Eye on Nature

Readers of The Irish Times  pose questions on nature.

Are rhododendron bushes growing close to streams poisonous to trout? Have grass-eating carp been brought to the north of England to keep canals clear of weeds?
Brian Devine, Newbridge, Co Kildare

Rhododendron bushes are not poisonous to fish but, unlike native bushes, do not harbour the insects that fish eat, and shade out the water. Grass carp came to Britain as ornamental fish many decades ago, but their introduction is prohibited now except under licence.

I rescued a fledgling songthrush from my cat and fed him until his tail feathers grew. I released him on a friend's property near Baltimore and now he comes every morning to her window to beg.
Caidy Charles, Durrus, Co Cork

Why is sea lettuce growing so profusely, clogging parts of the coast in Co Cork?
Patrick Harvey, Abbeyleix, Co Laois

Sea lettuce (Ulva lactuca) is an algae and thrives on the runoff of nitrates and phosphates from the land. It is edible and eaten as green laver, not to be confused with purple laver (Porphyra umbilicis).