Periphylla periphylla has a global distribution, usually confined to deep water
and with a low abundance, seldom reported higher than one per 1,000 m3.
However, in Lurefjorden, western Norway, anecdotal stories by fishermen describe mass
occurrence of this species causing problems for the fisheries. The current studies were
initiated in 1991 and have given new information about the life cycle, nutritional
ecology, bioluminescence physiology and chemistry, and population dynamics. Lurefjorden is
hydrographically an untypical fjord, by having a very narrow (200 m) and shallow (20 m)
sill entrance, which restricts Atlantic water from filling up the 450-meter deep basin.
There is neither any main freshwater supply from rivers, thereby reducing the fjord
Reasons for the high abundance of P. periphylla are suggested and problems related to quantification of gelatinous macrozooplankton are discussed. Future plans for a newly introduced deep-water ROV is also outlined.
Last updated: December 19, 2000