Helgol Mar Res (2004) 58:168–182DOI 10.1007/s10152-004-0182-6

O R I G I N A L A R T I C L E

C. Antoniadou · A. Nicolaidou · C. Chintiroglou

Polychaetes associated with the sciaphilic alga communityin the northern Aegean Sea: spatial and temporal variability

Received: 20 October 2003 / Revised: 14 April 2004 / Accepted: 22 April 2004 / Published online: 4 June 2004� Springer-Verlag and AWI 2004

Abstract Polychaete biodiversity has received little at-tention despite its importance in biomonitoring. Thisstudy describes polychaete diversity, and its spatial andtemporal variability in infralittoral, hard substrate as-semblages. Seven stations were chosen in the central areaof the northern Aegean Sea. At each station, one to threedepth levels were set (15, 30 and 40 m). Five replicateswere collected by scuba diving with a quadrat sampler(400 cm2) from each station and depth level duringsummer for the spatial analysis, and seasonally for thestudy of temporal changes. Common biocoenotic methodswere employed (estimation of numerical abundance,mean dominance, frequency, Margalef’s richness, Shan-non-Weaver index and Pielou’s evenness). A total of5,494 individuals, belonging to 79 species, were countedand classified. Diversity indices were always high. Clus-tering and multidimensional scaling techniques indicateda high heterogeneity of the stations, although these wereall characterized by the sciaphilic alga community. Aclear seasonal pattern was not detectable. Summer andautumn samples discriminate, while winter and springform an even group. The abundance/biomass comparisonindicated a dominance of k-strategy patterns, character-istic of stable communities.

Keywords Polychaeta · Infralittoral · Aegean Sea · Hardsubstrate · Biodiversity

Introduction

There is a growing interest in biodiversity, defined as thecollection of genomes, species and ecosystems occurringin a geographical region (CBDMS 1995). The most fun-damental meaning of this term is expressed at specieslevel by the concept of species richness (Bianchi andMorri 2000). Species richness does not simply refer to thenumber of species, but includes species variety, i.e.composition, which is an important indicator of diversityacross spatial scales (Costello 1998). According to theConvention of Biological Diversity definition, biodiver-sity concerns variability within species (individual/popu-lation level), between species (community level), and atthe ecosystem level (functional level). The value of bio-diversity as an indicator of environment health, and forthe functioning of ecosystems, is now largely recognized(Gaston and Spicer 1996; Bianchi and Morri 2000).

Polychaetes are among the most frequent and species-rich taxa in marine benthic environments (Fauchald andJumars 1979; Costello et al. 1996). Many authors havesuggested a key role of polychaetes in biomonitoringstudies (Reish 1978; Bellan 1980; Wenner 1988; Warwick1986, 1993; Damianidis and Chintiroglou 2000). Beforedata from polychaete assemblages can be used to identifydisturbances, as demanded by international directivesand conventions, it is necessary to provide a database onthe composition of natural assemblages (Pocklington andWells 1992; Gaston and Spicer 1996; Ergen and Cinar1997).

The distribution of polychaetes in hard-bottomed sitesis commonly related to algal structure and zonation(Giangrande 1988; Somaschini 1988; Sard� 1991). How-ever, the distribution of polychaetes depends on algalcover and epiphytes more than on the presence of par-ticular macroalgal species (Abbiati et al. 1987; Sard�1987; Giangrande 1988; Fraschetti et al. 2002). There is alarge amount of literature on polychaetes in midlittoraland infralittoral zones of the western Mediterranean(Retiere and Richoux 1973; Cardell and Gili 1988; re-viewed by Sard� 1991), yet much less information on the

Communicated by H.-D. Franke

C. Antoniadou · C. Chintiroglou ())School of Biology, Department of Zoology,Aristotle University,P.O. Box 134, 54006 Thessaloniki, Greecee-mail: chintigl@bio.auth.gr

A. NicolaidouZoological Laboratory,University of Athens,Panepistimiopolis, 15784 Athens, Greece

situation in the eastern Mediterranean (Nicolaidou et al.1986; Bellan-Santini et al. 1994; Chintiroglou 1996; Er-gen and Cinar 1997; Damianidis and Chintiroglou 2000).

According to Marinopoulos (1988), the infralittoralzone can be divided into three ecologically different belts.This study was restricted to the lowest belt (below 15 m),where the sciaphilic alga community occurs (Laubier1966; Margalef 1984; Antoniadou et al. 2004). Its aimwas to reveal the spatial and temporal variability of thepolychaete fauna associated with the sciaphilic algacommunity.

Methods

Sampling sites

Seven coastal stations were selected in the northern part of theAegean Sea (Fig. 1). These sites share some common physicalcharacteristics, such as hard substrate down to a depth of 30–40 mand an inclination of more than 50� (for details see Antoniadou etal. 2004), which lead to the establishment of the sciaphilic algacommunity in the lower infralittoral zone (15–40 m). According tothe vertical extension of the hard substrate, one to three depth levels(15, 30 and 40 m) were set at each station, covering the depth rangeof the local sciaphilic alga community. The main physical char-acteristics of the sampling sites are given in Table 1. For the spatialanalysis, the sites were sampled during summer 1998 (stations 1–6)or summer 1999 (station 7). Station 3 was chosen for the temporalanalysis (summer 1997 to summer 1998) due to its geomorphology

Table 1 Physical and biotic characteristics of the sampling sites

Station Slope (�) Maximum depth (m) Prevailing winds Depth level (m) Pilot algal species

1 Kakia Skala 90 65 N, NE, SE 15 Polysiphonia sp.30 Polysiphonia sp., Lithophyllum sp.40 Lithophyllum sp., Peyssonnelia sp.

2 Kelyfos 70 35 S, SW, SE, NW 15 Padina pavonica, Polysiphonia sp.30 Womersleyella setacea, Padina pavonica

3 Porto Koufo 90 50 SW 15 Womersleyella setacea30 Womersleyella setacea40 Lithophyllum sp., Peyssonnelia sp.

4 Armenistis 50–60 35 NE 15 Womersleyella setacea, Padina pavonica30 Womersleyella setacea

5 Vourvourou 55 18 N, SE 15 Pseudolithophyllum expansum, Gelidiumpectinatum

6 Eleftheronissos 70 30 NE, SE, N, S 30 Lithothamnion sp., Polysiphonia sp.7 N. Iraklitsa 65 35 NE, NW, SE 15 Cutleria multifida, Gelidium pectinatum

30 Cutleria multifida, Gelidium pectinatum

Fig. 1 Map of the study area

169

protecting it from the N, NE and NW winds that usually occur inthis area during winter.

Physico-chemical factors

Measurements of the main abiotic factors (temperature, salinity,conductivity, dissolved O2 and pH) were carried out along the watercolumn using a WTW salinity-conductivity-O2 meter and LovibondCheckit (pH meter) micro-electronic equipment. Water clarity wasdetermined using a Secchi disc. The inclination of the hard sub-stratum was calculated using a clinometer; currents (speed anddirection) were recorded using the autographic current meter Sen-sordata SD-4 in May 2000.

Data collection

Sampling was carried out by scuba diving using a quadrat sampler(Bellan-Santini 1969) covering a surface of 400 cm2 (Weinberg1978; Karalis et al. 2003). Following Marinopoulos (1988), fivereplicates were collected at each depth level and site (see Table 1).A total of 75 and 65 samples were available for the study of spatialand seasonal variations, respectively. All samples were sieved(0.5 mm mesh size) and preserved in a 10% formalin solution. Aftersorting, all polychaetes were counted, weighted (wet weight) andidentified to species level. Furthermore, the algae collected wereidentified, and the dominant species (in terms of percentage cover)were estimated.

Statistics

Common biocoenotic methods were employed to analyze the data(Hong 1982; Marinopoulos 1988; Antoniadou et al. 2004). Thus,the numerical abundance per square meter (A/m2), the meandominance (mD), the frequency (F), and a variety of diversity in-dices (Margalef’s richness, Shannon-Weaver H’ and Pielou’sevenness J’ based on log2) were calculated.

In order to check the null hypothesis (no significant variationsin polychaete abundance), a two-way mANOVA test was used toexamine the effects of two different factors: depth, and space ortime. A logarithmic transformation (logx+1) was used in order tonormalize the variance of numerical abundance data in both cases(Zar 1984; Clarke and Green 1988).

The data obtained from each sampling site were analyzed usingcluster and multidimensional scaling (MDS) techniques, based onthe Bray-Curtis similarity and log-transformed numerical abun-dances, using the PRIMER package (Clarke and Warwick 1994).The significance of the multivariate results was assessed using theANOSIM test. SIMPER analysis was applied in order to identifythe percentage contribution of each species to the overall similaritywithin a site, and to the dissimilarity among sites (Clarke andWarwick 1994). Moreover, an abundance-biomass comparison(ABC curves) was performed for each site in order to detect any

kind of disturbance in the examined assemblages (Warwick 1986).All the above techniques were employed in both the spatial andtemporal analysis.

Results

Spatial variation

Abiotic factors

The main abiotic parameters showed slight variations inrelation to depth and sampling site (Table 2). A detailedanalysis is given by Antoniadou et al. (2004). Watercurrents follow the general pattern of cyclonic circulationin the northern Aegean Sea (Stergiou et al. 1997; So-marakis et al. 2002).

Community description

All sites can be classified to the sciaphilic alga commu-nity (Augier 1982; P�r�s and Picard 1964; Bellan-Santiniet al. 1994). However, according to the dominant algae,four facies could be distinguished:

1. A facies of the red alga Polysiphonia sp. or Womer-sleyella setacea;

2. A facies of the red alga Gelidium pectinatum and thebrown alga Cutleria multifida;

3. A facies of the red algae Lithophyllum sp., Litho-thamnion sp. and Peyssonnelia sp.; and

4. A facies with the mixed occurrence of the red algaePseudolithophyllum expansum, Gelidium pectinatum,Lithophyllum sp. and Polysiphonia sp. (see Antoniadouet al. 2004).

The main biocoenotic parameters are presented inTable 3. Overall, 4,361 individuals were counted, be-longing to 79 species. Twenty-four species were the mostdominant: only Syllis hyalina and Nereis rava were pres-ent at all sites.

Table 2 Mean values of themain abiotic factors in the watercolumn (0–40 m) for stations1–7 (summer) and for seasons(station 3). T temperature, Ssalinity, C conductivity, WCwater clarity, CV water currentvelocity, CD water current di-rection

Station T (�C) S (psu) C (mS/cm) O2 (mg/l) pH WC (m) CV (cm/s) CD

1 23.1 35.4 48.2 6.98 8.6 21 2.69 NE2 23.1 35.3 48.1 7.42 8.2 22 1.93 N3 21.6 36.1 49.0 7.22 8.2 20 1.80 SW4 26.2 34.6 47.0 8.18 7.5 20 3.10 E5 25.9 34.9 47.3 7.64 8.2 12 2.74 SE6 23.1 34.8 47.5 7.73 8.1 21 11.40 N7 25.7 33.2 45.5 7.75 8.7 18 1.58 NWSeasonsSummer 21.6 36.1 49.0 7.22 8.2 20Autumn 19.3 36.8 50.2 6.72 8.2 23Winter 12.9 37.4 51.3 6.84 8.2 18Spring 14.1 36.9 50.8 8.25 8.2 16

170

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le3

Pol

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etes

from

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faci

esof

the

scia

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ical

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mm

unit

y(r

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cate

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ies,

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gale

fri

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ss,

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nnon

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tabi

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171

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15m

30m

40m

15m

30m

15m

30m

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2736

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5d

4.64

5.64

5.01

5.11

6.33

3.68

4.13

3.85

4.21

5.37

5.85

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4.04

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3.28

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830.

920.

810.

850.

710.

710.

910.

900.

890.

87

Tab

le3

(con

tinu

ed)

172

Abundance of polychaete fauna

Concerning the spatial distribution, mANOVA showedthat both depth and site had a significant effect (F=15.94,P=0.001 and F=13.30 P=0.001, respectively). The FisherPLSD test indicated that differences exist between thethree depth levels (15, 30 and 40 m) and between stations2 and 4 on the one hand, and the rest of the stations on theother. Stations 2 and 4 are discriminated mainly due to thepresence of high numbers of spirorbids. The decrease inpolychaete abundance with depth is probably related tothe algal vertical zonation: filamentous algae dominate inshallow waters, and encrusting algae in deep.

Composition and diversity of polychaete fauna

The spatial fluctuation of the diversity indices and of thetotal number of individuals (N) and species (S) at eachdepth level is shown in Fig. 2. Richness values (D) rangedfrom 3.80 to 6.60, H’ values from 3.28 to 4.35 and J’values from 0.72 to 0.91. These indices are a function ofthe number of species and individuals: high N and low Svalues result in low diversity indices. Spirorbids wereexcluded from the above calculation. They occurred athigh numbers at stations 2 (15 and 30 m) and 4 (15 m),reaching abundances of 9,380, 910 and 725 individuals/m2, respectively, thus altering the diversity values.

Affinity analysis

The affinity of the samples (station, depth) is given inFig. 3. Both analyses (cluster and non-metric MDS) in-

dicate a separation of the samples into four main groups atabout 55% similarity degree. The stress value for the two-dimensional MDS configuration is 0.16. The one-wayANOSIM test gave global R=0.87, at a significance levelof P<0.1, indicating a good discrimination between thefour basic groups. Further examination in order to localizethe differences among the groups by means of a pairwisetest did not reveal any significant variation in R values,yet did show higher similarities between groups A and B,and between C and D.

SIMPER analysis identified 6–9 (13–19) species asresponsible for 60% (90%) of the average similarity ofgroups, and 16–20 (38–46) species as responsible for 60%(90%) of the average dissimilarity of groups (Table 4).

The ABC curves (Fig. 4) show that, for most sites, thebiomass curve was above that of abundance. Accordingly,the k-dominance pattern was produced. For station 2,however, the situation was reverse, and for station 4 thetwo curves coincide. This is due to the extremely highnumber of spirorbids, species with very small body sizeand thus negligible biomass.

Temporal variation

Abiotic factors

The seasonal pattern of the main abiotic parameters issummarized in Table 2. A seasonal thermocline was de-tected at about 20 m depth (end of July), while salinityand conductivity gained lower values during summer.

Fig. 2 Biocoenotic parameters (above) and diversity indices (be-low) for each depth level (15, 30, 40 m) and stations in summer. dMargalef richness, H’ Shannon-Weaver index, J’ Pielou’s even-ness, S number of species, N number of individuals

Fig. 3 Affinity of summer samples from different sites (stations 1–7) and depths (15, 30, 40 m). Results of cluster (above) and MDS(below) analysis based on Bray-Curtis similarity index

173

Tab

le4

Per

cent

age

cont

ribu

tion

ofsp

ecie

sto

60%

sim

ilar

ity

(S)

wit

hin

grou

psan

d/o

rdi

ssim

ilar

ity

(DS)

amon

ggr

oups

,ac

cord

ing

toth

esp

atia

lm

ulti

vari

ate

anal

ysis

Spe

cies

AB

CD

A:B

A:C

A:D

B:C

B:D

C:D

S=

59.9

S=

63.2

S=

56.9

S=

67.7

DS

=48

.1D

S=

53.6

DS

=54

.5D

S=

49.4

DS

=51

.7D

S=

48.1

Har

mot

hoe

ljun

gman

i2.

243.

03H

arm

otho

esp

inif

era

1.87

Gru

beos

ylli

sli

mba

ta2.

233.

502.

83E

xogo

nena

idin

a3.

364.

093.

75Sp

haer

osyl

lis

piri

fera

6.70

8.35

3.19

2.40

2.25

4.48

4.15

Hap

losy

llis

spon

gico

laSy

llis

amic

a2.

062.

201.

90Sy

llis

corn

uta

5.87

5.61

2.65

3.26

Syll

isgr

acil

is2.

753.

73Sy

llis

hyal

ina

6.20

10.8

716

.81

7.87

1.85

Syll

ispr

olif

era

7.83

6.01

9.25

2.02

3.00

5.04

4.04

4.08

Syll

isvi

ttat

a2.

042.

221.

89T

rypa

nosy

llis

coel

iaca

1.88

Try

pano

syll

isze

bra

2.54

2.06

3.12

Ner

eis

rava

9.68

9.94

10.9

53.

913.

854.

663.

473.

60N

erei

szo

nata

7.29

3.49

3.40

2.18

2.00

Pla

tyne

reis

dum

eril

ii4.

585.

613.

074.

612.

684.

212.

232.

68G

lyce

rate

ssel

ata

9.45

10.9

04.

886.

616.

167.

964.

03E

unic

evi

ttat

a8.

537.

873.

632.

292.

145.

514.

02P

alol

asi

cili

ensi

s2.

70L

ysid

ice

nine

tta

9.54

6.51

2.40

2.33

1.94

2.73

2.45

Nem

aton

erei

sun

icor

nis

2.15

3.45

3.64

2.31

Dor

vill

earu

brov

itta

ta2.

583.

114.

21Sc

olet

oma

func

hale

nsis

2.04

3.80

2.38

1.85

Pol

yopt

halm

uspi

ctus

2.25

2.56

2.01

Pol

ydor

aca

eca

2.30

2.78

3.77

Am

phit

rite

vari

abil

is2.

662.

59A

mph

igle

nam

edit

erra

nea

7.83

6.40

1.84

5.18

3.12

4.69

2.35

2.70

Bra

nchi

omm

abo

mby

x2.

263.

34Se

rpul

aco

ncha

rum

6.51

3.01

3.51

5.66

Pom

atoc

eros

triq

uete

r5.

612.

113.

704.

73V

erm

ilio

psis

infu

ndib

ulum

7.98

7.25

2.33

2.16

1.88

2.28

2.02

2.15

Spi

rorb

idae

16.1

213

.42

14.5

912

.41

174

Community description

The main biocoenotic parameters are presented at Ta-ble 5. Overall 1,133 individuals were counted, belongingto 66 species. 24 species, largely the same as thosereported in the spatial survey, were dominant in theseasonal samples. Syllis hyalina, Sphaerosyllis pirifera,Glycera tesselata and Vermiliopsis infundibulum weredominant in all seasons.

Abundance of polychaete fauna

Only depth had a significant effect (mANOVA: F=6.58,P=0.002). The Fisher PLSD procedure revealed that thiseffect was restricted to 40 m versus 15 and 30 m. Nodirect seasonal effect on polychaete abundance was de-tectable (F=2.30, P=0.06).

Composition and diversity of polychaete fauna

The temporal fluctuation of the diversity indices, the totalnumber of individuals (N) and the number of species (S)at each depth level is shown in Fig. 5. Richness values (D)ranged from 3.91 to 6.48, H’ values from 3.45 to 4.41, andevenness values (J’) from 0.80 to 0.97. In general, di-versity indices varied among seasons.

Affinity analysis

The seasonal discrimination of samples is given in Fig. 6.Five groups (A–E) can be distinguished at about 50%similarity level. The stress value for the two-dimensionalconfiguration is 0.12, indicating a good ordination (Clarkeand Warwick 1994). The ANOSIM test confirms theresults of the discriminative techniques (R=0.88, P<0.1).The pairwise test showed that the variations were sig-nificant in all cases (R ranging from 0.75 to 1).

SIMPER analysis identified 5–7 (10–17) species asresponsible for 60% (90%) of the average similarity ofgroups, and 12–20 (22–38) species as responsible for 60%(90%) of the average dissimilarity of groups (Table 6).

The ABC curves for different seasons show biomasscurves being always above those of abundance (Fig. 7).Therefore, the k-strategy pattern dominated throughoutthe year.

Discussion

According to P�r�s and Picard (1964), the Mediterraneaninfralittoral zone comprises two distinct communities:the photophilic alga community (at the upper level) andthe sciaphilic alga community (at the lower level, oftenmentioned as precoralligenous and coralligenous). Thesetwo communities share some common characteristics:they both depend on the presence of different algal forms(Bellan-Santini et al. 1994) and are influenced by thehydrodynamism and light (Hong 1982; Marinopoulos1988).

Fig. 4 ABC curves for stations1–7 (summer)

175

Spe

cies

Sum

mer

1997

Aut

umn

1997

Win

ter

1998

Spr

ing

1998

AF

AF

AF

AF

15m

30m

30m

*40

m15

m30

m40

m15

m30

m40

m15

m30

m40

m

Lae

tmon

ice

hyst

rix

(Sav

igny

,18

20)

57

Har

mot

hoe

areo

lata

(Gru

be,

1860

)5

75

75

1020

Har

mot

hoe

ljun

gman

i(M

alm

gren

,18

67)

55

145

75

7

Har

mot

hoe

spin

ifer

a(E

hler

s,18

64)

55

57

55

145

514

Scal

iset

osus

frag

ilis

(Cla

pare

de,1

868)

57

Pho

loe

min

uta

(Fab

rici

us,

1780

)5

7C

hrys

opet

alum

debi

le(G

rube

,18

55)

57

57

Eup

hros

ine

foli

osa

Aud

ouin

&M

il-

neE

dwar

ds,

1833

55

57

Phy

llod

oce

mad

eire

nsis

(Lan

gerh

ans,

1880

)5

510

515

275

7

Kef

erst

eini

aci

rrat

a(K

efer

stei

n,18

62)

55

1020

145

1527

Syll

idia

arm

ata

Qua

tref

ages

,18

655

75

7P

iono

syll

isla

mel

lige

raS

aint

-Jos

eph,

1856

55

515

57

57

55

520

Exo

gone

naid

ina

Ors

ted,

1845

5510

2545

57

57

Gru

beos

ylli

sli

mba

ta(C

lapa

rede

,18

68)

4535

1045

57

Spha

eros

ylli

spi

rife

raC

lapa

rede

,186

813

050

5520

9015

6510

5435

3046

2565

54E

usyl

lis

blom

stra

ndi

Mal

mgr

en,

1867

2010

55

305

7P

tero

syll

isfo

rmos

aC

lapa

rede

,18

635

5H

aplo

syll

issp

ongi

cola

(Gru

be,

1855

)5

510

155

710

515

345

105

20Sy

llis

amic

aQ

uatr

efag

es,

1865

55

14Sy

llis

arm

illa

ris

Mul

ler,

1771

2014

57

Syll

isci

rrop

unct

ata

Mic

hel,

1909

57

Syll

isco

rnut

aR

athk

e,18

4335

525

2055

1510

534

255

540

Syll

ishy

alin

aG

rube

,18

4312

095

6510

580

3025

4010

3025

4695

505

54Sy

llis

kroh

nii

Ehl

ers,

1864

55

57

57

Syll

ispr

olif

era

Kro

hn,

1852

6510

1515

4515

1527

2510

534

2025

546

Try

pano

syll

isco

elia

caC

lapa

rede

,18

6810

1020

520

1015

205

2027

Try

pano

syll

isze

bra

(Gru

be,

1860

)15

55

1510

525

4620

2015

520

Cer

aton

erei

sco

stae

(Gru

be,

1840

)5

7N

erei

sra

vaE

hler

s,18

6810

05

3035

535

4635

4020

5455

1540

Ner

eis

zona

taM

alm

gren

,18

6710

55

1510

1527

510

1034

57

Pla

tyne

reis

dum

eril

ii(A

udoi

n&

Mil

neE

dwar

ds,

1833

)20

3035

5530

1554

1540

345

7

Ner

eidi

dae

Het

eron

erei

sst

age

1510

Gly

cera

tess

elat

aG

rube

,18

6311

511

065

4085

570

3067

6055

4067

4580

60G

lyci

nde

nord

man

ni(M

alm

gren

,18

65)

55

Gon

iada

mac

ulat

aO

rste

d,18

435

55

7A

rabe

lla

iric

olor

(Mon

tagu

,18

04)

Dor

vill

earu

brov

itta

ta(G

rube

,18

55)

55

Eun

ice

oers

tedi

iS

tim

pson

,18

545

55

715

527

155

20E

unic

eto

rqua

taQ

uatr

efag

es,

1865

107

57

Eun

ice

vitt

ata

(Del

leC

hiaj

e,19

29)

2065

305

5035

1027

655

3540

2025

540

Lys

idic

eni

nett

a(A

udoi

n&

Mil

neE

dwar

ds,

1833

)30

1535

405

514

1520

534

3520

554

Nem

aton

erei

sun

icor

nis

(Gru

be,

1840

)5

510

55

145

710

7L

umbr

iner

isco

ccin

ea(R

enie

r,18

04)

55

Scol

etom

afu

ncha

lens

is(K

inbe

rg,

1865

)35

155

3520

1010

3435

105

4010

1510

46

Onu

phis

sp.

55

57

Lao

nice

cirr

ata

(Sar

s,18

51)

55

Pol

ydor

aca

eca

(Ors

ted,

1843

)5

7P

olyo

ptha

lmus

pict

us(D

ujar

din,

1839

)5

514

55

14

Tab

le5

Pol

ycha

etes

from

seas

onal

sam

ples

ofth

esc

iaph

ilic

alga

com

mun

ity

atst

atio

n3

(rep

lica

tes

ofea

chde

pth

leve

lpo

oled

).N

num

ber

ofin

divi

dual

s,S

num

ber

ofsp

ecie

s,A

(=N

/m2)

abun

danc

e,F

freq

uenc

y,d

Mar

gale

fri

chne

ss,

H’

Sha

nnon

-Wea

ver

inde

x,J’

equi

tabi

lity

inde

x,30

m*

sam

plin

gin

July

1998

176

Spe

cies

Sum

mer

1997

Aut

umn

1997

Win

ter

1998

Spr

ing

1998

AF

AF

AF

AF

15m

30m

30m

*40

m15

m30

m40

m15

m30

m40

m15

m30

m40

m

Phe

rusa

sp.

57

57

Am

phit

rite

vari

abil

is(R

isso

,18

26)

1010

105

3045

1020

The

osto

ma

oers

tedi

(Cla

pare

de,

1864

)5

5P

olyc

irru

sau

rian

ticu

sG

rube

,18

605

7T

ereb

elli

des

stro

emi

Sar

s,18

3525

155

7A

mph

igle

nam

edit

erra

nea

(Ley

ding

,18

51)

120

3520

1565

1015

2040

515

4640

105

40

Bra

nchi

omm

abo

mby

x(D

alye

ll,

1853

)15

2515

3515

14Sa

bell

apa

voni

naS

avig

nyi,

1820

55

57

107

Hyd

roid

esps

eudo

unci

nata

Zib

row

ius,

1968

1014

Pla

cost

egus

crys

tall

inus

Zib

row

ius,

1968

55

145

7

Pom

atoc

eros

lam

arck

ii(Q

uatr

efag

es,

1865

)5

7

Pom

atoc

eros

triq

uete

r(L

inna

eus,

1865

)30

1030

57

55

1425

520

Jasm

inei

raca

ndel

a(G

rube

,18

63)

55

57

57

Jani

tafi

mbr

iata

(Del

leC

hiaj

e,18

22)

55

1520

57

Serp

ula

conc

haru

mL

ange

rhan

s,18

805

1515

57

255

27Se

rpul

ave

rmic

ular

isL

inna

eus,

1767

55

57

2014

1514

Ver

mil

iops

isin

fund

ibul

um(G

mel

in,

1788

)65

1015

1550

1510

1534

155

2034

4525

554

Pro

tula

sp.

55

510

20S

3727

1921

1818

2729

1923

2129

16N

233

122

8068

4962

6310

356

6693

8819

A1,

165

610

400

340

260

320

330

530

285

350

510

465

100

d6.

615.

414.

14.

744.

374.

126.

286.

044.

475.

254.

416.

255.

1H

‘4.

364.

013.

733.

593.

643.

464.

414.

293.

724.

153.

824.

123.

73J‘

0.84

0.84

0.88

0.82

0.87

0.83

0.93

0.88

0.87

0.92

0.87

0.85

0.97

Tab

le5

(con

tinu

ed)

177

Bellan (1964, 1969) studied the photophilic alga com-munity and found 128 species of Polychaeta which wereclassified, according to their ecological preferences, to 11discrete “stocks”. Cardell and Gili (1988) studied the fa-cies of Lithophyllum tortuosum and recorded 71 species.They concluded that this assemblage is very homogene-ous, both spatially and temporally. However, Sphaero-syllis pirifera and Platynereis dumerilii showed an in-crease in numerical abundance in summer. Most specieswere common in the hard substrate stock (Bellan 1969),and especially within the photophilic alga community:some species were characteristic of the concretionedsubstrate (Laubier 1966; Sard� 1991). Fraschetti et al.(2002) studied the facies of Cystoseira amentacea andfound 59 species of Polychaeta, most of which werecommon species among sublittoral photophilic algae(Sard� 1991). The same authors did not find any notice-able seasonal changes, with the exception of the largenumbers of Platynereis dumerilii in summer. Chintiroglou(1996) reported 87 species associated with Cladocoracaespitosa colonies at 5–18 m depth, and Damianidis andChintiroglou (2000) recognized 48 species associatedwith Mytilus galloprovincialis assemblages in the upperinfralittoral zone. Sard� (1991), in a study of hard sub-strate communities from 1 to 40 m depth, found 220species and discriminated five distinct communities: theLithophyllum lichenoides (with the lowest diversity), theshallow photophilic, the deeper photophilic, the Posido-nia oceanica rhizomes and the infralittoral sciaphilouscommunity. The contributions of the different ecological

stocks (Bellan 1969) to these communities change ac-cording to habitat complexity. In our study, we found 79species of polychaetes in the sciaphilic alga community(15–40 m), while Marinopoulos (1988) found 36 (21common) at similar depths. Most of these species aremembers of the photophilic alga community, but there isalso a significant contribution of cryptic, hard substrate,soft substrate and coralligenous (concretioned substrate)species. It seems that polychaetes have a large ecologicaltolerance and that their occurrence is largely dependenton substrate availability and complexity (Bellan 1964,1969; Hong 1982). We found clear spatial differences inpolychaete distribution, while temporal differences wereless apparent. The spatial distribution of polychaeteslargely corresponds with the occurrence of different algalfacies. We have noted a high affinity between stations 1and 3 at all depth levels. This could be expected, sincethese two sites share some common characteristics suchas the high inclination (~90�) and large bathymetricalextension of the rocky substrate. Station 7 is separated,probably due to abiotic parameters (low salinity). Itsrelatively moderate inclination sets station 7 near to sta-tions 5 and 6, while the sharpest slope ranks stations 2 and4 closer to stations 1 and 3. The depth level of 40 m(stations 1 and 3) shows high affinity with stations 5 and6, as it hosts a fairly low number of polychaete speciesand individuals. SIMPER analysis showed that both thesimilarities within groups and the dissimilarities betweengroups were the result of small contributions of a largenumber of species, indicating a diverse community with a

Fig. 5 Biocoenotic parameters (above) and diversity indices (be-low) over an annual cycle at station 3 (15, 30, 40 m depth). Ssummer, A autumn, W winter, Sp spring, d Margalef richness, H’Shannon-Weaver index, J’ Pielou’s evenness, S number of species,N number of individuals

Fig. 6 Affinity of seasonal samples from different depths at station3. Results of cluster (above) and MDS (below) analysis based onBray-Curtis similarity index

178

highly complex structure (Dahl and Dahl 2002). Thisheterogeneity may result from the presence of severalalgal species of different architecture (Chemello andMilazzo 2002). Fan-shaped structures and filamentousforms dominate group A, filamentous forms group B,encrusting forms group C, and filamentous bush-like en-crusting forms group D. Many authors have stated thatpolychaetes are not related to specific algal species, but tospecific algal architectures (Naim and Amoureux 1982;Sard� 1988; Gambi et al. 1995; Fraschetti et al. 2002).Groups A and B are characterized by high diversity andabundance in comparison to groups C and D. It should benoted that the high abundance in group A is mainly due tothe presence of high numbers of spirorbids attached to thethalli of Padina pavonica. Spirorbids are capable of set-tling immediately after release from parental tubes andare typically multiannual in the sense of Fauchald (1983),living in unstable environments. They probably perishwhen the thalli of Padina pavonica decay after mid-September (Diapoulis and Koussouris 1988). Spirorbidsstrongly influence the discrimination of group A, theABC analysis and the diversity indices. Another differ-ence was found in the polychaete fauna associated withthe two filamentous Rhodomelacea, Womersleyella se-tacea and Polysiphonia sp. An abundant and diversifiedpolychaete is associated only with the former. Womer-sleyella setacea is an introduced and probably invasivespecies (Boudouresque and Verlaque 2002) which hasspread over the Mediterranean (Verlaque 1989; Airoldi etal. 1995) and the northern Aegean Sea (Athanassiadis

1997). It forms paucispecific populations with increasingturf development. These turfs trap sediment, forming astratum that prevents the development of other algalspecies on the rocky substrate (Piazzi and Cinelli 2000).However, the entrapped sediment increases the com-plexity of the system, offering suitable microhabitats forthe settlement of many soft-sediment polychaete species.

The study of temporal changes in polychaete distri-bution revealed that summer is distinct from the otherthree seasons. Winter and spring form an even group,while autumn branches out according to depth. This is thecase for the upper depth levels (15 and 30 m), whereWomersleyella setacea dominated throughout the year.This species is capable of continuous vegetative repro-duction (Athanassiadis 1997), creating a very stable andhomogenous habitat which may contribute to the lack ofseasonality. The image is much more complicated at the40-mdepth level, where the dominant algae were repre-sented by various species of Corallinacea and Peysson-neliacea. Here, summer samples were similar to winterones, while autumn and spring samples discriminated.

According to the relevant literature, there is no distinctseasonality in the lower infralittoral zone, in contrast tothe upper one (Hong 1982; Marinopoulos 1988). How-ever, a discrimination of summer is frequently observed(Damianidis and Chintiroglou 2000) and may be duemainly to the massive recruitment of a few species, e.g.Platynereis dumerilii (Cardell and Gili 1988; Fraschetti etal. 2002). In our study, the bathymetric distribution ofpolychaetes changed with season, while the species in-

Fig. 7 ABC curves for differentseasons (station 3). S summer, Aautumn, W winter, Sp spring

179

Tab

le6

Per

cent

age

cont

ribu

tion

ofsp

ecie

sto

60%

sim

ilar

ity

(S)

wit

hin

grou

psan

d/or

diss

imil

arit

y(D

S)am

ong

grou

ps,

acco

rdin

gto

the

tem

pora

lm

ulti

vari

ate

anal

ysis

Spec

ies

CE

A:B

A:C

A:D

A:E

B:C

B:D

B:E

C:D

C:E

D:E

S=

51.5

S=

58.9

DS

=71

.4D

S=

57.8

DS

=67

.7D

S=

67.8

DS

=57

.8D

S=

53D

S=

57.1

DS

=54

.5D

S=

50.2

DS

=49

.9

Har

mot

hoe

spin

ifer

a2.

21P

hyll

odoc

em

adei

rens

is6.

024.

972.

474.

543.

002.

96Sy

llid

iaar

mat

a5.

403.

046.

083.

932.

37G

rube

osyl

lis

lim

bata

2.54

2.21

2.70

2.93

Exo

gone

naid

ina

Hap

losy

llis

spon

gico

la2.

412.

61Sy

llis

amic

a10

.34

3.69

6.68

6.27

7.54

4.24

3.24

5.34

4.73

3.22

Syll

isar

mil

lari

s3.

25Sy

llis

cirr

opun

ctat

a5.

405.

126.

084.

33Sy

llis

corn

uta

2.21

Syll

ishy

alin

a3.

973.

745.

35Sy

llis

kroh

ni11

.46

3.69

4.12

5.67

6.29

3.01

2.60

4.50

6.26

3.02

Try

pano

syll

isco

elia

ca6.

982.

863.

375.

244.

45T

rypa

nosy

llis

zebr

a4.

664.

972.

984.

414.

463.

07P

iono

syll

isla

mel

lige

ra3.

252.

162.

47N

erei

sra

va2.

212.

62N

erei

szo

nata

6.98

5.22

9.41

4.80

3.03

2.79

3.89

3.60

3.76

Cer

aton

erei

sco

stae

3.51

2.33

2.81

2.55

Pla

tyne

reis

dum

eril

ii8.

544.

665.

155.

242.

234.

462.

36H

eter

oner

eis

stag

eN

erei

dida

e15

.12

6.41

8.11

2.64

4.15

2.95

5.47

7.63

Gon

iada

mac

ulat

a17

.08

136.

5311

.59

3.14

8.94

7.21

7.68

Eun

ice

vitt

ata

3.69

3.50

2.91

Nem

aton

erei

sun

icor

nis

6.04

3.39

2.62

2.85

2.81

3.52

5.78

Lum

brin

eris

cocc

inea

16.1

66.

476.

503.

183.

124.

152.

268.

442.

456.

34P

olyd

ora

caec

a2.

842.

64P

olyc

irru

sau

rian

ticu

s2.

332.

212.

622.

10T

ereb

elli

des

stro

emi

2.48

2.13

2.44

2.85

Am

phig

lena

med

iter

rane

a3.

142.

62B

ranc

hiom

ma

bom

byx

10.7

76.

923.

253.

424.

414.

154.

95Sa

bell

apa

voni

na2.

572.

84Se

rpul

aco

ncha

rum

3.14

2.62

Serp

ula

verm

icul

aris

3.25

2.62

2.81

2.64

Pla

cost

egus

crys

tall

inus

3.69

3.14

3.50

2.87

2.81

Pom

atoc

eros

lam

arck

ii3.

142.

802.

622.

382.

812.

94V

erm

ilio

psis

infu

ndib

ulum

4.66

6.27

4.54

3.58

4.55

3.78

3.78

Hyd

roid

esps

eudo

unci

nata

2.35

2.35

180

ventory at the stations remained unchanged throughout theyear. Marinopoulos (1988) also found seasonal changes inthe abundance of polychaetes at different depths, with thesame species (Syllis hyalina, Syllis prolifera, Syllis vittata,Platynereis dumerilii and Sphaerosyllis pirifera) beingabundant at low depth during summer and in deeper wa-ters during winter. It seems that the seasonality of thesciaphilic alga community is mainly achieved by a verticalrearrangement of the abundances of different polychaetespecies.

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