Journal of Sea Research 85 (2014) 37–47

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Journal of Sea Research

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Biodiversity patterns of epifaunal assemblages associated with thegorgonians Eunicella gazella and Leptogorgia lusitanica in response tohost, space and time

Susana Carvalho a,⁎, João Cúrdia a,b, Fábio Pereira a, José Manuel Guerra-García c,Miguel N. Santos a, Marina R. Cunha b

a IPMA, Instituto Português do Mar e da Atmosfera, Av. 5 de Outubro, s/n, 8700-305 Olhão, Portugalb Departamento de Biologia and CESAM, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugalc Departamento de Fisiología y Biología Animal, Facultad de Biología, Universidad de Sevilla, Reina Mercedes 6, 41012 Sevilla, Spain

⁎ Corresponding author at: KAUST—King AbdullahTechnology, Red Sea Research Center, Thuwal 23955-628082908.

E-mail address: susana.carvalho@kaust.edu.sa (S. Carv

1385-1101/$ – see front matter © 2013 Elsevier B.V. All rihttp://dx.doi.org/10.1016/j.seares.2013.10.001

a b s t r a c t

a r t i c l e i n f o

Article history:Received 10 April 2013Received in revised form 10 September 2013Accepted 6 October 2013Available online 18 October 2013

Keywords:BiodiversityShallow water gorgoniansLeptogorgia lusitanicaEunicella gazellaEpibenthic assemblage structureNortheast Atlantic

Patterns of biodiversity (α- and β-diversity), abundance and community structure of the epifaunal assemblagesassociated with two gorgonians, Eunicella gazella and Leptogorgia lusitanica, were analysed in relation to host,colony size, location and time. Colony size and time were the major factors shaping attendant assemblages.Patterns of α-diversity and β-diversity were host-dependent. Assemblages associated with E. gazella showed asignificant inter-annual variability for most of the metrics analysed, while in those associated with L. lusitanicaonly Shannon–Wiener varied significantly between years. In L. lusitanica Hurlbert's expected number of taxawas significantly lower in small-sized than in medium- to large-sized colonies, but an opposite pattern wasdetected for β-diversity, reflecting the higher heterogeneity among small-sized colonies. The dbRDA analysissegregated the assemblages associated with each of the two hosts; the faunal patterns were mainly explainedby colony size related attributes (area, number of branches and, to a lesser extent, width) and the “colonial”epibiont cover. However, we suggest that altogether they may act as a metacommunity, with high temporaland spatial fluidity in their composition and structure related tomultiple factors including not only a componentof stochasticity but also life history events, biotic interactions and response to habitat heterogeneity andenvironmental variability.

© 2013 Elsevier B.V. All rights reserved.

1. Introduction

Coral habitats, such as gorgonian gardens and scleractinian reefs,support one of the most diverse marine biological assemblages(Knowlton et al., 2010). The complexity of their three-dimensionalstructure (Gratwicke and Speight, 2005; Idjadi and Edmunds, 2006;Lingo and Szedlmayer, 2006; Öhman and Rajasuriya, 1998; Wilsonet al., 2007) is attractive for several species, especially smallinvertebrates (Buhl-Mortensen and Mortensen, 2004a; Plaisance et al.,2011; Stella et al., 2010). These epifaunal organisms may rely on coralcolonies for food (e.g. Burkepile and Hay, 2007; García-Matucheskiand Muniain, 2010) and protection against predators (e.g. Bergsmaand Martinez, 2011; Edwards and Emberton, 1980; Vytopil and Willis,2001), and may display several interactions with their hosts, includingcommensalism (Kumagai, 2008), symbiosis (Bergsma, 2010; Buhl-Mortensen andMortensen, 2004a; Carricart-Ganivet et al., 2004; Stewart

University of Science and900, Saudi Arabia. Tel.: +966

alho).

ghts reserved.

et al., 2006), mutualism (Bergsma and Martinez, 2011; Holbrook et al.,2008; Stachowicz and Hay, 1999), predation (Burkepile and Hay, 2007;García-Matucheski and Muniain, 2010; Schoepf et al., 2010) andparasitism (e.g. Buhl-Mortensen and Mortensen, 2004a).

Studies on coral attendant invertebrate assemblages are relativelyscarce and most of them have been carried out in shallow-waterscleractinian reefs in Indo-Pacific regions (e.g. Coles, 1980; Edwardsand Emberton, 1980; Goh et al., 1999; Kumagai and Aoki, 2003;Patton, 1994; Stella et al., 2010; Vytopil and Willis, 2001). Todate, only a few quantitative studies on non-colonial invertebrateassemblages associated with corals were undertaken in cold-temperate Atlantic waters (Buhl-Mortensen and Mortensen, 2004a,b,2005; Buhl-Mortensen et al., 2010; Greene, 2008). Research on thedistribution of coral species and their attendant fauna is required tobetter understand their role on coastal ecosystems. This knowledge iscrucial for supporting sound, science-based conservation options forthe sustainable use of these vulnerable habitats. Coral habitats,considered a priority by the Convention for the Protection of theMarineEnvironment of the North-East Atlantic (OSPAR), include octocoralgardens, Lophelia pertusa reefs and sea pen fields. Despite being one ofthe richest ecosystems on the planet, coral habitats are also among the

38 S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

most endangered (Carpenter et al., 2008). Specialist species (those thatdepend on only one or two hosts) are particularly susceptible to habitatdegradation and loss (e.g. Munday, 2004) but a better understanding ofthe relationships between corals and their attendant assemblages (e.g. assmall invertebrates), is crucial for predicting potential biodiversity lossesresulting from coral degradation.

In marine systems, most studies of diversity change across spatialand temporal scales have been focused on local and regional diversity(usually known as α- and γ-diversity, respectively), largely neglectingβ-diversity (also known as turnover or complementarity) (Beckinget al., 2006; Gray, 2000; Magurran, 2004). However, more recently, β-diversity has gained renewed interest as a valuable conservation tool(Gering et al., 2003) and it has been applied to gain further insights onthe diversity patterns and their underlying processes inmarine biologicalassemblages at different spatial and temporal scales (e.g. Bevilacqua et al.,2012; Danovaro et al., 2009; Dimitriadis and Koutsoubas, 2011; Thrushet al., 2010). In this context, the present study aims at contributing to abetter knowledge of cold-temperate gorgonian gardens by analysing thepatterns of biodiversity, abundance and community structure of theepifaunal assemblages associated with Eunicella gazella and Leptogorgialusitanica in south Portugal (NE Atlantic). The contributions of α- and β-diversity will be analysed in relation to host, colony size, site locationand time (inter-annual). Our working hypotheses are: 1) the patternsin composition and structure are consistent for both hosts and notvariable in space and time; 2) the diversity, composition and structureof associated epifaunal assemblages will vary with colony size.

2. Materials and methods

2.1. Study species

The studied species, Leptogorgia lusitanica and Eunicella gazella,belong to two different genera with a worldwide distributional range.Although belonging to the family Gorgoniidae, L. lusitanica and E. gazellaare morphologically different: L. lusitanica colonies are generally largerinwidth than in height, while E. gazella colonies aremore evenly shaped(i.e. display similar width and height). L. lusitanica colonies may reachup to 60 cm in height, while E. gazella is a small-sized species reachinga maximum of 30 cm in height. Branches of L. lusitanica may have

Fig. 1. Photographs of Eunicella gazella (top) and Leptogorgia lusitanica (bottom), correspondinand large colonies. The scale bar represents 5 cm.

different colours and are more flexible, while E. gazella branches aregenerally thicker and white (Fig. 1). More details concerning thesespecies can be found in Cúrdia et al. (2013).

2.2. Sampling and laboratory procedures

Sampling was undertaken in two consecutive summers (2010 and2011) at Pedra daGreta (PG), themain rocky subtidal area in the centralpart of the Algarve coast, approximately 4 km in length and rangingfrom 20 to 90 m in width. In PG, two sites (PG1 and PG2) located atapproximately 15 m depth, were randomly selected to account forspatial variability. The summer period was chosen because it generallycorresponds to the peak of invertebrates' diversity and abundance inthis region.

Because of the variability in size of L. lusitanica and E. gazella, and toassess the influence of colony size in the biodiversity patterns, three sizeclasses were previously established based on size frequency distributionsof the two gorgonian species (Cúrdia, 2012). For L. lusitanica the sizeheight ranges were: small, b10 cm; medium, 10–30 cm; and large,N30 cm; whereas for E. gazella the height ranges were: small, b9 cm;medium, 9–17 cm; and large, N17 cm. At each site and sampling period,three replicates of each species and colony size were collected by scubadiving (36 colonies per sampling occasion). The entire colony wasenclosed in a plastic bag to prevent faunal loss and then carefullydetached from the substrate. All gorgonians were transported to thelaboratory for further processing. In the laboratory, the colonies werepreserved in 96% ethanol. Samples were washed through a 100 μmmesh sieve and colonies were observed under a magnifying glass toensure that all fauna (mobile and sessile epibionts) and flora had beenremoved. All specimens associated with each colony were preserved in96% ethanol and afterwards identified to the lowest practical taxonomiclevel. To estimate species richness, unidentifiable organisms were,whenever possible, differentiated into different operational taxonomicunits (OTUs). Juveniles and extremely damaged animals were excludedfrom the analyses. The abundance of macroscopic algae, cnidarians,bryozoans, sponges and hydrozoans was estimated by a semi-quantitative index ranging from 0 to 4, (0—absent; 1—rare; 2—common;3—abundant; 4—very abundant). This index will be the sum of the scoresof each epibiont observed for each colony. In order to minimize bias,

g to an exemplar of each of the three size categories analysed in the study: small, medium

39S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

scoring was always performed by the same observer and for simplicity,this relative index will be hereafter designated as CEC (as for “colonial”epibiont cover, where the term colonial is used loosely to representmodular organisms). CEC will be used to infer the enhancement offunctional intricacy of the gorgonian colonies derived from the presenceof attached sessile organisms that may provide additional ecologicalniches and/or a greater variety of food resources for the attendantinvertebrate assemblages. In the laboratory, measures of the maximumheight and width of each colony were taken. Colony surface area wasestimated using the image analysis software, ImageJ (Schneider et al.,2012), ondigital photographs taken in the laboratory. Thenumberof colonybranches was calculated by analysing skeleton binary images using theImageJ plugin AnalyzeSkeleton (Arganda-Carreras et al., 2010). Averagevalues of the analysed measures for each gorgonian host per site and timeare provided as supplementary material (Table S1). No spatial significantdifferences were detected in morphometric measures for both studyspecies based on the univariate analysis of variance (ANOVA).

2.3. Data analysis

Only taxa unambiguously assigned to different identities wereconsidered and included in the analyses. The number of taxa,Shannon–Wiener diversity (H′), Hurlbert (1971) expected speciesrichness (ES(n)) and classical and distance-based multivariate measuresof β-diversity (Anderson et al., 2006, 2011) were calculated and used todescribe patterns in biodiversity and to assess changes in communitystructure. The Hurlbert's expected number of species, rarefied to thesame number of individuals, is an adequate estimate of biodiversityfor the present study, because of the implications of differences in sizeand shape on the total available area for colonisation of each gorgoniancolony. The beta diversity measure devised by Whittaker (1960),namely β-Whittaker (βW, calculated asβW ¼ γ

ffiffiffiffi

αp

), provides ameasureof diversity based on species identities (Anderson et al., 2011) and is oneof the most commonly used indices. For the purposes of the presentstudy, we considered the total number of OTUs observed in both yearsand for both gorgonian species as a proxy to the total diversity of thehabitat, while the regional diversity (γ) that can be variable in time,was estimated for each year, as the total number of OTUs observedper sampling survey, following a similar approach to that applied byZajac et al. (2013). Concerning the distance-based multivariatemeasures of β-diversity we employed the average distance to thegroup centroid of sampling units in the space defined by aresemblance measure d cen (Anderson et al., 2006). Differentresemblance measures were employed to take into account differentaspects of variation in order to better analyse the rates of change inspecies composition. We used the Sorenson measure (Sor, presence/absence, related to βW) that tends to inflate β-diversity estimateswhen there are differences in the α-diversity of the assemblages beingcompared (e.g. Koleff et al., 2003). The Raup Crick measure (RC) wasalso employed. This is a probabilistic measure testing if two samplesshare fewer species than expected for samples randomly selectedfrom the species pool, which has been proposed to reduce such effect(Anderson et al., 2011). A distance measure using abundance data, theBray–Curtis (BC, square-root transformed data), was used to assesschanges in the variation that are due to more abundant taxa. Post-hoctests (Tukey Honest Significance Difference) were used wheneversignificant differences were found between groups of samples beingcompared.

2.3.1. Effect of colony size, time and siteChange in invertebrate assemblage patterns were analysed by a

combination of uni- and multivariate analyses for each gorgonianspecies separately. A three-way analysis of variance (ANOVA) withfactors colony size (3 levels, fixed), site (2 levels, random) and time(2 levels, random) was used to check for differences in univariatemeasures related to colony size and whether such differences were

consistent in space and time. Before the analyses, data were analysedfor homogeneity and normality.When any of the ANOVA's assumptionswere not met, data were log transformed, except the Shannon–Wiener diversity that fulfilled all the assumptions after square-roottransformation. For both gorgonian datasets, the effect of site wasconsistently found as non-significant (results not shown). To increasethe power of the analyses, this factor was eliminated and samples ofboth sites were used as replicates. Provided that no spatial differenceswere detected, a two-way ANOVA for factors colony size (3 levels,fixed) and time (2 levels, random) was performed. Pairwise a posterioricomparisons for the fixed factor were performed using the Student–Newman–Keuls test.

Amultivariate permutational analysis of variance (PERMANOVA)wasapplied in order to estimate differences in the epibenthic assemblagestructure in relation to colony size and to investigate whether thosedifferences were consistent in space and time. We followed the sameprocedure as for ANOVA, i.e. first we tested a three-way PERMANOVA(design as above) and because site was found to have no effect on theepibenthic patterns (main effect and interactions) samples from bothsites were used as independent replicates. The analyses were based onBray–Curtis dissimilarities on square-root transformed data (design asabove). The statistical significance of multivariate variance componentswere tested using 4999 permutations of residuals under a reducedmodel, with a significance level of α = 0.05. Only significant effectswere further investigated through a series of pairwise comparisonsusing the appropriate terms in the model.

To test for differences in multivariate dispersion, different samplex sample resemblance matrices were obtained for each one of theconsidered measures (Sor, RC and BC) and then permutational tests ofmultivariate dispersion (PERMDISP) based on the aforementionedmatrices were carried out for terms of interest.

Statistical analyses were performed using the open source softwareR version 12.1 (R Development Core Team, 2010), except for thePERMANOVA analyses and pair-wise comparisons thatwere performedusing the computer programme PERMANOVA.exe (Anderson, 2001,https://www.stat.auckland.ac.nz/~mja/Programs.htm).

2.3.2. Effect of gorgonian hostThe size classes that were defined for each gorgonian host do

not match. Therefore, and because size was found to influence theepibenthic assemblages, the replicates for each set of samples ofdifferent size ranges within each host cannot be pooled as they arenot independent (Anderson et al., 2011). The community needs to be“averaged” to remove the effect of size range. Because site variabilitywas not significant for the patterns analyzed, the “average” community(i.e. the centroid) for the group of samples corresponding to the threereplicates of each size for each host at each site and year. However,when using non-Euclidean measures such as the Bray–Curtisdissimilarity, the centroids in the multivariate space defined by themeasure are not the same as the arithmetic averages of the originalvariables (Anderson, 2001). By calculating the principal coordinates ofthe full Bray–Curtis dissimilarity matrix, the Bray–Curtis measures arepreserved but placed into a Euclidean framework (Terlizzi et al.,2005). The Euclidean distance between any pair of samples using thisprincipal coordinates is equivalent to the Bray–Curtis dissimilaritybetween those 2 points using the original variables (Terlizzi et al.,2005). The arithmetic average of the principal coordinates, the centroid,was calculated for each “pooled sample” (host x year x site) and thematrix with the Euclidean distance between each pair of centroidswas used as input matrix for the PERMANOVA algorithm. The twosampled sites provide the replicates needed to compare the twogorgonians (host, fixed factor), the two sampled years (year, randomfactor) and the interaction between these two factors under a fullyorthogonal design.

Differences in epifaunal assemblage structure between gorgonianhosts, as well as the relationship between assemblage structure and

40 S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

habitat characteristics, were analysed by a distance-based redundancyanalysis (dbRDA) (McArdle and Anderson, 2001). In the present study,dbRDA was performed to order biological samples from each colonyas a function of the attendant epifaunal composition and structure,using gorgonian colony metrics (total surface area, maximum widthand number of branches) and CEC as explanatory variables. For thepresent analysis the Bray–Curtis dissimilarity measure was used afterremoving singletons (i.e. taxon represented by a single organism orfound on a single colony) from the community data matrix. Colonymaximum height was not selected for the model because of its highcorrelation with colony surface area and colony maximum width, thusavoidingmulticolinearity problems. The significance of the contributionof each variable to explain the variation in the multidimensional spaceprovided by species data is tested by permutation in two ways: as if itwas the only explanatory variable in test (marginal effects); and theireffect when entered in the model after removing the effect of thevariables already in the model (sequential tests).

To analyse the contribution of each species to the dissimilaritybetween the epifaunal assemblages associated with both gorgonians,the indicator value (IndVal) was used (Dufrêne and Legendre, 1997).Epifaunal species overlap and the occurrence of potential habitat-specialists was also analysed by comparing both datasets with andwithout singletons. According to Stella et al. (2010), potential habitat-specialists are distinguished from rare taxa based on their frequencydistribution across replicates of each gorgonian species. Indeed, taxacollected from only one of the hosts could either be: i) rare taxa thathave a low rate of occurrence regardless of host; ii) species that do notuse gorgonians as a preferred habitat and therefore are rarely found;or iii) habitat-specialists that only occur on certain hosts (Stella et al.,2010). Consequently, the occurrence rates were also evaluated whensingletons were removed from the dataset (Stella et al., 2010).

Fig. 2. Variation of the mean values (±standard error) of abundance (i.e. numberof individuals per colony), number of OTUs per colony, Hurlbert's expected numberof species per 100 individuals (ES100), Shannon–Wiener diversity (Shannon He) andβ-Whittaker (βW) for Eunicella gazella and Leptogorgia lusitanica per colony sizeclass (S—small; M—medium and L—large), and year (2010 and 2011).

3. Results

3.1. Biodiversity patterns

3.1.1. Effect of colony size, time and siteThe number of OTUs (S) and individuals (N) per colony ranged 4–55

and 6–358, respectively in E. gazella, and 5–63 and 8–737, respectively,in L. lusitanica. Hurlbert's ES(100) ranged from 19.8 to 34.6 in E. gazella,and from 18.4 to 34.5 in L. lusitanica (Fig. 2). Large colonies of E. gazellaand medium colonies of L. lusitanica had the highest ES(100) and offeredmore redundancy to the overall biodiversity (Fig. 3A, D); but, as awhole,the epibenthic assemblages associated with each of the two gorgonianhosts have similar contributions to the overall expected number ofspecies (Fig. 3C).

Despite an apparent increase in N, S, H′ and ES(100) with colony size,these changes were only significant for ES(100) between small andmedium to large colonies in L. lusitanica (Table 1). Significant inter-annual variability was detected in E. gazella for N, S and ES(100)(2011 N 2010 for all variables; Table 1; Fig. 3D), while the apparentincrease from 2010 to 2011 in values from L. lusitanica assemblages(Fig. 3D) were not significant (Table 1). On the other hand, inter-annual variation of Shannon–Wiener diversity (H′) showed nosignificance within the assemblages associated with E. gazella, while itvaried significantly in L. lusitanica (Table 1).

ANOVA also identified a significant inter-annual variability in βW forthe epifaunal assemblages associated with E. gazella, with higher valuesin 2010 than in 2011; the same trend was detected using BC inmultivariate dispersion but only for small-sized colonies (Tables 1and 2). In this case, RC measure also identified a significant lower β-diversity between small and large colonies in 2011 (Table 2). InL. lusitanica, βW (as for ES(100)) varied significantly in relation to thecolony size (Table 1). However, in this case, significantly higher valueswere observed for small-sized colonies when compared to other sizes,

contrary to the observed for multivariate dispersion with the RCmeasure (Tables 1 and 2; Fig. 2).

PERMANOVA results showed that the interaction colony size x timewas significant for the assemblages associated with both gorgonians.Pair-wise a posteriori comparisons indicated that structure andcomposition of attendant assemblages in E. gazella were significantlydifferent between small and medium- to large-sized colonies but notbetween medium and large colonies in 2011, while in 2010 nodifferences were detected (Table 3). Inter-annual changes in speciescomposition resulted mostly from the replacement of rare species butalso from changes in the dominant species (Tables 4 and 5). Only afew exclusive taxa (singletons excluded) per colony size and yearwere found, and no clear trend was detected for the relationshipbetween the number of exclusive taxa and the total number of taxa ordominance (Tables 4 and 5).

3.1.2. Effect of gorgonian hostA total of 181 taxa were identified from the 72 gorgonian colonies

(E. gazella—124 taxa; L. lusitanica—144 taxa). These taxa were ascribedto 11 phyla, 15 classes, 41 orders, 99 families and 150 genera comprisinga total of 7284 individuals. Overall, L. lusitanica colonies had more taxa

Fig. 3.Comparison of rarefaction curves (Hurlbert's expectednumber of species) for different colony sizes (S—small;M—medium; L—large) in (A) Eunicella gazella (EG) and (B) Leptogorgialusitanica (LL) and hosts (C) and (D) years.

41S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

and harboured more individuals than those of E. gazella (L. lusitanica—4382 individuals; E. gazella—2902 individuals). Taxonomic compositionat the highest taxonomic level was very similar for both gorgonianspecies. Epifaunal assemblages were numerically dominated byarthropods, accounting for up to 48% and 65% of total abundance inE. gazella and L. lusitanica, respectively. Molluscs were also abundantin both gorgonians (18% in E. gazella and 22% in L. lusitanica) andPlatyhelminthes, which were exclusive of E. gazella epifaunalassemblages, were the second most abundant group associated with

Table 1Summary of results of two-way ANOVA for univariate data performed separately for each gorgoofOTUs; ES(100), Hurlbert's expected number of species;H′, Shannon–Wiener diversity;βW,β-W

N S

Source of variation df F P F P

Eunicella gazellaColony size, Cs 2 2.04 0.329 10.039 0.091Time, Ti 1 7.28 0.011 6.712 0.015CsxTi 2 3.27 0.052 0.487 0.619Residual 30

Leptogorgia lusitanicaColony size, Cs 2 7.61 0.116 15.295 0.061Time, Ti 1 2.91 0.098 0.004 0.951CsxTi 2 1.04 0.366 0.004 0.951Residual 30Total 35Post-hoc comparisons

this species. In terms of richness (i.e. the number of different OTUs),annelids (and especially polychaetes) were highly diverse (over 33%of total species on both gorgonians).

Of the 181OTUs identified, 48.1% (87 species) were common to bothgorgonian hosts, whereas 37 species (20.4%) were exclusively found inE. gazella colonies and 57 species (31.5%) in L. lusitanica. Removingsingletons from the analysis, the percentage of exclusive taxa droppedto a total of 16% (corresponding to 29 taxa, 11 exclusive of E. gazellaand 18 exclusive of L. lusitanica, Table 5). Only the taxon Turbellaria

nian host (see text for further details). Univariatemeasures used: N, abundance; S, numberhittaker. Significant P-values are presented in bold (pb0.05). S, small;M,medium; L, large.

ES(100) H′ βW

F P F P F P

7.07 0.124 2.11 0.322 2.92 0.2557.47 0.010 0.46 0.503 5.73 0.0230.68 0.517 0.84 0.441 1.51 0.237

38.38 0.025 2.70 0.270 60.09 0.0160.66 0.422 4.82 0.036 0.01 0.9080.27 0.767 1.48 0.245 0.20 0.818

L=M N S L=M b S

Table 2Multivariate dispersion tests (PERMDISP) using the Sorenson (Sor), Raup–Crick (RC) andBray–Curtis (BC)measures for Eunicella gazella (EG) and Leptogorgia lusitanica (LL). Colonysize was tested for each gorgonian host and for each year. Differences were tested usingthe Tukey's HSD test (Tukey).

EG F P Tukey LL F P Tukey

Colony sizeSor 2010 2.228 0.1422 – 2010 0.922 0.4190 –

2011 2.326 0.1318 – 2011 0.107 0.8991 –

RC 2010 2.647 0.1036 – 2010 9.114 0.0026 S bM=L2011 7.509 0.0055 S b L 2011 2.530 0.1130 –

BC 2010 3.076 0.0759 – 2010 1.114 0.3539 –

2011 1.721 0.2125 – 2011 0.222 0.8038 –

42 S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

und. was frequent and abundant within E. gazella colonies. BesidesTurbellaria, five other taxa occurred in more than 10% of the colonies,namely the bivalve Glans sp. in E. gazella and Ophiuridae sp. B, and thepolychaetes Lumbrineris tetraura, Serpula vermicularis and Syllis cf.columbretensis in L. lusitanica (Table S2). The remaining taxa displayedeither low abundance or frequency of occurrence (Table S2). The IndValidentified Turbellaria und. as the only taxonwith a significant associationwith Eunicella gazella (IndVal=0.986, pb0.001). On the other hand, themolluscs Simnia spelta (IndVal = 0.850, P b 0.001) and Tritonia sp.(IndVal=0.757, P b 0.01), the crustaceans Astacilla sp. (IndVal=0.773,p b 0.001), Caprella fretensis (IndVal=0.723, pb 0.001), Janira maculosa(IndVal = 0.590, p b 0.01) and Stenothoe cf. cavimana (IndVal = 0.543,p b 0.05), as well as the anemone Corynactis viridis (IndVal = 0.657,pb0.01) were all significantly associated with L. lusitanica.

The dbRDA (Fig. 4) indicated that the first two ordination axesexplain 84% of the fitted variation (explained size-related attributesand CEC) comprising about 15% of the total variation. The ordinationplot revealed a general separation of the epifaunal assemblages

Table 3Summary of results of two-way PERMANOVA for factors colony size (S, small; M,medium;L, large) and time (2010, 2011). Analyses were performed separately for each gorgonianspecies (see text for details) based on the Bray–Curtis dissimilarity measure, calculatedon epifaunal abundances after square-root transformation. Significant P-values arepresented in bold (P b 0.05).

Source of variation df MS F P

Eunicella gazellaColony size, Cs 2 0.4482 1.0102 0.4952Time, Ti 1 0.7096 3.3492 0.0004CsxTi 2 0.4437 2.0941 0.0014Residual 30 0.2119Total 35Pair-wise a posteriori comparisonsTests among levels of factor Cs

2010 L=M=S2011 M=L≠ S

Tests among levels of factor TiS 2010≠ 2011M 2010=2011L 2010≠ 2011

Leptogorgia lusitanicaColony size, Cs 2 0.6531 1.6357 0.1142Time, Ti 1 1.1756 4.414 0.0002CsxTi 2 0.3993 1.4993 0.0324Residual 30 0.1856Total 35Pair-wise a posteriori comparisonsTests among levels of factor Cs

2010 L=M≠ S2011 L=M≠ S

Tests among levels of factor TiS 2010≠ 2011M 2010=2011L 2010≠ 2011

associated with the two gorgonian species (along the XX axis,dbRDA1), evidencing the complementarity between assemblages. Thenumber of branches and surface area of gorgonian colonies werefound to be significant to explain the variance between samples(Table S3). These variables present small overlap and explain 80% ofthe fitted variation (sequential tests, Table S3). CEC is also relevant;the small size of its vector suggests that this variable presents highvariability between samples and was not related to gorgonian size, butcontributed to the discrimination between hosts (Fig. 4). The lengthand the direction of the vectors indicate that size-related attributes ofthe hosts, especially the number of branches, were relevant for thediscrimination of samples with different sizes, especially small colonies.Within each host there is also a clear separation of the samplesaccording to size attributes (along the YY axis, dbRDA2), mainlybetween small and medium to large-sized colonies (Fig. 4). The mainseparation observed between the assemblages associated with bothgorgonians was confirmed by PERMANOVA (F=45.59, P=0.030).

4. Discussion

Epifaunal assemblages associated with the gorgonians Eunicellagazella and Leptogorgia lusitanica present in shallow waters of southPortugalwere rich (181 taxa; 11 phyla) and abundant (7284 individuals).Values observed are comparable to the ones on four scleractinian corals inthe Lizard Island (Great Barrier Reef, Australia) (Stella et al., 2010), andmuch larger than those found by Goh et al. (1999) and Kumagai andAoki (2003) in shallow water gorgonians' from Singapore and Japan,although mesh-sieves are not comparable.

The epifaunal assemblages of both gorgonian species werenumerically dominated by Amphipoda, while Polychaeta was therichest group. The dominance of amphipod species among crustaceanfauna associated with gorgonians had also been reported for shallow(Greene, 2008) and deep (Buhl-Mortensen and Mortensen, 2004b,2005) Atlantic waters, as well as for shallow waters from the Indo-Pacific region (Goh et al., 1999; Kumagai and Aoki, 2003). In general,the composition of amphipod fauna was very similar (especially atfamily and genus level) to the one reported for other coral habitatsfrom Atlantic areas (Greene, 2008; Mortensen and Buhl-Mortensen,2004), with the dominance of Caprellidae, Ischyroceridae, Photidaeand Stenothoidae genera. Species of the genera Caprella, Stenothoe,Erichthonius and Jassa are also found among the dominant fauna ofartificial reefs in the Algarve region (Moura et al., 2007, 2008) or insoft bottoms (Carvalho et al., 2007, 2012) and therefore are notgorgonian specialists.

4.1. Host attributes and associated biodiversity patterns

In general, L. lusitanica harboured richer and more abundantassemblages, which can be at least partially explained by the resultinggreater colonisable area of their colonies. Nevertheless, when bothdatasets were compared (colony size and year pooled) both gorgonianscontributed similarly to the overall biodiversity in terms of the expectednumber of species. Within each species, large E. gazella and mediumL. lusitanica colonies contributed the most to the overall biodiversity,which agrees with the morphologies of their colonies: broaderin L. lusitanica and more rounded in E. gazella. Colony size and/ortime (and not location) were the main drivers of variability in theattendant assemblages of the two gorgonian species. Increasingcolony size translates directly into an increasing colonisable area, and,consequently, into a species-area effect, while inter-annual variabilitymay reflect the dynamics of species life cycles (e.g. availability ofrecruits, success of recruitment), the response of individual species toenvironmental variability and at least partially a random drift in thecomposition of the assemblages from one year to another.

Although live surface area of corals was found to have no correlationeither with abundance or species richness in Acropora colonies (Vytopil

Table 4Tenmost abundant taxa for Eunicella gazella epibenthic assemblages per colony size class and year (2010 and 2011). Exclusive taxa (excluding singletons—see text for further details) arealso given. N, total number of individuals; %TN—relative taxon abundance. A, Arthropoda; An, Annelida; M, Mollusca; P, Platyhelminthes; Po, Porifera.

2010 2011

Small coloniesTaxa N %TN Taxa N %TN

P Turbellaria 17 18.5 A Ericthonius punctatus 145 36.7M Hiatella arctica 12 13 P Turbellaria 93 23.5A Ostracoda 11 12 A Ostracoda 29 7.34M Tritonia sp. 9 9.78 M Musculus sp. 1 25 6.33M Musculus sp. 1 7 7.61 A Gammaropsis cf. crenulata 15 3.8A Ischyrocerus inexpectatus 6 6.52 M Tritonia sp. 14 3.54A Phtisica marina 5 5.43 A Caprella acanthifera 12 3.04M Bivalvia sp. 1 4 4.35 M Bivalvia sp. 1 11 2.78Po Porifera sp. 2 3 3.26 A Ischyrocerus inexpectatus 6 1.52A Caprella fretensis 2 2.17 A af. Leptochelia savygni 6 1.52

82.6 90.1Exclusive taxa

Po Porifera sp. 2 3 A Leptocheirus sp. 3

Medium coloniesTaxa N %TN Taxa N %TN

P Turbellaria 137 20.4 A Ericthonius punctatus 244 35.5A Ostracoda 107 16 P Turbellaria 156 22.7A Ericthonius punctatus 101 15.1 A Gammaropsis cf. crenulata 43 6.26M Bivalvia sp. 1 59 8.81 A Ostracoda 38 5.53A Stenothoe cf. gallensis 50 7.46 M Modiolus sp. 17 2.47A Ischyrocerus inexpectatus 40 5.97 N Nematoda 16 2.33M Hiatella arctica 30 4.48 M Tritonia sp. 14 2.04A Gammaropsis cf. crenulata 25 3.73 M Bivalvia sp. 1 13 1.89M Musculus sp. 1 14 2.09 M Musculus sp. 1 10 1.46A Stenothoe cf. cavimana 13 1.94 M Hiatella arctica 9 1.31

86 81.5Exclusive taxa

M Rissoidae 3 A Anoplodactylus pygmaeus 2M Loripes sp. 2

Large coloniesTaxa N %TN Taxa N %TN

P Turbellaria 118 32.8 P Turbellaria 230 33A Ostracoda 55 15.3 A Ericthonius punctatus 84 12M Bivalvia sp. 1 39 10.8 A Ostracoda 38 5.44A Ericthonius punctatus 19 5.28 A Gammaropsis cf. crenulata 29 4.15C Corynactis viridis 10 2.78 M Bivalvia sp. 1 26 3.72A Gammaropsis cf. crenulata 9 2.5 M Tritonia sp. 22 3.15M Hiatella arctica 8 2.22 A Thoralus cranchii 18 2.58M Pectinoida 8 2.22 M Musculus costulatus 16 2.29A Astacilla sp. 7 1.94 A af. Leptochelia savygni 14 2.01A Stenothoe cf. gallensis 7 1.94 M Modiolus sp. 13 1.86

77.8 70.2Exclusive taxa

An Hydroides nigra 2 A Colomastix pusila 4

43S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

andWillis, 2001), the dbRDA analysis indicated significant relationshipsof size-related attributes (especially surface area and number ofbranches) and the faunal patterns of assemblages associated withboth gorgonians. For both gorgonian species, small-sized coloniescontributed the least for the overall α-diversity (especially in terms ofexpected number of species) and showed significantly differentepifaunal composition and assemblage structure compared tomedium- and large-sized colonies. However, in terms of β-diversitythe opposite pattern was detected. Higher βW values were estimatedfor small-sized colonies in both gorgonians, even though this trendwas only significant for L. lusitanica. This indicates a higher variabilityin the species composition of the assemblages associated with small-sized colonies. These results not only confirm the relevance of colonysize to both α- and β-diversity patterns in gorgonian gardens but alsopoint out to the complementary information provided by differentdiversity measures, which may highlight different features of theassemblage (Anderson et al., 2011). Biodiversity patterns were host-dependent: changes in the assemblages associated with L. lusitanicawere mainly related to colony size (both α- and β-diversity, namelyES(100) and βW), while in E. gazella mainly differed inter-annually. Themorphological differences of the gorgonian host are likely to contribute

to explaining these patterns because the increase in colonisable areafrom small to large sized colonies is considerably greater in L. lusitanicathan in E. gazella. The patterns were less divergent concerning theassemblage structure.

The “colonial” epibiont cover (e.g. macroscopic algae, sponges,bryozoans)was also observed to contribute to the structure of epifaunalassemblages of both gorgonian species. It is known that some of thedominant epifaunal taxa, such as amphipods, may also be closelyassociated with some of these colonial epizoans (e.g. briozoans,hydroids) (Aoki and Kikuchi, 1990; Bradshaw et al., 2003; Guerra-García, 2001). Previous studies in seagrass meadows showed thatepiphytes might have a relevant role on the patterns of associatedmobile epifauna, resulting from a combining effect of the increases insecondary structure or habitat heterogeneity (Edgar and Robertson,1992; Hall and Bell, 1988) and in trophic resource availability(Bologna and Heck, 1999). Therefore, it is difficult to discern whethertheir abundance is due to the gorgonian itself or to the associatedmodular organisms. However, it was apparent that a higher frequencyof occurrence of these secondary hosts is present in medium and largecolonies, which agrees with the increase in biodiversity and abundanceobserved within these colonies when compared to the small-sized. On

Table 5Ten most abundant taxa for Leptogorgia lusitanica epibenthic assemblages per colony size class and year (2010 and 2011). Phylum for each taxon is presented. Exclusive taxa (excludingsingletons—see text for further details) are also given. N, total number of individuals; %TN—relative taxon abundance. A, Arthropoda; An, Annelida; C, Cnidaria; M, Mollusca.

2010 2011

Small coloniesTaxa N %TN Taxa N %TN

A Caprella fretensis 68 22.2 A Ericthonius punctatus 49 19.9A Ischyrocerus inexpectatus 56 18.3 A Gammaropsis cf. crenulata 48 19.5A Astacilla sp. 45 14.7 A Ostracoda 31 12.6A Ostracoda 28 9.15 M Tritonia sp. 27 11M Tritonia sp. 21 6.86 A Phtisica marina 11 4.47A Gammaropsis cf. crenulata 20 6.54 M Simnia spelta 10 4.07M Hiatella arctica 16 5.23 A Astacilla sp. 8 3.25A Phtisica marina 8 2.61 A Caprella acanthifera 8 3.25M Musculus sp. 1 7 2.29 M Bivalvia sp. 1 6 2.44A Gammaropsis sophiae 4 1.31 M Kellia sp. 5 2.03

89.2 82.5Exclusive taxa

M cf. Scacchia zorni 3

Medium coloniesTaxa N %TN Taxa N %TN

A Ostracoda 221 16.4 M Simnia spelta 41 12.8A Gammaropsis cf. crenulata 198 14.7 A Ostracoda 37 11.6M Hiatella arctica 130 9.65 M Tritonia sp. 31 9.69A Stenothoe cf. cavimana 117 8.69 M Modiolus sp. 15 4.69C Corynactis viridis 86 6.38 M Bivalvia sp. 1 14 4.38M Bivalvia sp. 1 69 5.12 C Corynactis viridis 14 4.38A Caprella fretensis 46 3.41 M Hiatella arctica 11 3.44M Ostrea edulis 38 2.82 A af. Leptochelia savygni 11 3.44A Ericthonius punctatus 37 2.75 A Ericthonius punctatus 10 3.13A Ischyrocerus inexpectatus 33 2.45 A Gammaropsis cf. crenulata 10 3.13

72.4 60.6Exclusive taxa

M Corbula gibba 25M Jujubinus striatus 5An Ophryotrocha labronica 4M Calliostoma zizyphinum 2

Large coloniesTaxa N %TN Taxa N %TN

A Caprella fretensis 560 49.7 A Ericthonius punctatus 258 24.9A Ostracoda 187 16.6 A Ostracoda 97 9.35M Bivalvia sp. 1 59 5.24 C Corynactis viridis 76 7.33A Ischyrocerus inexpectatus 40 3.55 M Simnia spelta 59 5.69A Astacilla sp. 34 3.02 A Gammaropsis cf. crenulata 56 5.4M Hiatella arctica 30 2.66 M Tritonia sp. 42 4.05M Simnia spelta 25 2.22 A af. Leptochelia savygni 38 3.66C Corynactis viridis 21 1.87 M Bivalvia sp. 1 34 3.28A Gammaropsis cf. crenulata 21 1.87 M Musculus sp. 1 33 3.18A Phtisica marina 15 1.33 An Syllidia armata 29 2.8

88.1 69.6Exclusive taxa

A Maera sp. 2 An Cirratulidae 2M Phanerobranchia 2

44 S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

the other hand, secondary hosts are present across the whole colony,and no relationship between their location and associates was evident.

4.2. Host specificity and gorgonian-obligates

In general, the current findings do not support the existence of highlevels of host-specificity in the epifaunal species found among thegorgonian gardens of the South Portugal, which agreeswith thefindingsof Buhl-Mortensen and Mortensen (2004b) for cold and temperatewaters in theNorth of Europe. Only one taxon (Turbellaria und.) provedto be significantly associated with Eunicella gazella colonies by itsexclusivity to this host and by its abundance and frequency ofoccurrence. These white flatworms, which colour resembles the colourof E. gazella branches, may take advantage of crypsis (Goh et al.,1999). They are mainly found on the junctions of gorgonian branches,and after washing the colonies to remove the organisms, in most ofthe cases they were still attached to the branches and were removedby hand. We hypothesize that this specificity may reflect a strategy to

avoid predation. Besides Turbellaria, only six among the exclusive taxaobserved in each species showed a frequency of occurrence over 10%:the bivalve Glans sp. in Eunicella gazella; the polychaetes Lumbrineristetraura, Serpula vermicularis and Syllis cf. columbretensis and Ophiuridaesp. B in L. lusitanica. However, these species have been already reportedfor other marine habitats either to the study area (Malaquias et al.,2006; Moura et al., 2007, 2008; unpubl. data concerning L. tetraura andS. cf. columbretensis) or to other European areas (Bone and Klein, 2000;Gambi et al., 1998; Giangrande et al., 2003; Mastrototaro et al., 2010).

Taking into account the current scenario of ongoing degradation ofcoastal habitats, further research is needed, as obligate associationsand habitat specialization may contribute to a greater risk of extinctionof associated invertebrates, especially when obligate specimens arerarer than their hosts (Buhl-Mortensen and Mortensen, 2004a).However, regardless of the level of dependence on their host, alltaxonomic components of the attendant assemblages should beconsidered, as all have the capacity to contribute to the functioning ofcoral habitats (Gates and Ainsworth, 2011).

Fig. 4. Distance based Redundancy analysis (dbRDA) ordination biplot for epifaunalassemblages associated with Eunicella gazella (circles; different shades represent colonysize) and Leptogorgia lusitanica (squares; different shades represent colony size). Samplesare plotted as points using weighted averages of species scores in each constrained axis.The vector lines reflect the relationship of size-related gorgonian colony attributes (totalarea, width and number of branches) and colonial epibiont cover (CEC) to the ordinationaxes; their length is proportional to their relative significance. Years are not discriminated.

45S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

4.3. Biodiversity patterns: implications for future studies

Overall, gorgonians, as foundation species (Roff and Zacharias, 2011)in themarine environment, promote the presence of a wide diversity ofspecies, which may reflect the multiple microhabitats available withineach colony (Buhl-Mortensen and Mortensen, 2005). Our results shownot only the high values of α-diversity in the epifaunal assemblagesassociated with the gorgonian hosts but also intricate patterns ofvariability in the composition and structure of these assemblagesleading to high values of β-diversity. The analysis of diversity showedthat individual colonies of different sizes and of different host speciesadd up to a substantial greater species pool in a coral garden but thosepatterns may be host-dependent. Moreover, there is an importanttemporal (inter-annual) turnover in the attendant assemblages. Eachindividual colony encloses a small and highly variable subset ofthe total pool of species. The aggregation of colonies facilitates ametacommunity dynamic within the coral garden for which randomdrift of individuals between colonies may have a strong contributionand explains the lack of significant spatial variation at the local level.In a metacommunity dynamic resulting from ecological connectivity(Leibold et al., 2004), patterns of biodiversity are more affected bychanges in the relative abundance of dominant species rather than infaunal composition. On the other hand, some characteristics of theattendant assemblages appear to be driven or at least affected by theattributes of their hosts. The host species may be relevant in attractingpreferentially some attendant species and somehow also determiningdominance patterns. Any space made available by death or migrationof one individual is likely to be replaced randomly by any otherindividual of the same or another species from the garden pool (andtherefore high levels of α- but mostly β-diversity are maintained). Thestochastic component of biodiversity may be therefore significant inthe gorgonian colonies (especially in the smaller ones) if we assumethat each species behave according to the principle of neutralitypostulated by Hubbell (2001), i.e. changes in the assemblages resultfrom the interaction of mortality and colonisation (from the gardenspecies pool). The identities and the abundance of individuals available

in the garden pool are subjected to the seasonal fluctuations in thepopulations determined by their life cycles. Typically in this regionperacarid crustaceans and other invertebrates generally show twopeaks of abundance per year, not necessarily synchronous for all species(Drake and Arias, 1995; Fidalgo e Costa, 2003; Malaquias and Sprung,2005). The higher variability in the estimates of abundance, speciesrichness and evenness for the larger colonies suggests that, with theincreasing complexity and colonisable area, some species mayaggregate and become dominant (in this case species neutrality doesnot apply and the stochastic component of biodiversity is less relevant).This agreeswith the habitat heterogeneity hypothesis that assumes thatstructurally complex habitats lead to an increase in species diversity byproviding a higher number of distinct niche dimensions and diverseways of exploiting resources (MacArthur and Wilson, 1967). Thishypothesis postulates that specialization arises through microhabitatexploitation and niche partitioning. However, at the scale of thegorgonian gardens, dominant species vary from one colony to anotherand in time (significant inter-annual variability). The low degree ofhost-specificity (specialization) does not contribute to explain thesepatterns, which could only be elucidated by a greater knowledge ofeach species life-history traits. In fact, the perception of habitat (andhabitat heterogeneity) by different taxa is dependent on their size,mobility and dispersal capability (Morris, 1987). At the scale ofthese gorgonian gardens, temporal fluctuations are probably thereforebetter explained by the disequilibrium explanation of the habitatheterogeneity hypothesis (contemporaneous disequilibrium, Grassleand Sanders, 1973): predation, patchy food inputs, and disturbancemaintain a series of successional mosaics.

4.4. Final remarks

We hypothesize that the observed high turnover in the gorgonianattendant assemblages mirrors a temporal fluidity in composition andstructure related to multiple factors including not only a componentof stochasticity but also life history events, biotic interactions andresponse to habitat heterogeneity and environmental variability. Ourobservations show that an accurate perception of the habitat and itsdynamics must take into account not only α- but also β-diversity atdifferent spatial and temporal scales as they provide complementaryinformation. This has important implications for the design of futurebiodiversity assessment studies. More than focusing on a singlegorgonian species, conservation efforts should be placed on the wholehabitat encompassing different hosts and the size structure of theirpopulations.

Acknowledgements

S.C. (SFRH/BPD/26986/2006) and J.C. (SFRH/BD/29491/2006) benefitfrom post-Doctoral and PhD grants, respectively, awarded by the“Fundação para a Ciência e a Tecnologia” (FCT). The authors are gratefulto the three anonymous reviewers and to the associate editor, Dr. JudiHewitt, for providing valuable comments and suggestions, whichimproved an earlier version of the manuscript.

Appendix A. Supplementary data

Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.seares.2013.10.001.

References

Anderson, M.J., 2001. A newmethod for non parametric multivariate analysis of variance.Aust. Ecol. 26, 32–46.

Anderson, M.J., Ellingsen, K.E., McArdle, B.H., 2006. Multivariate dispersion as a measureof beta diversity. Ecol. Lett. 9, 683–693.

Anderson, M.J., Crist, T.O., Chase, J.M., Vellend, M., Inouye, B.D., Freestone, A.L., Sanders,N.J., Cornell, H.V., Comita, L.S., Davies, K.F., Harrison, S.P., Kraft, N.J.B., Stegen, J.C.,

46 S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

Swenson, N.G., 2011. Navigating the multiple meanings of β-diversity: a roadmap forthe practicing ecologist. Ecol. Lett. 14, 19–28.

Aoki, M., Kikuchi, T., 1990. Habitat adaptations of caprellid amphipods and theimportance of epiphytic secondary habitats in a Sargassum patens bed in Amakusa,southern Japan. Publ. Amakusa Mar. Biol. Lab. 10, 123–133.

Arganda-Carreras, I., Fernandez-Gonzalez, R., Munoz-Barrutia, A., Ortiz-De-Solorzano, C.,2010. 3D reconstruction of histological sections: application to mammary glandtissue. Microsc. Res. Tech. 73, 1019–1029.

Becking, L.E., Cleary, D.F.R., Voogd, N.J., Renema, W., Beer, M., Soest, R.W.M., Hoeksema,B.W., 2006. Beta diversity of tropical marine benthic assemblages in the SpermondeArchipelago, Indonesia. Mar. Ecol. 27, 76–88.

Bergsma, G.S., 2010. Tube-dwelling coral symbionts induce significant morphologicalchange in Montipora. Symbiosis 49, 143–150.

Bergsma, G.S., Martinez, C.M., 2011. Mutualist-induced morphological changes enhancegrowth and survival of corals. Mar. Biol. 158, 2267–2277.

Bevilacqua, S., Plicanti, A., Sandulli, R., Terlizzi, A., 2012. Measuring more of β-diversity:quantifying patterns of variation in assemblage heterogeneity. An insight frommarine benthic assemblages. Ecol. Indic. 18, 140–148.

Bologna, P.A.X., Heck Jr., K.L., 1999. Macrofaunal associations with seagrass epiphytes:relative importance of trophic and structural characteristics. J. Exp. Mar. Biol. Ecol.242, 21–39.

Bone, D., Klein, E., 2000. Temporal variations in a tropical soft-bottom community,Venezuela. J. Coast. Res. 16, 278–286.

Bradshaw, C., Collins, P., Brand, A.R., 2003. To what extent does upright sessile epifaunaaffect benthic biodiversity and community composition? Mar. Biol. 143, 783–791.

Buhl-Mortensen, L., Mortensen, P.B., 2004a. Symbiosis in deep-water corals. Symbiosis 37,33–61.

Buhl-Mortensen, L., Mortensen, P.B., 2004b. Crustacean fauna associated with the deep-water corals Paragorgia arborea and Primnoa resedaeformis. J. Nat. Hist. 38, 1233–1247.

Buhl-Mortensen, L., Mortensen, P.B., 2005. Distribution and diversity of species associatedwith deep-sea gorgonian corals off Atlantic Canada. In: Freiwald, A., Roberts, J.M.(Eds.), Cold-Water Corals and Ecosystems. Springer-Verlag, Berlin/Heidelberg,pp. 849–879.

Buhl-Mortensen, L., Vanreusel, A., Gooday, A.J., Levin, L.A., Priede, I.G., Buhl-Mortensen, P.,Gheerandyn, H., King, N.J., Raes, M., 2010. Biological structures as a source of habitatheterogeneity and biodiversity on the deep ocean margins. Mar. Ecol. 31, 21–50.

Burkepile, D., Hay, M., 2007. Predator release of the gastropod Cyphoma gibbosumincreases predation on gorgonian corals. Oecologia 154, 167–173.

Carpenter, K.E., Abrar, M., Aeby, G., Aronson, R.B., Banks, S., Bruckner, A., Chiriboga, A.,Cortés, J., Delbeek, J.C., DeVantier, L., Edgar, G.J., Edwards, A.J., Fenner, D., Guzmán,H.M., Hoeksema, B.W., Hodgson, G., Johan, O., Licuanan, W.Y., Livingstone, S.R.,Lovell, E.R., Moore, J.A., Obura, D.O., Ochavillo, D., Polidoro, B.A., Precht, W.F.,Quibilan, M.C., Reboton, C., Richards, Z.T., Rogers, A.D., Sanciangco, J., Sheppard, A.,Sheppard, C., Smith, J., Stuart, S., Turak, E., Veron, J.E.N., Wallace, C., Weil, E., Wood,E., 2008. One-third of reef-building corals face elevated extinction risk from climatechange and local impacts. Science 321, 560–563.

Carricart-Ganivet, J.P., Carrera-Parra, L.F., Quan-Young, L.I., García-Madrigal, M.S., 2004.Ecological note on Troglocarcinus corallicola (Brachyura: Cryptochiridae) living insymbiosis with Manicina areolata (Cnidaria: Scleractinia) in the Mexican Caribbean.Coral Reefs 23, 215–217.

Carvalho, S., Barata, M., Gaspar, M.B., Pousão-Ferreira, P., Cancela da Fonseca, L., 2007.Enrichment of aquaculture earthen ponds with Hediste diversicolor: consequencesfor benthic dynamics and natural productivity. Aquaculture 262, 227–236.

Carvalho, S., Cunha, M.R., Pereira, F., Pousão-Ferreira, P., Santos, M.N., Gaspar, M.B., 2012. Theeffect of depth and sediment type on the spatial distribution of shallow soft-bottomamphipods along the southern Portuguese coast. Helgol. Mar. Res. 66, 489–501.

Coles, S.L., 1980. Species diversity of decapods associated with living and dead reef coralPocillopora meandrina. Mar. Ecol. Prog. Ser. 2, 281–291.

Cúrdia, J.L.S., 2012. Gorgonians of the South of Portugal: Biology, Ecology andConservation. (Ph. D. dissertation) Universidade de Aveiro, Aveiro.

Cúrdia, J., Monteiro, P., Afonso, C.M.L., Santos, M.N., Cunha, M.R., Gonçalves, J.M.S., 2013.Spatial and depth-associated distribution patterns of shallow gorgonians in theAlgarve coast (Portugal, NE Atlantic). Helgol. Mar. Res. 67, 521–534.

Danovaro, R., Canals, M., Gambi, C., Heussner, S., Lampadariou, N., Vanreusel, A., 2009.Exploring benthic biodiversity patterns and hotspots on European margin slopes.Oceanography 22, 16–25.

Dimitriadis, C., Koutsoubas, D., 2011. Functional diversity and species turnover of benthicinvertebrates along a local environmental gradient induced by an aquaculture unit:the contribution of species dispersal ability and rarity. Hydrobiologia 670, 307–315.

Drake, P., Arias, A.M., 1995. Distribution and production of Microdeutopus gryllotalpa(Amphipoda: Aoridae) in a shallow coastal lagoon in the Bay of Cádiz, Spain.J. Crustac. Biol. 15, 454–465.

Dufrêne, M., Legendre, P., 1997. Species assemblages and indicator species: the need for aflexible asymmetrical approach. Ecol. Monogr. 67, 345–366.

Edgar, G., Robertson, A.I., 1992. The influence of seagrass structure on the distribution andabundance of mobile epifauna: pattern and process in a Western AustralianAmphibolis bed. J. Exp. Mar. Biol. Ecol. 160, 13–31.

Edwards, A., Emberton, H., 1980. Crustacea associated with the scleractinian coral,Stylophora pistillata (Esper), in the Sudanese Red Sea. J. Exp. Mar. Biol. Ecol. 42,225–240.

Fidalgo e Costa, P., 2003. The oogenic cycle of Nereis diversicolor (O.F. Muller, 1776)(Annelida: Polychaeta) in shallow water environments in southerwestern Portugal.Bol. Inst. Esp. Oceanogr. 19, 17–29c.

Gambi, C.M., Conti, G., Bremec, C.S., 1998. Polychaete distribution, diversity andseasonality related to seagrass cover in shallow soft bottoms of the Tyrrhenian Sea(Italy). Sci. Mar. 62, 1–17.

García-Matucheski, S., Muniain, C., 2010. Predation by the nudibranch Tritonia odhneri(Opisthobranchia: Tritoniidae) on octocorals from the South Atlantic Ocean. Mar.Biodivers. 41, 287–297.

Gates, R.D., Ainsworth, T.D., 2011. The nature and taxonomic composition of coralsymbiomes as drivers of performance limits in scleractinian corals. J. Exp. Mar. Biol.Ecol. 408, 94–101.

Gering, J.C., Crist, T.O., Veech, J.A., 2003. Additive partitioning of species diversity acrossmultiple spatial scales: implications for regional conservation of biodiversity.Conserv. Biol. 17, 488–499.

Giangrande, A., Delos, A.L., Fraschetti, S., Musco, L., Licciano, M., Terlizzi, A., 2003.Polychaete assemblages along a rocky shore on the South Adriatic coast(Mediterranean Sea): patterns of spatial distribution. Mar. Biol. 143, 1109–1116.

Goh, N.K., Ng, P.K., Chou, L., 1999. Notes on the shallow water gorgonian-associated faunaon coral reefs in Singapore. Bull. Mar. Sci. 65, 259–282.

Grassle, J.F., Sanders, H., 1973. Life histories and the role of disturbance. Deep-Sea Res. 20,643–659.

Gratwicke, B., Speight, M.R., 2005. The relationship between fish species richness,abundance and habitat complexity in a range of shallow tropical marine habitats.J. Fish Biol. 66, 650–667.

Gray, J.S., 2000. The measurement of marine species diversity, with an application tothe benthic fauna of the Norwegian continental shelf. J. Exp. Mar. Biol. Ecol. 250,23–49.

Greene, A.K., 2008. Invertebrate Endofauna Associated with Sponge and OctocoralEpifauna at Gray's Reef National Marine Sanctuary off the Coast of Georgia. (M. S.dissertation) The Graduate School of The College of Charleston.

Guerra-García, J.M., 2001. Habitat use of the Caprellidea (Crustacea: Amphipoda) fromCeuta, North Africa. Ophelia 55, 27–38.

Hall, M.O., Bell, S.S., 1988. Response of small motile epifauna to complexity of epiphyticalgae on seagrass blades. J. Mar. Res. 46, 613–630.

Holbrook, S.J., Brooks, A.J., Schmitt, R.J., Stewart, H.L., 2008. Effects of sheltering fish ongrowth of their host corals. Mar. Biol. 155, 521–530.

Hubbell, S.P., 2001. The Unified Neutral Theory of Biodiversity and Biogeography.Princeton University Press, Princeton.

Hurlbert, S.H., 1971. The nonconcept of species diversity: a critique and alternativeparameters. Ecology 52, 577–586.

Idjadi, J.A., Edmunds, P.J., 2006. Scleractinian corals as facilitators for other invertebrateson a Caribbean reef. Mar. Ecol. Prog. Ser. 319, 117–127.

Knowlton, N., Brainard, R.E., Fisher, R., Moews, M., Plaisance, L., Caley,M.J., 2010. Coral reefbiodiversity. In: McIntyre, A.D. (Ed.), Life in the World's Oceans: Diversity,Distribution and Abundance. Wiley-Blackwell, pp. 65–77.

Koleff, P., Gaston, K.J., Lennon, J.J., 2003. Measuring beta-diversity for presence–absencedata. J. Anim. Ecol. 72, 367–382.

Kumagai, N.H., 2008. Role of food source and predator avoidance in habitat specializationby an octocoral-associated amphipod. Oecologia 155, 739–749.

Kumagai, N.H., Aoki, M.N., 2003. Seasonal changes in the epifaunal community on theshallow-water gorgonian Melithaea flabellifera. J. Mar. Biol. Assoc. U. K. 83,1221–1222.

Leibold, M.A., Holyoak, M., Mouquet, N., Amarasekare, P., Chase, J.M., Hoopes, M.F., Holt,R.D., Shurin, J.B., Law, R., Tilman, D., Loreau, M., Gonzalez, A., 2004. Themetacommunity concept: a framework for multi-scale community ecology. Ecol.Lett. 7, 601–613.

Lingo, M.E., Szedlmayer, S.T., 2006. The influence of habitat complexity on reef fishcommunities in the northeastern Gulf of Mexico. Environ. Biol. Fish 76, 71–80.

MacArthur, R.H., Wilson, E.O., 1967. The Theory of Island Biogeography. PrincetonUniversity Press, Princeton.

Magurran, A.E., 2004. Measuring Biological Diversity. Blackwell Science Ltd, Oxford.Malaquias, M.A.E., Sprung, M.J., 2005. Population biology of the cephalaspidean mollusc

Haminoea orbygniana in a temperate coastal lagoon (Ria Formosa, Portugal). Estuar.Coast. Shelf Sci. 63, 177–185.

Malaquias, M.A.E., Bentes, L., Erzini, K., Borges, T.C., 2006. Molluscan diversity caughtby trawling fisheries: a case study in southern Portugal. Fish. Manag. Ecol. 13,39–45.

Mastrototaro, F., D'Onghia, G., Corriero, G., Matarrese, A., Maiorano, P., Panetta, P.,Gherardi, M., Longo, C., Rosso, A., Sciuto, F., Sanfilippo, R., Gravili, C., Boero, F.,Taviani, M., Tursi, A., 2010. Biodiversity of the white coral bank off Cape SantaMaria di Leuca (Mediterranean Sea): an update. Deep-Sea Res. II 57, 412–430.

McArdle, B.H., Anderson, M.J., 2001. Fitting multivariate models to community data: acomment on distance-based redundancy analysis. Ecology 82, 290–297.

Morris, D.W., 1987. Ecological scale and habitat use. Ecology 68, 362–369.Mortensen, P.B., Buhl-Mortensen, L., 2004. Distribution of deep-water gorgonian corals in

relation to benthic habitat features in the Northeast Channel (Atlantic Canada). Mar.Biol. 144, 1223–1238.

Moura, A., Boaventura, D., Cúrdia, J., Carvalho, S., Cancela da Fonseca, L., Leitão, F., Santos,M.N., Monteiro, C.C., 2007. Effect of depth and reef structure on early macrobenthiccommunities of the Algarve artificial reefs (southern Portugal). Hydrobiologia 580,173–180.

Moura, A., Cancela da Fonseca, L., Cúrdia, J., Carvalho, S., Boaventura, D., Cerqueira, M.,Leitão, F., Santos, M.N., Monteiro, C.C., 2008. Is surface orientation a determinant forcolonisation patterns of vagile and sessile macrobenthos on artificial reefs? Biofouling24, 381–391.

Munday, P.L., 2004. Habitat loss, resource specialization, and extinction on coral reefs.Glob. Chang. Biol. 10, 1642–1647.

Öhman, M.C., Rajasuriya, A., 1998. Relationships between habitat structure and fishcommunities on coral. Environ. Biol. Fish 53, 19–31.

Patton, W.K., 1994. Distribution and ecology of animals associated with branching corals(Acropora spp.) from the Great Barrier Reef, Australia. Bull. Mar. Sci. 55, 193–211.

47S. Carvalho et al. / Journal of Sea Research 85 (2014) 37–47

Plaisance, L., Caley, M., Brainard, R., Knowlton, N., 2011. The diversity of coral reefs: whatare we missing? PLoS One 6, e25026.

R Development Core Team, 2010. R: A language and environment for statisticalcomputing. Vienna, Austria: R Foundation for Statistical Computing.Rasband, W.S.,1997–2010. Image J.National Institutes of Health, USA (Bethesda, Maryland, U. S.).

Roff, J., Zacharias, M., 2011. Marine Conservation Ecology. Routledge.Schneider, C.A., Rasband,W.S., Eliceiri, K.W., 2012. NIH Image to ImageJ: 25 years of image

analysis. Nat. Methods 9, 671–675.Schoepf, V., Herler, J., Zuschin, M., 2010. Microhabitat use and prey selection of the coral

feeding snail Drupella cornus in the northern Red Sea. Hydrobiologia 641, 45–57.Stachowicz, J.J., Hay, M.E., 1999. Mutualism and coral persistence: the role of herbivore

resistance to algal chemical defense. Ecology 80, 2085–2101.Stella, J.S., Jones, G.P., Pratchett, M.S., 2010. Variation in the structure of epifaunal

invertebrate assemblages among coral hosts. Coral Reefs 29, 957–973.Stewart, H.L., Holbrook, S.J., Schmitt, R.J., Brooks, A.J., 2006. Symbiotic crabs maintain coral

health by clearing sediments. Coral Reefs 25, 609–615.

Terlizzi, A., Benedetti-Cecchi, L., Bevilacqua, S., Fraschetti, S., Guidetti, P., Anderson, M.J.,2005. Multivariate and univariate asymmetrical analyses in environmental impactassessment: a case study of Mediterranean subtidal sessile assemblages. Mar. Ecol.Prog. Ser. 289, 27–42.

Thrush, S.F., Hewitt, J.E., Cummings, V.J., Norkko, A., Chiantore, M., 2010. β-diversity andspecies accumulation in Antarctic coastal benthos: influence of habitat, distanceand productivity on ecological connectivity. PLoS ONE 5, e11899.

Vytopil, E., Willis, B., 2001. Epifaunal community structure in Acropora spp. (Scleractinia)on the Great Barrier Reef: implications of coral morphology and habitat complexity.Coral Reefs 20, 281–288.

Whittaker, R.H., 1960. Vegetation of the Siskiyou Mountains, Oregon and California. Ecol.Monogr. 30, 279–338.

Wilson, S., Graham, N., Polunin, N., 2007. Appraisal of visual assessments of habitatcomplexity and benthic composition on coral reefs. Mar. Biol. 151, 1069–1076.

Zajac, R.N., Vozarik, J.M., Gibbons, B.R., 2013. Spatial and temporal patterns inmacrofaunaldiversity components relative to sea floor landscape structure. PLoS ONE 8, e65823.