I didn’t know that the enzyme can be affected by temperature. You listed many possible solutions to even out the ratio of males to females, but are there any ongoing solutions that scientists are currently implanting, and if there are, which solutions are viable? I hope the green sea turtle will be successful. It seems like many species are going extinct or are on the endangered species list, and it’d be great if we could prevent some from going extinct.
ReplyDelete-Angelina Weng (3)
The solutions I mentioned are being implemented as we speak, and are having positive effects! Some seem to have drawbacks however - one solution scientists have tried is having sprinkler systems around the nesting areas to keep them cool. This sounds like a great idea, but has resulted in fungal infections in some eggs.
Delete-- Hannah Kullberg (2)
Climate change is having such an effect on so many different things. The fact that it is causing these turtles to produce more females rather than males is such an unthought of aspect of climate change. It is good to hear that this decrease in the male population of these turtles isn't effecting them too much right now but in the future I'm sure this will be something to worry about if not now.
ReplyDelete-Sarah Aboody (1)
It is alarming how many behind the scenes events are taking place in response to climate change! And while it isn't a dire situation right now, it is still a major issue that can hopefully be better controlled in the future.
Delete-- Hannah Kullberg (2)
It is very interesting to see the genetic implications that the environment can have, and the threats that this poses as our climate changes. I am also fascinated by the fact that temperature is capable of even determining the sex of the offspring to begin with. Has this been demonstrated in any other species? Are there other environmental factors capable of sex determination in reproduction? It is definitely an intriguing new topic and I am interested in seeing where it leads.
ReplyDeleteHarris Jackson (1)
It seems to be prominent in some reptiles, like the crocodile and bearded dragon, and other lizard species. I believe photoperiods also have effects on sex-determination.
Delete-- Hannah Kullberg (2)
It's crazy how there is only 1% left of male green sea turtles left in comparison to 99% females. I actually learned about this in ecology class this semester and how temperature determines their gender. With the increase in temperatures, I have a reason to believe that climate change is involved and this just raises an alarming concern. Maybe some people think that just because we don't use sea turtles as a source of food, that maybe it's not an issue they are being endangered, but all species exist for a reason and that's why we have a balance of nature. I hope climate change can be slowed down one way or another.
ReplyDelete-Catherine Tsang (3)
It is a scary thing! While this ratio only applies to the green sea turtles of the Great Barrier Reef to my knowledge, it is a pressing issue that definitely needs more attention!
Delete-- Hannah Kullberg (2)
Its crazy to think that the climate change is effecting organisms. The fact that the climate change has caused there to be a higher percentage of females than males is very shocking to me. Besides moving the turtle nest to cooler areas are there other researches that have helped the male production rate? Although males practice polygamy why are females not having as many male babies? Overall I found this to be very interesting and I've gained a further interest in wanting to know what is happening to these organisms.
ReplyDelete- Tatiana Silveira (3)
There are some great solutions! As mentioned above, spreading out lighter colored sand over the nesting sites help with this issue, as well as planting more vegetation, help to some degree. Even though one male mates with multiple females, the many eggs that are laid by the female are still all determined by the temperature.
Delete-- Hannah Kullberg (2)
I thought this was a very interesting blog, climate change is having such a vast impact on all different organisms. Its unfortunate that this species of turtles is struggling to maintain a healthy gender ratio. Im sure this would also impact other species that share the same ecosystem. This did make me wonder what the scientists plan to do to directly support the livelihood of these turtles.
ReplyDeleteIt is very sad. Hopefully the future is brighter for this species!
Delete-- Hannah Kullberg
I wonder how much farther global warming has to go in order for all of the sea turtles that are born to be female. If this happens slow enough, I wonder if these turtles will be able to develop an adaptation to either change the effect of temperature on the offspring's sex or even go so far as to become successful at reproducing without a dependance on gender.
ReplyDeleteGrace Houghton (1)
That could be a possibility. They have survived through many trying circumstances so hopefully they can do it here too.
Delete-- Hannah Kullberg
Such a cute little species... it's sad to hear they're endangered! I vaguely knew that temperature determined the sex of the offspring, but I didn't know the exact mechanism of how it worked! Interesting it comes down to the activity of the aromatase enzyme at certain temperatures! I also think the part on polygyny is key- imagine how much worse the situation would be if the species were monogamous! It's scary that climate change is having such an effect on this species, but as you pointed out, I agree that there is still plenty of hope for these little creatures! :)
ReplyDelete- Nicole Ayres (1)
I did not know the mechanism behind it either until coming across this article. Cool Stuff!
Delete-- Hannah Kullberg (2)
I learned about this problem in both my ecology and behavioral neuroendocrinology classes! My ecology class went on to outline the problems you mentioned; many marine animals are being affected by climate change, mostly because these temperature changes threaten their habitat, and in this case, reproduction. In my behavioral neuroendocrinology class, we learned about the importance of aromatase, and how the conversion of testosterone during a critical period can affect the 'masculinity' of male individuals in many species. I'm surprised to learn that this also plays a role in sex determination!
ReplyDelete- Rund Tawfiq (3)
It is surprising, and pretty cool too. I was unaware of a lot of this until I found the article.
Delete-- Hannah Kullberg (2)