Aquaculture 356–357 (2012) 48–54

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Spatial variation of benthic infaunal communities in baie de Gaspé(eastern Canada) — Influence of mussel aquaculture

Christopher W. McKindsey a,b,⁎, Philippe Archambault b, Nathalie Simard a

a Fisheries and Oceans Canada, Institut Maurice-Lamontagne, Environmental Sciences Division, 850 route de la Mer, P.O. Box 1000, Mont-Joli (Québec) Canada G5H 3Z4b Institut des sciences de la mer (ISMER), Université du Québec à Rimouski, 310, allée des Ursulines, CP 3300, Rimouski (Québec) Canada G5L 3A1

⁎ Corresponding author at: Fisheries and OceanLamontagne, Environmental Sciences Division, 850 roMont-Joli (Québec) Canada G5H 3Z4. Tel.: +1 418 775

E-mail address: chris.mckindsey@dfo-mpo.gc.ca (C.W

0044-8486/$ – see front matter. Crown Copyright © 20doi:10.1016/j.aquaculture.2012.05.037

a b s t r a c t

a r t i c l e i n f o

Article history:Received 27 October 2011Received in revised form 25 May 2012Accepted 28 May 2012Available online 6 June 2012

Keywords:Suspended bivalve aquacultureMusselBenthosEnvironmental impact

This study examines the effect of mussel farming on benthic infaunal communities in baie de Gaspé, easternCanada, at two spatial scales: 10 m (directly under vs. between mussel longlines — Position) and 100 m(between mussel farm and reference locations — Treatment, each of which was replicated at 4 Sites). Noneof the evaluated univariate descriptors of benthic communities (abundance, taxonomic richness, Shannon–Weiner diversity, AMBI, and M-AMBI) differed between Treatments or among Positions within Sites in anyconsistent way. Similarly, multivariate community structure also did not differ among Treatments. In contrast,multivariate community structure directly under mussel lines differed from that between mussel lines in 3 of4 mussel farm sites whereas none of the reference sites showed such 10 m-scale variation. Of the species thataccounted for the greatest proportion of the dissimilarity between Positions within mussel farm sites, second-order opportunistic species (Prionospio steenstrupi and Pectinaria granulata) were consistently more abundantdirectly under mussel lines than between them. Species belonging to other ecological groups did not showany consistent trends. It is suggested that studies that do not considerwithin-site (10 m-scale, below vs. betweenlonglines) variationmay fail to detect the influence of suspended bivalve culture in some cases. Overall, effects ofmussel culture in baie de Gaspé were slight and within the natural variation of benthic communities in the area.This suggests that the current industry should be sustainable. However, plans to expand the industry in theregion remain to be evaluated with respect to the ecological carrying capacity of the entire bay.

Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved.

1. Introduction

The farming of bivalves has been increasing worldwide at anaverage annual rate of about 7% since 1970 (FAO Fisheries andAquaculture Department, 2010). The practice is often considered tohave less of an influence on the sea bottom than fish culture asbivalves do not require any inputs for growth, obtaining their foodfrom the surrounding natural environment (National ResearchCouncil, 2009). However, bivalves in culture filter considerablevolumes of water and undigested material sinks rapidly to the bottomas feces and pseudofeces, potentially leading to localized organicenrichment. Suspended bivalve culture has been shown to havebenthic effects ranging from undetectable (e.g., Crawford et al., 2003)to great (e.g., Mattsson and Lindén, 1983) and may affect sedimentcharacteristics, benthic communities, oxygen consumption, and nutri-ent fluxes (see recent reviews in Dumbauld et al., 2009; Forrest et al.,

s Canada, Institut Maurice-ute de la Mer, P.O. Box 1000,0667; fax: +1 418 775 0718.. McKindsey).

12 Published by Elsevier B.V. All rig

2009; McKindsey et al., 2011). There is thus concern that the practicemay further stress already overtaxed coastal areas.

The development of integrated coastal zone management (ICZM)and ecosystem-based management (EBM) has led to a general increasein the knowledge of the general public on issues relating to coastalresources, including aquaculture (Byron et al., 2011). The sustainabilityof an area for bivalve culture is a function of its ecological carryingcapacity — the level of culture that can be supported that does notlead to significant changes in local ecological processes, species,populations or communities (Gibbs, 2007), with the benthic environ-ment being a primary factor of importance (Fabi et al., 2009).

Recently, there has been increasing concern that suspended bivalve(mussel) aquaculture in the baie de Gaspé, eastern Canada, is having anegative impact on benthic communities in the bay. Local communityand environmental groups have requested that work be undertakento determine the sustainability of current bivalve culture operationsand the ecological carrying capacity of the bay for suspended bivalveculture. There are also plans to greatly expand aquaculture activitiesin the bay through the establishment of areas dedicated to aquacultureactivities. However, there is currently no information about the benthiccommunities in the bay or about the influence of aquaculture on them.To that end, this paper reports the results of an initial scoping study to

hts reserved.

49C.W. McKindsey et al. / Aquaculture 356–357 (2012) 48–54

determine the spatial variation in benthic infaunal communities as theyrelate to the distribution of mussel culture leases within the bay. Thisinformationwill serve to initiate the process of determining the sustain-ability of the bay for bivalve aquaculture operations.

Sedimentation related to mussel biodeposit production may varyconsiderably within mussel farms with consequent impact on patternsof benthic communities (McKindsey et al., 2011). In general, weakcurrents are associated with a concentration of biodeposits directlybelow farms (Weise et al., 2009) and, accordingly, effects may be con-centrated in or limited to areas directly below mussel lines or close tofarms (Callier et al., 2007, 2008). A sampling design able to detectthese small-scale effects as well as larger-scale effects is thus rec-ommended. This present study uses such an approach, which describesthe natural variation of benthic communities at 2 spatial scales to eval-uate the effect of suspended mussel culture in the study area.

2. Material and methods

2.1. Study area

This study was done in baie de Gaspé, eastern Canada. The studyarea covers about 20 km2 and has a maximum depth of about 25 m.The part of baie de Gaspé where bivalve culture is done is a semi-enclosed area with a sand-spit separating this portion of the bayfrom the outer portion (Fig. 1). Two main rivers enter the innerbay: the York and Dartmouth rivers, which enter from the west andnorthwest, respectively. The discharge of both rivers varies from aminimum of about 1 m3 s−1 during the winter to a maximum ofabout 80 to 90 m3 s−1 during spring floods and is between about 3and 10 m3 s−1 for a little more than half of the year (Centred'expertise hydrique du Québec, 2011). Mussel production in the baystarted in 1994 and there are currently several lease areas (Fig. 1).Given the infrastructure presently in the bay, there is the possibility ofproducing almost 500 t of mussels annually, although production ismuch below this level at about 70 t (C. Cyr, pers. comm.).

2.2. Sampling design

Four sites were sampled within mussel farms (farm sites) and afurther 4 sites sampled outside of the farms at a distance of at least100 m from the closest farm site and at similar depths and similarenvironmental conditions (reference sites). Sampled sites were be-tween 14 and 22 m deep and mean depth did not differ betweenmussel farm and reference sites (t-test, p=0.273, mean of 17.2 and18.7 m in reference and farm sites, respectively). Within each site, 5sample cores (10 cm diameter, 10 cm deep) were collected by scubadivers in each of 2 positions. In farm sites, 5 cores were taken directlybelow mussel lines with commercial-size (2 years old) mussels

Fig. 1. Location of study area and sampling sites in baie de Gaspé, eastern Canada. Polygons rby ■, ▼, ●, and ▲ for reference sites 1 through 4 and by ♦, , ★, and ✚ for mussel farm si

(northeast — NE position) and 10 m southwest of these, directly be-tweenmussel lines (SW position), to account for small-scale variationin benthic communities due to localized effects related to relativelygreater biodeposition directly below lines. Reference sites weresampled in the same manner with respect to NE and SW positionsbut without the presence of mussel lines. This sampling strategyallows for both 10 m- and ca. 100 m-scale effects to be evaluated andto avoid confounding with natural variation in community structure(Callier et al., 2007). All sampling was done over a 3 day period inOctober 2008.

Samples were washed through a sieve with a 500 μmmesh and allmaterial thus trapped was preserved in 7% buffered formalin untilbeing processed in the laboratory. The recovered fauna was identifiedto the highest taxonomic resolution possible, usually to species. Sam-ples were characterized in terms of abundance, taxonomic richness,Shannon–Weiner diversity, multivariate community structure, andin terms of 2 marine biotic indices: the AZTI Marine Biotic Index(AMBI, Borja et al., 2000) and Multivariate-AMBI (M-AMBI Muxikaet al., 2007). AMBI and M-AMBI were calculated using AMBI 4.1.When an identified species was not in the AMBI database, the mostsimilar species was used to represent it for subsequent calculationsor, if the sensitivity of a species or a closely related groupwas unknown,it was removed from subsequent analyses. Thus 11 species wereremoved, accounting for less than 1% of all individuals collected andnever more than 10% of taxa and 6% of individuals recovered from anyone sample. For the calculation of M-AMBI, default “bad” and “high”reference conditions in the software were used (i.e., AMBI, richnessand diversity values of 6, 0, and 0 for “bad” conditions and the smallestAMBI and greatest richness and diversity values observed in the currentproject for “high” conditions, respectively) as historical data were notavailable for the study area (Borja et al., 2012; Muxika et al., 2007).

2.3. Statistical analyses

Variation in univariate measures of benthic community structurewas evaluated using ANCOVA, with Treatment (mussel farm or refer-ence sites), Position (NE and SE, corresponding to directly below andbetween mussel lines in farm sites, respectively) and Depth (by itselfand crossed with Treatment) as fixed factors and Site (nested withinTreatment) as a random factor using Mixed Model Analysis in SYSTAT13. Subsequent ANOVA models (see Results section) were run usingGMAV5 for Windows. Homoscedasticity and normality of univariatedata were evaluated using Cochran's Tests (Underwood, 1997) and byexamination of residual plots (Quinn and Keough, 2002), respectively,and no issues were detected. Differences between treatment meanswere evaluated with Student–Newman–Keuls tests. Variation in multi-variate community structure was visualized using non-metric multi-dimensional scaling (MDS) and evaluated using PERMANOVA (global

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epresent existing mussel farms at the time of sampling. Sampling sites are representedtes 1 through 4, respectively.

50 C.W. McKindsey et al. / Aquaculture 356–357 (2012) 48–54

test) and ANOSIM (paired tests within sites) using PRIMER 6 andPERMANOVA+. The SIMPER procedure (Clarke, 1993) was used todetermine which species contributed the most to the dissimilaritybetween paired NE–SE samples within sites in which there were signif-icantmultivariate Position effects (see below). All multivariate analysespresented were done using raw abundance data as typical transforma-tions yielded roughly equivalent results.

3. Results

There were clear depth-related effects for most univariate mea-sures of infaunal community structure (Fig. 2) and the effect ofdepth never interacted with Treatment (i.e., the effect of Depth didnot vary between reference and farm sites, ANCOVA, p>0.25 in allcases, data not shown — see Fig. 2). The removal of the factor Depthdid not change the outcome of the statistical tests and thus it wasremoved from subsequent analyses to facilitate interpretation. Themean abundance, taxonomic richness, and Shannon–Weiner diversityof infauna varied between 42.4 and 120.6 individuals, 7.2 and 24 taxa(of a total of 117 identified), and 0.96 and 2.11, respectively, per corewithin positions in sampling sites and did not vary significantly be-tween Treatments, Positions, or as a consequence of the interactionbetween Treatment and Position (Fig. 3, Table 1). In contrast, therewas significant variation among replicate Sites within Treatmentsfor all univariate measures. Taxonomic richness varied between Posi-tions among Sites within Treatments although not in a consistentmanner (Fig. 3, Table 1).

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r2 = 0.01, P = 0.26

r2 = 0.48, P < 0.001

r2 = 0.61, P < 0.001

Fig. 2. Effect of sample site depth on the abundance, taxonomic richness, Shannon–Weiner dData from within single sites (i.e., from samples taken from northeast and southwest posiprobabilities indicated in each subfigure are the results of linear regressions using raw data

Individual AMBI values varied from 1.57 through 3.72 (slightlypolluted through meanly polluted) but mean values within positionsin sites were all classified as slightly polluted. AMBI did not vary as afunction of Treatment, Position, or their interaction but did varyamong Sites within Treatments and as a function of the interactionbetween the three main effects (Table 1, Fig. 4). Similarly, individualM-AMBI values varied from 0.88 through 0.44 (moderate throughhigh condition) and mean values within positions in sites were eithermoderate or good. Unlike for AMBI, M-AMBI varied significantly onlyamong Sites within Treatments (Table 1, Fig. 4).

Multivariate community structure varied greatly between Siteswithin Treatments but not between Treatments (i.e., not betweenfarm and reference sites, Table 1). Consequently, there is a great over-lap of symbols representing samples from different Treatments in theassociated MDS graph and individual sites overlap to a lesser degree(Fig. 5). Globally, Position did not interact with Treatment althoughthe influence of Position varied among Sites within Treatments(Table 1). Examination of the pattern of variation in multivariatecommunity structure at the 10 m-scale shows that, within farmsites, samples in the NE position (under lines) generally differedfrom those from the SW position (between mussel lines) whereaspaired Positions in reference sites never did (Table 2, Fig. 5).

A closer inspection of the multivariate data shows that relativelyfew species contributed to the dissimilarity of samples from Positionsunder and between mussel lines within farm sites (Table 3). More-over, when the ecology of the different species that contribute themost to dissimilarity between Positions is considered, there is a generaltrend for those classified as being second-order opportunistic species

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iversity, and AMBI and M-AMBI values (±SE) for infaunal samples from baie de Gaspé.tions within sampling sites) are pooled for graphical representation. Correlations and(i.e., all 80 data points).

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Fig. 3. Variation in the abundance, taxonomic richness, and Shannon–Weiner diversity(+SE) of benthic infaunal communities from reference (R-1 through R-4) and mussel(M-1 through M-4) sites in baie de Gaspé. Filled and empty bars represent samplestaken from northeast (i.e., below mussel lines in farm sites) and southwest (i.e., betweenmussel lines in farm sites) positions within sampling sites, respectively.

Sample sitesR-1 R-2 R-3 R-4 M-1 M-2 M-3 M-4

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Fig. 4. Variation inmean AMBI andM-AMBI values (+SE) for benthic infaunal communi-ties from reference (R-1 through R-4) and mussel (M-1 through M-4) sites in baie deGaspé. Filled and empty bars represent samples taken from northeast (i.e., below mussellines in farm sites) and southwest (i.e., between mussel lines in farm sites) positionswithin sampling sites, respectively.

51C.W. McKindsey et al. / Aquaculture 356–357 (2012) 48–54

(Group IV from AMBI — see Borja et al., 2000) to be more abundantunder mussel lines than between them. In contrast, species from eco-logical groups I through III (very sensitive though tolerant to excessorganic enrichment) showed no consistent trends with respect to Posi-tion and those from Group V (first-order opportunistic species) did notcontribute to any extent to the dissimilarity of samples from below andbetween mussel lines within farm sites.

Table 1Summarized results (probabilities) of ANOVAs (abundance, taxonomic richness – richnesscommunity structure — Multivar) to evaluate the spatial variation in benthic community strsites for each treatment) and Position (northeast and southwest — under and between mu

Source of variation Abundance Richness

Treatment (Treat) 0.222 0.811Site (Treat) b0.001 b0.001Position 0.301 0.387Position×Treat 0.126 0.212Position×Site(Treat) 0.290 0.010

4. Discussion

This study shows that the effects of mussel aquaculture activities inbaie de Gaspé on benthic infaunal communities are indistinguishablefrom natural variation in the embayment. At the scale of 100 m, noneof the univariate or multivariate indices measured in the presentstudy varied between farm and reference sites, although there wasconsiderable variation among farm sites and among reference sites.Likewise, the univariate indices abundance, taxonomic richness, andShannon–Weiner diversity and biotic indices AMBI and M-AMBI alsodid not vary among Positions (NE/under mussel lines, relative to SW/between mussel lines) in any consistent manner. In contrast, multivar-iate analysis showed that 3 of four farm sites had communities directlyunder mussel lines that differed from those 10 m distant, between themussel lines, whereas position had no effect within reference sites.

These results are similar to those of Callier et al. (2007) who evalu-ated the influence of suspended mussel culture in Great-Entry Lagoon,îles de la Madeleine, eastern Canada, using a sampling design similarto the one used in the present study. In short, that study compared in-faunal communities below and between mussel lines (or with respect

, Shannon–Weiner diversity – H′, AMBI, and M-AMBI) and PERMANOVA (multivariateucture in baie de Gaspé due to Treatment (farm or reference sites), Sites (four separatessel lines, respectively, in farm sites). Statistically significant values indicated in bold.

H′ AMBI M-AMBI Multivar

0.741 0.558 0.777 0.615b0.001 b0.001 b0.001 0.0010.162 0.890 0.103 0.5880.904 0.901 0.567 0.7550.316 0.002 0.508 0.001

Fig. 5. MDS plot of benthic infaunal communities (untransformed data) from reference (gray) sites 1 through 4: ■, ▼, ●, ▲ and mussel (black) sites 1 through 4: ♦, , ★, ✚,respectively, in baie de Gaspé. Filled and empty symbols represent samples taken from northeast (i.e., below mussel lines in farm sites) and southwest (i.e., between mussellines in farm sites) positions within sampling sites, respectively. The plot on the right provides detail of the MDS plot on the left.

Table 3List of species that contribute most to the multivariate dissimilarity between Positionswithin Sites that differed significantly in baie de Gaspé. Data includes average dissim-ilarity (AD) between samples from the 2 Positions, the names of the most importanttaxa that contributed to the dissimilarity, the ecological groups to which each speciesbelongs (EG), the average abundance of each species in northeast/below (NE) andsouthwest/between (SW) Positions, its average contribution dissimilarity between po-sitions (AvDiss), its total % contribution to the total dissimilarity between Positions

52 C.W. McKindsey et al. / Aquaculture 356–357 (2012) 48–54

to geographic ordinations) in sites with 1 year old (0+) and 2 year old(1+) mussels and reference sites. Infaunal communities did notdiffer among Treatments with respect to abundance but did in termsof taxonomic richness (0+>Ref>1+) and Shannon–Weiner diversity(0+=Ref>1+); the effect of Positionwas never significant. Multivar-iate community structure varied among all Treatments and betweenPositions within 1+ sites. Unlike the present study, Callier et al.(2007) found that this effect was general for the study area such thatindividual sites within Treatments (reference and 2 age classes ofmussels) were indistinguishable. A further study by Callier et al.(2008) compared spatial variation in infaunal communities along tran-sects leading away from directly below the outer longline in 2 musselfarms in îles de la Madeleine and found that abundance, taxonomicrichness, and biomass changed very rapidly such that samples fromdirectly under mussel lines differed from those only 3 m away in onefarm but not the other.

Together with the results of the present study, this suggests thatsmall-scale (10 m or less) influences of longline mussel culture maybe common and that studies should consider this when beingdesigned and interpreted as effects may be limited to directly belowlines and not be greater than the natural variability of the study sys-tem. To our knowledge, other than Callier et al. (2007, 2008) andthe present study, only Christensen et al. (2003) have also comparedcommunities directly below and between mussel lines using precisesampling methods (i.e., diver-collected cores). They found that com-munities within the studied New Zealand mussel farm differed fromthose at a reference site but did not vary between Positions belowand between mussel lines. However, the proximity of the differentsampling locations in this study is not clear and thus the reported100 m-scale effects and lack of 10 m-scale effects may be confoundedwith natural spatial variation in benthic communities.

Table 2Results of within-site pair-wise comparisons (ANOSIM) of multivariate communi-ty structure from samples from northeast and southwest positions in baie deGaspé. Sites R-1 through R-4 and M-1 through M-4 refer to reference and musselfarm sites, respectively. Statistically significant values indicated in bold.

Site R statistic p

R-1 −0.052 0.627R-2 0.060 0.262R-3 0.036 0.325R-4 −0.124 0.913M-1 0.378 0.016M-2 0.368 0.024M-3 0.052 0.246M-4 0.422 0.016

Netto and Valgas (2010) sampled nematode assemblages directlybelow mussel lines in Brazil using divers and compared these to ref-erence areas outside of the farm. Other studies that have comparedinfaunal assemblages directly below mussel longlines to those in ref-erence locations (e.g., da Costa and Nalesso, 2006; Miron et al., 2005)have used remote methods (i.e., grabs) but the precision of this sam-pling method is unknown. Thus, it is not clear if mussel farm-relatedpatterns observed by Netto and Valgas (2010) are general for thestudied culture site or restricted to the areas directly under mussellines whereas this uncertainty is compounded in the latter 2 studiesbecause of the imprecise nature of sampling with remote grabs. Inter-pretation of studies that do not specify how collected samples wereorganized spatially within farm sites or state that they were collectedrandomly is difficult as potential spatial structure at the 10 m-scale(i.e., under vs between mussel lines) may mask larger-scale effects.At a larger scale, given the evident spatial variation in benthic infau-nal community structure observed in the present study, if only a sin-gle farm site and reference site had been compared, very differentconclusions would have been drawn, depending on which sites hadbeen compared. This underlines the importance of sampling multiplesites within and outside of farms, as an increasing number of studieshave done (e.g., Danovaro et al., 2004; Fabi et al., 2009; Netto andValgas, 2010).

(Cont %), and the cumulative % dissimilarity between Positions (Cum %).

Site (AD) EG NE (#) SW (#) AvDiss Cont % Cum %

M-1, AD=34.66Prionospio steenstrupi IV 17.6 7.2 9.97 28.78 28.78Scoloplos armiger III 2.6 7.2 5.57 16.07 44.85Aglaophamus neotenus II 22.6 23.6 4.96 14.30 59.15Aceroides latipes * 3.2 1.8 2.31 6.65 65.80

M-2, AD=41.59Aglaophamus neotenus II 32.8 32.2 18.35 44.13 44.13Prionospio steenstrupi IV 12.4 2.8 8.34 20.05 64.18Scoloplos armiger III 8.6 9.8 2.5 6.01 70.19

M-4, AD=52.76Prionospio steenstrupi IV 31.0 13.2 18.15 34.40 34.40Aglaophamus neotenus II 8.8 10.0 5.34 10.12 44.52Scoloplos armiger III 2.2 5.2 2.89 5.49 50.01Tellina agilis I 2.8 0.6 2.59 4.90 54.91Pectinaria granulata IV† 2.4 0.4 2.14 4.06 58.97

*Listed as Halicreion sp. and not assigned in AMBI. †As assigned by Callier et al. (2008).

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That multivariate methods were better able to detect the impactsof mussel farms than were univariate methods has been reported in anumber of other studies (e.g., Callier et al., 2007, 2008; Chamberlainet al., 2001; Ysebaert et al., 2009). In contrast, that the use of the bioticindicators AMBI and/or M-AMBI were not able to detect trends dueto bivalve culture is in contrast to many other studies that haveshown that they are (e.g., Borja et al., 2009; Bouchet and Sauriau,2008; Callier et al., 2008). However, use of the ecological informationon which the indices is based (i.e., species classifications ranging fromvery sensitive to organic enrichment through first-order opportunisticspecies; see Grall and Glémarec, 1997) together with results fromSIMPER analysis may help describe how infaunal communities areaffected by bivalve culture. Second-order opportunistic species contrib-uted the most to explaining Position-specific dissimilarities withinfarm sites as they consistently showed logical changes in abundances(i.e., increased) under mussel lines relative to between mussel lines.One of these species, the polychaete Pectinaria granulata has previouslybeen suggested by Callier et al. (2008) to have increased abundanceundermoderate increases in organic loading related to mussel aquacul-ture. The current study suggests that the polychaete Prionospiosteenstrupi may respond similarly. Indeed, this species has alreadybeen shown to be more abundant, larger, and more productive closeto fish farms in Norway (Kutti et al., 2007, 2008). In Hawaii, the specieswas shown to be characteristic of sites at intermediate distances from afish farm site (Lee et al., 2007). The polychaete Scoloplos armiger is char-acteristic of organically enriched areas (Carvalho et al., 2001) and typi-cally tolerant to organic matter enrichment (Borja et al., 2000).However, its abundancewas greater betweenmussel lines than directlyunder them, suggesting that the increased organic loading due tofarmed bivalves decreased its abundance in that position. It is notclear why patterns related to other functional groups are also not evi-dent. Perhaps the additional organic loading directly under mussellines was sufficient to stimulate infauna that could take advantage ofit but insufficient to cause a reduction in those species that are classifiedas being more sensitive. Likewise, perhaps organic loading was notsufficiently increased to promote first-order opportunistic species.

The results from the present study show a pattern consistent withthe hypothesis that mussel culture in the bay induces low levels of or-ganic loading and consequently influences benthic communities.However, the observed effects following greater than 10 years ofaquaculture activities in the area are slight and within the naturalvariation of benthic communities in the study area. Although somestudies have suggested that suspended bivalve culture may influencethe benthic environment at the scale of embayments (Hargrave et al.,2008), this is unlikely to be the case in baie de Gaspé given the rela-tively low stocking densities and that fine-scale effects are evident.At present, mussel culture dominates aquaculture activities withinthe inner embayment but trials are also underway for scallop andoyster culture. In addition, there are plans to greatly expand aquacul-ture activities in both the inner and outer areas of baie de Gaspéthrough the establishment of areas dedicated to aquaculture activi-ties. Although the limited effects of the current level of bivalve culturein the area likely pose little threat to the sustainability of the currentindustry, a greatly increased level of farming may also have a conse-quently greater influence on the benthic environment. The resultspresented here will serve as a baseline and will aid in the develop-ment of management plans to ensure the sustainability of the indus-try over the long-term.

Acknowledgments

The authors thank F. Hartog and M. Lemay for their help in the fieldand Bernard Boucher for lab sorting and identification of the benthicsamples. We also thank the mussel growers (Stéphane Morrisette andJacques Dufresne) who allowed us to work in their sites. Thanks toA. Weise for the map and for proof reading the text. This study was

funded by Fisheries and Oceans Canada's Program for AquacultureRegulatory Research (PARR).

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