A consideration of the allele-frequency spectrum suggests that these new introns in Daphnia (also known as the water flea) are indeed deleterious, bringing to mind a famous poem by Jonathan Swift ("On Poetry: A Rhapsody", pub. 1733):
"So nat'ralists observe, a flea
Hath smaller fleas that on him prey,
And these have smaller fleas that bite 'em,
And so proceed ad infinitum."