Blake Expeditions
34
very slow deposition of detrital (~detritus, geol.) materials. ~deep-sea sediments.
Blake Expeditions (between 1877 and 1886) this US ship carried out current
measurements under John Elliott Pillsbury at 39 anchor stations at great
depths in the Gulf Stream. These measurements are classical data that 40
years later made it possible to demonstrate the correctness of the later methods
used for computing the so-called geostrophic currents (~geostrophic balance).
Alexander Agassiz was responsible for the zoological part of the expeditions
on which he published his book Three cruises of the U.S.C.G.S. steamer Blake
(1888) in which he i.a. rejected Darwin's theory of atoll formation. Darwin
suggested that atolls form by reef growth on slowly sinking volcanic islands;
Agassiz preferred John Murray's theory which explained atolls as the growth
of reefs on submerged mountains which had reached the shallow water zone
of reef growth by the gradual accumulation of planktonic sediments. Holes
drilled later into Eniwetok atoll, penetrating more than l300 m of shallow
water corals before reaching the volcanic base, proved Darwin's theory to be
correct.
blooms (in marine systems) in nature, reproduction and density of species are
normally limited by the available resources like space, nutrients, and energy,
by predation, and other mortalities. When during short periods these limitations are absent, explosive increases in number are possible, called
blooms. Good examples are the phytoplankton spring blooms characteristic
of the seas of the temperate region: due to low light irradiance, there is only
a very low production of algae during winter, and since growing algae are
the main consumers of dissolved inorganic nutrients, N-, P- and Si-concentrations increase. When in spring irradiance exceeds a certain threshold, the
production season starts with exponential increase in numbers of diatoms
and flagellates. In temperate seas, 50-75 % of the annual primary production
occurs during these spring blooms in March-April. Other examples are red
tides: blooms of flagellates in the surface water layer after exceptional temperature increase in summer.
blue-green algae ~Cyanobacteria.
BOD ~biological oxygen demand.
bongo net ~nets.
boomer ~seismic instruments.
bore a sharply developed front of a tidal flood wave, occurring in some rivers or
estuaries with a large tidal range, and caused by their typical topography. The
34
very slow deposition of detrital (~detritus, geol.) materials. ~deep-sea sediments.
Blake Expeditions (between 1877 and 1886) this US ship carried out current
measurements under John Elliott Pillsbury at 39 anchor stations at great
depths in the Gulf Stream. These measurements are classical data that 40
years later made it possible to demonstrate the correctness of the later methods
used for computing the so-called geostrophic currents (~geostrophic balance).
Alexander Agassiz was responsible for the zoological part of the expeditions
on which he published his book Three cruises of the U.S.C.G.S. steamer Blake
(1888) in which he i.a. rejected Darwin's theory of atoll formation. Darwin
suggested that atolls form by reef growth on slowly sinking volcanic islands;
Agassiz preferred John Murray's theory which explained atolls as the growth
of reefs on submerged mountains which had reached the shallow water zone
of reef growth by the gradual accumulation of planktonic sediments. Holes
drilled later into Eniwetok atoll, penetrating more than l300 m of shallow
water corals before reaching the volcanic base, proved Darwin's theory to be
correct.
blooms (in marine systems) in nature, reproduction and density of species are
normally limited by the available resources like space, nutrients, and energy,
by predation, and other mortalities. When during short periods these limitations are absent, explosive increases in number are possible, called
blooms. Good examples are the phytoplankton spring blooms characteristic
of the seas of the temperate region: due to low light irradiance, there is only
a very low production of algae during winter, and since growing algae are
the main consumers of dissolved inorganic nutrients, N-, P- and Si-concentrations increase. When in spring irradiance exceeds a certain threshold, the
production season starts with exponential increase in numbers of diatoms
and flagellates. In temperate seas, 50-75 % of the annual primary production
occurs during these spring blooms in March-April. Other examples are red
tides: blooms of flagellates in the surface water layer after exceptional temperature increase in summer.
blue-green algae ~Cyanobacteria.
BOD ~biological oxygen demand.
bongo net ~nets.
boomer ~seismic instruments.
bore a sharply developed front of a tidal flood wave, occurring in some rivers or
estuaries with a large tidal range, and caused by their typical topography. The