We run active nest pretty much year round. Periodically we run into outbreaks / eruptions of mites and seed shrimp that collect in nest. Former we are very confident damage embryos and nest bound prolarvae. Latter we suspect do the same.
A peculiar behavior we see female sunfish of all species doing before spawning we call rock-biting may be a way of assessing a nest for such outbreaks. The outbreaks may in part be a function of males being fed while nesting.