neuston
208
the catch in such a torpedo is continuously enveloped and preserved during
sampling, the gear is called Continuous Plankton Recorder. Different depth layers
can be sampled with the multi-net, a rosette of small plankton nets with
opening and closing mechanisms towed vertically upwards. For the collection of macroplankton (e.g., jellyfish, mysids, euphausids, and fish larvae)
pelagic plankton trawls are available, such as the Isaacs-Kidd Midwater Trawl
and the Rectangular MidwaterTrawl (RMT). These large nets with mesh sizes of
1 to 5 mm are generally towed from the A-frame of research ships, while
depressors are mounted to force the nets downwards; acoustic releases may be
used to open and close these nets under water in order to sample a certain
depth interval. The bongo net is special in that it actually consists of two conical plankton nets with circular openings attached symmetrically to both
sides of the fishing line, to reduce the disturbing effect of lines and connections in front of the net opening.
neuston the typical community of bacteria, plants and animals living at the very
surface. Species living day and night in or above the microlayer form the
euneuston (including the only marine Insecta Halobates); species not attached
or confined to the surface form the pseudoneuston; buoyant organisms subject to wind drift form the pleuston (Sargassum weed, the coelenterates
Physalia, Velella). ---7surface film.
neutral surface ---7isentropic surface.
new production primary production based on newly incorporated nutrients,
imported into the euphotic zone from elsewhere, as opposed to regenerated production based on nutrients recycled in the euphotic zone. The {-ratio is the
ratio between new production and total production. The rate of export of
organic matter from the euphotic zone by either sedimentation or transport
with the currents, and new production by phytoplankton may be unbalanced
over short periods but they have to be in balance over a I-year period if phytoplankton is to maintain itself.
niche the role or function of a species in the community or ecosystem (often wrongly used for the habitat in which a species occurs).
Nino ---7EI Niiio.
Niskin bottle ---7seawater sampler.
nitrate inorganic nitrogen compound in which the nitrogen atom is in its highest oxidation state. Chemical symbol N0 3 -. In nature nitrates are the end
product of aerobic degradation of nitrogeneous organic compounds. They are
an important nitrogen source for phytoplankton growth, especially when ambi-
208
the catch in such a torpedo is continuously enveloped and preserved during
sampling, the gear is called Continuous Plankton Recorder. Different depth layers
can be sampled with the multi-net, a rosette of small plankton nets with
opening and closing mechanisms towed vertically upwards. For the collection of macroplankton (e.g., jellyfish, mysids, euphausids, and fish larvae)
pelagic plankton trawls are available, such as the Isaacs-Kidd Midwater Trawl
and the Rectangular MidwaterTrawl (RMT). These large nets with mesh sizes of
1 to 5 mm are generally towed from the A-frame of research ships, while
depressors are mounted to force the nets downwards; acoustic releases may be
used to open and close these nets under water in order to sample a certain
depth interval. The bongo net is special in that it actually consists of two conical plankton nets with circular openings attached symmetrically to both
sides of the fishing line, to reduce the disturbing effect of lines and connections in front of the net opening.
neuston the typical community of bacteria, plants and animals living at the very
surface. Species living day and night in or above the microlayer form the
euneuston (including the only marine Insecta Halobates); species not attached
or confined to the surface form the pseudoneuston; buoyant organisms subject to wind drift form the pleuston (Sargassum weed, the coelenterates
Physalia, Velella). ---7surface film.
neutral surface ---7isentropic surface.
new production primary production based on newly incorporated nutrients,
imported into the euphotic zone from elsewhere, as opposed to regenerated production based on nutrients recycled in the euphotic zone. The {-ratio is the
ratio between new production and total production. The rate of export of
organic matter from the euphotic zone by either sedimentation or transport
with the currents, and new production by phytoplankton may be unbalanced
over short periods but they have to be in balance over a I-year period if phytoplankton is to maintain itself.
niche the role or function of a species in the community or ecosystem (often wrongly used for the habitat in which a species occurs).
Nino ---7EI Niiio.
Niskin bottle ---7seawater sampler.
nitrate inorganic nitrogen compound in which the nitrogen atom is in its highest oxidation state. Chemical symbol N0 3 -. In nature nitrates are the end
product of aerobic degradation of nitrogeneous organic compounds. They are
an important nitrogen source for phytoplankton growth, especially when ambi-