Newly-discovered life history characteristics of the endemic deepwater stonefly Capnia lacustra in Lake Tahoe
Lake Tahoe’s endemic deepwater stonefly (Capnia lacustra) was originally described in 1963. Completing its life cycle underwater, C. lacustra is strongly associated with deepwater plant beds of skunkweed (Chara spp.) and moss. Recently, a dramatic decline in deepwater plants and invertebrate populations (including the stonefly) has been observed due to cultural eutrophication and introduction of invasive species. Recently, we discovered some of C. lacustra’s unique life history characteristics. First, C. lacustra populations in Lake Tahoe have two separate cohorts that develop on staggered cycles each year: adults develop eggs in May and November, a characteristic very unusual for stoneflies. Ovoviviparity has also been observed in adult females, with egg development occurring inside the body cavity. After a period of incubation, eggs hatch within the mother’s body and live birth occurs shortly after hatching. Stable temperatures and habitat conditions in Lake Tahoe’s deepwater plant beds have likely promoted the evolution of these remarkable life history characteristics in C. lacustra.
Diver's view of Camp Richardson Chara bed. Video credit: New Millennium Dive Expeditions.