These structures were founded in zooplankton and fitoplankton tows offshore and inshore and we really don´t know which body part do. your comments will be very helpfull for us.
They can be found when butterflies fall in the water, but I never saw them in large amount in the plankton. Do you know if there are some concentrations of butterflies in your areas?
I would wote for lepidopteran scales! I found them very frequently in the pools in the caves, where the bats rest during a day. And the bats eat the moths/buterflies. Usually forms No. 4 and 5 were present there, but structures No. 1-3 also resembles to the buterflies scales. So it is quite possible that some buterflies felt on the lakes' surface and died there.
Dear Edgar, I also find these structures in plankton of Brazilian reservoirs, until then did not know what it was, but support the hypothesis of the butterflies scales because find especially at the beginning of the year, the period with the highest concentration of butterflies.
nobody said they were (diatoms) and identification by exclusion can be lengthy. It seems that there is a general consensus that they are butterly (lepidopterans) wing scales.
Hello everyone, thank you very much for taking the time to answer our question, everyone I bring great information related to reviewing the information obtained by you. we believe in the hypothesis that are flakes wing butterflies, some of these samples were collected close to areas with mangroves while others were collected offshore in the Colombian Caribbean, which may indicate that these scales belong to butterflies falling into the water during their long annual migrations.
My opinion is that the translucent structure with striations are fish scales.
To give you some idea of my background, for my Masters of Science I examined thousands of plankton samples off Puerto Rico primarily looking at ichthyoplankton.
I hope this helps. If you know the top ten dominant fish, I would suggest getting samples from a local museum for comparison.
The butterfly/moth scales. But which species/group (diurnal or nocturnal)? - I have no idea. Quite common in samples from the caves where bats' excrements are present.
In addition - some bat species feed on freshwater fish (in tropics), but I found scales in temperate/cold zone exclusively.