It took them about 2 1/2 weeks, but the mass of Bryopsis is gone.  The slugs consumed a lot, spending almost all of their time face down in the stuff, but some of the algae may have died due to my inability to keep NO3 and PO4 at measurable levels.  I have been adding KH2PO4 and KNO3, but the plants have been consuming it like crazy.

Here is what the tank looks like now. Rather different from a week or so ago when it was stuffed with fresh algae.

A couple of them were chasing each other.  Courtship?  Will we finally see eggs?

I came into the office on Sunday to find hundreds of dead amphipods in the box of slugs.  Because there is plenty of vegetable material and no predation, the amphipods had multiplied rapidly, but I was surprised at the sheer number of dead little bugs.

Dead amphipoods 9/14/14

Naturally, I was anxious about the slugs, but they seemed unconcerned.  In fact, none of the other inhabitants seemed at all bothered, including the corals.

Snails?  Fine.  They have been happily grazing away on the glass and other surfaces.

Columbellid snail

Isopods?  Fine.  If anything, they seemed more bold than usual.  So, whatever it was did not affect all arthopods equally.

Isopods in slug box

The sabellid worms that came in with the Bryopsis were also unaffected.

Small sabellid worm

I learned later that there had been a power outage, which explains why the low-flow alarms for the fume hoods in the lab were ringing when I arrived Sunday.  Perhaps the amphipods were more sensitive to the loss of circulation in the tank than were the other invertebrates.  Maybe amphipods just don’t like big piles of Bryopsis.  We may never know.  Will the amphipod population rebound?  We’ll see.