Luke:
My pond is under overhanging limbs of large maple and "ornamental" peach & pear trees.....hahahahahahaha. I was in denial about fruit trees since that had very little fruit the first year. Every year since - literally thousands of golf balls sized pears drop like bombs all over the place - BIG pain in the butt.
Pros: delightful shade for fish, for shade plants, and for people, trees are pretty when flowering
Cons: Springtime: fallen flower petals -
I think mulberrys have catkins as well - messy
Summer: Gazillion $#%&#*@ pears & peaches everywhere that must be picked up daily to avoid rotten squishy mess, squirrels eat fruit and throw them all over the place, fruit gets in pond and hits you on the head.
Isn't mulberry fruit sort of like a big raspberry? I do know that birds love the berries, and that the juice from the berries is used as a dye - strong pigment. Could be messy around your pond with purple berry mess & bird poo.
Fall: leaves - cover pond to keep them out of pond b/c build up & decay very quickly
Winter - no big deal
I would strongly consider a tree species that has less crap falling off of it, from experience.
FYI: List of toxic plants I came across online a few months back. Was surprised to see azalea & rhododendron - often see them in Japanese garden pix:
Poisonous Plants What most new ponders may not realize is that many plants can be harmful or even fatal for their fish and water life. Here is a partial list of plants that can be harmful and should not be planted near your pond. Azalea (leaves) Baneberry (berries & roots) Black Locust (bark,sprouts & foliage) Boxwood (leaves & stems Buckthorn (fruit & bark) Buttercup (sap & bulbs) Calla Lily (leaves) Caster Bean (beans & leaves) Cherry Tree (bark, twigs, leaves & pits) Daffodil (bulbs) Daphine (berries) Delphinium (all parts) Elephant Ear (Leaves and flowers) Eggplant (All parts except for the fruit) English Ivy (berries & leaves) False Henbane (all parts) Foxglove (leaves & seeds) Golden Chain (all parts) Henbane (seeds) Holly (berries) Horse Chestnut (nuts & twigs) Hyacinth (bulbs) Hydrangea (flower buds) Jack-In-The-Box (All parts) Iris-Blue Flag (bulbs) Lima Bean (uncooked bean) Jimsonweed ((leaves & seeds) Juniper (needles, stems & berries) Larkspur (all parts) Laurel (all parts) Lily of the Valley (all parts) Lobelia (all parts) Locoweed (all parts) Mayapple (all parts except the fruit) Mistletoe (berries) Mock Orange (fruits) Monkshood (leaves & roots) Morning Glory (all parts) Narcissus ((bulbs) Nightshade (berries & leaves) Oak (acorns & foliage) Oleander (leaves, branches, blossems) Philodendron (leaves & stem) Poinsetta (leaves & flowers) Potato (eyes & new shoots) Privet (all parts & berries) Rhododendrom (all parts) Rhubarb (leaves) Skunk Cabbage (all parts) Sweet Peas (seed & fruit) Virginia Creeper (sap) Wisteria (all parts) Yew (needles & seed)