Contribution of Gammarus lacustris to phosphorus recycling in a fishless alpine lake

We estimated the net P transport by Gammarus lacustris from the benthic to pelagic regions of a fishless alpine lake and compared it with P regenerati on by the entire plankton community. Gammarus lacustris released between 5. 2 and 18.1 ng P.L-1.h(-1) (adults only and adults plus immatures, respectiv ely) in the pelagic region during nighttime vertical migration. Additional P released into and removed from the water column due to predation on zoopl ankton was estimated at 1.87 and 2.3 ng P.L-1.h(-1), respectively The net d aily regeneration of 52.2-181.4 ng P.L-1.day(-1) by the G. lacustris popula tion represented 9.5-32.9% of the total P regenerated by the planktonic com munity. The majority of the P released by G. lacustris represents "new" P t o the pelagic zone because it originated in sediments. We conclude that G. lacustris can represent an important link in benthic-pelagic coupling in ol igotrophic mountain lakes.