94
of magnitude than those recorded for offshore waters.
In particular,
several phytoplankton blooms were observed along a narrow strip (about
2 Km) off Naples in July-August 1983. The spatial distribution and temporal succession of these blooms may reflect the small'-scale heterogeneity of nutrient enrichment. Figure 3 shows the uncoupled fluctuations
co
3.
·2.
:c
"15
I.
J U HE
JULY
AUGUST
Fig. 3 - Variations in surfac~
chlorophyll a,values at stations
1 (---)and 3 (----) in the summer of 1983.
in chlorophyll a values recorded at two nearby stations.
The core of the biomass was
confined to surface waters
where chlorophyll a values
up to 50 mg m- 3 and primary
production values up to 2
g C m- 3 d- 1 were recorded.
A rapid reduction in light
intensity, with extinction
coefficients reaching 0.4,
was observed for the first
five meters, restricting the
euphotic zone to a depth of
10-15 m.
Cell numbers commonly
varied from 10 to 40 million
-1
cel~l
, but higher values up to 120 million were also recorded. Bloom
populations included several species of diatoms (Chaetoaeros simp~ex,
Leptoay~indrus daniaus, L. minimus, Nitzsahia a~osterium, Ske~etonema
aostatum, Tha~assiosira deaipiBns) together with Emi~iania hyx~eyi and
Eutreptie~~a sp .• These species alternately dominated the phytoplankton
whereas dinoflagellates and small flagellates rarely exceeded 20% of
the total cell numbers. Values for species diversity from 1.70 to 3.04
(x 2.36) were mainly due to the concurrent dominance of more than one
species.
Factors controlling the structure and dynamics of these populations
are not well understood. The observed values for species diversity and
the frequent dominance of small, fast-growing diatoms could be related
to intense nutrient inputs in addition to wind driven turbulence of sur-
of magnitude than those recorded for offshore waters.
In particular,
several phytoplankton blooms were observed along a narrow strip (about
2 Km) off Naples in July-August 1983. The spatial distribution and temporal succession of these blooms may reflect the small'-scale heterogeneity of nutrient enrichment. Figure 3 shows the uncoupled fluctuations
co
3.
·2.
:c
"15
I.
J U HE
JULY
AUGUST
Fig. 3 - Variations in surfac~
chlorophyll a,values at stations
1 (---)and 3 (----) in the summer of 1983.
in chlorophyll a values recorded at two nearby stations.
The core of the biomass was
confined to surface waters
where chlorophyll a values
up to 50 mg m- 3 and primary
production values up to 2
g C m- 3 d- 1 were recorded.
A rapid reduction in light
intensity, with extinction
coefficients reaching 0.4,
was observed for the first
five meters, restricting the
euphotic zone to a depth of
10-15 m.
Cell numbers commonly
varied from 10 to 40 million
-1
cel~l
, but higher values up to 120 million were also recorded. Bloom
populations included several species of diatoms (Chaetoaeros simp~ex,
Leptoay~indrus daniaus, L. minimus, Nitzsahia a~osterium, Ske~etonema
aostatum, Tha~assiosira deaipiBns) together with Emi~iania hyx~eyi and
Eutreptie~~a sp .• These species alternately dominated the phytoplankton
whereas dinoflagellates and small flagellates rarely exceeded 20% of
the total cell numbers. Values for species diversity from 1.70 to 3.04
(x 2.36) were mainly due to the concurrent dominance of more than one
species.
Factors controlling the structure and dynamics of these populations
are not well understood. The observed values for species diversity and
the frequent dominance of small, fast-growing diatoms could be related
to intense nutrient inputs in addition to wind driven turbulence of sur-