J. Phycol. 18, 349-3!>{j (1982)
RESPONSE OF PROROCENTRUM MARIAE-LEBOURIAE (DINOPHYCl<:AE) TO LIGHT
OF DIFFERENT SPECTRAL QUALITIES AND IRRADIANCES:
GROWTH AND PIGMENTATIONl
Maria A. Faust
Smithsonian Institutioll. Chesapeake BilY Center for Envimnmental Studies. P.O, Box 18. Edgewater, Maryland 21037
.John C. Sager
Radiation Biol'ogy Laboratory, J2441 Parklawl'l Drive, Rockville. Maryland 20853
and
Blanche W, Meeson
Smithsonian InstiiuUOll. Chesapeake Bay CClller for Environmental Studies. P.O. Box 2'8. E.dgewater, Maryland 21037
ABSTRACT
Growth and pigmmt cO'nrentra#o'/1,1' of the estuarinetli?
niflagellate, Prorocentrum mariae-lebouriae (Parke
and Ballantine) comb. nov., Wfre measured in cultures
grown in 'white,blue, green and red rmliation at three
different irradiances. White irmdiances (400-800 nm)
were 13.4, 4.0 and 1.8 W "m-2 with photon flux densities
C?/58.7 ? 3.5,17.4 ? 0.6 and 7.8 ? 0.3 pM quanta'
TIl ~'2 ?S -1, respectively. AII other spectral qualities had thr
same photon .flux densities. Concmtmtions if chlorophyll
a and chlorophyll c WPrI:' invrrse(v relafRd to irradiance.
A decrease if 7- to 810M in photon flux density resulted
in a 210ld increase in chlorophyll a and c and a 1.6- to
2.41old increase in both peridinin and /(;tal carotenoid
concentrations. Cells grown in green light contained 22 to
32% mo-rrperidinin per cell and exhibiied 10 to 16%
higher peridinin to chlorophyll a -ratios than cells grown
in white light. Orowth decreased as a junction of irradi?
anee in white, green and 1'fd light grotllri cells but was the
same at all blue light irradiances. Maximum growth rates
occurred at 8 f.AJ'W quanta? TIl -;! ? S -I in blue light; 'whilein
red and white light maximum growth rates occurred at
considerably highe-rphoto1l.. fiux densities (24 to 32 pJ'vl
quanta' m -2 ?S -1). The fastest growth rates occurred itt blue
and'rl'fl radiatio-fz. White radiation producing mfJ,Xirnum
gro'toth was onl)1 as iffective as red and blue light when
the photon .flux density in rither the red or blue portion of
the white light 8pn:trum W(l.,5 equivalent to thai of a red or
of blue light treatml'1lt which produced maximum growth
rates. These difffmmces in growth and pigmentation in?
dicate that P. mariae-lebouriae .,.e,~ponds to the spel'lml
quality und.('1? which it i~ grown.
Key index wonk spectral quali(v; blue, gretm, red and
whitt!; irradiances; pigments; chloTOphyU a and c, peridi?
nin, camtenoids; dinoflagellates; photoadaptation; radia?
tion; growth; productivity
Phytoplankton comain a variety of photosynthetic
pigments including- chlorophylls, phycobiliproteins
I /leaptf'{l: 2 Mafl'lI /982.
349
and carotenoid:.. These pigments define the spectral
radi<ition which a species can use for photosynthesis
and hence, growth (Halldal 1970, Bogorad 1975).
In aquatic environments the light which penetrates
a Water column is highly variable in both irradiance
and spectral quality. The red region of the visible
spectrum is absent at depth in dear waters because
the water and dissolved salts absorb at these wave?
lengths. Consequently. the primary spectral quality
at these depths is blue-green. However, in turbid
waters, where suspended particles absorb most of
the blue radiation, green and yellow-orange wave?
lengths predominate. Since blue-green radiation is
the primary spectral irradiance in marine waters. it
is thought to be important in regulating the pho?
tosynthetic capacity of the phytoplankton which live
there (Atlas and Bannister 1980, Vesk and Jeffr~)'
1977, Haxo 1960). Yet. in highly sedimented estu?
aries such as the Rhode River and Chesapeake Bay,
downwelling radiation is primarily green to or<inge
(500 to 650 nm). Its importance in regulating pho?
tosynthetic rates is probably of equal importance to
that of blue-green radiation in clear oceanic waters.
In either case. the ecological significance of spectral
quality has not been demonstrated.
White light of different irradiant:es C<in induce
changes in algal.growth and respiration (Brown and
Richardson 1968), pigment composition (Vesk and
Jeffrey 1974, Mandelli 1972), pigment ratinsUones
and Myers 1965, Brody and Emerson 1959. Fujita
and Hattori 1959), ultrastructure Ueffrey and Vesk
1977) and the peridinin-chlorophyll a-protein com?
plex (PCP) (Prezelin et a!. 1976, Prezelin and Swee?
ney 1978, Meeson and Sweeney 1.981). However.
light of other spectral qualities can result in faster
growth rates and a change in the major accessory
pigments for photosynthesis. Growth rates aregen?
erally higher in blue than in white light grown cells
with the magnitude of the response mediated by the
species as weUas the ambientirradiance (]effn'Y and
Vesk 1977, Hess and Tolbert 1967). In algae with
phycobilins, green light can enhance the synthesis
350 MARIA A, FAUST ET AL.
F'tG. 1. Sp~ctral quality of the white. red, blue and grecnlighl
environments of the growth chamber.
of phycoerythrin and reduce phycocyanin synthesis
(Fujitaand Hattori 1959, Bennett and Bogorad 1973,
Tandeau de Marsac 1977), while red light causes the
opposite e!fect. (M.ann and ~yers !968, Bo~orad
1975). This shift 1n syrithes1s of pigments m re?
sponse to a change in spectral quality has been
termed chromatic adaptation. Chromatic adapta?
tion, thus is a response of some algal groups to al?
terations in the energy distribution in the visible light
environment. As a consequence of this phenome?
non, the pigment!:> which absorb in the incident
wavelength of spectral quality become predominant
(Bennett and Bogorad 1973).
Our knowledge about chromatic adaptation in di?
noflagellates is very limited. A large number of di?
noflagellate species have notable difference!:> in their
response to irradiance (Vesk and Jeffrey 1977, Wall
and Briand 1979), but little information is available
on the growth and pigmentation of these organisms
when grown in light of different spectral qualities
(Halldal 1974). However, it is known that dinofla?
gellates possess three major photosynthetic pig?
ments, chlorophyll a, chlorophyll c and peridinin
Ueffrey et al. 1975). The chromoproteins, PCP and
the chlorophyll a-ehlorophyll c-protein are known
major light harvesting components in this class (Boc?
zar et aI. 1980). Because of their absorption spec?
trum, these two chromoproteins allow dinoflagel?
Lates to utilize radiation in lhe blue-green (458-553
nm) and orange (585-647nm) regions of the visible
spectrum.
Prorocentrum micans is responsible for red tides off
the coast of southern California in the summer
months (Sweeney 1975),P. mariae-lebouriae forms red
tides in the Chesapeake Bay during late spring and
summer (Faust 1974, Tyler and Seliger 1978). In
these systems, spectral attenuati()n is significant over
the year. Our aim was to explore the light require?
ment of P. ma'riae-lebouriae, which must adapt to be
a successful estuarine species. little is known aboUl
the factors affecting the penetration of solar radia?
tion in turbid waters, or the effect of these changes
upon phytoplankton growth and pigmentation (Se?
liger and Loftus 1974).
In the present study, we explored the possibility
of using P. mariae-lebouriae as an experimental sys?
tem to determine growth and photosynthetic pig?
ment responses, Experiments in growth chambers
were set up to identify effects on wowth of white,
blue, green and red spectral quahty radiation ad?
justed to the same photon flux densities. In addi?
tion, photosynthetic pigment composition as a func?
tion of spectral response was determined.
FIG. 2. Map illustrating the Rhode River tidal estuary and
statiot! 2A.
MATERIALS AND METHODS
BaTch experiments were designed to measure a change in cell
numbers and pigmenL<1tion of P. rrwriat-iebou7"iat. Prior to the
experiments, unialgal cultures ofP. 'IIUlTio.e,-iebouriae (obtained from
M. A. Tyler. University of Delaware. Lewes. DE) were grown in
fl2 medium (Guillard and Ryther 1962) at 15% salinity and 2(}O
C in Erlenmeyer flasks which were illuminated from a.bove' with
daylight fluorescent (Westinghouse HOD) lamps. All cultures prior
u) treatment were grown on a 12: 12 h LD cycle with an irradiance
of2.fl W'm-'. Twenty-five mL of the P.mariae-IRblJuria;, culture
described above were added 10 175.tnL of fresh medium to give
an initial inoculum density of 1.68 x 10' cell-ml-', DUling the
experimem the cultures were maintained 011 a 16;8 h LD cycle
a.t 20 ~ 10 C. The cells were grown at three photon flux densities
(PFD's) at each of four spectra.l qualities, while, blue, green and
BLUE
RED
WHITE
GREEN
2
60
40
20
60
40
w 100
'"z 80o
lL
'"Wa:
>
!::
'"zw
o
X
:J
-'J.L.
Z
o
...
o
Z
Go
RESPONSE OF PROROCENTRU"l'f TO LIGHT
TABLE I. Inddent and solar radiation, af the ,furjaa and I and 2 'Ill dl'Plhs atsla/lrm 2A if! Ihf' Rllilrif' Rivf'r.
-5]'1<'<'''''' qualll)
Wh.ile Bloe GI;t:1H1 RedD",. I ,1~fJ Depth
~1.l(J-75U IJIlI 4UO-551). Hill :t5IWiI.lO 11m tiOU-7SU tun
W'rn-' (%1 W'm.'('ll'.1' "1'?",'1%) ....??",-'1%1
Cleur da.~
June 17 Surface 281.5 (l00) 86.0 (JOD) 54.0 (IOU) 141.4 (100)
I m 38.6 (13.7.) 9.1 (10.6) 10.0 i 18.5) 19.4 (13.7)
~m 10.8 (3.8) 1.7 (2JI) 3.4 16.3) 5.1 (3.l;)
OIWTCrist da.y
MaY 13 Surface 128.9 (100) 41.0 (lflO) 26,0 (100) 61.8(100)
I m IU/(9.2l 1..8 (4.4) 3.8 (14.6) 6.4 (10.4)
2 m' 2.7 (2.l) 0.3 (0.7) 1.0 (3.8) 1.4 (2.3)
"
351
red, as measvred by a (:-3 Spectral Scanning System (Galllllia
Sdcntiflc. San Diegl), CAl. The PFD's were adjusted with fiber?
glass screening, so thar they were equivalent for all four spectral
qualiLies. I.n white light. the irradiam;es wcreapproximatety 13.4.
4.0 and 1.8 W' m; and were designated as high. mediunl and low.
The corresponding PFD's were 58.7 ? 3.5, 17.4 ? 0.6 and 7.8
? 0,3 ILM quanta 'm ,;. S-l between 400-c800 nm. The experi?
mental~lllt,ureswere irradiat!'d from above using spectral phos?
phor of daylight fluorescent lamps, Sylvania FY48Tl2NHO blue
No, 246. grCt'Jl :--.In. 2282, <U1d red;.Jn, 236 in coml)inaliol1lvlth
plastic Rosolel1~' filters blue Nfl. 863, green ;.Jo. 874 and red No.
832. rt$penivel)' (KliegI Brothers, Universal Ele~lric Sl'age Light_
ing Co .. Longlsland, NY). The plastic filters were used to narrow
tht, spcctral <loality and reduce the irradiance from the mercury
bands inherent ill the fluorescent lamps (Fig, I). Eight replicares
were u.~l'd at eaLh PFD and spectral (juatir)?. The emire experi?
meur was repealed at leasl once.
After 12 days of treatment. aJi(IUDIS were taken for pigment
analysis and cell counts. Mean growth was estimated from changes
in cell llumbt-rs betweclldliY I and dar 12 of the treatment.
Duplicate samples. from each Aask werecouored in a Scdgwick?
Rafter counting chamber and ceIl density was expressed as tl'um?
bel' of cdls per mL (SLein 1973), Division rates were estimated
("rom cdl umnts:(Guillard 1973). Only TWO growth t:hambel's were
available at a given time so- rhe experiments werenmducted in
pairs with the white light treatment t'cpeated each time. Sin~:e
the experiments \';<"l'e separated in time, mean growth rates and
pigmclll compoSition were expressed relative to the white light
tre<ltm enl.
The photusYllthetk pigments, <:hhH'ophyIIs a and (" \:'Ine ex?
tracted and estimated according 10 Jeffrey and Humphrq' (1975)
and total carotenoids as proposed by Suiddand ami Pal'sons
(1972). Quantitative' thin larer chtOltlEltography (TLC) according
to the method of Jeffrey (1968, 1981) was used to estimate till'
peridinirr content on each ,culture aL thc end of the 12 day treat?
nwnl. Small amounts of wncentrated pit,'TTlcllts wete spoLted otltD
Baker-flux cellulose p1ate~ (Baker Chemkal Co" Phildelphia. PAl,
pigmcnLs separated and concentrations determined,
incident radiation a.nd downwellingirradiances were surveyt.'d
,(400-800 nm at 50 nm band wkhhsl for eight spectral ballds at
station 2A in rhe Rhode River (Fig. 2). A water tight version of
tht, scanning radiometer built by the' SmiThStmian's Radiation Bi?
ology Laborar,()r.y was used to measure this r<.l(!iariotl (G{lldberg
and Klein, [(J74}. The unit was Gi.li'bnucr! with a National Bureau
of Standard spectral I'derence srandard and wmparcd loan
Epple)' precision pyromet.cr. Im.ident surface radiation as well as
thc radiation at ()l1e and 2 m ckpths was measured. Ught pen?
etratilln was caku']ated as the percenl of tot.al surface radiation.
An in vivo absorption spectrum of P. mllrUlp?lefJU'urlap grnwn in
whire light was determined with acmnputerized recording spec?
lropho[omet:er a{'('orcfing to the method of Massit.' and, Nol'l;s
(lfl76).
Spectral quality <.Ind radiation parameters are expn:ssed as rec?
ommended by Tibbitts and Kozlowski (1979). The radiation pa?
rameTers used. t.o describe Ihe propagation of f"lectromagnetic
waves arc: 1) spectral quality. the wavelength distribution or pre?
dominant spectrum nflight energies a\'aihihle: 2) irradianct.'. the
amoull.L of radiant energy pel'unit area per unit. time; and 3) the
photon flux density (PFD). the moles of radialJl. quanta per unit
area per unit rime.
RESULTS.
The spectral distribution of radiation at the sur?
face and at one and 2 m depths at station2A in the
Rhode River are shown on a dear and overcast day
(Table I). A significant population of P. mt.lriae-le?
bouriae was present in the water column on these
two days. Although incident radiation was much
lower on a cloudy day (when most of the radiation
was highly scattered), the spectral distributions ,'vere
similar. On both clear and oven:ast days, the inci?
dent and downwelling radiation were highest in the
orange-red to red region (600-750 I1rn) of the spec?
trum. At all depths, however, a greater proportion
of green and yellow-orange light (500-600 11m) pen?
etrated the water column, than either the blue
(400-550 nm) or red (600-750 mIl), On a cloudy
day proportionally less radiation in each spectral
range penetrated the water column.
Growth occurred in all treatments over the 12 dar
period (Table 2). Mean cell division rates (i<) of P.
maria(!-IFbouTiae at high photr>n Jinx densities were
similar in all spectral qualities (k = 0.24 ? 0.02 di?
visions d -L). In the white and green treatmenLS, the
lowest P1'D had one-sixthlhe number of cells as the
higher treatment, while in the red radiation it was
about one-half. Cell division rates declined with PFn
(Fig. 3). However, in blyc light, mean growth rates
were about the same (k = 0.27 ? 0.01 d- 1) at all
photon flux densities (Fig. 3).
Promcentrum grown in white light rdlected the
presence of the three major photosynthetic pig?
ments (Fig. 4). By comparing the in vivo and acetone
extracted absorption spectra of cells grown in white
radiation with that of purified peridinin in acetone,
it app~ared that peridinin contributed to the whole
cell absorption in the range of 470 to 530 nm. This
352 MARIA A. FAUST ET AL.
I'IG. 3. Relative grov.th of P. m(J,riM-leb~riaf. irradiated at three
different photon ,flux densities and four spe<:tral qualities (\\'hile,
blue, green. and red). The PFDs were 58.7 :': 3.5 ,u.M quanta'
m-"s'l fOl?high. 17.4 ? 0.6,u.M quanta-m'??s?l for medium
and 7.8 :': 0.3 ,u.M quanta?m-t?s -I for low irradiances.
DISCUSSION
Measurements in the estuarine waters of the
Rhode River showed green to red radiation (550-650
nm) as the principal component in the water col?
umn. The total irradiance was generally very low.
pigment accounted for about 52% of the total ca?
rotenoid content of whole cells.
The pigment content of P. mariaP-lebouriae
changed markedly with changes in radiation (Fig.
5). In all spectral qualities chiorophylls a and c, per?
idinin and total carotenoids were about two-fold
greater in cells grown at low PFD. than in those
grown at the higher ones. Cells grown in blue light
contained 2 or 3-fold lower chlorophylls a and c,
peridinin and total carotenoids at all irradiances than
the other spectral qualities. The highest concentra?
tion of each pigment occurred in different light
qualities, chlorophyll a was the highest when grown
in red light while chlorophyll c, peridinin and total
carotenoid were greatest when grown in green light.
The ratios chlorophylls a: c, peridinin: total ca?
rotenoid were also examined (Table 3). Chlorophyll
a content per cell was approximately twice the chlo?
rophyll c and did no~ vary with photon flux density
i.e. the ratios were approximately 2.0 (Table 3). The
ratio of chlorophylls a and c : total carotenoid ranged
from 0.75 to 0.93 in the white, 0.74 to 0.95 in the
green, 0.79 to 1.04 in the red and 0.59 to 0.70 in
the blue radiation grown cells. In addition, total ca?
rotenoid concentrations were about the same at a
single PFD for all spectral qualities except blue. Un?
der the blue radiation the carotenoid content was
notably lower than under another spectral quality
at the same PFD. Peridinin as a proportion of total
carotenoid also varied with PFD. Cells grown in the
green radiation apfeared to have proportionally the
highest 52-61%, 0 total carotenoid content per cen;
medium levels occurred in the white, 48-55%; and
in the red, 36-49%; and the lowest amount in the
blue, 32-43% radiation, respectively.
rho"", flW< den';ty 1-inal cell densiq ('rowtb rolle, (kJ
,u.M quanla'm-I'!i-~ ? Rlil Cells x Hi"ml-' '" SE" lJivisinns r1- 1
White irradiance
58.7 ? 3.5 12.20 ? 0.06 0.25
17A ? 0.6 4.36 ? 0.06 0.13
7.8 ? 0.3 2.46 ? 0.04 0.06
Blue inadiance
.~8.7 ? 3.5 8.80:': 0.04 0.26
17.4 ? 0.6 9.40 ? 0.06 0.27
7.8 ? 0.3 10.00 ? 0.10 0.27
Green irradiance
58.7 :!: 3.5 13.00 ? 0.05 0.25
17.4 :!: 0.6 6.40:': 0.04 0.16
7.8 ?0.3 2.20 ? 0.01 0.04
Red ilTadiance
58.7 ? 3.5 12.40 ? 0.10 0.21
17.4 ? 0.6 8.50 ? 0.cl6 0.17
7.8 ? 0.3 !l.OD ? 0.09 0.10
TAB.LE 2. Photrmflux dmsity (PFD),jinal cell density andr;rawth rate
of Prorocentrum mariae?lebouriae after 12 da}!.
? R = ranges of PFD.
b Sf:. = values are standard error means of 6 to 12 replicate
samples. Initial cell density was 1.68 x [O~ cells?ml-!.
In order for phytoplankton to survive there they
must be able to adapt to this low radiation and par?
ticular spectral environment. Dinflagellates are ca?
pable of adapting to very low irradiances(Prezelin
1976, Meeson and Sweeney 1981), but little is known
about their ability to adapt to radiation of different
spectral qualities. In the pl'esent work, radiation
measured as photon flux density of four spectral
qualities. identified differences between responses
to irradiance and spectral quality. All spectral qual?
ities had approximately the same PFD (measured as
fLM quanta? m-2 ?S-l) as those existing in situ. The
data presented here indicated that P. ntariae-lebour?
iae which ocCurs in the turbid waters of the Rhode
River and Chesapeake Bay utilized estuarine radia?
tion levels of each treatment to maintain cell division
and synthesize pigments. Mean growth rates in blue
spectral quality were similar at low, medium and
high radiation levels, whereas white. ted and green
spectral qualities allowed only suboptimal growth.
The principal result was to establish that the di?
noflagellate P. mariae-iehouT'iae has the potential to
adapt to different spectral radiations. Cells grown
in a green spectral quality contained the highest cel?
lular concentration of peridinin and peridinin to
chlorophyll a ratios. Peridinin is the principal pho?
toreceptor fOT photosynthesis for P. mariae-lebouriae,
since none of the other pigment components pres?
ent in dinoflagellates including chlorophylls a and c
contribute to the absorption maxima at 500-560 nm
wavelengths (Prezelin and Haxo 1976). Of particu?
lar interest is the increase of peridinin-chlorophyll
a-protein complex (PCP) of P. mariae-Iebouriae in
low green radiation (500-560 nm). indicating that it
probably is required to provide additional energy
i!l! HIGH
W MEDIUM
? LOW
WHITE BLUE GREEN RED
GROWTH
J:
I-
==o
a:
(!)
w*100
> ....
I-
0(
-oJ
W
a:: 0
WHITE BLUE GREEN REO WHITE BLUE GREEN RED
FIG. 5. Relative photo.\Yllthetlc pigmcnt collCClllrdtions for cells
ofP. mmitu-l~b(juriaeafter 12 days of grcMth at three photon flux
densities (PFD) and fOUf spenral qualities (whil,.e, bllle. gn~en and
red), 111C treatment PFD werc 58.7 ?3.5/;LM qu,Ullil'm-"s-1
101' high. 17.4 ? 0.6 p.M quaI1l<t'm-"s-1 for medium and 7.8 ?
0.3 Il'M quama' m-" 5- 1 for low irradiance.
W
t>
Z
<
.lI1
a:
o
en
.lI1
<
RESPO:\,SE OF PROROc[mTRUM TO LIGHT
.CHLOROPHYlL a
t 20
(I)
2
o
i=
<
r:r:
I ?
2
IU
o
2
o
o
~ 200
i=
<
..1.
W
r:r: 100
CHLOROPHYLLc
353
? HIGH
?if MEDIUM
_LOW
400 450 500 550 600 650 700
WAVELENGTH (nm)
FIG. 4. Pror()cenlru,m mariae?/tibuuriaff absorption spectra: 1) In
vivll absorption spectrum of whole celL~; 2) absorption spectrum
of wtal pigmeol.\ in 90% acetone; 3) and 4). cmnpollent pigment
absvrptjof\ spectra in 100% acetone separated un TLC plates for
chlorophyll Ii (3) and peridinin (4), respec.:uve!y,
COl' photosynthesis under very low irradiance level
as in Gll'nodinium sp. (Prezelin, 1976). This is exactly
what might be expet:ted since PCP absorbs in the
blue-'green region of the visible spectrum. The en?
hancement appears as a shoulder and is seen in the
photosynthetic action spectra of Gleno4inium sp.
gro\lm in white radiation (Preze1in eta!' 1976).
The spectral quality of estuarine radi;ition fits the
absorption spectrum of accessory pigmeIltS of this
dinoHagellate species, in which radiation is effec?
tively absorbed over a wide spectral region. Radia?
tion in the orange to red region waS efficiently cap?
tured by P. mmiae-lebouT'iae for chlorophylls a and r
synthesis. Whether chlorophyll r (at 630 nm) was an
effective accessory pigment or not for absorbing the
orange wavelength of radiation for the moment is
unanswered. Similarly, among dominant estuarine
phytoplankton groups, diatoms contain accessory
pigments chlorophyll c and the carotenoid fucoxan?
thin, and dinoflagellates contain the acces!lory pig?
ments chlorophyll c and the carotenoid peridinin,
with related llbsorption characteristics of fucoxan?
thin. In addition, cryptophyte algae are the next most
numerous phytoplankton to dinoflagellates in the
Rhode River (Faust and COlTell 1976) and also have
chiorophylls a and c and phycocyanin (Faust and
Gantt 1973) pigments. Thus, they are abundant
probably because they effectively absorb estuarine
radiation as an energy source in the presence of
essential nutrients. .
Our knowledge regarding physiological responses
to spectral qualities has shown that in addition to
chlorophyll a the accessory pigments present within
an organism define the radiation spectrum which is
potentially available for photosynthesis (Bogorad
197.15, Pn(:zelin 1976). The best understood systems
are in certain blue-green algae (Tandeau de Marsac
1977) that adapt to changes in spectral quality by
altering the relative composition of the accessory
pigments. phycoerythrin and phyco('yanin (Bogo?
rad 1975). In green radiation, the synthesis of
phycocyanin was greatly redu(ed and that of phyco?
erythrin accelerated. Consequently, most of Ihe flex?
ibility in the pigment system of P. marlae-lebouriae to
changes in spectral quality and irradianre is attrib?
utable to the RUt:tuating concentrations of chloro?
phyll a and accessory pigments, chlorophyll c, per?
idinin, and minor carotenoids. This type of
photoadaptive-response enabled this species to in?
crease the radiation absorbing capabilities of pig?
ments in its potential spectral environments and to
maintain growth comparable to that in a white spec?
trum with equal PFD.
The growth of P. mariae-ll'bourial' in various ra?
diation nmditions followed different patterns.
Growth at low PFD was less in white, green and red
light and decreased with decreasing radiations.
However, similar growth rates at all irradiancc!l in
354 MARIA A. FAUST ET AL
TAIH$ 3. Mea,,! ctlncentra,tianJ chlorophylls a an.d (', IOfal (,'Uf!)ll'tloids (1,'14 peri4inin in Prnnx:enlrum mariae-Iebouriae cells grOll'/! (II diffmmt
photon flux densitil!S aft~ 12 days of growth.
:Photo Ilux dCl1sil)'
!,g~hl a 1'1\ ChI ( I'K 'ulal 1'1\ ChI a, ~ (C,,,I rr (arnt~nnid!i ~",g Pcr1dizl~n Pt."ridinil1
I'M "Iuanta "i,lotal
rm-:;e'$'-I::!::: _Rl~ IU' ,,"II. 10" <c1I. (,hi ( HI" ,,,,11. IU' <ell. Chl. carQleJJoicb
White irl'adiance
58.7 ? 3.5 1.981' 0.95 2.08 3.90 1,86 0,94 0.75
17.4 ? 0.6 3.41 1.83 1.86 5.77 3.18 0.93 O,!11
7.8 ? 0.3 3.99 2.21 LBO 6.67 3.70 0.93 0,93
Blue irradiance
58.7:!: 3.5 !J.91 0.42 2.16 2.26 0.73 0.90 0.59
17.4 ? n.G 1.89 0.87 2.17 4.26 1.55 0,82 D.65
7.8 ? 0.3 2.19 0.g8 2.52 4.52 1.94 0.88 1).70
Green irradiance
5.87 ? 3.5 2.25 1.24 1.81 4.73 2.45 1.09 0,74
17.4 ? 0.6 3.80 2.02 1.88 6.38 3.8g 1.02 !J,91
7.8:!:O.~l 4.55 2.77 1.64 7.69 4.68 1.03 0.95
Red irradiance
:18.7 ? 3,5 2.00 0.95 2.10 3,73 1.33 0.66 0.79
17.4 ;:t 0.6 4.67 2.40 1.94 6,90 2.85 0.61 1.02
7.8 ? 0.3 4.52 2.36 1.!11 fl,60 3.23 0.71 1.0 I
a R = ranges of PFD.
II Values are means with standard error of pigment concentrations 51 :!: 0.20 and SE :t 0.03 of pigment ratios for 6 to 12 measure-
ments.
the blue region indicate that growth was not light
limited. This organism has a variety of photosyn?
thetic pigments, most of which absorb radiation in
the 400 to 550 11m range of wavelengths and which
could account for the efficient use of blue radiation
even at low PFD levels. Since, the PFD was equiva?
lent for white and narrow spectral irradiances, the
effectiveness of the blue irradiance appear~ to be
due to the absorbing ability of the cells at low PFD.
Other studies also showed that algae generally grow
faster in a blue than in a white spectral quality and
that the magnitude of the response is mediated by
the species and the PFD (Wallen and Geen 1971,
Jeffrey and Vesk ,1977, Jones and Galloway 1979).
Jeffrey and Vesk (1977) reported better growth
in blue and blue-green radiation for Stephanopyxis
turn than in white at 4 W' rn- 2. Since PFD is lower
in blue-green than in white for equal irradiance, the
higher efficiency of fewer quanta in the blue-green
spectral region in producing a higher rate oflho?
tosynthesis Can be postulateCi. ThiS was indee the
case. Carbon fixation, as they measured it (f1.m mole
CO~ uptake'mg- I chJ a and eh- I ) was 41% higher
in blue~green grown cultures than in white light
grown cultures a.t high irradiance level (25 W' in-~).
The blue-green radiation showed no advantage over
white light treatment Oeffrey and Vesk 1977).
It appears that reactions of algae to low light ir?
radiances (below 12.5 W?rn-2) are two types. Gony?
aulax polyedra exhibits a photostress response. At low
irradiance levels, cells of thJs species are smaller, di?
vide more slowly, and contain much less pigment
(Prezelin and Sweeney 1978). In contrast, Glenodi?
niurn sp. remains unaltered at low lrradiance levels,
but simply does not receive sufficient radiant energy
to photosynthesize at rates which support maximal
growth (Prezelin ct al. 1976).
Prorocenlrum mariaeclebmtriae appears to respond
similarly to Glenodinium sp. at low levels of irradi?
ance. The quanta received should have sufficiently
high energy for effective photosynthesis. but they
can be at various wavelen~hs of the J,Jhotosynthet?
ically active spectrum. PhotosynthesIs was main?
tained at the high level of the white spectral quality
where approximately 30% of the total PFD (18 p.M
quanta' m- 2. S-I) was in the blue spectral region.
When the white rddiation was decreased to medium
and low PFD levels, PFD in the blue spectrum cor?
respondingly decreased (5.2 and 2.3 f1.M quanta?
m-2. s-I, respectively). If this is compared widl the
PFD received in the blue spectral region, it is evident
that the lowest blue PFD level (7.8 ? 0.3 ,uM quanta?
m-~'s-l) was higher than the PFD of the blue spec?
tral region of low and medium PFD white light
treatments. Thus, it appears that the maximal pho?
tosynthetic rale of P. mariae-lebouriae was supported
by a PFD of about 8 p.M quanta' m-~'S-1 in the blue
region and when it was not received, photosynthetic
activity was not saturated and cell division de?
creased.
The maximum photosynthetic rate for growth of
P. mariae-lebouriae appears to be supported by a red
radiation at a PFD level of 58.7 ? 3.5 p,M quanta'
in-~'S-I, but it definitely required more than 17A ?
O.6p.M quanta? m-2. s- J. The broad white radiation
rCLeived at low irradiance appears not to be effective
unless one of the photoreceptors receives the critical
irradiancc to drive the system. The critical PFD to
RESPONSE OF PROROCENTRUM TO LIGHT 355
drive the photoreceptor system in P. mariae-wbour?af
appears to be at least three times highel' in the red
than in the blue spectral region. ~evertheless" a very
low PFD is able to drive the photosynthetic system
in this organism. Consequen tly.P. mariae-lebouriae
seems ro maintain metabolic activities at low radia?
tionconditions of the estuary. It is able to utilize
very low levels of blue radiation and somewhat
higher levels of red radiation separately or in com?
bination for growth. It also appears that more red
radiation is available in the estuary and red radia?
tion levels are high enough to drive the photosyn?
thetic system at depths below 2 m? At the same time,
P. muriae-Iebouriae prouably cau utilize the: blue por?
tion of the spectrum for growth only when close to
the surface.
The success of P. manae-ltbouriae ina fotming a
ted tide is probably due to the complement of pig~
ments which enable cells to absorb a wide range
of wavelengths in the visible spectrum. Consequent?
ly, an understanding of the environmental control
of the photosynthetic processes is paramount to the
understanding of aquatic primary production. There
has been speculation that adapt:itions to changes in
spectral quality can explain the existence of algal
populations which exist in blue-green spectra of deep
downwelling regi,ms of low total irradiance (Jeffrey
and Vesk 1977). The changes observed that were
mediated by spectral quality in whole cell pigmen?
tation and growth of P; mariae-lebouriae confirms this
speculation. Further work is underway to assess the
photosynthetic responses of this species when adapt?
ed to radiation of different spectral distribution.
The authors wish to acknowledge partial suppmt hy the Scholarly
Studies Program of the Striithsonian Institution.
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PHAGOTROPHY IN GYMNODINIUM FUNGIFORME (PYRRHOPHYTA): THE PEDUNCLE
AS AN ORGANELLE OF INGESTION l
Howard1- Spero 2
Department of Oceanography, Texas A&M University, College Station, Texas 77843
ABSTRACT
The non~photosynthetic phagotrophic dinoflagellate,
Gymnodinium fungiforme Anissimova, ingests prey cy.
toplasm through a highly extensiblt> structure called the
peduncle. Although the pedunck is not observable when
G. fungiforme is swimming, it protrudes 8-12 f.Lmfrom
the sulcal-Cingular vicinity if the cell during feeding, and
is approximately 3.3 f.Lm wille when the cytoplasm if its
pnry is floiiling through it. A circular-oval ring if over?
lapping microtubules, the 'microtubular basket' may be seen
in transmission electron microscope sections of G. fungi?
forme and it is inferred that this st:ructUrl' is a cross section
if a retracted peduncle. The mil:rotubular basket-pedullcle
complex is discussed in relation Lo similar structures in
other dinqflagellates and to the tentack o.f the sttc/orian
ciliates which have a homologous ingestion sy.~tem.
Key index word.~: dinq/lagellate; Gymnodium fungi?
forme; microtubular basket; peduncle; phagotrophy; suc?
torian ciliates
Interest in the non-photosynthetic?dinoflageHates
has increased recently because they may be impor?
tant links in estuarine and planktonic food webs
(16,24). Although some of these non-photosynthetic
species have been cultured heterotrophically, for ex?
ample, Gyrodinium lebouriae (13), Crypthecodinium
coh!1'ii (18.27) and Oxyrrhis marinll (10), many are
1 Accepted., 2 March 1982.
? Present address: Department of Biological Sdelll~s, Univer?
sity of California, Santa Barbara, CalifOITlia 93 J06.
phagotrophic, cap?lble of ingesting a variety of pro?
tozoan and metazoan prey (24. for review). Three
basic feeding types have been described within the
phagotrophicgroup; (i) Prey is 'stunned' and held
near the sulcal region as in Gyrodinium pavillardi (4)
or brought near the cytostome via water currents set
up by the transverse flagella of Kofoidinium (6), and
subsequently engulfed; (ii) prey is captured by a ten?
tacle in which case it is either engulfed immediately
as in Noctilztca (22) and Peridinium gargantua (4) or
digested extracellularly and subsequently ingested
as in Erythropsis pavillardi (11), and (iii) the dinaRa?
gellate attaches to its prey and ingests the cytoplasm
or body fluids through a peduncle as described in
Gym.nodinium fungiforme (4,23,24) and Gyrodinium
vorax (4).
The details of the life cycle and feeding behavior
of the obligate heterotroph Gymnodinium fungif()rtlle
Anissimova, was described recently (23,24). Large
numbers of G. fungiforme were reported to form dy?
namic aggregations around a prey organism and
subsequently attach to it, ingesting the prey cyto~
plasm through a peduncle. The present paper fur?
ther examines the phagotrophic feeding hehavior of
G. fungiform.e and discusses a possible mechanism for
the functioning of the peduncle.
MATERIALS AND METHODS
The general methods for culture and the Lechlliques f~'lt elec?
tron microscopy have been described (24). Gymnodinium fungi.
jrmne was grown pbagotrophkally in mixed Lultures with DllTl?
a1iel~a .wtina (UTEX 1644). Light micrographs were taken with a
Zeiss IGM-405 inverted rnilToscope usinK Nomarski interference