GROWTH RATES OF NATURAL POPULATIONSOF MARINE DIATOMS
AS DETERMINED IN CAGE CULTURES
G.A. VARGO
Department of Marine Science, University of South Florida,
140, Seventh Ave S, St. Petersburg, Florida 33701, USA.
Introduction
The term 'cage' culture,
(1978), refers to " a population
membrane .which is permeable to
as defined by Sakshaug and Jensen
of living organisms retained behind a
the dissolved constituents of the
growth medium as well as to the soluble metabolites excreted by the
organisms."
Two types of cage culture chambers are commonly used; tubes made
of dialysis membrane (Sakshaug and Jensen, 1978) and p1exig1ass
chambers
using Nuc1epore (R) filters as cage walls (OWens et al.,
1977). For simplicity, dialysis chambers will be called tubes and
'cages' will refer to filter-walled chambers.
Considering the interest in and the problems involved with
estimating the growth and production rates of phytoplankton assemblages in oligotrophic, oceanic waters (Goldman et a1.,1979; Goldman,
1980; Eppley, 1980,1981), cage cultures should be ideally suited for
obtaining estimates of the potential in situ growth rates of
individual species in natural assemblages. Populations enclosed in a
porous membrane and incubated in situ or in tanks of flowing sea'water
allows them to react to "natural" spatial and temporal variations in
temperature, salinity, nutrient concentrations and irradiance.
The
response of the entire assemblage and individual species can be
obtained.
No other method is available which can yield similar
results. More commonly used methods e.g. 14c , O 2 , proximate analyses,
measure the response of the community as a whole.
While microautoradiography offers some potential for estimating the production
rates of individual species the technique is even more laborious than
using cage cultures.
Estimates of growth rates for populations in
14
oligotrophic, oceanic waters based on
C uptake requires answers to
AS DETERMINED IN CAGE CULTURES
G.A. VARGO
Department of Marine Science, University of South Florida,
140, Seventh Ave S, St. Petersburg, Florida 33701, USA.
Introduction
The term 'cage' culture,
(1978), refers to " a population
membrane .which is permeable to
as defined by Sakshaug and Jensen
of living organisms retained behind a
the dissolved constituents of the
growth medium as well as to the soluble metabolites excreted by the
organisms."
Two types of cage culture chambers are commonly used; tubes made
of dialysis membrane (Sakshaug and Jensen, 1978) and p1exig1ass
chambers
using Nuc1epore (R) filters as cage walls (OWens et al.,
1977). For simplicity, dialysis chambers will be called tubes and
'cages' will refer to filter-walled chambers.
Considering the interest in and the problems involved with
estimating the growth and production rates of phytoplankton assemblages in oligotrophic, oceanic waters (Goldman et a1.,1979; Goldman,
1980; Eppley, 1980,1981), cage cultures should be ideally suited for
obtaining estimates of the potential in situ growth rates of
individual species in natural assemblages. Populations enclosed in a
porous membrane and incubated in situ or in tanks of flowing sea'water
allows them to react to "natural" spatial and temporal variations in
temperature, salinity, nutrient concentrations and irradiance.
The
response of the entire assemblage and individual species can be
obtained.
No other method is available which can yield similar
results. More commonly used methods e.g. 14c , O 2 , proximate analyses,
measure the response of the community as a whole.
While microautoradiography offers some potential for estimating the production
rates of individual species the technique is even more laborious than
using cage cultures.
Estimates of growth rates for populations in
14
oligotrophic, oceanic waters based on
C uptake requires answers to