I have used White Labs WLP001 California Ale Yeast for a hydromel before with some success. Since it has a fairly neutral flavor and is listed on White Labs' site as being good for honey ales, I figured it would do well with mead. It's also available at most homebrew shops. It may have a higher nutrient requirement, though, since it's intended for beer. As for ABV, that linked fact page says it is "high," which White Labs indicates as being 10% - 15%
Wyeast 1388 Belgian Strong Ale makes an outstanding mead pretty quickly at all ABV's (up to 19%, if you baby it enough), and is yeast used in the BOMM (Bray's One Month Mead) (I know, there are two BOMM links there, but it's worth it.). It's also one of the few yeasts that seems to be a great fit across all styles. It can be hard to find, so I typically purchase it from the Northern Brewer's website. I mostly use it for regular strength meads (12% - 15%), so it will have no problem getting you to 8%.
Aside from that, I've seen Lalvin EC-1118 (a champagne yeast with neutral flavors; good to 18%) and Lalvin K1-V1116 (lots of esters, good to 18%, treats honey well) both used successfully in hydromel recipes (and a lot of mead recipes, in general). DV10, another champagne yeast, might be also good candidate, but I haven't personally tried it. EC-1118 and K1-V116 are pretty widely available.
Basically, if the yeast makes a good mead, it should make a good hydromel.
Here is a list of yeasts that I've seen typically used in meads, in no particular order:
- *Wyeast 1388 Belgian Strong Ale
- *Lalvin EC-1118
- *Lalvin K1-V1116 (often abbreviated "K1V"; sometimes listed as "ICV K1")
- Lalvin D47
- Lalvin 71B-1122 (abbreviated "71B")
- Lalvin DV10
- Lalvin D21
- Lalvin RC-212 (it's a nutrient hog)
- Red Star Montrachet
- Red Star Côte des Blancs
- Fleischmann's Bread Yeast (in JAOM only)
*Yeasts I think would be good for a most hydromels
That seems like a lot, but all of them bring out different qualities in mead.
Of course, if you're feeling really ambitious, you can email a meadery that you know produces hydromels commercially, like B. Nektar or Crafted Artisan Meadery, and ask them what yeast they use for theirs. A lot of commercial mead makers are more than willing to give some tips, since they typically started as homebrewers too.