211
nutrients
stant and the alternating current is maximal. In astronomy a node is the
crossing-over point of the equator and the track of a celestial body (such as
the moon). The nodes of the moon gradually move along the equator and
this is the cause of a variation in the tidal amplitude with a period of about
18 years (nodal factor).
noncoral reef ~reef.
nondimensional parameters ~similarity theory.
Norwegian North Atlantic Expedition (1876-1878) with the Voringen under
Captain C. Wille, this expedition carried out depth soundings, measured
currents and water temperature every summer and studied the biology of
the Norwegian Sea between Norway, Iceland, Svalbard and Jan Mayen. H.
Mohn (physicist) and G.O. Sars (biologist) were on board.
notochord skeletal rod of large vacuolated cells packed within a firm sheath.
Present during any stage of development in all Chordata.
Nuda class of the phylum Ctenophora, without tentacles.
Nudibranchia order of the Opisthobranchia, phylum Mollusca. Marine slug-like snails,
which lack a shell and true ctenidia. Instead, they have often external structures that take over the respiratory function of the ctenidia. These secondary gills can have the form of one feathered lateral tentacle, many long dorsal appendages (cerata), or branched tufts around the anus. They are carnivores, and are often spectacularly colored, warning predators that they are
unpalatable. Some eat sea anemones (Actiniaria), and use the cnidoblasts for
their own defense.
nursery area an area which offers favorable circumstances for food (growth) and
shelter for juvenile stages of the population of a certain species.
nutrients term that refers to inorganic compounds which are essential for phytoplankton growth. They consist of N-compounds like ammonia, nitrate, and
nitrite, P-compounds like HP0 4 2- and H Z P0 4 -, which are taken up by algal
cells and are built in as atoms in amino acids, proteins, nucleic acids, fats, etc.
Also dissolved silicate has to be considered a nutrient because it is essential
for diatoms to build up their skeletons, which consist of biogenic silicate
(opal). The inorganic N-, P-, and Si-compounds are often referred to as
macronutrients to discriminate them from metal ions, the so-called micronutrients, which are essential because they are part of enzyme systems, but are
taken up by the cells in much smaller quantities than the macronutrients.
Because uptake of nutrients by algae is restricted to the upper part of the
nutrients
stant and the alternating current is maximal. In astronomy a node is the
crossing-over point of the equator and the track of a celestial body (such as
the moon). The nodes of the moon gradually move along the equator and
this is the cause of a variation in the tidal amplitude with a period of about
18 years (nodal factor).
noncoral reef ~reef.
nondimensional parameters ~similarity theory.
Norwegian North Atlantic Expedition (1876-1878) with the Voringen under
Captain C. Wille, this expedition carried out depth soundings, measured
currents and water temperature every summer and studied the biology of
the Norwegian Sea between Norway, Iceland, Svalbard and Jan Mayen. H.
Mohn (physicist) and G.O. Sars (biologist) were on board.
notochord skeletal rod of large vacuolated cells packed within a firm sheath.
Present during any stage of development in all Chordata.
Nuda class of the phylum Ctenophora, without tentacles.
Nudibranchia order of the Opisthobranchia, phylum Mollusca. Marine slug-like snails,
which lack a shell and true ctenidia. Instead, they have often external structures that take over the respiratory function of the ctenidia. These secondary gills can have the form of one feathered lateral tentacle, many long dorsal appendages (cerata), or branched tufts around the anus. They are carnivores, and are often spectacularly colored, warning predators that they are
unpalatable. Some eat sea anemones (Actiniaria), and use the cnidoblasts for
their own defense.
nursery area an area which offers favorable circumstances for food (growth) and
shelter for juvenile stages of the population of a certain species.
nutrients term that refers to inorganic compounds which are essential for phytoplankton growth. They consist of N-compounds like ammonia, nitrate, and
nitrite, P-compounds like HP0 4 2- and H Z P0 4 -, which are taken up by algal
cells and are built in as atoms in amino acids, proteins, nucleic acids, fats, etc.
Also dissolved silicate has to be considered a nutrient because it is essential
for diatoms to build up their skeletons, which consist of biogenic silicate
(opal). The inorganic N-, P-, and Si-compounds are often referred to as
macronutrients to discriminate them from metal ions, the so-called micronutrients, which are essential because they are part of enzyme systems, but are
taken up by the cells in much smaller quantities than the macronutrients.
Because uptake of nutrients by algae is restricted to the upper part of the