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Eu opean Jou nal o Phycology
ISSN: 0967-0262 (P in ) 1469-4433 (Online) Jou nal homepage: h p://www. and online.com/loi/ ejp20
Pho oacclima ion and pho o egula ion s a egies
o Co allina (Co allinales, Rhodophy a) ac oss he
NE A lan ic
Ch is ophe J. Williamson, Rupe Pe kins, Ma ian L. Yallop, Césa Pe ei o,
Noemí Sanchez, Ka l Gunna sson, Maggie Gamble & Julie B odie
To ci e his a icle: Ch is ophe J. Williamson, Rupe Pe kins, Ma ian L. Yallop, Césa Pe ei o,
Noemí Sanchez, Ka l Gunna sson, Maggie Gamble & Julie B odie (2018) Pho oacclima ion and
pho o egula ion s a egies o Co allina (Co allinales, Rhodophy a) ac oss he NE A lan ic, Eu opean
Jou nal o Phycology, 53:3, 290-306, DOI: 10.1080/09670262.2018.1442586
To link o his a icle: h ps://doi.o g/10.1080/09670262.2018.1442586
© 2018 The Au ho (s). Published by In o ma
UK Limi ed, ading as Taylo & F ancis
G oup.
View supplemen a y ma e ial
Published online: 17 May 2018.
Submi you a icle o his jou nal
A icle iews: 161
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Pho oacclima ion and pho o egula ion s a egies o Co allina (Co allinales,
Rhodophy a) ac oss he NE A lan ic
Ch is ophe J. Williamson
a,b
, Rupe Pe kins
c
, Ma ian L. Yallop
b
, Césa Pe ei o
d
, Noemí Sanchez
e
,
Ka l Gunna sson
, Maggie Gamble
b
and Julie B odie
a
a
The Na u al His o y Museum, Depa men o Li e Sciences, C omwell Road, London SW7 5BD, UK;
b
School o Biological
Sciences, Li e Sciences Building, Uni e si y o B is ol, 24 Tyndall A enue, B is ol BS8 1TQ, UK;
c
School o Ea h and Ocean
Sciences, Ca di Uni e si y, Ca di CF10 3AT, Glamo gan, UK;
d
Ins i u o Español de Oceanog a ia (IEO), Cen o Oceanog á ico
de San ande , P omon o io de San Ma ín, 39004 San ande , Spain;
e
Uni e si a de Gi ona (UdG), Facul a de Ciències, Campus
de Mon ili i s/n., 17071 Gi ona, Spain;
Ma ine Resea ch Ins i u e, Skúlaga a 4, PO Box1390, 121 Reykja ik, Iceland
ABSTRACT
This s udy cha ac e izes he pho oacclima ion and pho o egula ion mechanisms ha allow calci ied mac oalgae o he genus
Co allina (Co allinales, Rhodophy a) o domina e ock pool habi a s ac oss he NE A lan ic despi e he highly a iable
i adiance egimes expe ienced. Rapid ligh cu es (RLCs) we e pe o med wi h pulse ampli ude modula ion (PAM)
luo ome y in si u ac oss a ull seasonal cycle in he UK in e idal wi h C. o icinalis and C. caespi osa. La i udinal
compa isons we e pe o med ac oss he ull ex en o C. o icinalis’ ange in he NE A lan ic (Iceland–no he n Spain),
and o C. caespi osa in no he n Spain. Ex si u RLCs wi h da k eco e y we e u he employed o assess he op imal, as
compa ed wi h ac ual, pho ophysiology ac oss seasons and la i udes. Co allina species we e shown o pho oacclima e a
seasonal imescales o changing i adiance, inc easing ligh -ha es ing du ing low-ligh au umn/win e pe iods and
p o ec ing pho osys ems du ing high-ligh summe condi ions. Seasonal pho oacclima ion was achie ed h ough al e a ion
in he numbe o pho osys em (PS) uni s (PSII and ligh ha es ing an ennae) o e ime. Non-pho ochemical quenching
(NPQ) se ed as an impo an pho o egula ion mechanism u ilized by Co allina o p e en o minimize pho oinhibi ion
o e sho e ime scales (seconds–hou s), hough he e iciency o NPQ was dependen on he seasonal-acclima ed s a e.
Wi h inc easing la i ude he e iciency o pho o egula ion dec eased, ep esen ing po en ial di e en ial pho oadap a ion o
Co allina ac oss species anges in he NE A lan ic. In con as , highly conse ed in e -speci ic pa e ns in pho ophysiolo-
gical esponses o i adiance we e appa en . This s udy demons a es he pho ophysiological mechanisms allowing Co allina
o op imize use o he a iable i adiance condi ions appa en in ock pool en i onmen s, when and how hey a e employed,
and hei limi a ions.
ARTICLE HISTORY Recei ed 18 Sep embe 2017; e ised 15 Janua y 2018; accep ed 19 Janua y 2018
KEY WORDS Co allina; NE A lan ic; NPQ; pho oacclima ion; pho o egula ion; apid ligh cu e
In oduc ion
I adiance is an essen ial, ye highly a iable, esou ce
o mac oalgal g ow h and su i al (Henley & Ramus,
1989). In he in e idal, luc ua ions in i adiance occu
o e a a ie y o ime scales, anging om seconds o
less, o diu nal and seasonal-scale a ia ions ha a e
bo h p edic able (changes in dayleng h and sola angle)
and unp edic able (cloudiness, u bidi y and un-o )
(De a & Go don, 1968; Henley & Ramus, 1989; Lobban
&Ha ison,1994). In e idal species mus cope wi h
la ge g adien s in i adiance ha depend on bo h he
daily cou se o sola i adiance, and he idal ange and
empo al coincidence o maximum i adiance a mid-
day wi h he iming o low ide (Goss & Jakob, 2010).
Fo a ben hic mac oalga in a ixed posi ion in he
in e idal zone, he challenge is he e o e o op imize
he use o he a iable i adiance egime expe ienced
(Henley & Ramus, 1989).
To complica e his u he , he quan i y o pho o-
syn he ically ac i e adia ion (PAR, c. 400–700 nm)
expe ienced by in e idal mac oalgae is o en in excess
o ha needed o sa u a e pho osyn hesis, pa icula ly
du ing summe pe iods (F anklin & Fo s e , 1997). In
mos in e idal mac oalgae, he pho ochemical appa a-
us ope a es o op imize pho osyn hesis a low ligh
le els associa ed wi h imme sion, wi h he esul ha
eme sed plan s a e exposed o a la ge excess o ligh
ene gy (Da ison & Pea son, 1996). An excess o
abso bed ligh ene gy can esul in pho o-damage o
he pho osyn he ic appa a us (Hänel e al., 1993),
leading o pho o-oxida i e damage ia inc eased p o-
duc ion o eac i e oxygen species, which in ex eme
cases can cause pigmen bleaching and dea h (Mülle
e al., 2001). As such, in e idal mac oalgae mus
espond o changes in i adiance in a manne ha
bo h op imizes pho osyn hesis and g ow h, whils con-
olling o po en ial s ess (Mülle e al., 2001).
Th ee gene al p ocesses allow algae o manage p e-
ailing i adiance condi ions: adap a ion, acclima ion
and egula ion (Huo & Babin, 2011). Pho oadap a ion
CONTACT Ch is ophe J. Williamson [email p o ec ed]
EUROPEAN JOURNAL OF PHYCOLOGY, 2018
VOL. 53, NO. 3, 290–306
h ps://doi.o g/10.1080/09670262.2018.1442586
© 2018 The Au ho (s). Published by In o ma UK Limi ed, ading as Taylo & F ancis G oup.
This is an Open Access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License (h p://c ea i ecommons.o g/licenses/by/4.0/), which pe mi s
un es ic ed use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed.
Published online 17 May 2018
is a long- e m selec ion p ocess in esponse o i adi-
ance, ul ima ely esul ing in gene ically di e en eco-
ypes (Huo & Babin, 2011;Bee e al., 2014). In
con as , pho oacclima ion e e s o a pheno ypic plas-
ic esponse o a change in i adiance (Huo & Babin,
2011;Bee e al., 2014). This is ypically achie ed by
ei he an al e a ion o he size o numbe o pho o-
syn he ic uni s (pho osys em II (PSII) and associa ed
an ennae pigmen s) (Falkowski & LaRoche, 1991;
Mülle e al., 2001;Bee e al., 2014). Du ing sho -
e m (seconds o hou s) i adiance luc ua ions, pho o-
egula ion u he se es o p o ide a pho o-p o ec i e
ne wo k ha allows pho osyn he ic e iciency o be
apidly uned by sa ely dissipa ing excess abso bed
ligh ene gy as hea and/o he exci a ion ene gy o
be balanced wi hin PSs o p e en o lowe po en ial
damage (Huo & Babin, 2011; La aud & Lepe i , 2013).
Non-pho ochemical quenching (NPQ) is one mechan-
ism o pho o egula ion ha quenches pho ochemis y
h ough non-pho ochemical p ocesses, e.g. con e sion
o many o he exci a ions in he an ennae complex o
hea (Consal ey e al., 2005). Du ing NPQ, he ligh -
d i en de-epoxida ion o speci ic xan hophyll pig-
men s ( ypically iolaxan hin, an he axan hin and
zeaxan hin) and he da k eco e y o he ini ial pool,
e med he xan hophyll cycle, is associa ed wi h he -
mal ene gy dissipa ion (Demmig-Adams & Adams,
1996; Es eban e al., 2009; Goss & Jakob, 2010).
This s udy add esses he pho ophysiology o wo
in e idal mac oalgae o he genus Co allina
(Co allinales, Rhodophy a) ac oss he NE A lan ic,
namely Co allina o icinalis Linnaeus and Co allina
caespi osa Walke , B odie & I ine. These calci ied,
genicula e (a icula ed) species o m ex ensi e u s
ha co e la ge a eas o he in e idal and p o ide
subs a um, habi a and e ugia o a numbe o
impo an ma ine o ganisms (Johansen, 1981; Coull
&Wells,1983;Kelahe ,2002,2003;Ho manne al.,
2012;Pe kinse al., 2016). Howe e , hey a e p edic ed
o be signi ican ly ulne able o u u e an h opogenic
change, including wa ming seawa e empe a u es and
ocean acidi ica ion (Ho mann e al., 2012; Egilsdo i
e al., 2013;Noise ee al., 2013). As such, much ecen
esea ch has been aimed a gaining a be e unde -
s anding o Co allina ecophysiology, pa icula ly in he
NE A lan ic (e.g. B odie e al., 2013,2016; Williamson
e al., 2014a,2014b,2015,2017; Pe kins e al., 2016).
The aim o his s udy was o build on he ini ial wo k
o Williamson e al.(2014b) in o de o iden i y he
sui e o pho oacclima ion and pho o egula ion
mechanisms ha allow Co allina o op imize ligh
use in he a iable in e idal en i onmen , hus con-
ibu ing o hei dominance o NE A lan ic ock
pools, and o cha ac e ize he use o hese mechanisms
in space and ime. Pho ophysiological assessmen s
we e pe o med in si u ac oss a ull seasonal cycle in
he UK in e idal, and complemen ed wi h ex si u
echniques unde labo a o y condi ions. La i udinal
compa isons we e u he pe o med o C. o icinalis
ac oss he ull ex en o he species’ ange in he NE
A lan ic (Iceland–no he n Spain, Williamson e al.,
2015), and o C. caespi osa in no he n Spain.
Me hods
Sampling si es
Seasonali y in C. o icinalis and C. caespi osa pho o-
physiology was assessed in si u using apid ligh
esponse cu es (RLCs, Pe kins e al.,2006) ac oss a
comple e annual cycle a Combe Ma in (CM), No h
De on, UK (Table 1,Fig. 3), and complemen ed wi h
ex si u RLC wi h da k eco e y assessmen s. Combe
Ma in lies wi hin he middle o C. o icinalis’ ange
in he NE A lan ic (Iceland–no he n Spain), hough
is compa a i ely close o he cu en ly known no h-
e n edge (no he n England) o C. caespi osa
(Williamson e al., 2015). Williamson e al.(2014b)
p e iously assessed he pho ophysiology o bo h spe-
cies in ela ion o idal eme sion in his si e, and as
such, idal assessmen was no epea ed he e. Combe
Ma in is a no h-wes acing ocky in e idal si e,
posi ioned wi hin a ela i ely shel e ed bay.
Co allina caespi osa inhabi s a na ow zone (c. 2 cm
Table 1. Si e and sampling in o ma ion.
Si e
Combe Ma in UK Þo lákshö n ICE Comillas NSP
Loca ion 51°12’13N 4°2’19W 63°53’36N 21°23’45W 43°23’18N 4°17’21W
Tidal Range MHWS–MLWS MHWS–MLWS MHWS–MLWS
9.2–0.68 (8.52) 3–0.2 (2.8) 4.7–0.2 (4.5)
MHWN–MLWN MHWN–MLWN MHWN–MLWN
6.9–3.1 (3.8) 2.3–1 (2.2) 3.2–1.4 (1.8)
Sampling Da es
Win e 27.01.12
Sp ing 10.03.12
Summe 20.06.12 17.07.12 13.08.13
Au umn 03.09.12 05.09.13 19.10.12
Species sampled C. o icinalis C. o icinalis C. o icinalis*
C. caespi osa C. caespi osa
Sho e heigh s sampled Uppe (5.5) Lowe (1.5) Uppe (3.0)
*Co allina o icinalis is accessible only du ing summe in NSP.
EUROPEAN JOURNAL OF PHYCOLOGY 291
deep) a he uppe wa e line o la ge (c. 40 m
3
, 0.5 m
dep h) uppe sho e ock pools c ea ed by a man-
made walkway, wi h C. o icinalis domina ing below
(Fig. 4). Ac oss he lowe in e idal, C. o icinalis
domina es ock pools and d ainage channels, whils
C. caespi osa is absen .
La i udinal pa e ns in Co allina pho ophysiology
we e u he examined ac oss he species’ anges in
he NE A lan ic, including si es in Iceland and no h-
e n Spain (Fig. 3). In si u assessmen s o pho ophy-
siology we e conduc ed o C. o icinalis in
Þo lákshö n, SW Iceland (ICE, Fig. 1), du ing sum-
me and au umn (Table 1), a he s a , middle and
end o day ime idal eme sion, wi h ex si u analyses
pe o med in all sampling mon hs. Co allina
o icinalis is he sole Co allina species ound in
Icelandic ock pools, and is p esen as a well-de el-
oped u in ock pools a Þo lákshö n (Figs 1,2). In
Comillas, no he n Spain (NSP, Fig. 5), an exposed
no h- acing ocky sho e is co e ed by a well-de el-
oped Co allina and Ellisolandia assemblage. Co allina
caespi osa occupies e y shallow (c. 2 cm deep) wa e
co e ed a eas o he in e idal whe eas C. o icinalis is
a ypically sub idal species, es ic ed o he in e idal
in la ge ock pools (c. >1 m deep), ound only in
small pa ches accessible on sp ing ides (Fig. 5). In
si u pho ophysiology assessmen s we e he e o e con-
duc ed o bo h species a hei espec i e posi ions
on sho e du ing summe in NSP (Table 1), hough
o only C. caespi osa du ing au umn, as C. o icinalis
Figs. 1–5. Sampling si es, loca ions and species, showing: Fig. 1. in e idal ock pools a Þo lákshö n, Iceland, domina ed by
Fig. 2. u s o C. o icinalis,Fig. 3. he loca ions o sampling si es ac oss he NE A lan ic, Fig. 4. he uppe laye o C.
caespi osa (black a ow) in in e idal ock pools a Combe Ma in, UK, wi h C. o icinalis ( ed a ow) below, and Fig. 5. he
well-de eloped u ing assemblage o co allines ac oss he in e idal a Comillas, no he n Spain.
292 C. J. WILLIAMSON
was no accessible. In si u assessmen s we e made
ac oss day ime idal eme sion and complemen ed
wi h ex si u assessmen s.
In si u pho ophysiology
In he UK, RLCs we e pe o med on n=5 andomly
selec ed Co allina onds o each species immedia ely
a he s a o idal eme sion pe iods. Gi en idal
impac s o Co allina pho ophysiology demons a ed
p e iously a his loca ion (Williamson e al.2014a),
RLCs we e pe o med a he s a o idal eme sion
pe iods o minimize in luences on seasonal pa e ns.
The o de o RLC de e mina ion was u he ando-
mized ac oss species o minimize po en ial diu nal
e ec s. Fo pho ophysiology assessmen in ICE, RLCs
we e pe o med a e Williamson e al.(2014a)onn=
3 onds andomly selec ed om each o h ee uppe
sho e ock pools, a he s a , middle and end o day-
ime idal eme sion. S a and end eme sion pe iods
we e de ined as being wi hin 1.5 h o idal isola ion
(s a ) and idal econnec ion (end) o he ock pool o
he main idal wa e mass. Middle eme sion was he
midway be ween hese ime poin s. In NSP, RLCs we e
pe o med on n= 3 onds o C. caespi osa a he s a ,
middle and end o idal eme sion, and n= 3 onds o
C. o icinalis a he s a and middle o eme sion only,
gi en he sho e du a ion o access o C. o icinalis a
i s lowe posi ion on sho e a his la i ude.
In all cases, RLCs we e pe o med on apical ond
egions o a oid po en ially sel -shaded egions (Pe kins
e al., 2016), and on he side o onds acing di ec
sunligh , as he unde side o onds p obably demon-
s a e di e en s a es o pho oacclima ion. RLCs we e
pe o med using a Walz Wa e -PAM luo ome e using
a sa u a ing pulse o c. 8600 μmol pho ons m
–2
s
–1
, o
800 ms du a ion, and wi h nine 30 s inc emen ally
inc easing ligh s eps om 0 o 1944 μmol pho ons
m
–2
s
–1
. Ligh s ep du a ion was selec ed o balance
po en ial pho o egula ion occu ing du ing longe
ligh s eps (60 s), wi h e o s associa ed wi h sho e
ligh s eps (10 s) when samples ha e been exposed o
high i adiance (Pe kins e al., 2006). Ambien pho o-
syn he ically ac i e adia ion (PAR, μmol pho ons m
–2
s
–1
) and ock pool wa e empe a u es we e moni o ed
in pa allel o in si u RLCs a 30 min in e als using a 2-
pi LI-COR cosine-co ec ed quan um senso posi ioned
c. 5 cm abo e he su ace o ock pools, and a digi al
he mome e (accu acy ±0.1°C), espec i ely. Fo each
PAR measu emen , a 15 s a e age was aken using an
au oma ed unc ion on he senso .
Ex si u pho ophysiology assessmen
Ex si u assessmen o Co allina pho ophysiology was
pe o med du ing he p esen s udy o allow de e mi-
na ion o pho oacclima ion and pho o egula ion
dynamics unde educed in luence o in si u abio ic
condi ions, acili a ing iden i ica ion o longe - e m
seasonal, la i udinal and in e -speci ic pa e ns in
pho ochemis y. Ex si u RLCs wi h da k eco e y
phase we e pe o med o n=3C. o icinalis and C.
caespi osa samples om CM du ing win e , summe
and au umn, and o n= 3 samples o all species
p esen a ICE and NSP du ing summe and au umn
(Table 1). In all cases, 3 disc e e samples o each
Co allina species we e sampled by hand om he
in e idal a he end o idal eme sion. Samples we e
placed sepa a ely in o 1 l con aine s con aining si e
seawa e ob ained om ock pools a he ime o
sampling and anspo ed immedia ely in da kness
o nea by labo a o y acili ies. In he labo a o y, sam-
ples we e le subme ged in si e seawa e in 1 l aqua-
ia o a u he 1 h in da kness o allow e-oxida ion
o Q
A
, elaxa ion o NPQ and PSII epai (Ralph &
Gademann, 2005); seawa e was eplenished e e y
0.5 h o main ain ae a ion and ambien si e empe a-
u es (Table 3). Following he 1 h da k adap a ion
pe iod, ex si u RLCs wi h eco e y we e pe o med
on an apical ond egion o each sample. RLCs we e
pe o med as in si u, wi h eco e y o pho ochemis y
subsequen ly acked o e a 17.5 min pe iod o da k-
ness using he Walz Wa e -PAM inbuil p og amme
o eco e y phase, wi h quan um e iciency measu e-
men s a 10, 40, 100, 160, 460 and 1060 s.
Da a ea men
To a oid long pe iods o da k-adap a ion p io o in
si u RLCs, which would lead o modi ica ion o he
pho oacclima ion s a e o he cells in es iga ed (Ralph
& Gademann, 2005; Pe kins e al., 2010), he max-
imum ligh u iliza ion e iciency o in si u RLCs (F
/
F
m
) was calcula ed om F
m
and F
o
alues ob ained
du ing he ini ial RLC s ep o 30 s da kness (see
Table 2 o luo escence pa ame e de ini ions and
de i a ions). Fo ex si u RLCs, ull da k adap a ion
was appa en , hough F
/F
m
was also calcula ed as
abo e. Elec on anspo h ough PSII was calcula ed
om all RLCs in ela i e uni s ( ETR), assuming an
equal di ision o PAR be ween PSI and PSII. Analysis
o all RLCs ( ETR s. PAR) ollowed Pe kins e al.
(2006), wi h i e a i e cu e i ing using he ‘nls’
unc ion o R base package (R Co e Team, 2014)
and calcula ion o he ela i e maximum elec on
ans e a e ( ETR
max
), he maximum ligh u iliza-
ion coe icien (α) and he ligh sa u a ion coe icien
(E
k
) ollowing Eile s & Pee e s (1988). Down- egula-
ion in he o m o S e n–Volme non-pho ochemical
quenching (NPQ) was calcula ed om he quenching
o he maximum luo escence yield (i.e. he educ ion
om he da k-adap ed maximum yield, F
m
, o he
ope a ional maximum yields in he ligh , F
m
’).
Gi en he sho da k-adap a ion pe iod applied
EUROPEAN JOURNAL OF PHYCOLOGY 293

du ing in si u RLCs (30 s), luo escence quenching
was obse ed in he da k-adap ed s a e (i.e. F
m
’>
F
m
) and hus in si u NPQ was calcula ed using he
maximum F
m
’ alue (F
m
’
m
) a e Se ôdio e al.(2005).
Two NPQ pa ame e s we e subsequen ly calcula ed
o each in si u RLC; NPQ a he ini ial RLC s ep
(NPQ
RESID
), ep esen ing esidual NPQ due o in si u
i adiance, and NPQ a he inal RLC s ep
(NPQ
INDUC
) ep esen ing he amoun o NPQ
induced by he RLC i sel . Gi en he long da k-adap-
a ion pe iod p io o ex si u RLCs, luo escence
quenching in he da k-adap ed s a e was no obse ed
and hus ypical S e n–Volme NPQ was calcula ed
using F
m
. Quan um e iciency as a p opo ion o F
/
F
m
( he ela i e quan um e iciency, RQE) was calcu-
la ed o each ex si u RLC s ep and da k eco e y
measu emen o allow compa ison o induc ion and
eco e y dynamics ac oss seasons, species and
la i udes.
Da a analysis
All s a is ical analyses and plo ing o da a we e pe -
o med using R .3.0.2 (R Co e Team, 2014). P io o
all analyses, no mali y o da a was es ed using he
Shapi o–Wilk es and examina ion o equency his-
og ams. I da a we e no no mally dis ibu ed, Box–
Cox powe ans o ma ion was applied using he
boxcox unc ion o he MASS package (Venables &
Ripley, 2002), and no mali y e-checked. Following
he applica ion o models o da a, model assump ions
we e alida ed by examina ion o model c i icism
plo s. S a is ical compa isons o RLC (and eco e y)
pa ame e s be ween independen a iables we e pe -
o med whe e app op ia e using ei he - es , analysis
o a iance (ANOVA), o linea mixed-e ec s models
(LMER) wi h es ic ed maximum likelihood (REML)
c i e ion (Ba es e al., 2013), as de ailed below.
Seasonal pho ophysiology in he UK
Di e ences in ambien i adiance and wa e em-
pe a u e be ween sampling mon hs a CM
(Table 1) we e analysed by 1-way ANOVA wi h
he ac o mon h (4 le els). Seasonal and in e speci-
ic di e ences in in si u pho ophysiological pa a-
me e s we e analysed using 2-way ANOVA wi h
he ac o s mon h (4 le els) and species (2 le els),
and in e ac ion e m. Ex si u pho ophysiology was
analysed using 1-way ANOVA wi h he ac o sea-
son o C. o icinalis (3 le els), and - es analysis
wi h he ac o season (2 le els) o C. caespi osa.
ICE and NSP la i udinal compa isons
Fo ICE da a, di e ences in ambien i adiance
be ween seasons and o e idal eme sion pe iods
we e examined using 2-way ANOVA wi h he ac-
o s season (2 le els) and ide (3 le els), and in e -
ac ion e m. Rock pool wa e empe a u es and in
si u pho ophysiological pa ame e s om ICE we e
analysed using LMER wi h he ixed ac o s season
(2 le els) and ide (3 le els), and ock pool (3
le els) as andom e m. Ex si u pho ophysiology
was analysed using - es compa isons o pa a-
me e s in ela ion o season (2 le els). Fo NSP
da a, i adiance and wa e empe a u e we e exam-
ined using 2-way ANOVA wi h he ac o s season
(2 le els) and ide (3 le els), and in e ac ion e m.
Co allina caespi osa in si u pho ophysiology was
analysed using 2-way ANOVA wi h he ac o s
season (2 le els) and ide (3 le els) and in e ac ion,
and in e speci ic compa isons wi h C. o icinalis a
s a and middle summe idal eme sion achie ed
wi h 1-way ANOVA wi h he ac o species (2
le els), and ide as andom e m (2 le els). NSP
C. caespi osa ex si u pho ophysiological pa ame e s
we e examined be ween seasons using - es wi h
he ac o season (2 le els).
Resul s
Seasonal pho ochemis y o UK Co allina
Ambien i adiance and ock pool wa e empe a-
u es anged om 270±16 o 1143±124 μmol pho ons
m
–2
s
–1
, and 7.7±0.4 o 19.2±0.9°C du ing sampling a
Combe Ma in (CM), espec i ely, wi h signi ican ly
Table 2. Fluo escence pa ame e s, de ini ions and de i a ions (a e Cosg o e & Bo owi zka, 2011).
Pa ame e De ini ion De i a ion
F
o
Minimum luo escence yield (da k adap ed, all RCIIs open)
F
m
Maximum luo escence yield (da k adap ed, all RCIIs open wi h no NPQ)
F
Maximum a iable luo escence F
m
–F
o
F
/F
m
Maximum quan um e iciency (da k adap ed) (F
m
–F
o
)/F
m
F’Fluo escence yield in ac inic ligh
F
m
’Maximum luo escence yield in ac inic ligh
F
m
’
m
The maximum alue o F
m
’
F
q
’Fluo escence quenched in ac inic ligh F
m
’–F’
F
q
’/F
m
’E ec i e quan um e iciency in ac inic ligh (F
m
’–F’)–F
m
’
RQE Rela i e quan um e iciency (F
q
’/F
m
’)/(F
/F
m
) × 100
ETR Rela i e elec on anspo a e ( h ough PSII) F
q
’/F
m
’× PAR × 0.5
NPQ (S e n–Volme ) Non-pho ochemical quenching (F
m
–F
m
’)/F
m
’
Non-pho ochemical quenching calcula ed wi h he maximum alue o F
m
’(F
m
’
m
) a e Se ôdio e al.(2005)(F
m
’
m
–F
m
’)/F
m
’
All pa ame e s a e dimensionless (PAR = pho osyn he ically ac i e adia ion).
294 C. J. WILLIAMSON
inc eased i adiance (F
3,16
= 116.06, P< 0.01) and
wa e empe a u e (F
3,16
= 42.04, P< 0.001) appa en
du ing June and Sep embe as compa ed wi h
Janua y and Ma ch, and no di e ence be ween
espec i e pai s o mon hs (Table 3).
S ong seasonali y in RLCs and de i ed pa ame e s
was appa en o bo h C. o icinalis and C. caespi osa
ac oss sampling mon hs a CM (Figs 6,7,
Supplemen a y able 1). F om Janua y o June,
declines in C. o icinalis F
/F
m
, ETR
max
and α,
e lec ed inc eased pho o-s ess and co esponding
supp ession o pho ochemis y, wi h some eco e y
in Sep embe . Highly compa able pa e ns we e also
obse ed o C. caespi osa, hough a mo e ab up shi
in pa ame e s was e iden be ween Ma ch and June
in compa ison wi h C. o icinalis (Fig. 7). Al hough
a iable, E
k
did no di e signi ican ly be ween sam-
pling mon hs o ei he species. Ambien i adiance
was less han E
k
du ing Janua y and Ma ch, sugges -
ing ligh -limi a ion o pho osyn hesis. Con e sely,
ambien i adiance was c. 2.4- and 1.8- imes E
k
du -
ing June, and 3.6- and 2.5- imes E
k
du ing Sep embe ,
o C. o icinalis and C. caespi osa, espec i ely, sug-
ges ing sa u a ion and hence po en ial o induce
pho o-s ess. No in e speci ic di e ences in F
/F
m
,
ETR
max
,αo E
k
we e obse ed du ing any sampling
mon h.
Non-pho ochemical quenching (NPQ) a ied
be ween seasons o bo h C. o icinalis and C. caespi-
osa (Fig. 7, Supplemen a y able 1). NPQ induced
unde in si u condi ions was g ea es du ing summe /
au umn as demons a ed by inc eased NPQ
RESID
,
wi h minimal NPQ
INDUC
appa en a he end o sum-
me /au umn RLCs. The opposi e ends we e
obse ed du ing win e , demons a ing minimal
ac i e NPQ unde in si u condi ions, bu induc ion
o NPQ by RLC i adiance. No signi ican in e spe-
ci ic di e ences in NPQ pa ame e s we e e iden
ac oss mon hs (Supplemen a y able 1).
In con as o in si u pho ophysiology, no signi ican
di e ence in C. o icinalis o C. caespi osa ETR
max
,αo
E
k
was e iden be ween seasons as de e mined by ex si u
RLCs wi h da k eco e y (Fig. 8,Table 4,
Fig. 6. In si u apid ligh esponse cu es (RLCs) o C. o icinalis (ci cles and solid lines) and C. caespi osa ( iangles and
dashed lines) pe o med a Combe Ma in, UK, du ing Janua y, Ma ch, June and Sep embe , showing (a–d) ela i e
elec on anspo a es ( ETR) and (e–h) non-pho ochemical quenching (NPQ) ac oss RLCs (mean ± SE, n= 5). Do ed
e ical lines ep esen he a e age ambien i adiance eco ded in si u a he ime o RLC de e mina ion.
Table 3. Mean (± SE) wa e empe a u e and i adiance
measu ed a si es du ing RLC pho ophysiology assessmen s.
Si e Da e Season
Tidal
pe iod
Wa e
empe a u e
(°C)
Ambien
i adiance
(μmol
pho ons
m
–2
s
–1
)
Combe
Ma in,
UK
27.01.12 Win e S 7.87±0.07 311±42
10.03.12 Sp ing S 7.72±0.41 270±16
20.06.12 Summe S 17.30±2.80 1111±267
03.09.12 Au umn S 19.24±0.91 1143±124
Þo lákshö n,
Iceland
17.07.12 Summe S 15.05±0.03 712±83
M 15.25±0.03 630±60
E 15.57±0.07 616±66
05.09.13 Au umn S 9.66±0.08 861±76
M 10.20±0.14 1152±63
E 11.20±0.11 1215±70
Comillas,
no he n
Spain
13.08.13 Summe S 20.94±0.27 1160±59
M 22.68±0.19 1568±142
E 23.67±0.11 1405±344
19.10.12 Au umn S 18.68±0.07 500±29
M 18.90±0.04 510±48
E 18.94±0.04 264±24
S = s a , M = middle and E = end idal eme sion.
EUROPEAN JOURNAL OF PHYCOLOGY 295
Supplemen a y able 2). F
/F
m
and NPQ
INDUC
we e
signi ican ly lowe in summe as compa ed wi h
au umn and win e o C. o icinalis. Un o una ely,
ins umen a ion ailu e p e en ed ex si u pho ophysiol-
ogy assessmen o C. caespi osa du ing summe .
Rela i e quan um e iciency (RQE) dec eased o 14.7
±1.5% in C. o icinalis and 14.9±0.9% in C. caespi osa a
he end o ex si u RLCs, wi h no seasonal di e ence
appa en o ei he species. The magni ude o da k
eco e y in RQE was g ea es du ing summe (87.3
±9.3%) and au umn (88.3±3.2%) in compa ison wi h
win e (60.1±6.8%) o C. o icinalis, and du ing
au umn (91.5±6.9%) in compa ison wi h win e (55.9
±6.1%) o C. caespi osa. NPQ elaxa ion du ing da k
eco e y was as es du ing summe (160 s), hen
au umn (460 s), wi h slowes elaxa ion in win e
(17.5 min) o C. o icinalis. NPQ elaxa ion was as e
o e all o C. caespi osa, wi h simila seasonal dynamics
(160 s in au umn, 460 s in win e ).
Icelandic Co allina pho ophysiology
I adiance was signi ican ly lowe du ing summe in
ICE as compa ed wi h au umn, wi h no signi ican
change in i adiance appa en o e idal eme sion
pe iods du ing ei he season (F
1,24
= 50.80, P<
0.001) (Table 3). Rock pool wa e empe a u es we e
signi ican ly inc eased du ing summe as compa ed
wi h au umn (F
1,24
= 6973.01, P< 0.001), and sig-
ni ican ly inc eased a he end o idal eme sion du -
ing bo h seasons (F
2,24
= 86.55, P< 0.001).
Fig. 7. Pa ame e s de e mined om in si u apid ligh esponse cu es o Co allina o icinalis (unshaded ba s) and C.
caespi osa (shaded ba s) a Combe Ma in, UK, du ing Janua y (Jan), Ma ch (Ma ), June (Jun) and Sep embe (Sep),
showing: he maximum quan um e iciency in he da k adap ed s a e (F /Fm), he ela i e maximum a e o elec on
anspo ( ETRmax), he ligh u iliza ion e iciency (α), he ligh u iliza ion coe icien (Ek), and non-pho ochemical
quenching (NPQ) a he s a - and end- o RLCs (mean ± SE, n= 5). Lowe -case le e s deno e Tukey’s HSD homogeneous
subse s in ela ion o sampling mon h.
296 C. J. WILLIAMSON
Fig. 8. Ex si u apid ligh esponse cu es (RLCs) wi h eco e y o Co allina o icinalis (le hand panels) and C. caespi osa
( igh hand panels) du ing summe (ci cles and solid lines), au umn ( iangles and dashed lines) and win e (squa es and
do ed lines), om Combe Ma in, UK. Showing (a & b) ela i e elec on anspo a es ( ETR) o e he induc ion phase o
RLCs, and (c & d) ela i e quan um e iciency (RQE) and (e & ) non-pho ochemical quenching (NPQ) o e he induc ion
(whi e backg ound) and da k eco e y (g ey backg ound) phases (mean ± SE, n= 3).
EUROPEAN JOURNAL OF PHYCOLOGY 297
Addi ional o seasonal a iabili y, he p esen
s udy u he indica es la i udinal pa e ns in he
pho o egula ion capaci y o Co allina ac oss he
NE A lan ic. The as e NPQ e u ns o 0 in da k-
ness is an indica o o a plan ’s ole ance o high
ligh (Ralph & Gademann, 2005). By moni o ing
elaxa ion kine ics a e ex si u RLCs i was hus
possible o examine eco e y om ligh exposu e,
allowing he a ious componen s o NPQ o be
dis inguished. The componen o NPQ which
elaxes quickly (seconds–minu es) is associa ed
wi h he emo al o ene gy-dependen NPQ (qE),
and is linked o elaxa ion o he p o on g adien
ac oss he hylakoid memb ane (Ralph &
Gademann, 2005). In con as , a slowe elaxa ion
o NPQ (>10 min, up o hou s), is associa ed wi h
pho oinhibi ion (qI) and changes in ene gy dis i-
bu ion in a ou o PSII (Ralph & Gademann,
2005). qE was shown he e o be he majo com-
ponen o Co allina NPQ, wi h apid elaxa ion o
0 by a maximum o 160 s o da kness obse ed
du ing summe and au umn in he UK and no h-
e n Spain o bo h Co allina species. In con as ,
qI was iden i ied o Icelandic C. o icinalis du ing
bo h summe and au umn, gi en he pe sis ence o
NPQ ollowing 17.5 min o da kness. Reco e y o
quan um e iciency by he end o da k pe iods
u he showed la i udinal g adien s, wi h he
g ea es eco e y obse ed in lowe ela i e o
highe la i udes, in all seasons. Co allina popula-
ions hus demons a ed an inc eased suscep ibil-
i y o pho os ess, and educed capaci y o
pho o egula ion, wi h inc easing la i ude ac oss
he NE A lan ic.
Species wi h an ex ended la i udinal dis ibu ion
can be exposed o high en i onmen al a iabili y ha
may p omo e pheno ypic plas ici y and/o eco ype
di e en ia ion as an adap i e esponse o empo al
and spa ial a ia ion (Lynch & Gab iel, 1987). Gi en
ha he ne amoun o sola adia ion eaching he
ea h’s su ace dec eases wi h inc easing la i ude
(Beaug and, 2014), da a may e lec low-ligh pho o-
acclima ion (o pho oadap a ion) o highe la i ude
Co allina popula ions ac oss he NE A lan ic, wi h
consequen inc eases in sensi i i y o pho os ess
ela i e o lowe la i ude popula ions. This may be
u he exace ba ed by low empe a u e es ic ions
on enzyma ic eco e y p ocesses a highe la i udes,
which can mimic he impac s o high-ligh s ess
(Ensminge e al., 2006; Hune e al., 1996). In his
espec , he capaci y o NE A lan ic Co allina popu-
la ions o e ec i ely pho o egula e may dec ease wi h
inc easing la i ude due o di e en ial pho oacclima-
ion coupled wi h low- empe a u e es ic ions o
physiology.
In e speci ic di e ences in pho ochemis y
Da a highligh ed highly conse ed pho ophysiology
be ween C. o icinalis and C. caespi osa, consis en
wi h he indings o Williamson e al.(2014b). Fo
example, seasonal pa e ns in in si u pho ophysiology
in he UK we e almos iden ical be ween he wo
species, wi h no signi ican di e ence in F
/F
m
,
ETR
max
,αo E
k
obse ed. Fu he mo e, whe e in e -
speci ic di e ences we e appa en in si u, hese
e lec ed local esponses o di e en ial abio ic s ess
gi en hei espec i e posi ions on he sho e (Va ela
e al., 2006), and we e absen wi h emo al o ex si u
analyses o pho ochemis y. Known di e ences in he
global dis ibu ions o he Co allina species s udied
he e (Williamson e al., 2015) do no , he e o e,
appea o ela e o di e en ial capaci y o pho o-
chemis y. As such, u he esea ch is equi ed o
examine he physiological mechanisms unde lying
in e speci ic di e ences wi hin he genus Co allina.
Disclosu e s a emen
No po en ial con lic o in e es was epo ed by he
au ho s.
Funding
This wo k was unded by he NERC g an (NE/H025677/1).
Au ho con ibu ions
C. Williamson, R. Pe kins, M Yallop and J. B odie: o iginal
concep and s udy design; All au ho s: ield suppo , ield
sampling and manusc ip p epa a ion.
Supplemen a y in o ma ion
The ollowing supplemen a y ma e ial is accessible ia he
Supplemen a y Con en ab on he a icle’s online page a
h ps://doi.o g/10.1080/09670262.2018.1442586.
Supplemen a y able 1. Analysis o a iance o UK C.
o icinalis and C. caespi osa seasonal pho ophysiology.
Supplemen a y able 2. Analysis o a iance and - es
analysis o UK C. o icinalis and C. caespi osa ex-si u pho o-
physiology pa ame e s in ela ion o he ac o ‘season’.
Supplemen a y ig. 1.Ex-si u apid ligh esponse cu es
wi h eco e y o C. o icinalis du ing summe and au umn
a Þo lákshö n, Iceland, showing (a) ela i e elec on ans-
po a es ( ETR) o e he induc ion phase o RLCs, and
(b) ela i e quan um e iciency (RQE) and (c) non-pho o-
chemical quenching (NPQ) o e he induc ion and da k
eco e y phases.
Supplemen a y ig. 2.Ex-si u apid ligh esponse cu es
wi h eco e y o C. caespi osa du ing summe and au umn
a Comillas, no he n Spain, showing (a) ela i e elec on
304 C. J. WILLIAMSON

anspo a es ( ETR) o e he induc ion phase o RLCs,
and (b) ela i e quan um e iciency (RQE) and (c) non-
pho ochemical quenching (NPQ) o e he induc ion and
da k eco e y phases.
Supplemen a y ig. 3.Ex-si u apid ligh esponse cu es
wi h eco e y o C. o icinalis du ing summe a Comillas,
no he n Spain, showing (a) ela i e elec on anspo
a es ( ETR) o e he induc ion phase o RLCs, and (b)
ela i e quan um e iciency (RQE) and (c) non-pho oche-
mical quenching (NPQ) o e he induc ion and da k eco -
e y phases.
ORCID
Césa Pe ei o h p://o cid.o g/0000-0003-0698-3573
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