Caretta caretta eggs of a nest guarded by volunteer operators (Puglia, Italy), have not hatched, after the "digging" the embryos were analyzed by eco-doppler and declared dead.
Is it correct to exclude the massive presence of microplastic in the Mediterranean Sea among the causes of their death?
Hatching success is never one hundred percent and there are so many causes that could disturb incubation... I would say if the nest looks physicaly intact (not excavated by predator and not eroded) and if there it is not rotten inside at the moment you dig (if only on egg got rotten during incubation it can make the total nest failed), the cause maybe i) environmental condition not suitable for proper incubation (temperature, humidity, pH, compacted sand...) ii) some microscopic factors (fungus, bacteria, pollutant). Among pollutants I won't exclude chemicals from plastics contaminating the beaches. But I don't know if there are published papers on the potential impact of chemicals from plastic on sea turtle eggs and incubation.
So if the eggs were intacts at the time you dug, according to me you should explore further the environmental (season, rains, flooding of the nest) and microscopic agents.
Another point : how long did you wait before digging : because sometime bad temp condition can lead to delay in hatching, did you wait long enough before digging the nest ?
hey Ines!
Is that the Caretta nest located near Campomarino? that's sad news, i spent a couple of nights guarding that nest too (as one of activities organized by greenrope summerschool)
According to Casale et al (2012 - ref1), there are only 30-40 nests per year in whole Italy, and mean hatching success for those on Sicily was around 25%, some having no hatchlings at all. Now, they mention suboptimal sand temps there, and Sicily is more south than Puglia and therefore should have higer temps. That could be one of the reasons.
Also, if this is the nest I am thinking about, if I remember correctly, it was relocated from the original spot after a person stuck a sun- umbrella into it, and only a dozen or so (18 or 21) eggs were not smashed. I didn't know one dead (rotten) egg could ruin the whole nest, but maybe if one of those 'saved' was also dead, that could be the reason?
Or, during relocation, maybe one of the eggs was not properly orientiered, which could be the reason for it not surviving also, and consequently infecting the rest.
Also, I am really not sure how moist the sand usually is, too moist sand could hinder the developement too, and this was quite a wet summer (at least here in croatia)
Microplastic particles could change the physical properties of the sand (Carson et al 2011 , Ref 2 ), but as far as I saw, on that beach there weren't that many microplastic particles present.
Out of curiosity, how big were the embryos when you undug the nest?
Shame the little guys didn't make it , you can never have too many sea turtles :/
References;
Ref 1: Acta Herpetologica 7(1): 181-188, 2012
Exceptional sea turtle nest records in 2011 suggest an underestimated nesting potential in Sicily (Italy)
P. Casale, G. Palilla, A. Salemi, A. Napoli, M. Prinzi, L. Genco, D. Bonaviri, A. Mastrogiacomo, M. Oliverio, M. Lo Valvo
Ref 2 : Marine Pollution Bulletin 62 (2011) 1708–1713
Small plastic debris changes water movement and heat transfer through
beach sediments
Henry S. Carson ⇑, Steven L. Colbert, Matthew J. Kaylor, Karla J. McDermid
Dear Alexander,
many many thanks for your answer and your interesting informations,
in those weeks there had been several days of rain...unfortunatelly.
so that should be happened even for this reason.
thanks again
Hey Nina,
is a really sad news, whenever even a turtle reaches the sea is truly a miracle to watch, but when it fails no ... and when is not only the hand of nature but man's ...
thank you for the interesting references too.
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