Au ho 's Accep ed Manusc ip
Di e en ial p ocessing o an h opogenic ca -
bon and ni ogen in ben hic ood webs o A
Co uña (NW Spain) aced by s able iso opes
An onio Bode, Consolación Fe nández, Ca men
Mompeán, San iago Pa a, Fe nando Rozada,
Joaquín Valencia-Vila, Inés G. Viana
PII: S0967-0645(13)00374-3
DOI: h p://dx.doi.o g/10.1016/j.ds 2.2013.09.033
Re e ence: DSRII3520
To appea in: Deep-Sea Resea ch II
Ci e his a icle as: An onio Bode, Consolación Fe nández, Ca men Mompeán,
San iago Pa a, Fe nando Rozada, Joaquín Valencia-Vila, Inés G. Viana,
Di e en ial p ocessing o an h opogenic ca bon and ni ogen in ben hic
ood webs o A Co uña (NW Spain) aced by s able iso opes, Deep-Sea Resea ch
II, h p://dx.doi.o g/10.1016/j.ds 2.2013.09.033
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Di e en ial p ocessing o an h opogenic ca bon and ni ogen in ben hic ood webs o A
Co uña (NW Spain) aced by s able iso opes
An onio Bode*1, Consolación Fe nández2, Ca men Mompeán1, San iago Pa a1, Fe nando
Rozada1,3, Joaquín Valencia-Vila1 and Inés G. Viana1
* e-mail: an onio.bod[email p o ec ed]
1 Ins i u o Español de Oceanog a ía. Cen o Oceanog á ico de A Co uña. Apdo. 130. 15080 A
Co uña, Spain
2 Unidad de Ecología. Depa amen o de Biología de O ganismos y Sis emas. Uni e sidad de
O iedo. 33071 O iedo, Spain
3 P esen add ess: Ins i u o de Ganade ía de Mon aña, CSIC-Uni e sidad de León, Finca
Ma zanas, C a. G ulle os, 24346 León, Spain
Abs ac
In his s udy he e ec o inpu s o o ganic ma e and an h opogenic ni ogen a small spa ial
scales we e in es iga ed in he ben hos o he Ria o A Co uña (NW Spain) using s able ca bon
and ni ogen iso opes. This ia is cha ac e is ically en iched in nu ien s p o ided ei he by
ma ine p ocesses (as coas al upwelling) o by u ban and ag icul u al was e. S able iso ope
composi ion in ophic guilds o in aunal ben hos e ealed spa ial di e ences ela ed o hei
nu ien inpu s. The main di e ence was he p esence o an addi ional chemoau o ophic ood
web a he si e wi h a la ge accumula ion o o ganic ma e . The en ichmen in hea y ni ogen
iso opes obse ed in mos compa men s sugges s he in luence o sewage-de i ed ni ogen,
despi e la ge inpu s o ma ine ni ogen. Mac oalgae (Fucus esiculosus) esul ed signi ican ly
en iched a he si e in luenced by es ua ine wa e s. In con as , no di e ences we e ound in
mussels (My ilus gallop o incialis), hus sugges ing a majo dependence on ma ine nu ien
sou ces o his species. Howe e , he es ima ions o an h opogenic in luence we e la gely
dependen on assump ions equi ed o model he di e en con ibu ions o sou ces. The
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measu emen o s able iso ope signa u es in a ious compa men s e ealed ha , despi e
an h opogenic nu ien s a e eadily inco po a ed in o local ood webs, a majo in luence o
na u al ma ine nu ien sou ces canno be disca ded.
Keywo ds: δ15N, δ13C, sub idal, in e idal, was ewa e , upwelling, chemoau o ophy
1. In oduc ion
Coas al ood webs a e inc easingly al e ed by p essu es om eu ophica ion and pollu ion as
mos o he human popula ion concen a es nea he coas . An h opogenic nu ien s, as hose
de i ed om u ban and ag icul u al was ewa e s ha e been iden i ied as one o he main causes
o changes in he s uc u e and composi ion o ood webs because o hei impac in he nu ien
cycles (McClelland and Valiela, 1998; Cas o e al., 2007). The excess nu ien s may lead o
la ge inc eases in p ima y p oduc ion and clea signs o eu ophica ion, including hypoxia when
he emine alisa ion o he p oduced o ganic ma e exhaus s he oxygen in he wa e , bu o en
he changes emain unno iced because some coas al ecosys ems a e al eady highly p oduc i e.
Es ua ies, o ins ance, display enhanced p oduc ion and speci ic ood webs ela ed o hei
di e se inpu s o nu ien s om ma ine and e es ial sou ces. Simila ly, coas al upwelling
causes ele a ed le els o p ima y p oduc ion by he inpu o signi ican amoun s o nu ien s
om deep wa e s.
The Galician coas (NW Spain) is one pa adigma ic egion o s udy he e ec s o he
an h opogenic and na u al sou ces o nu ien s. I is loca ed a he no he n limi o he eas e n
bounda y upwelling sys em o he N A lan ic and cha ac e ised by high p ima y p oduc ion due
o he inpu o nu ien - ich deep ocean wa e s nea he coas (Al a ez-Salgado e al., 2002). The
e ilising e ec o he upwelling is ampli ied by he ias and bays ha e ain and exchange
wa e wi h he shel and a ou apid mine alisa ion o he p oduced o ganic ma e (Al a ez-
Salgado e al., 1997). Es ua ine zones in he ias a e gene ally small because o he low low o
mos i e s in his egion (Rio Ba ja and Rod iguez Les egás, 1996) and upwelling dynamics
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domina e nu ien luxes (Noguei a e al., 1997). Howe e , mos o he u ban and indus ial
popula ion o Galicia concen a es nea he ias. Nea 57% o a o al popula ion o 1.5 million
inhabi an s li es in he wo majo u ban a eas o Vigo and A Co uña (P ecedo Ledo e al., 2008)
loca ed inside wo o he main ias.
The Ria o A Co uña is o med by a bay o 15.7 km2 and a small es ua ine zone (Ria do Bu go)
in he mou h o he i e Me o (Cosme de A ilés and P ego, 1995). The i e basin d ains 385
km2 bu i s mean annual low is only 6.6 m s-1. The ma ine in luence is high in he bay (Cabanas
e al., 1987) e lec ing he nu ien dynamics d i en by he win e mixing and summe upwelling
in he nea by shel (Casas e al., 1997; Bode e al., 2004a, b). The in luence o es ua ine wa e s
is es ic ed o he inne bay whe e he e was also an e ec o he ha bou in as uc u es
causing enhanced nu ien and phy oplank on concen a ions (Va ela e al., 1994; Va ela and
P ego, 2003). U ban popula ion nea he ia amoun s ca. 250,000 inhabi an s acco ding o he
Spanish O icial Popula ion Census (h p://www.ine.es/inebase) hus ha ing a la ge po en ial
impac on nu ien inpu s o coas al wa e s. U ban and indus ial de elopmen s in he a ea
collec and ea was ewa e in a wa e ea men plan ecen ly imp o ed wi h seconda y and
e ia y ea men (h p://augasdegalicia.xun a.es/es/eda s/ACOR.h ml). This plan is designed
o a popula ion o up o 600,000 inhabi an s and he ea ed wa e s each he open ocean
h ough a subma ine ou all loca ed ou side and 7.5 km wes o he mou h o he bay.
Ne e heless he possible in luence o di use inpu s o nu ien s o he ia by local poin
sou ces, occasional leaks in he sani a ion sys em o o e lows du ing s o ms is no known.
Disc imina ion be ween nu ien sou ces o species o ood webs can be made by measu ing he
na u al abundance o s able iso opes. As ligh iso opes a e mobilised as e in chemical eac ions
han hea y ones, each molecule has a cha ac e is ic iso opic signa u e e lec ing he pa hways
ollowed in i s o ma ion. The eac an s a e p og essi ely en iched in hea y iso opes while he
p oduc s a e ela i ely deple ed. The iso ope en ichmen o he eac an (ε) is cha ac e is ic o
each eac ion (Ma io i e al., 1981; Ruby e al., 1987; Wasse e al., 1998; Needoba e al., 2004)
and allows o a di e en ia ion o nu ien s wi h di e en o igins (Hea on, 1986). Ni ogen om
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u ban and ag icul u al was ewa e s is gene ally en iched in hea y iso opes because o he la ge
ac iona ion associa ed wi h ni i ica ion (Ma io i e al., 1981). This ea u e was employed in
nume ous s udies o de e mine he in luence o was ewa e in coas al sys ems (McClelland and
Valiela, 1998; Sa age and Elmg en, 2004; Cas o e al., 2007; Bode e al., 2011; Viana e al.,
2011; Viana and Bode, 2013). Simila ly ca bon iso opic signa u es e lec he o igin o he
o ganic ma e in ma ine ood webs (Spi o e al., 1986; Ci uen es e al., 1988; Dando and Spi o,
1993; Machas e al., 2003; Ma ineau e al., 2004; Bode e al., 2006; Male e al., 2008;
Sakamaki and Richa dson, 2008; Bode e al., 2011). Howe e , p e ious s udies ocus on a ew
species o ben hic compa men s, hus limi ing he gene alisa ion o hei conclusions o he
whole ecosys em.
The objec i e o he p esen s udy is o de e mine he e ec o inpu s o o ganic ma e and
an h opogenic ni ogen a small spa ial scales in he Bay o A Co uña (NW Spain). Fo his
pu pose he na u al abundance o s able ca bon and ni ogen iso opes was examined in di e en
compa men s, including wa e , ses on, sub idal sedimen s and in auna and in e idal o ganisms.
Each compa men was selec ed as ep esen a i e o nu ien e ec s a ins an aneous (su ace
wa e ) o longe ime-scales (sedimen s and ben hic o ganisms). In e idal ben hos was chosen
as indica o o he con ibu ion o di e en nu ien sou ces in su ace wa e , while sub idal
in auna was in ended o e lec nu ien sou ces nea he sedimen . The seasonal a iabili y was
aken in o accoun by sampling ac oss annual seasons and he es ima ions o an h opogenic
con ibu ions included a ia ions in iso opic ac iona ion.
2. Me hods
2.1 Sub idal sedimen s and in auna
Samples o sub idal sedimen s and in auna we e collec ed bimon hly (Janua y 2010 o
No embe 2011) a s a ions B2 (9 m dep h) and DB (17 m dep h) using R/V Lu a (Fig. 1).
These s a ions we ep esen a i e o he spa ial a iabili y o in aunal ben hos in he a ea (López-
Jama and Meju o, 1985). A each sampling da e i e box-co e samples (Bouma- ype box-co e ,

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sampling a ea = 0.0175 m2) we e pooled o ob ain ep esen a i e es ima es o in aunal species
composi ion and biomass (López-Jama e al., 1986). The uppe 2 cm o he co e sample
sedimen s we e analysed o o al o ganic ma e con en (ash- ee d y weigh ) and
g anulome ic cha ac e is ics (Buchanan, 1984). In addi ion pa icula e o ganic ca bon and
ni ogen concen a ions (POC and PON) and s able iso ope abundance we e de e mined in
subsamples o hese sedimen s. The in aunal samples we e sie ed h ough a 0.5 mm mesh,
anaes he ized wi h magnesium chlo ide (7% w/ ), and hen p ese ed in 5% bu e ed
o maldehyde p e iously con aining Rose Bengal as a s aining agen o acili a e he so ing o
o ganisms. Specimens in ended o s able iso ope de e mina ions we e ob ained om addi ional
box-co e samples, so ed immedia ely a e sampling in he labo a o y and kep o 24 h in small
aqua ia con aining il e ed seawa e o acili a e e acua ion o gu con en s. Fo ophic analysis
species we e classi ied in ophic guilds ( il e eede s, deposi eede s, omni o es and
ca ni o es) om he in o ma ion p o ided in he li e a u e.
2.2. Wa e
Tempe a u e, salini y and chlo ophyll- luo escence p o iles o wa e abo e each sub idal
sedimen s a ions we e ob ained a each sampling da e using a CTD SBE-25. Fluo escence was
con e ed o chlo ophyll-a concen a ions a e calib a ion wi h ace onic ex ac s o disc e e
wa e samples collec ed wi h Niskin bo les. In addi ion, su ace wa e nu ien s we e
de e mined in samples collec ed mon hly du ing 2011 a s a ions W1 and W2, loca ed nea he
sedimen s a ions and, acco ding o p e ious s udies (Cabanas e al., 1987; Va ela e al., 1994;
Va ela and P ego, 2003), ep esen a i e o ma ine and es ua ine end-membe s, espec i ely
(Fig. 1). Addi ional wa e samples we e collec ed nea he coas concu en ly wi h samples o
in e idal o ganisms. Dissol ed ni a e, ni i e and ammonium concen a ions we e de e mined
by segmen ed- low analysis (Casas e al., 1997).
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2.3. In e idal ben hos
Samples o he b own alga Fucus esiculosus and he mussel My ilus gallop o incialis we e
collec ed mon hly du ing 2010 and 2011 a wo in e idal si es (Fig. 1). Me a was loca ed a he
ou e bay in he less u banized pa o he s udy a ea. In con as , Ria do Bu go was loca ed in
he a ea o di ec es ua ine in luence and hea y u ban popula ion. Algal samples o s able
iso ope de e mina ions we e collec ed om he apical 2 cm o he hallus o 25-35 cm long
specimens, while mussel samples we e collec ed om he adduc o muscle o 40-50 cm (shell
leng h) indi iduals a bo h si es.
2.4. S able iso ope analysis
Sedimen and biological samples o s able iso ope de e mina ion we e d ied (50 ⁰C, 24 h),
g ound o a ine powde and weigh ed (± 0.002 mg). The iso opic composi ion o o al ni a e
(NO3
-+NO2
-) was de e mined by p e ious con e sion in o ammonium and la e eco e y o
ammonium on a solid phase (Ahad e al., 2006). The p ocedu e is an adap a ion o he di usion
me hod (Sigman e al., 1997) in ol ing he incuba ion o samples in wo s eps. Fi s , aliquo s o
he samples we e incuba ed (50 °C, 1 week) in he same collec ing lask wi hou cap o educe
he olume and concen a e ni a e. Ashed MgO was added o aise pH abo e 9.7 o emo e
ammonia by ola iliza ion. In he second s ep (50 °C, 2 weeks), ashed De a da´s alloy was
added o he educed olume sample o con e ni a e and ni i e in o ammonium. The high pH
(>11) o he mix u e ensu ed also he con e sion o ammonium in o ammonia gas ha was
collec ed on a s e ilized glass- ib e disk (Wha man, GF/F), acidi ied wi h 0.5 ml o 0.25N
H2SO4 and hooked on a needle ixed o he inne side o he lask (Slawyk and Raimbaul ,
1995). A e he incuba ion, he disk il e s con aining ammonium sulpha e we e d ied and
p epa ed o iso opic analysis. The s able iso ope composi ion o ammonium was de e mined in
ano he aliquo o he wa e samples by an adap a ion o he di usion me hod (Holmes e al.,
1998). This me hod in ol es gas-phase di usion as desc ibed o he second s ep o he o al
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ni a e ex ac ion. In all cases co ec ions o iso opic ac iona ion du ing he whole incuba ion
and di usion s eps we e made (Holmes e al., 1998).
Samples we e placed in in capsules and in oduced in o an iso ope- a io mass spec ome e
(The mo Finnigan Ma Del a Plus) ia an elemen analyse (Ca lo E ba CHNSO 1108). Iso opic
esul s a e exp essed in del a no a ion (δ15N o δ13C) ela i e o a mosphe ic N o VPDB ( Bode
e al., 2011). P ecision (SE o 5 eplica es) was be e han 0.05 ‰ o ei he δ15N o δ13C. The
coe icien o a ia ion o iplica e sample aliquo s was always <2%. P ecision o δ15N
de e mina ions in bo h ni a e and ammonium was be e han 0.4 ‰.
The con ibu ions o an h opogenic ( a) and ma ine (1- a) sou ces o ni ogen composi ion o
p ima y p oduce s (δ15NP) we e es ima ed using a mixing model o wo end membe s:
δ15NP = a δ15Na + (1- a) δ15Nm - ε
whe e δ15NP is he iso opic composi ion o phy oplank on, mic ophy oben hos o mac oalgae,
es ima ed om he analysis o ses on, su ace sedimen s o F. esiculosus, espec i ely. The
iso opic composi ion o ni ogen sou ces was ep esen ed by he mean alue o o al ni a e in
su ace ma ine wa e s (δ15Nm) o an h opogenic ni ogen (δ15Na). As i was di icul o ob ain
ep esen a i e samples om he di use sou ces o an h opogenic ni ogen in he s udy a ea, we
used a mean δ15Na alue ob ained om measu emen s in samples o u ban was ewa e eleased
om se e al wa e ea men plan s in he s udy egion (17.8±0.6‰ se, n=7). The model
included an iso opic en ichmen ac o (ε) be ween he sou ce (ni a e) and he p oduc (p ima y
p oduce ni ogen). Se e al alues o ε we e employed o cons ain he es ima ed con ibu ions.
2.5. S a is ical analysis
Di e ences be ween s a ions in he alues o he en i onmen al a iables we e de e mined using
non pa ame ic ANOVA (Mann-Whi ney U) while di e ences in iso opic composi ion among
ophic guilds we e analysed using pa ame ic ANOVA and a pos e io i es s (Dunne C). As
he main objec i e o his s udy is o compa e di e en loca ions in he s udy a ea, all alues
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om he same sampling si e we e a e aged. The species composi ion o he in aunal
communi ies in sub idal sedimen s was analysed using a clus e analysis (B ay-Cu is dis ance,
g oup a e age me hod) on log- ans o med species biomass o each sampling da e. Only
species con ibu ing >0.1% o o al biomass we e selec ed o his analysis. The con ibu ion o
species o simila i y wi hin each s a ion was de e mined using he p ocedu e SIMPER o
PRIMER s a is ical package (Cla ke and Wa wick, 2001).
3. Resul s
3.1. Wa e and sedimen s
Su ace wa e om he s a ion W2 was signi ican ly less saline han wa e om W1 bu
o he wise bo h s a ions ha e simila mean alues o SST, ni ogenous nu ien s o chlo ophyll
(Table 1). The in luence o he es ua ine wa e s was mo e e iden in he ses on composi ion, as
POC and PON alues a W2 wa e s we e ca. 2.5 imes highe han hose o W1, ha ing also an
excess o ca bon as indica ed by he C:N a io. Howe e , he e we e no signi ican di e ences
in he a e age iso opic composi ion o ses on o wa e a bo h s a ions.
The wa e collec ed a bo h in e idal sampling si es did no show ei he di e ences in he wa e
a iables analysed, excep in he δ15N alues o ni a e ha we e signi ican ly lowe a he
es ua ine si e (Table 1).
Simila esul s we e ound when compa ing wa e cha ac e is ics abo e bo h in auna sampling
s a ions, as bo h ha e equi alen empe a u e, salini y, and in eg a ed chlo ophyll alues (Table
2). The only signi ican di e ence was in he a e age amoun o ligh eaching he sedimen
su ace (21% a S . B2 and 7% a S . DB).
Despi e he simila i ies in wa e -column p ope ies, he e we e la ge di e ences in sedimen s
om he in aunal s a ions (Table 3). Sedimen s om S . DB showed a mix u e o sands bu
we e cha ac e ised mainly by a la ge ac ion o mud and o ganic ma e han hose om S .
B2. To al o ganic ma e (%AFDW), ca bon (%C o al) and ni ogen con en a S . DB we e >5,
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Ni a e de i ed om was ewa e s and manu e is cha ac e is ically en iched in 15N because o he
la ge ac iona ion associa ed wi h ni i ica ion and dini i ica ion p ocesses (Ma io i e al.,
1981) wi h bo h ni a e and ammonium δ15N gene ally abo e 10‰ (Tucke e al., 1999; Sa age
and Elmg en, 2004). The alue assumed o δ15Na is compa able wi h ha ound in was ewa e s
om o he a eas e en i exceeded ou measu emen s in he wa e , sedimen s o bio a. This
would indica e ha he e we e no la ge inpu s om u ban o ag icul u al was ewa e s o he bay,
despi e o he la ge u ban popula ion. This is suppo ed by he small en ichmen in 15N (<2‰)
ound be ween ni a e, ses on and su ace sedimen s (Tables 1 and 3). Howe e , he e we e
ela i ely high en ichmen s in some guilds (e.g. DF) o species (F. esiculosus), sugges ing he
po en ial impac o ni ogen om was ewa e , a leas in he inne zone o he bay. The
en ichmen could be explained by he accumula ion o hea y ni ogen in s uc u al issues wi h
low u no e a es while ligh ni ogen is apidly exchanged wi h he wa e , as ound in o he
s udies (Sa age and Elmg en, 2004). In addi ion, di use sou ces o hea y ni ogen may a ec
ben hic o ganisms a small spa ial scales. Recen measu emen s o δ15N in ni a e om
in e s i ial wa e s in uppe 10 cm o sedimen s om he inne es ua y (unpub. esul s) p oduced
alues (mean±se 17.2±0.9‰, n=3) which we e close o hose ound in was ewa e s. This
sugges s ha es ua ine sedimen s play a majo ole o in he emine alisa ion o di use inpu s o
was ewa e ni ogen. Ou es ima ions indica e an a e age low inpu o was ewa e
(an h opogenic) ni ogen o ses on o sedimen s, and e en o F. esiculosus in he es ua ine
zone, bu hese es ima ions we e la gely dependen on he iso opic ac iona ion employed.
Assimila ion o ni a e is gene ally associa ed wi h iso opic ac iona ion ac o s be ween 0-
20‰, bo h in phy oplank on (Wase e al., 1998; Needoba e al., 2004) and mac oalgae (Naldi
and Wheele , 2002) bu mos es ima es a e nea 5‰. In con as assimila ion o ammonium is
assumed o ha e almos no ac iona ion a he low ambien concen a ions no mally ound in
ma ine wa e s (Wase e al., 1998). The e o e he use o a mean ac iona ion ac o o 3‰ in
ou es ima es o an h opogenic ni ogen inpu s ep esen s a conse a i e comp omise be ween
he assimila ion o bo h ni a e and ammonium by phy oplank on and mac oalgae.
No wi hs anding he upwelling pulses o ni a e in he s udy a ea, s udies wi h iso opic ace s

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indica ed ha a leas phy oplank on uses equi alen amoun s o ni a e and ammonium a
seasonal ime scales (Bode e al., 2004a). The esul ing low in luence o an h opogenic ni ogen
is consis en wi h p e ious s udies in he Galician coas (Bode e al., 2006; 2011; Viana e al.,
2011; Viana and Bode, 2013). Howe e , he la ge in luence o he alue o he iso opic
ac iona ion ac o employed in he es ima ed con ibu ion o di e en ni ogen sou ces is no
gene ally acknowledged in pollu ion s udies (Sa age and Elmg en, 2004; Lamb e al., 2012) and
ou esul s add o he g owing e idence ha δ15N alues alone do no p o ide an unequi ocal
p oo o a majo in luence o an h opogenic ni ogen on coas al ecosys ems.
Acknowledgemen s
We a e g a e ul o he c ew o R/V Lu a o hei collabo a ion du ing wa e and sedimen
sampling. Nu ien concen a ions we e de e mined by R. Ca ballo and sedimen cha ac e is ics
by J. F. Feijoo. We also acknowledge he pa icipa ion o A.F. Lamas in sample collec ion and
p epa a ion o s able iso ope analysis and o M.C. Vázquez in he analysis o in aunal species.
S able iso ope de e mina ions we e made by he Se icio de Apoyo a la In es igación o he
Uni e sidad de A Co uña (Spain). This esea ch was unded by p ojec s ANILE (CTM2009-
08396 and CTM2010-08804-E) o he Plan Nacional de I+D+i (Spain), and RADIALES o he
Ins i u o Español de Oceanog a ía (IEO, Spain). C.M. and I.G.V. we e suppo ed by FPI
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23

8.44° 8.40° 8.36° 8.32°
43.32°
43.36°
43.40°
Me a
Ria do Bu go
DB
B2
W1
W2
A Co uña
8° 4° 0° 36°
40°
44°
48°
Ibe ian
Peninsula
Figu e 1. Loca ion o sampling s a ions o sub idal in auna (DB and B2), in e idal ben hos
(Me a and Ria do Bu go) and su ace wa e p ope ies (W1 and W2) in he Bay o A Co uña
(NW Spain).
24

G oup a e age
DB
DB
DB
DB
DB
DB
B2
B2
B2
B2
B2
B2
Sam
p
les
100
80
60
40
20
0
Simila i y
T ans o m: Log(X+1)
Resemblance: S17 B ay Cu is simila i y
S . DB S . B2
Figu e 2. Clus e o in aunal samples (g oup a e age me hod) compu ed om B ay-Cu is
simila i y index on log- ans o med biomass alues o species con ibu ing a leas 0.1% o o al
biomass.
31

SSS 30.4 2.4 34.0 0.6 n.s.
NO3
- 38.62 33.77 14.21 10.65 n.s.
NO2
- 0.76 0.15 0.53 0.11 n.s.
NH4
+ 4.72 1.13 3.51 1.32 n.s.
δ15NNH4 0.2 0.7 0.2 0.7 n.s.
δ15NNO3 3.1 0.2 4.2 0.3 0.007
Table 2. Mean (se: s anda d e o ) alues o a iables measu ed in he wa e column abo e
in auna s a ions (B2 and DB). SST: sea su ace empe a u e (°C), SSS: sea su ace salini y,
bo om: empe a u e 1 m abo e he bo om (°C), Chlain : wa e column in eg a ed chlo ophyll-a,
%PARbo om: pe cen o su ace i adiance (PAR) a he bo om. numbe o samples = 12. P:
signi icance o Mann-Whi ney U o di e ences be ween s a ions. n.s.: P>0.05
B2 DB
mean se mean se P
SST 14.95 0.49 14.65 0.52 n.s.
SSS 33.82 0.51 34.43 0.59 n.s.
bo om 14.82 0.34 14.34 0.28 n.s.
Chlain 16.01 5.46 45.17 13.96 n.s.
%PARbo om 20.81 3.13 6.66 1.37 0.001
Table 3. Mean (se: s anda d e o ) alues o sedimen a iables measu ed a he in auna s a ions.
Q50 φ: median o he dis ibu ion o pa icle diame e (φ = log2(mm)), S0: selec ion coe icien ,
%Coa se sand: pe cen o >500 µm diame e pa icles (by weigh ), %Fine sand: pe cen o 62-
500 µm diame e pa icles (by weigh ), %Mud: pe cen o <62 µm diame e pa icles (by
weigh ), %AFDW: pe cen ash- ee d y weigh , %C o al: pe cen o al ca bon (including

32

ca bona es), %N: pe cen ni ogen, C:N: mola C:N a io, δ13C o al: na u al abundance o 13C
(including ca bona es), δ13Co g: na u al abundance o 13C (o ganic ma e ), δ15N: na u al
abundance o 15N. numbe o samples = 9. P: signi icance o Mann-Whi ney U o di e ences
be ween s a ions. n.s.: P>0.05.
S a ion
B2 DB
mean se mean se P
Q50 φ 2.95 0.01 3.62 0.08 0.000
S0 1.44 0.01 2.06 0.03 0.000
%Coa se sand 1.02 0.14 3.20 0.37 0.000
%Fine sand 91.19 0.46 56.61 1.74 0.000
%Mud 7.79 0.39 40.19 1.90 0.000
%AFDW 2.07 0.18 10.30 0.55 0.000
%C o al 1.90 0.16 4.60 0.12 0.000
%N 0.03 0.00 0.20 0.01 0.000
C:N 76.86 7.97 27.41 1.14 0.001
δ13C o al -2.8 0.3 -13.4 0.3 0.000
δ13Co g -25.3 0.1 -24.9 0.1 n.s.
δ15N 5.2 0.1 5.1 0.1 n.s.
Table 4. Mean (se: s anda d e o ) alues o δ13C, δ15N and biomass (B, mg esh weigh m-2)
o selec ed in aunal species a s a ions B2 and DB. The axonomic g oup (all species) and
ophic guild (only species analysed o s able iso opes) a e indica ed. %sim: pe cen
con ibu ion o species o B ay-Cu iss simila i y o each s a ion (SIMPER analysis, Cla ke and
Wa wick, 2001). n: numbe o samples (o indi iduals o s able iso opes). FF: il e eede ,
FFs: il e eede wi h symbion s, DF: deposi eede , O: omni o e, P: p eda o .
33

δ13C δ15N B2 DB
G oup species
Gui
ld
me
an
s
e
me
an
s
e n
%si
m
mea
n se n
%si
m
mea
n se n
Mollusca
Pha us
legumen FF
-
15.
5
0.
17.7
0.
29
16.
8
760
6.2
529
2.4 6 --- --- ---
-
-
-
Polychae
a
Pa adoneis
a ma a --- ---
--
- ---
--
-
-
-
-
11.
1
416.
8 61.2 6 --- --- ---
-
-
-
Mollusca
Chamelea
gallina FF
-
17.
4
0.
37.3
0.
2
1
29.0
228
9.3
138
8.0 5 --- 2.6 --- 1
O he s Neme ea --- ---
--
- ---
--
-
-
-
-8.3
293.
4
215.
7 7 ---
251
6.3
227
1.3 6
Polychae
a
Magelona
ili o mis --- ---
--
- ---
--
-
-
-
- 7.3 80.5 23.7 6 --- --- ---
-
-
-
Mollusca
My ea
spini e a FFs
-
27.
5
0.
5
-
1.9
0.
5
1
8 --- --- ---
-
-
-
10.
4
177
5.0
574.
5 6
Polychae
a
No omas us
la e iceus DF
-
17.
5
0.
58.3
0.
4 9 --- 75.5 74.3 4 8.8
435.
1
115.
8 7
Polychae
a
Euclymene
oe s edi DF
-
18.
1
0.
38.7
0.
4 7 --- --- ---
-
-
-8.3
528.
5
233.
6 7
34

Polychae
a
Chae ozone
gibbe DF
-
19.
3
0.
47.6
0.
3 8 --- 0.3 --- 1 8.0
792.
6
213.
4 7
Mollusca Nucula sp. --- ---
--
- ---
--
-
-
-
- --- 69.7 68.9 2 7.4
455.
8
131.
1 6
Polychae
a
Chae ozone
se osa --- ---
--
- ---
--
-
-
-
- --- --- --- 0 7.2
100
6.5
808.
8 7
Echinode
ma a
Lep osynap a
be gensis DF
-
16.
6
0.
3
11.
8
1.
5 4 ---
155.
1 91.8 6 --- 75.7 28.8 5
Echinode
ma a
Lep osynap a
inhae ens DF
-
16.
7
0.
4
10.
8
0.
0 3 --- 99.8 --- 1 ---
362.
8
337.
0 2
Mollusca Ab a ni ida DF
-
18.
1
--
- 6.6
--
- 1--- 0.9 0.64---
131.
7 71.2 3
Mollusca Co bula gibba FF
-
16.
9
0.
27.1
0.
2 8 --- --- ---
-
-
----
560.
6
367.
1 3
Mollusca
Mac a
s ul o um FF
-
15.
9
0.
17.9
0.
2 7 ---
581
7.6
324
1.4 5 ---
237
9.2 --- 1
Mollusca
Nassa ius
e icula us O
-
16.
5
0.
4
10.
8
0.
3
1
4---
412
5.4
363.
3 2 ---
100
0.0
465.
5 4
35

Mollusca
Thyasi a
lexuosa FFs
-
28.
5
0.
3
-
6.3
0.
7 5 --- 0.3 --- 1 ---
112.
1 32.3 6
Polychae
a
Diopa a
neapoli ana C
-
17.
3
0.
3
10.
6
0.
4 5 ---
569.
2
354.
7 3 --- --- ---
-
-
-
Polychae
a Glyce a sp. C
-
17.
5
0.
2
11.
3
0.
6 6 --- 3.7 3.0 3 ---
369.
9 58.5 2
Polychae
a
Neph ys
hombe gii C
-
16.
7
0.
49.2
0.
6 6 ---
384.
3
285.
6 6 --- 15.0 11.7 4