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Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles ofvertical diel migration, water column, bedload transport and biologicaltraits' expression

Aldo S. Pacheco a,⁎, Roberto A. Uribe b, Martin Thiel c,d, Marcelo E. Oliva a, Jose M. Riascos a

a Instituto de Investigaciones Oceanologicas, Universidad de Antofagasta, Av. Universidad de Antofagasta 02800, P.O. Box 170, Antofagasta, Chileb Programa Doctorado en Ciencias Aplicadas Mención Sistemas Marinos Costeros, Universidad de Antofagasta, Antofagasta, Chilec Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chiled Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile

a b s t r a c ta r t i c l e i n f o

Article history:Received 16 July 2012Received in revised form 21 October 2012Accepted 23 October 2012Available online 30 October 2012

Keywords:Emerging BenthosBottom CurrentsSoft-bottom CommunitiesHumboldt Current Ecosystem

Post-larval dispersal along the sediment–water interface is an important process in the dynamics of macrobenthicpopulations and communities in marine sublittoral sediments. However, the modes of post-larval dispersal in lowenergy sublittoral habitats have been poorly documented. Herein we examined the specific dispersal mechanisms(diel vertical migration, water column, and bedload transport) and corresponding biological traits of the dispersingassemblage. At two sublittoral sites (sheltered and exposed) along the northern coast of Chile, we installed differenttrap types that capture benthic organisms with specific modes of dispersal (active emergence and passive watercolumn drifting) and also by a combination of mechanisms (bedload transport, passive suspension and settlementfrom the water column). Our results show that even though there were common species in all types of traps, thepost-larval macrobenthic assemblage depended on specific mechanisms of dispersal. At the sheltered site, abun-dant emerging taxa colonized sediments that were placed 0.5 m above the bottom and bedload-transported inver-tebrates appeared to be associated to the passive drifting of macroalgae. At the exposed site, assemblage dispersalwas driven by specific mechanisms e.g. bedload transport and active emergence. At both sites the biological traits“small size, swimming, hard exoskeleton, free living and surface position” were associated to water column andbedload dispersal. This study highlights the importance of (i) the water–sediment interface for dispersal of post-larvae in sublittoral soft-bottom habitat, and (ii) a specific set of biological traits when dispersing either along thebottom or through the water column.

© 2012 Elsevier B.V. All rights reserved.

1. Introduction

Dispersal is a key process influencing the dynamics of populationsand the patterns of diversity in marine benthic habitats (Levin, 2006).Connectivity between populations, distributional ranges, juvenile–adult interactions, colonization and recovery after a disturbance aresome examples of important processes that depend on the dispersalcapabilities of the respective organisms. Dispersal via meroplanktoniclarvae is driven by a combination of oceanographic transport processesand behavioral traits of larvae (Cowen and Sponaugle, 2009; Levin,2006; Metaxas, 2001). For many sessile hard-bottom species the disper-sive stage endswith settlementwhen larvae attach to a fixed position onthe substratum. However, in mobile meio- and macro-fauna inhabiting

soft-bottom habitats dispersal continues during post-larval or adultstages as there is no permanent attachment to the sediment (Armonies,1992, 1994; Ólafsson et al., 1994; Pacheco and Stotz, 2006). This is alsotrue for many species with direct development (Johnson et al., 2001;Levin, 1984; Ullberg and Ólafsson, 2003).

Post-larval dispersal of soft-bottom organisms is also mediated bymorphological and behavioral adaptations of the respective speciesand the effects of the hydrodynamics along the sediment–water inter-face. For example, mucus threads in bivalves and gas-bubbles retainedin the mantle cavity of some gastropods might act as buoyancy devicesfor passive dispersal (Cañete et al., 2007; Commito et al., 1995; Hunt,2004). In addition, marine sediment communities are dominated bycrawling, burrowing and swimming invertebrates, capable of activemovement and dispersal (Lenihan and Micheli, 2001).

A combination of behavior and hydrodynamics determines thedispersal dynamics of the emerging benthos, i.e. meio- and macro-fauna that regularly (daily or seasonally) migrate into the water col-umn. These organisms usually move at night but during daytime

Journal of Sea Research 77 (2013) 79–92

⁎ Corresponding author. Tel.: +56 55 637404; fax: +56 55 637804.E-mail address: [email protected] (A.S. Pacheco).

1385-1101/$ – see front matter © 2012 Elsevier B.V. All rights reserved.http://dx.doi.org/10.1016/j.seares.2012.10.004

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they assume a resting position in, on, or near the substratum, e.g. manyamphipods, cumaceans, ostracods, nematodes and other benthic taxa(Kaartvedt, 1986;Mees and Jones, 1997; Thistle, 2003). These organismsare dispersed by currents during their nocturnal incursion to the pelagos.

The relationship between dispersal of post-larvae and/or adultsand near-sediment hydrodynamics has been studied mainly in in-tertidal habitats where tidal currents provide the main mediumfor transport of organisms (e.g. Armonies, 1992; Hunt et al., 2009;Le Hir et al., 2007; Norkko et al., 2001). Some organisms may active-ly emerge during high tide, preferring weak currents for swimmingand migrating into the water column (e.g. Abello et al., 2005). Also,moderate (Commito et al., 1995; Turner et al., 1997) and very weakflow (Valanko et al., 2010a,b) may actively trigger benthic fauna toemerge, facilitating passive transportation along the seabed orthrough the water column. Stronger flow may erode the sedimentand thus transport many species, particularly small-sized fauna(Palmer, 1988; Zühlke and Reise, 1994). In turn, other species maybury deeply into the sediment to avoid being transported (Palmer,1988). Examples of such dynamics are scarce for sublittoral habi-tats, even though bottom currents may have the same intensity asin the intertidal zone (e.g. Valle-Levinson et al., 2000).

Most studies dealing with post-larval/adult dispersal or connectivityhave been evaluating dispersal rates, traveled distances, relationships be-tween dispersal and hydrodynamics (e.g. strength and seasonality), fo-cusing either on single species or on the whole assemblages (Commitoet al., 1995; Turner et al., 1997; Valanko et al., 2010a,b). However, theadaptive value of using a particular or a combination of dispersal mecha-nisms can be better understood by including the biological traits of thedispersive assemblage into the analysis (e.g. Boström et al., 2010). Thiswill allow, for example, evaluating if a specific transport mechanism fa-vors the dispersal of brooding species over species with planktonic larvaldevelopment, or the advantages/constraints in terms of size and bodyflexibility during dispersal.

Herein we study different mechanisms of post-larval dispersalincluding diel (i.e. daily) vertical migration, water column andbedload transport in two sublittoral sedimentary habitats (i.e. protectedand exposed) in northern Chile (Humboldt Current System). Theprotected site has weak bottom currents and low tidal energy, andthus active post-larval dispersal is thought to be important and pas-sive transport by resuspension events may only occur during un-usually strong wave conditions while at the exposed site passivedispersal may dominate under most current conditions (Pachecoet al., 2012). However, the contribution of the different dispersalmodes among the benthic assemblage remains unknown. We pre-dict that species with biological traits such as small body size,swimming capacity, direct development and living in the sedimentsurface will characterize the dispersal assemblage involving a morepelagic dispersal while traits such as large body, broadcast spawner,less motile and infaunal species will be depicted by a post-larvalspecies dispersing through bedload.

2. Materials and methods

2.1. Study sites

Macrobenthos patterns of diel vertical migration, water column andbedload transportwere studied using a set of different traps deployed attwo sublittoral sites in northern Chile, near Antofagasta (Fig. 1). This re-gion is characterized by strong upwelling, where cold waters with highnutrient and low oxygen contents rise to the surface (González et al.,2000; Guiñez et al., 2010; Pacheco et al., 2011). The first site (Bolsico:23°28′S; 70°36′W) is a small cove at the southern part of PeninsulaMejillones (Fig. 1). The second site (Colorado: 23°30′S; 70°31′W) is lo-cated in thenorthernpart of Antofagasta bay (Fig. 1). Both sites are shel-tered areas with relative calm conditions year round, which allowed usto conduct experiments in subtidal habitats. Nevertheless, Colorado is

more exposed to the prevalent northward wind and during days ofstrongwave swell, bottom currents may reach high velocity values. De-tailed descriptions of the abiotic conditions at both sites are available inPacheco et al. (2012).

2.2. Trap deployment

2.2.1. Re-entry trapsSpecies that perform diel vertical migration were quantified, as

they returned to the benthos, using re-entry traps which simulatednatural defaunated sediments (Fig. 2). Traps consisted of containers(plastic boxes of 26 cm high, 35×35 cm side, 1225 cm2 surface area),filled with defauned sediment. The sediment was collected from theupper and driest fringe of the beaches at both study sites. To ensurethat the sedimentswere similar between the two sites, granulometric pa-rameters of the experimental sediment (i.e. sorting degree, grain size av-erage and asymmetry) were estimated by sieving 100 g dry sedimentthrough geological sieves (from 4 to 0.063 mm), and then compared tothe parameters of sediments from the experimental sites. Although werecognize that the experimental sediment might cause different re-sponses for colonizing taxa, i.e. by attracting some taxa or repellingothers, previous experiments at both study sites had demonstrated thatthese experimental sediments are useful for capturing a representativefraction of benthic organism dispersing in the water column (Pachecoet al., 2010, 2012).

Two treatments were designed for these traps, “re-entry low”with low elevation that consisted of a container placed about26 cm above the bottom and “re-entry high”, with a higher eleva-tion that was achieved by placing the settlement container aboveanother, empty and inverted container that served as a supportplatform. This provided an elevation of 52 cm of the experimentalsediment above the natural bottom. During the night, vertical mi-grants emerged from the benthos, swam up into the water column,and then re-entered the sediment. Therefore, any colonizer in thehigh containers should have dispersed vertically at a height of atleast 52 cm above the bottom.

All containers (36 in total, 16 per treatment and four extras in case ofunforeseen losses) were installed on the bottom in two parallel lines,leaving 1.5 m distance between containers. Once a container was posi-tioned, closed bags with defaunated sediment were deposited inside.When all containers were installed, four scuba divers worked togetherin opening and filling the containers, trying to avoid disturbance of thesurrounding bottom as much as possible. All eight containers (i.e. eightfour high and four low treatments) were closed with plastic lids, leavingopen only those that were designed to be sampled after 24 h. During thenext day all the open containers were sampled and thereafter closed im-mediately. Once all the sampled containers were closed, a new set ofeight containers (four for each treatment) randomly assigned was leftopen until the next day. This sampling strategy was repeated duringfour consecutive days. None of the containers were sampled twice. Sed-iment collection was done in the sameway as for the reference samples,see explanation below.

2.2.2. Emergence trapsThese traps were designed to quantify macrobenthic organisms

that actively emerge from the sediment. The effect produced by thebottom hydrodynamics was reduced in this experiment in order toavoid passive resuspension. We used emergence traps (e.g. Junkinset al., 2006; Valanko et al., 2010a) that isolate a patch of seabedfrom the surrounding currents. Traps were constructed from 5 l cy-lindrical plastic buckets (21 cm diameter and 24 cm height) withan inverted funnel inside. The inner part of the cylinder lid was re-moved and replaced with a 0.5 mm mesh. The cylinder and themesh lid were white in color to ensure that the covered sediment re-ceived normal light levels during the day. The inner funnel (bottomdiameter 21 cm and top 4.5 cm) was made from translucent plastic.

80 A.S. Pacheco et al. / Journal of Sea Research 77 (2013) 79–92


The distance that the emerging organisms had to swim was 14 cm(length of the funnel) and the area of sediment from which animalscould emerge was ~1090 cm2. Two metal bars extending 20 cm

into the sediment were attached at two opposite sides of the trapto fit it in place. Five replicate emergence traps at each site were ex-posed for 24 h and then sampled. This deployment was repeated

0 10 20 Km

BahíaAntofagasta

Colorado

Bolsico

Antofagasta BayPacific Ocean

N

Isla Santa Maria

Antofagasta City

PenínsulaMejillones

23° 30’ S

70° 40’ W

Fig. 1. Location of study sites around the southern area of Peninsula Mejillones in northern Chile.

Sea floor

EmergenceRe-entry Water column drift Bedload

Emerging organismsentering into the

experimental sediment

Active emergence from the sediment

Water columntransport at 5 cm and

20 cm above the natural bottom

Bed load transport, water

column and motile organisms

HighLowHighLow

Fig. 2. Schematic representation of the trap designs and dispersal mechanisms evaluated in this study.

81A.S. Pacheco et al. / Journal of Sea Research 77 (2013) 79–92


during four consecutive days at each experimental site, adding up totwenty replicates in total. During sampling, traps were carefully re-moved by SCUBA divers and a rubber plug was inserted into theinner funnel for transport to the boat. Onboard, lids were removedand the interior part was washed with seawater over a 0.3 mmmesh. The collected organisms were then deposited in plastic bagssealed with marked rubber bands and preserved in a 10% formalin–methanol solution stained with Bengal rose. The emergence trapswere carefully washed and again placed at the sampling site for thenext sampling period.

2.2.3. Water column drift trapsOrganisms that are passively transported in horizontal direction

through the water column, i.e. the number of drifters passing througha site, were quantified using water column traps. These traps werebuilt by adapting the design used by Armonies (1994). Traps wereconstructed by cutting out the bottom of a plastic jar (16 cm diameterand 25 cm long) which was surrounded by a conical mesh sleeve(0.5 mm mesh size) that extended 40 cm from the bottom part ofthe jar to the end of the cone mesh. In order to keep the opening ofthe trap vertically positioned and perpendicular to the bottom, a0.5 l plastic bottle was tied to one side and a 10 cm steel bar anchorwas installed at the opposite side (see Fig. 2). The anchor was buriedin the sediment to keep the trap in a fixed position. Both flotationand anchoring devices were attached to the trap using snap hookswhich allowed the trap to freely rotate in its vertical axis, alwaysself-adjusting into the current direction without contact with thesediment. Two treatments were assigned, four traps elevated 5 cm(measured from the edge closest to the bottom) from the sedimentsurface, and another four traps at a distance of 26 cm from the bottom.Traps were installed on a line separating each trap by 1.5 m from thenext trap. In a pilot experiment exposing the traps for 12 h intervalin Bolsico, we determined that three days of exposure were necessaryto collect representative samples of dispersing organisms, thereforetraps were exposed for 3 days at each experimental site and this de-ployment was repeated four times. During sampling, the opening ofthe traps was closed with plastic lids, then removed from the snaphooks and put in plastic bags by SCUBA divers. Onboard the supportboat, the traps were deposited in large plastic buckets and rinsedwith seawater. The collected organisms were deposited in labeledplastic bags with the preservation solution. Traps were carefullywashed and again placed at the sampling site for the next samplingperiod.

2.2.4. Bedload transport and water column settlementBedload transport of macrobenthos along the bottom and settle-

ment from the water column was quantified using bedload traps.Traps consisted of funnels made of two cylindrical PVC pieces. Theupper part consisted of a funnel-shaped cylinder with 10 cm diam-eter at the opening and 3 cm diameter at the funnel end. The endpart was connected to a PVC cylinder of 15 cm length that servedas a collecting chamber. Traps were closed with plastic lids andinstalled by pushing them into the bottom until the top part wasflush with the sediment surface. Once all traps were installed thelids were removed. Five replicate bedload traps were deployed for24 h at each site. During sampling, the traps were closed and re-moved from the sediment and carefully deposited in mesh bags. On-board, all the collected material was transferred to labeled plasticbags with the preservation solution. Thereafter, the traps wereagain installed on the bottom. This deployment was repeated dur-ing four consecutive days. Since these traps also collected sedimentand drifting algae, organisms were separated and sediments weredried for 48 h at 70 °C and weighed (0.01 g precision). For algae thewet mass was recorded. Sediment and algae accumulating in the trapswere expressed in g day−1.

2.2.5. Natural reference communitiesTo obtain reference data from the natural community for compari-

sons with trap assemblages at both study sites five samples were hap-hazardly taken during each of the four consecutive sampling dates.We used a sampling core (10 cm diameter and 15 cm high) that waspushed 10 cm into the sediment in the ambient surrounding sediment.The collected sediment was carefully deposited in plastic bags andsealed with a marked rubber ring. In the field, samples were fixed in a10% formalin–methanol solution stained with Bengal rose. In the labo-ratory, samples from all traps and reference sediments were washedand sieved through a 0.5 mm mesh with a 0.3 mm mesh underneath,in order to retain very small organisms. Organisms were sorted, andidentified under a stereo-microscope to the lowest taxonomical levelpossible and counted.

At Bolsico sampling was successfully conducted during the exper-imental time, but at Colorado an unexpected very strong wave swelloccurred one day after the installation of the traps which swept awayre-entry traps and water column traps. Only four “high re-entry” andeight “low re-entry” traps were sampled. For the same reason, watercolumn traps at Coloradowere sampled only on two dayswith four rep-licate traps per day. Emergence and bedload traps together with refer-ence sediments were sampled completely.

2.3. Statistical treatment

2.3.1. Taxonomic compositionCorrespondence analyses were used to examine the association be-

tween taxa and the different trap types using the total taxonomic rich-ness. This analysis produces a biplot where adjacent points (samequadrants) are used to determine the association between taxa andtraps. The significance of the ordinations was tested using a chi-squaretest (Quinn and Keough, 2002). As the entire species/abundance matrixresulting from both experimental sites comprised 90 different taxa (seeAppendix), it was difficult to visualize associations in ordination plots.Therefore the BVSTEP routine was used to select the subset of specieswhich generates the samemultivariate sample pattern as would the en-tire assemblage set (Clarke and Gorley, 2006). This analysis uses Spear-man rank correlation to determine the minimum number of variables(i.e. taxa) that shows the highest correlation with the complete matrix.The selected sub-set of species was analyzed using multiple correspon-dence analyses looking for specific taxon associations with particulartrap types (i.e. dispersal mechanisms).

To evaluate significant differences between assemblages collect-ed in each trap type and reference assemblage a one-way ANOSIMwas conducted using the entire taxon data set. A previous two-wayANOSIM (considering sampling time and trap type as factors) didnot detect significant differences, neither for sampling time nor forthe interaction with trap type. Therefore the final analysis used thedata pooled per trap type. Due to the differences in volume andarea size of the different trap models used in this study, ANOSIMwas conducted based on the presence/absence Bray-Curtis similari-ty/dissimilarity distance matrix. Since this study focused on macro-and some meiobenthic organisms, other taxa such as fish, fish eggsand algae were not included in the ANOSIM. When the ANOSIM Rstatistics were significant, pair-wise comparisons were conducted.The packages BVSTEP and ANOSIM were run using PRIMER v6 (Clarkeand Gorley, 2006).

2.3.2. Biological trait analysisFor this analysis we selected eight biological traits divided into a

total of 37 categories (Table 1). The selected traits reflected adaptivecharacteristics for each species which are relevant during post-larvaldispersal processes (e.g. reproductive type, movement mode). Eachtaxon was coded for each trait category using the fuzzy-coding proce-dure (Chevenet et al., 1994). To perform this technique we used ascoring range of 0 to 3, with 0 meaning no affinity to a trait category



and 3 being total affinity. For example, the razor clam Tagelus dombeiiis primarily a filter feeder but it can switch to surface deposit-feedingdepending on food availability, and consequently it was coded 3 (fil-ter feeder) and 2 (surface deposit feeder) and 0 for the rest of the traitvariables corresponding to “feeding strategy”. This method is flexibleas the scores can be assigned based on expert opinions, own observa-tions and relevant literature (for information on species traits and thecorresponding references see supplementary data). This is importantin situations where the life history of many species is not yet welldocumented in the primary literature (Bremner, 2008; Törnroos andBonsdorff, 2012), as is the case for many species from the HumboldtCurrent Ecosystem.

Fuzzy correspondence analyses (Chevenet et al., 1994) were usedto evaluate differences between trait compositions among the differ-ent trap types. This ordination method works similarly like a multiplecorrespondence analyses using eigenvalues to reveal differences amongassemblages, based on the biological traits exhibited by each speciespresent in each trap type, weighed by their abundance. Correspondenceanalyses were performed using the software STATISTICA 6.0. To evalu-ate if the multivariable ordinations observed for assemblages' structurematch the ordinations produced by biological trait analysis both matri-ces were correlated using the RELATE routine implemented in PRIMERsoftware. This analysis allows the comparison of distance/similarityma-trices between two data sets using the Spearman-rank correlation coef-ficient (ρ) and the significance is assessed with a permutation test(Clarke and Gorley, 2006). Thus, the assemblage data set (Bray–Curtisdissimilarity matrix from abundance/taxa per trap) and the categories'trait data set (dissimilarity matrix based on Euclidian distance fromtrait scores pooled from the taxa abundance for each trap) were corre-lated for each study site.

3. Results

At Bolsico, the sheltered site, a total of 58 taxa were recorded with32 taxa exclusively found in traps. Twenty six taxa were registered inthe reference samples with 20 also present in the traps (Appendix 1).At Colorado, the exposed site, 78 taxa were recorded with 26 taxa ex-clusively found in traps. Forty seven taxa were registered in the refer-ence samples with 33 also present in the traps (Appendix 2).

Multiple correspondence analyses showed that, although therewere some taxa present inmore than one type of trap, particular assem-blages of dispersing organisms were associated to a specific trap, andconsequently ordinations were significant at both study sites (Fig. 3).At the protected site (Bolsico) the reference sampleswere clearly differ-entiated from all the trap samples, whereas at the more exposed site(Colorado) the reference samples were grouped together with the lowre-entry and the bedload traps (Fig. 3).

The principal species found in this study differ in their affinity totraps that capture organisms from the water column versus trapsthat accumulated organisms transported passively in the bedload(Fig. 4). Species that were abundant in the reference samples (e.g.Heterophoxus sp., Mysella sp., Branchiostoma elongatum and poly-chaetes) were also common in bedload traps, but showed relativelylow abundances in those traps that involve transport through thewater layer above the bottom (Fig. 4). In contrast, species thatwere abundant in water column traps (i.e. more pelagic speciessuch as harpacticoid and calanoid copepods, Aora typica) showedrelatively low abundances in the reference samples (Fig. 4), indicat-ing that large proportions of their populations regularly disperse via thewater column. The intermediate is exemplified by Eudevenopus gracilipesand nematodes, showing important abundances in dispersal traps andreference samples (Fig. 4). One-way ANOSIM (presence/absence data)comparing assemblages from all types of traps and reference assem-blages detected significant differences within both sites, Bolsico (R=0.55; Pb0.05) and Colorado (R=0.33; Pb0.05). Pairwise comparisonsshowed that with the exception of assemblages collected in re-entrytraps, there were significant differences among assemblages from alltypes of traps in Bolsico (Table 2). In Colorado, pairwise comparisonsshowed no difference among bedload, water column and re-entry traps.

3.1. Re-entry traps

At Bolsico amphipods species such as E. gracilipes, A. typica,Ampelisca sp., ostracods of the family Cylindroleberidae and Diastylisplanifrons were the most abundant taxa colonizing sediment sur-faces at 26 and 52 cm above the bottom. A one-way ANOSIM(square-root data transformed) detected no significant effects ofheight above the sediment on the assemblages colonizing re-entrytraps (R=−0.056; P>0.05). At Colorado, nematodes, lancelets B.elongatum and polyps of cnidarians were only found in containersthat were 26 cm above the bottom. At this site, no colonizers werefound in the few recovered high re-entry traps.

3.2. Emergence traps

In emergence traps fromBolsico, similarly as in the re-entry traps, am-phipods E. gracilipes and A. typica, and the cumaceans D. planifrons wereabundant, however, harpacticoid and calanoid copepods were also cap-tured in high densities. Some taxa such as gastropods like Nassarius gayiand Turritela cingulata were collected but not considered true emergingspecies because these were adults that most likely crawled through theinner funnel andwalls of the trap. At Colorado, harpacticoid and calanoidcopepods, nematodes,A. typica andB. elongatumwere commonemergingspecies, but the most abundant species were unidentified cnidarianpolyps. Emergence traps at this site showed the highest number of taxabut some species were not true emerging benthos, e.g. the gastropodsAenator fontanei, Mitrella unisfaciata, N. gayi, and some other species

Table 1Biological trait variables and categories used to describe macrobenthic assemblagescollected in the different sets of traps.

Trait Category

Size (measured as bodymass [gr])

Small (0.0001–0.01)Medium–small (0.02–0.1)Medium–large (0.2–1)Large (>2)

Movement method NoneSwimCrawl/creep/climbBurrow

Reproductive mode Asexual reproductionIndirect development (broadcast spawner)Indirect development (egg layer — planktonic larvae)Direct development (egg layer/brooder-mini adults)

Feeding strategy ProducerGrazerCarnivoreFilter feedersSurface deposit feedersSubsurface deposit feedersCarnivore/surface deposit feedersOmnivoreCommensalist/surface deposit feeders

Body design Soft-protected (tube/tunic cover)Hard exoskeletonHard shell Tube

Living habitat Permanent burrowTemporary burrowCrevice/hole/under stoneEpizoic/epiphyticTubeFree

Living location/position SurfaceInfauna: 0–5 cmInfauna: 6–10 cm



such as Tegula luctuosa. Ophiuroidswere likely to bepushed into the trapsdue to the turbulence caused by strong currents during the two first daysof the experiment.

3.3. Water column traps

At Bolsico, water column traps situated closer to the natural bot-tom captured slightly more taxa than those elevated 26 cm abovethe bottom (Appendix 1). One-way ANOSIM revealed significant

effects of the position above the bottom on the captured assemblage(R=0.07; Pb0.05). The most abundant taxa in these traps wereharpacticoid and calanoid copepods, amphipods E. gracilipes, A. typica,caprellids Caprella sp., cumaceans D. planifrons, brachyuran zoea andpolychaetes of the family Nereidae. At Colorado, no differences weredetected between assemblages collected in both types of water columntraps (ANOSIMR=−0.06; Pb0.05). In both trap types, caridean shrimps,harpacticoid and calanoid copepods were the most abundant collectedorganism.

Re-entry high

Re-entry low

Emergence

Bedload

Water column high

Watercolumnlow

Reference

Eudevenopus gracilipes

Aora typica

Dyastilis planifrons

Cylindroleberididae 1

Cylindroleberididae 2

Heterofoxus

Caprella sp.

Harpacticoidea

Mysella sp. Tagelus dombeii

Nereidae

Cirratulidae

Semele sp.

-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0

66.75% of Inertia

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

27.0

3% o

f In

erti

a

X2 = 6469.62; df = 72; P < 0.05

Bolsico

X2 = 606.496; df = 35; P < 0.05

Re-entry low

Emergence

Bedload

Water column high

Water column low

Reference

Branchiostoma elongatum

Aora typica

Nematoda ind.

Harpacticoidea

Calanoidea

Nereidae

Glyceridae

Orbinidae

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0

79.62% of Inertia

- 0.8

- 0.6

- 0.4

- 0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

10.1

9% o

f In

erti

a

Colorado

Fig. 3. Ordination plots obtained from the correspondence analysis using the taxa sub-set selected by the BVSTEP routine. Crustacea (C), Mollusca (M), Polychaeta (P), Nematoda(N), Urochordata (U).



3.4. Bedload transport

At Bolsico, this type of trap collected the highest number of taxacomparedwith the rest of the traps (Appendix 1). Diel verticalmigrantssuch as harpacticoid copepods, E. gracilipes, Heterophoxus sp., ostracodsof the family Cylindroleberididae, crawlers Pagurus spp., Pilumnoidesperlatus, Betaeus truncatus, N. gayi, and a few other species were collect-ed. In addition, drifting algae were also present in the bedload traps.Green algae (Ulva spp.) (7.2±7.8 g day−1), red algae Rhodymeniales(2.7±7.1 g day−1) and fragment of kelps Lessonia spp. and Macrocystisspp. (1.1±4.4 g day−1) were collected. Abundant amphipod A. typicawas collected within green algae pieces. Low quantities of transported

sediments were recorded in bedload traps site (2.7±13.4 g day−1).Similarly, at Colorado several taxa were collected in bedload traps, withpolychaetes (Glyceridae, Capitellidae), nematodes and harpacticoidcopepods being the most abundant. No drifting algae were collectedat this site, and in contrast to Bolsico, the amount of sediment col-lected in traps was higher (122.0±86.1 g day−1).

3.5. Biological traits and dispersion mechanisms

In line with the results of the species composition analysis, theexpression of the traits at both sites were successfully distinguishedamongwater column, bedload transport and reference samples as all

-1000 -500 0 500 1000 1500 2000 2500 3000 3500

CirratulidaeP

NereidaeP

Tagelusdombeii M

Semelesp. M

Cylindroleberididae1 C

Caprellasp. C

Cylindroleberididae 2 C

Diastylisplanifrons C

Mysellasp M.

Heterophoxussp C.

Eudevenopusgracilipes C

Aora typica C

HarpacticoidaC

Reference Bedload Emergence Water column low Re-entry low Water column high Re-entry high

BENTHIC PELAGIC

Numberof individuals/trap

-200 -150 -100 -50 0 50 100 150

Aora typica C

HarpacticoidsC

CalanoidsC

Branchiostomaelongatum U

Nematodaind. N

NereidaeP

GlyceridaeP

OrbinidaeP

Eudevenopusgracilipes C

Number of individuals/trap

Reference Bedload Emergence Water column low Re-entry low Water column high

Fig. 4. Total abundance of the taxa sub-set selected by the BVSTEP routine per each trap type and reference samples. Upper plot Bolsico, lower plot Colorado.



ordination analyses showed significant values (see Chi-square andprobability values in Fig. 5). At Bolsico three main associations weredetected: re-entry samples were associated to surface and subsurfacedeposit feeder, medium–small (size), soft-protected, egg layer/broodermini-adults, crawl/creep/climb and crevice/hole/under stone. Bedloadsamples were associated to filter feeder, surface, free, grazer, asexualand egg layer/brooder-planktonic larvae.Water column and emergencesamples showed affinities with small, tube, epizoic/epiphytic, swim,hard exoskeleton, and carnivore biological trait categories (Fig. 5). At Col-orado, bedload and water column samples showed affinities with hardexoskeleton, grazer, free, swim, omnivore and medium–small biologicaltraits. Asexual, tube, filter feeder, crevice/hole/under stone and surfacewere associated to emergence samples. Traits associated to re-entrysamples were accounted by soft-protected (tube/tunica cover), carni-vore, commensalist, broadcast spawner, soft, hard shell, small andmedi-um–large (Fig. 5). At both sites, traits such as permanent burrow andinfauna 0–5/6–10 cm were exclusively associated with reference sam-ples. The RELATE analysis between the ordination data matrices of thedispersal assemblages and trait categories showed significant correla-tions for both sites (Bolsico; ρ=0.74, Pb0.05 and Colorado; ρ=0.41,Pb0.05).

4. Discussion

This study shows for the first time in subtidal soft-bottom habitatshow macro-benthic organisms use distinct mechanisms of dispersalalong the bottom and water column. Mechanisms of dispersion in-cluded diel vertical migration, bedload and water column transportwhich resulted in distinct assemblages. The role of bottom hydrody-namics is important during dispersal. For instance, at the shelteredsite passive transport and driftingmacroalgae contributed to high levelsof bedload dispersal of macrobenthos. At the exposed site, where bot-tom currents were strong, a diverse assemblage of taxa was predomi-nantly eroded from the natural bottom.

4.1. Patterns of dispersal by emergence

Here we demonstrated that a rich and diverse assemblage emergedfrom the bottom during night and subsequently resettled to the naturalbottom. At Bolsico, where bottom currents were weak, invertebratessuch as amphipods, ostracods, cumaceans and polychaetes were con-spicuous colonizers of re-entry traps as they appeared at least 0.5 mabove the natural bottom. Reaching high above the bottom is importantfor dispersal and habitat selection during settlement (Ullberg and

Ólafsson, 2003), but also contributes to benthic–pelagic coupling(e.g. Vallet and Dauvin, 2001). Emerging benthos herein dispersedat least 0.5 m above the bottom, and experiments using re-entrytraps elsewhere have demonstrated that many of these taxa mayreach up to 6.5 m above the sediment surface, albeit densities areusually higher near the bottom (Alldredge and King, 1985; Boeckneret al., 2009). Emergence occurs under a wide range of hydrodynamicconditions ranging from intertidal (e.g. Armonies, 1988; Palmer, 1988)to sublittoral sheltered areas (Alldredge and King, 1985; Boeckneret al., 2009). However, our results suggest that active emergence intothe water column occurs preferably in weak current conditions. At Colo-rado, our exposed site, re-entry traps captured very few taxa and lowerdensities and nothing was collected in the re-entry traps placed higherabove the bottom. This was in contrast with the diverse and abundantinvertebrates collected in emergence traps whichwere deployed inten-tionally to exclude the current effects. The literature suggests that ben-thic organism may bury deeper in the sediment to avoid erosion whenbottom currents pass a certain threshold and sediments become erod-ed, and those species that are suspendedmaynot reach higher positionsin the water column (Armonies, 1994; Palmer, 1988; Valanko et al.,2010a; Zühlke and Reise, 1994). An alternative explanation would bethat species may actively emerge but the strong horizontal bottomflow precludes swimming up in the water column for reaching our ex-perimental sediments.

4.2. Patterns of bedload and water column dispersal

At the sheltered site, Bolsico, several taxa were collected but again,abundant water column migrants such as harpacticoid copepods, os-tracods, amphipods, and caprellids were likely to settle down fromthe water column into the collecting chamber of the bedload trap.Transport by means of drifting on algae was important as they tumblealong the seabed (e.g. Arroyo et al., 2006; Holmquist, 1994). Inbedload-trap samples containing green algae, abundant amphipods(mainly A. typica) were found. When developing in large blooms,green algal mats could impact benthic communities in multiple waysi.e. by producing either favorable or detrimental effects on speciespopulations (Bonsdorff, 1992; Norkko and Bonsdorff, 1996; Thieland Watling, 1998). At Bolsico, green algal mats were not toodense but enough to transport large quantities of A. typica.Similarly, high abundances of the amphipod Corophium volutatorin drifting green algae have been reported on subtidal sandybottoms in the Baltic Sea (Bonsdorff, 1992). Crawling species suchas hermit crabs Pagurus sp., gastropods and species that likelyarrived via passive resuspension e.g. bivalves Linucula pisum,Tagelus dombeii, Semele sp. were collected in bedload traps. Ourresults showed that at Bolsico, which is the low energy site, theinterface between sediment surface and water column is animportant zone for post-larval dispersal, thus underlining the re-sults of Valanko et al. (2010a) highlighting the importance of thistype of dispersal in low energy areas (i.e. non-tidal) in the BalticSea.

At Colorado, the exposed site, taxa were less abundant but rates ofsediment deposition were higher compared to Bolsico. Polychaetesand harpacticoid copepods were dominant at this location. Our find-ings of harpacticoids in bedload traps are not simple to explain: insublittoral areas with energetic flow, emergence of these copepodsis suppressed (Thistle, 2003), so at moments of calm conditions, e.g.at night when wind stress relaxes in this area, these species emergedand then settled in the collecting chamber where they are trappedwith the incoming sediment. This explanation is further supportedby the presence of harpacticoids in the water column traps, particu-larly those installed near the bottom. Other studies suggested thatharpacticoids are highly mobile, thus being very effective colonizers ofbare substratum by reentry into the sediment (e.g. Bell et al., 1989;Chertoprud et al., 2005). Overall, the results found at this location

Table 2ANOSIM R values of pairwise comparisons among assemblages collected in the differ-ent traps and reference samples. Re-entry high (REH), re-entry low (REL), emergence(EME), bedload (BL), water-column high (WCH), water column low (WCL) and refer-ence (REF). *Significant R values at 0.05 level.

REH REL EME BL WCH WCL

BolsicoREL −0.05EME 0.63* 0.54*BL 0.42* 0.41* 0.22*WCH 0.91* 0.78* 0.37* 0.28*WCL 0.91* 0.82* 0.32* 0.35* 0.07*REF 0.93* 0.8* 0.96* 0.5* 1* 0.99*

ColoradoEME – 0.48*BL – 0.11* 0.23*WCH – 0.07 0.29* 0.06WCL – 0.07 0.28* 0.05 −0.06REF – 0.73* 0.39* 0.27* 0.81* 0.83*



support our prediction thatmechanismof dispersal is associated to spe-cific organisms however some taxa (e.g. harpacticoids) disperse in abroad vertical front across all levels above the sediment surface.

In our water column traps, harpacticoid copepods were the mostabundant taxa togetherwithA. typica, calanoid copepods and brachyuranzoea. The presence of A. typica in such traps indicated that this amphipod

Bolsico Total inertia = 0.22; Chi2 = 75278.7; d.f. = 210; P < 0.05

Re entry high

Re entry low

Emergence

Bedload

WCHWCL

Reference

SmallMedium-small

Medium-large

Large

Asexual

Broadcast spawner

Egg layer/brooder-planktonic larvae

Egg layer/brooder mini -adults

Soft

Soft -protected (tube/tunica cover)

Hard exoskeleton

Hard Shell

Tube

Permanent burrow

Temporary burrow

Crevice/hole/under stoneEpizoic /epiphytic

FreeSurfaceInfauna 0-5cm

Infauna 6-10cm

Producer

Carnivore

Grazer

Omnivore

Filter feeder

Surface deposit feeder

Subsurface deposit feeder

Commensalist

None(movement method)

Swim

Crawl/creep/climb

BurrowJump

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

0.2-

0.0

0.2

0.4

0.6

0.8

Colorado Total inertia = 0.18; Chi = 8190,2; df = 170; P < 0.05

Re entry low

Emergence

BedloadWCH

WCL

Reference

Small

Medium-small

Medium-large

Large

Asexual

Broadcast spawner

Sexual (egg layer/brooder-planktonic larvae)

Egg layer/broodermini-adults

Soft

Soft-protected (tube/tunica cover)

Hard exoskeleton

Hard Shell

Tube

Permanent burrow

Temporary burrow

Crevice/hole/under stone

Epizoic/epiphytic

Free

Surface

Infauna 0-5cm

Infauna 6-10cm

Carnivore

Grazer

Omnivore

Filter feeder

Surface deposit feeder

Subsurface deposit feeder

Commensalist

None (movement method)

SwimCrawl/creep/climb

Burrow

-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Fig. 5. Ordination plots obtained from the correspondence analysis using the biological trait categories obtained from the fuzzy correspondence analysis. Re-entry high (REH),re-entry low (REL), water column high (WCH), water column low (WCL).



uses several ways of dispersal, either passively on drifting algae or by acombination of active swimming and current transport. The latter mech-anism is also evident for several other invertebrates. While harpacticoidcopepods are often reported in studies dealing with emergence patterns(e.g. Teasdale et al., 2004; Thistle, 2003; Thistle and Sedlacek, 2004;Thistle et al., 2007), the presence of calanoid copepods in water columntraps, near the bottom at both study sites, showed to be an importantindicator of dispersal also. In the Humboldt Current System calanoidcopepods are often regarded as the link transferring the huge prima-ry production of the system to higher trophic levels in the pelagicrealm, occurring in the shallowest and well-oxygenated fringe ofthe water column (Vargas et al., 2004). Their presence near the sea-bed shows that these organisms could also be important componentsof the sediment–water interface assemblage. However, their role andpossible interaction with benthic component need to be assessed infuture studies.

4.3. Mechanisms of post-larval dispersal and its expression in biologicaltraits

Post-larval and adult dispersal capability is an important character-istic of soft-bottom macrobenthic assemblages (e.g. Commito and Tita,2002; Grantham et al., 2003). Our analyses suggest that our set of bio-logical traits characterizes the dispersal mechanisms of this soft-bottomassemblage. At both sites, the biological traits that there weremost important for dispersal in the water column and bedload, in-cluding small size, swimming, hard exoskeleton, free-living andsurface position favor transport via these mechanisms of dispersal.Along the same line, Boström et al. (2010) showed that a similarset of biological traits (i.e. semi-mobile, direct development, detriti-vore and crawler) characterized the post-larval dispersal assemblage inthree contrasting habitats, dense seagrass meadows, seagrass patchesand unvegetated sediment, even though the assemblage compositionvaried considerably.

Since a large proportion of soft-sediment macrofauna speciesshowed direct development (as in Grantham et al., 2003; Ullbergand Ólafsson, 2003), we asked whether this trait filters out all possi-ble post-larval dispersal mechanisms assessed in this study. At bothsites, the trait “direct development” was associated with re-entrytraps. This suggests that species with direct development may emergeand take advantage of the currents for dispersal and the colonizationof new sedimentary habitat (mimicked by our traps with azoic sedi-ments). This strategy differs from the results from emergence traps inwhich no close association with any particular reproductive traits was

recorded. In terms of feeding strategy, the reference samples containedmost of the trait displayed in this category and no common patternswere elucidated from the correspondence analysis. This suggests plas-ticity in the way that the dispersive post-larval assemblages exploitfood resources (e.g. Cesar and Frid, 2012).

5. Conclusion and outlook

This study shows the mechanisms of post-larval dispersal of ben-thic organisms in sublittoral soft-bottom habitats in northern Chile(Humboldt Current System). Since our results represent a temporalsnapshot, future studies on seasonal variability could provide mean-ingful rates of water column and bedload dispersal of macro–meiobenthic assemblages in sublittoral habitats. Nevertheless, this studyshows the patterns of variation of biological traits involved duringpost-larval dispersal with the advantage that this is not merely in-ferred from the taxonomical composition analysis. Post-larval dis-persal is a key element of the recovery processes in sedimentaryhabitats after disturbance, thus the addition of biological trait analysiscan add important information about the functioning of the recover-ing assemblage.

Acknowledgments

We appreciate the help of E. Montanares, G. Benavides, L. Campos, K.Soto, P. Huerta, P. Romero, A. Sarmiento, R. Sarmiento, and F. Casas, dur-ing field and laboratorywork. P. Davila and J. Valdes helped uswith cur-rent measurements. Comments by J. Bremner and an anonymousreviewer helped us to improve an early version of this manuscript.R. A. Uribe is sponsored by a MECESUP scholarship. This research wasfunded by the FONDECYT post doctoral grant no. 3100085 to A.S.Pacheco.

Appendix 1

Abundance of taxa (mean±standard deviation per replicatesand sampling day, standardized per trap mouth area) recorded inexperimental traps at Bolsico. Re-entry high (REH, individuals/core 0.0078 m2), re-entry low (REL, individuals/core 0.0078 m2), emer-gence (EME, individuals/trap 0.346 m2), bedload (BLD, individuals/core0.0078 m2), water-column high (WCH, individuals/trap 0.201 m2),water column low (WCL, individuals/trap 0.201 m2) and reference(REF, individuals/core 0.0078 m2).

Taxa REH REL EME BLD WCH WCL REF

MolluscaNassarius gayi 0.3±0.9 1.05±1.4 0.13±0.34 0.11±0.32Mysella sp. 0.05±0.2 1.04±1.49 20.2±22.9Tagelus dombeii 0.05±0.2 0.63±0.88 3.44±2.91Linucula pisum 0.29±1.08 4.89±5.85Semele sp. 0.35±1.14 0.17±0.48 3.78±2.9Turritella cingulata 0.05±0.2 0.04±0.2Chiton sp. 0.04±0.2Mitrella unisfaciata 0.05±0.2Mytilid post-larvae 0.06±0.25 0.15±0.37 0.05±0.2 0.13±0.45Bivalve post-larvae 0.05±0.2 0.1±0.31

CrustaceaEudevenopus gracilipes 11.2±7.2 12.4±9.02 12.9±16.83 1.79±3.65 7.45±13.8 3.05±3.69 25.56±19.98Aora typica 1.13±1.5 7.5±26.31 3.1±2.19 25.83±33.7 14.15±7.34 27.95±18.7 0.56±1.1Diastylis planifrons 1.06±1.2 0.7±1.5 2.9±3.6 0.13±0.45 2.6±6.04 0.95±1.39 1.44±2.06Cylindroleberididae 1 0.44±0.7 0.35±0.75 0.14±0.36 1±1.29 0.1±0.31 0.15±0.49 2.44±3.76Cylindroleberididae 2 1.25±0.9 1.5±1.05 0.62±1.02 1.02±2.19 0.1±0.31 0.3±0.73 2.89±1.41Sarsiellidae 28.11±31.56Ampelisca sp. 0.25±1 0.9±2.36 0.05±0.2 0.04±0.2 0.05±0.2



Appendix 2

Abundance of taxa (mean±standard deviation per replicates andsampling day) recorded in experimental traps at Colorado. Taxa denot-ed with “*” were considered not true emerging benthos. -entry high

(REH, individuals/core 0.0078 m2), re-entry low (REL, individuals/core0.0078 m2), emergence (EME, individuals/trap 0.346 m2), bedload(BLD, individuals/core 0.0078 m2), water-column high (WCH,individuals/trap 0.201 m2), water column low (WCL, individuals/trap 0.201 m2) and reference (REF, individuals/core 0.0078 m2).

Appendix 1 (continued)

Taxa REH REL EME BLD WCH WCL REF

Mysidacea 0.06±0.25 0.1±0.31Pagurus post-larvae 0.19±0.5 0.1±0.31 0.05±0.2Heterofoxus sp. 0.19±0.87 1.46±2.47 36±15.44Campylonotus sp. 0.24±0.7 0.08±0.28 0.9±1.68Caridea 0.05±0.2 0.15±0.37Caprella sp. 0.76±2.39 1±3.65 1.4±1.23 1.75±1.59Harpacticoida 0.06±0.25 0.1±0.31 12.2±17.61 46.2±53.02 33.15±49.2 43.9±58.8Calanoida 3.86±6.39 1.88±3.39 5.3±7.63 8±13.49Stomatopoda 0.05±0.22Pagurus sp. 0.05±0.2 2.33±4.87 0.11±0.32Peracarida ind. 0.65±1.18Zoea brachiura 0.05±0.22 2.38±2.56 0.17±0.48 4.25±5.97 3.9±3.82Pilumnoides perlatus 0.08±0.28Betaeus truncatus 0.13±0.45 0.05±0.22Megalopa 0.24±0.44 0.04±0.2 0.1±0.31 0.3±0.57 0.22±0.65Majidae post-larvae 0.08±0.41Isopoda 0.1±0.3Melita sp. 0.11±0.32Tanaidacea 0.13±0.61Caligidae 0.05±0.22 0.05±0.22

PolychaetaPolynoidae 0.05±0.22 0.08±0.28 1.56±2.18Boccardia sp. 0.31±0.79 0.1±0.31 0.52±0.68 0.42±1.02 0.35±0.81 0.33±0.69Nereidae 0.25±0.79 0.05±0.22 0.58±1.1 1.75±2.24 1.05±1.15 0.11±0.32Phyllodocidae 0.08±0.28 0.55±1.15Cirratulidae 0.15±0.49 0.1±0.3 0.17±0.38 0.05±0.22 3.11±2.4Spiophanes bombyx 6.67±9.06Paraprionospio pinnata 0.33±0.69Maldanidae 0.21±1.02 0.22±0.43Arenicola sp. 0.2±0.89Polychaeta larvae 0.19±0.68 0.29±0.75 0.45±0.94 0.35±0.67Gliceridae 0.11±0.32

NemerteaNemertea ind. 0.33±0.49

EchinodermataOphiuroidea 0.05±0.22

NematodaNematoda ind. 0.13±0.34 0.65±2.25 0.05±0.22 0.29±0.75 0.05±0.22 0.22±0.65

ChordataFish egg 0.43±0.81 0.9±2 1.3±2.03Fish larvae 1.05±2.58 0.08±0.28 0.05±0.22

CnidariaCnidaria ind. (jellyfish) 0.1±0.3 0.1±0.4

AlgaeGreen (g) 7.16±7.8Red (g) 2.67±7.1Brown (g) 1.05±4.49

Taxa REL EME BLD WCH WCL REF

MolluscaTransenella pannosa 0.09±0.29 0.27±0.54Nassarius gayi* 0.03±1.9Trigonostoma sp.* 0.03±1.9 0.05±0.21 0.05±0.21Tegula luctuosa* 0.03±1.9Mitrella unisfaciata* 0.03±1.9Argobuccinun rude 0.09±4.2

(continued on next page)





Crucibulum sp. 0.05±0.21Semele sp. 0.09±0.29Xantochorus buxea* 0.03±1.9 0.05±0.21 0.14±0.34Oliva peruviana 0.05±0.21 0.91±1.38Cancelaria buccinoides 0.05±0.21Aenator fontanei* 0.03±0.19 0.09±0.29Chiton sp. 0.05±0.21 0.05±0.21Bivalve post-larvae 0.03±0.19 0.05±0.21 0.18±0.65Polinices uber 0.05±0.21

CrustaceaMysidacea 0.05±0.21Ampelisca sp. 0.05±0.21Eudevenopus gracilipes 0.14±0.58 0.05±0.21Liljeborgiidae 0.1±0.41 0.09±0.29Aora typica 0.86±1.79 0.05±0.21 0.63±1.19 0.5±1.41 0.09±0.29Pagurus post-larvae 0.07±0.26Cylindroleberididae 1 0.14±0.44 0.13±0.35Diastylis planifrons 0.1±0.31Sarsiellidae 0.14±0.34Paracorophium sp. 0.05±0.21 0.14±0.62Heterophoxus sp. 0.03±0.19 0.05±0.21Campylonotus sp. 0.17±0.38 0.5±1.07Caridea 1.13±3.18 0.25±0.46Caprella sp. 0.07±0.26Harpacticoida 1.48±2.73 1.14±2.57 0.75±1.49 4.5±8.07 0.05±0.21Calanoida 0.48±0.83 0.05±0.21 0.75±1.75 3.13±5.64Peracarido ind.1 0.05±0.21Isopoda 0.03±0.19 0.13±0.35Pagurus sp. 0.05±0.21Zoea brachiura 0.41±1.18 0.09±0.43 0.63±1.19Melita sp. 0.03±0.19Tanaidacea 0.03±0.19 0.09±0.29 0.09±0.29Caligidae 0.03±0.19 0.18±0.57Cancer setosus post-larvae 0.14±0.35Peracarida ind.2 0.07±0.37Lopadorynchidae 0.09±0.29

PolychaetaNereidae 0.41±0.73 0.18±0.66 0.13±0.35 2.41±2.93Phyllodocidae 0.07±0.37Cirratulidae 0.05±0.21Nephtyidae 0.05±0.21Polynoidae 0.03±0.19 0.14±0.62Spiophanes bombyx 0.14±0.62Polychaeta larvae 0.03±0.19Spionidae 0.03±0.19 0.05±0.21 0.13±0.35Arenicola sp. 0.14±0.34Gliceridae 0.59±1.53 3.41±5.17Lumbrineridae 1.05±1.4Orbinidae 0.05±0.21 3.41±5.42Diopatra sp. 0.09±0.29Ophelidae 0.09±0.29Dorviellidae 0.14±0.52 0.05±0.21Goniadidae 0.05±0.21 0.32±0.63Capitellidae 0.55±2.34 10±11.94Pilargidae 0.05±0.21 0.45±1.7Hesionidae 0.03±0.19 0.09±0.29 0.32±0.76Sabellaridae 0.05±0.21Syllidae 0.09±0.42Pisionidae 0.14±0.46Terebellidae 0.05±0.21Apistobranchidae 0.05±0.21Polychaeta ind. 0.03±0.19 0.91±2.52

NematodaNematoda ind. 0.4±1.26 0.41±1.21 0.41±0.8 3.36±6.35

EchinodermataOphiuroidea* 0.1±0.31 0.09±0.29Asteroidea post-larvae 0.03±0.19

ChordataBranchiostoma elongatum 0.2±0.63 0.76±1.06 0.27±1.08 7.05±6.17Fish egg 1.83±3.21 0.23±0.75 10.38±15.6 15±31.9Fish larvae 0.1±0.56

2



Appendix 3. Supplementary data

Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.seares.2012.10.004.

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CnidariaCnidaria ind. Polips. 0.1±0.32 3.14±9Cnidaria ind. (jellyfish) 0.28±1 0.09±0.29

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