Subsurface phytoplankton blooms fuel pelagic production in the North Sea

The seasonal phytoplankton biomass distribution pattern in stratified tempe rate marine waters is traditionally depicted as consisting of spring and au tumn blooms. The energy source supporting pelagic summer production is beli eved to be the spring bloom. However, the spring bloom disappears relativel y quickly from the water column and a large proportion of the material sedi menting to the bottom following the spring bloom is often comprised of inta ct phytoplankton cells. Thus, it is easy to argue that the spring bloom is fueling the energy demands of the benthos, but more difficult to argue conv incingly that energy fixed during the spring bloom is fueling the pelagic p roduction occurring during summer months. We argue here that periodic phyto plankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goerin g, Limnol. Oceanogr., 12, 196-206, 1967)] occurring in these blooms may be greater than that occurring in the spring bloom in the same regions. Thus, such blooms may explain apparent discrepancies in production yields between different temperate marine systems.