Structure and Dynamics of Epifaunal Assemblages on Intertidal Macroalgae Ascophyllum Nodosum and Fucus Vesiculosus in Nova Scotia, Canada

MARINE ECOLOGY PROGRESS SERIES Vol. 37: 209-227, 1987 - Published May 6 Mar. Ecol. Prog. Ser. I

Structure and dynamics of epifaunal assemblages on intertidal macroalgae Ascophyllum nodosum and Fucus vesiculosus in Nova Scotia, Canada

S. C.Johnson & R.E. Scheibling

Department of Biology. Dalhousie University, Halifax. Nova Scotia B3H 451, Canada

ABSTRACT: Abundance and species composition of epifauna on Ascophyllum nodosum and Fucus vesiculosus on a rocky shore in Nova Scotia show pronounced seasonal variation. Total density of epifauna declined by 2 orders of magnitude between summer and winter. Harpacticoid copepods and their nauplii, nematodes, and halacarid mites were numerically the most important components of the assemblage throughout the 13 mo study (May 1983 to Jun 1984).Density was positively correlated with epiphytic algal biomass for most epifaunal taxa. Cluster analysis and multidimensional scaling also indicate that epifaunal sample groupings were strongly related to epiphyte biomass. There was a greater tendency for samples to cluster according to the 2 macroalgal species during the winter, when epiphyte biomass was low, suggesting that epiphytes obscure differences in morphology andlor microbial surface fllrns between A. nodosum and F. vesiculosus.

INTRODUCTION in these assemblages have been poorly documented (e.g. Colman 1940, Dahl 1948, Ohm 1964, Hagerman A number nf sti~di~shave documented seasonal fluc- 1966, Zavodnik 1967). Most studies have emphasized tuations in epifaunal assemblages on marine benthic single taxa, or only the macrofauna, except for those of macroalgae (see review in Hicks 1985). In general, Colman (1940), Ohm (1964), and Hagerman (1966) these studies have been Limited to either meiofaunal or which provided detailed taxonomic descriptions of all macrofaunal size classes or specific taxa. Few studies taxa in both the meiofaunal and macrofaunal size frac- have investigated the entire epifaunal assemblage. tions. Temporal and spatial variabhty in epifaunal assem- This study investigates seasonal changes in the blages or specific taxa on rnacroalgae have been attri- species composition and abundance of epifaunal buted to a variety of abiotic and biotic factors, e.g. assemblages (both meiofauna and macrofauna) on 2 temperature (Hagerman 1966, Gunnill 1983). dessica- common intertidal macroalgae, Ascophyllum nodosum tion (Colman 1940), tidal exposure (Gunnill 1983), and Fucus vesiculosus, on a rocky shore in Nova physiological or growth state of the plant (Hagerman Scotia. Classification and ordination techniques are 1966, Mukai 1971, Gunnill 1983, Trotter & Webster used to elucidate temporal patterns and to provide 1983), abundance of epiphyhc algae (Colman 1940, insight into the role of epiphytic algae as a determi- Wieser 1959, Hagerman 1966, Zavodnik 1967, Nagel nant of assemblage structure and dynamics. 1968, Kito 1977, Kangas 1978, Edgar 1983, Gunnill 1983), abundance of specific microorganisms (Trotter & Webster 1983), predation (Hagerman 1966, Edgar MATERIALS AND METHODS 1983), and intra and interspecific competition (Hager- man 1966, Hicks 1977c, Hicks 1980). Epifauna on Ascophyllum nodosum and Fucus Members of the family Fucaceae, including the gen- vesiculosus were sampled monthly between May 1983 era Ascophyllum and Fucus, are the predominant and June 1984 on the rocky shore of a moderately intertidal macroalgae of the northern hemisphere. exposed bay at Lower Prospect, Nova Scotia (Fig. 1). These algae are known to support abundant and The bay is shallow (mean depth = 3 m) with a sand diverse epifaunal assemblages, but seasonal changes and cobble substratum. The shoreline consists of

O Inter-Research/Printed in F. R. Germany Mar. Ecol. Prog. Ser. 37: 209-227, 1987

Fig. 1. Map of Nova Scotia, Canada, showing study site (*) at Lower Prospect

gradually sloping bedrock extrusions separated by fine indicating random sampling of all taxa.) Between 1 sand beaches. The intertidal macroalgal community is and 5 subsamples were sorted to include at least 200 dominated by luxuriant beds of A. nodosum and F. specimens of the dominant taxa (excluding nematodes ves~culosus. and crustacean nauplii which were extremely abun- Three specimens each of Ascophyllum nodosum and dant). Epifauna were identified to species or to hlgher Fucus vesiculosus were collected from random loca- taxa for some groups (e.g. Foraminifera, Turbellaria, tions along a 50 m transect approximately 0.1 m above Nematoda, Ostracoda, Halacaridae, Chironomidae). mean low water shortly after exposure at low tide. Filamentous epiphyhc algae were scraped from Individual specimens were cut from their holdfasts and Ascophyllum nodosum and Fucus vesiculosus with a placed in plastic bags with 5 '10 formaldehyde solution. scalpel and samples retained for identification. Macro- Epifauna were washed from each specimen with fil- algal specimens were divided into distinct plant re- tered seawater through 0.50 and 0.063 mm sieves and gions: blade, eroded blade, or stalk. Five pieces from hand-sorted under a dissecting microscope. The frac- each region were selected at random and photocopied. tion retained on the 0.063 mm sieve was subsampled in The surface area of these pieces was determined by May through September 1983, and May through June computer-diqtizing the photocopy images. Pieces 1984; the entire fraction was sorted for all other from each region, the remaining portion of the macro- months. Five replicate subsamples (1/20 volume) were algal specimen, and the epiphytes were dried sepa- taken using a large bore automat~cpipette. (Counts rately to a constant weight at 60.0°C. For each regon were checked for agreement with a Poisson series the ratio of surface area to dry weight was calculated as Johnson & Scheibling: Epifaunal assemblages on macroalgae

the average of the 5 pieces. The weight of a given region (weight of the pieces and remaining portion of that region) was then multiplied by the corresponding ratio to give the surface area for that region. Total plant surface area is the sum of the total surface area for each of the regions. Density of epifauna is expressed as number of individuals m-2 of plant surface. The normality of the data was checked and the best transformation for each taxon was estimated using the procedure of Box et al. (1978). For all taxa, logarithmic transformation was indicated; log(x+l) was used to accommodate rare Fig. 2. Water (m), air (*), and algal mat (0) temperatures species. Differences among months and between ma- (measured with a mercury thermometer) at sampling times between May 1983 and Jun 1984 at Lower Prospect. Nova croalgal species were investigated by analysis of var- Scotia iance. Residual error terms were tested for normality, independence and noncorrelation using SAS pro- Two-way ANOVA indicates that the biomass of cedures (Ray 1982). Transformation reduced depar- epiphytic algae on A. nodosum and F. vesiculosus tures from these assumptions, although ANOVA is a (Fig. 3) varied significantly among months (p<0.001) relatively robust test procedure especially when and between the 2 macroalgal species (p<0.001) with applied to balanced designs (Underwood 1981). Rela- a significant interaction between month and macro- tions among samples were examined using the similar- algal species (p < 0.01). (A significant interaction indi- ity matrix and classification program ORDANA (Bloom cates that the direction of difference between macro- et al. 1977) and the non-metric multidimensional scal- algal species varied among months.) Epiphytes were ing program SCAL02 (Maquire 1969). Density data abundant in the spring and summer and rare to absent were double root transformed (Field et al. 1982) and a through the late fall and winter. Elachistea fucicola similarity matrix involving all taxa was constructed (Vell.) Aresch. and Pilaiella littoralis (L.) Kjellm were using the Bray Curtis Index (also known as the dominant epiphytic species; other species included Czekanowski's Quantitative Index) (Field et al. 1982). Ptilota serrata Kutz., Bonnemaisonia hamifera Hariot., This matrix was used to construct classification dia- and Leptonematella fasciculata (Reinke) Silvia. grams of percent similarity using group average sort- ing (Field et al. 1982). it was also iised iii non-metric multidimensional scaling analysis (Kruskal 1964a, b, Seasonal patterns in density Field et al. 1982). Fifty-three species or multispecies groupings (Appendices 1 & 2) were identified from Ascophyllum RESULTS nodosum and Fucus vesiculosus. The density of the total epifauna shows pronounced seasonal variation Habitat description (Fig. 4; Appendices 1 & 2). Density on both macroalgal

Surface water temperatures (recorded monthly) ranged from -l.O°C (Jan 1984) to 18.7"C (Jul 1983) and air temperatures ranged from -4.5 "C (Jan 1984) to 25.0°C (Jun 1984) (Fig. 2). Temperatures within the macroalgal bed are lower in the summer and higher in the winter than the air temperatures, demonstrating a thermal buffering capacity of the mat. An ice sheet, several centimetres thick, frequently formed during low tide on the surface of the algal mat in January and February. Sea surface salinity ranged from 29.0 to 31.1 %o. Fig. 3. Biomass of filamentous epiphytic algae on The abundance of macroalgae did not vary notice- Ascophyllum nodosum and Fucus vesiculosus at Lower Pros- ably throughout the year. In September 1983, mean pect, Nova Scotia. Dark shading: mean density on A. biomass SE) was 2.7 1.2 kg dry weight m-' rock nodosum; Light shading: mean density on F. vesiculosus; (f f open: 1 standard error of the mean. Sample size is 3 for each surface for Ascophyllum nodosum, and 0.6 f 0.2 kg macroalgal species. (X+) Months with statistically significant dry weight m-2 rock surface for Fucus vesiculosus. differences between macroalgal species (t-test, p<0.05) Mar Ecol. Prog. Ser 37: 209-227, 1987

TOTAL EPIFAUNA 31 to 82 % of the epifauna of A. nodosum and 32 to 70 % of the epifauna of F. vesiculosus (Fig. 5). Density of copepod nauplii was comparable to that of adults and copepodites in most months (Fig. 6). Maximum density of harpacticoid copepods and nauplii occurred around June on both macroalgal species although the period of peak abundance was more protracted on A. nodosum than on F. vesiculosus (Fig. 6). MJ JASONDIJFMAMJ The density of each of the major harpacticoid species 1983 1984 (or multispecies groupings) varied significantly among Fig. 4. Density of total epifauna on Ascophyllum nodosum and Fucus vesiculosus collected at Lower Prospect, Nova months and between macroalgal species (with the Scotia. See Fig. 3 for explanation of shading. Sample size is 3 exception of Harpacticus sp. 2, Parastenhelia spinosa, for each macroalgal species and Heterolaophonte discophora) (Tables 1 & 2). Except for Harpacticus sp. 2, Tisbe spp., Mesochra sp. 1, and H. discophora the interactions between month species was maximal in June 1983 and declined by 2 and macroalgal species were significant. Density of orders of magnitude to a minimum in mid winter. most species was highest between June and August Eighteen species or multispecies groupings of har- and declined throughout the fall and winter. During pacticoid copepods from 9 families are identified from the period of maximum abundance, the genus both Ascophyllum nodosum and Fucus vesiculosus Heterolaophonte was dominant (Fig. 7). Other numeri- (Appendices 1 & 2). Harpacticoids (including nauplii) cally important species at this time include Harpac- were the most abundant component of the epifaunal ticus sp. 2, P. spinosa, Amphiascopsis sp., Mesochra sp. assemblages of both macroalgal specles, representing 2, and Nitocra typica (on Fucus vesiculosus only).

" May June July Aug Sept Oct Nov DCC Jan Feb Mar Apr flay June

May June July Aug Sept Oct Nov Dec Jan Feb Mar Apr flay June

Foraminifera Harpacticoida m( Turbellar~a m Harpacticoida Nauplii 0 Nernatoda Diptera Fig. 5. Percentage composition of major epifaunal taxa on Ascophyllum nodosum (top) and Fucus vesiculosus (bottom) Halacaridae 5 Others collected at Lower Prospect, Nova Scotia Johnson & Scheibling: Epifaunal assemblages on macroalgae

Harpacticoida 1OOOOOO1 Harpacticolda

100000 100000

10000 l0000 - l000 0Q, 1000 m loo -L 100 3 10 cn 10 -m lDO0000 1 Halacarldae Nernatoda 100000

Turbellaria 10aoOO1 Chironornldae

Fig.E. Eensity of major :&X; on Ascophy2um nodosum azd Fucus vcsjcn!cszs co!!ected at Lo:z.er Prospect, Nova Scotia. See _Fig. 3 for explanation of shading. Sample size is 3 for each macroalgal species. (*) Months with statistically significant differences between macroalgal species (t-test, p < 0.05)

Mesochra sp. 1 and N. typica (on Ascophyllum declined by 2 to 3 orders of magnitude by February nodosum) were most abundant in the fall and early 1984 (Fig. 6). Members of the genus Rhombognathides winter (Fig. 7). Tisbe spp. showed little seasonal fluc- accounted for >90 % of the total mite density on both tuation in density (Fig. 7). macroalgal species throughout the year. Nematodes were the second most abundant taxon, Turbellarians represented < 1 to 16 % of the representing 8 to 56 O/O of the epifauna on AscophyUum epifauna on Ascophyllum nodosum and < 1 to 8 O/O of nodosum and 5 to 34 % of the epifauna on Fucus the epifauna on Fucus vesiculosus (Fig. 5).Pronounced vesiculosus (Fig. 5). Nematode density varied signifi- seasonal changes in density of turbellaria occurred on cantly between macroalgal species and among months both macroalgal species (Fig. 6). Turbellarian density with a significant interaction between month and ma- varied significantly between macroalgal species and croalgal species (Table 1). Maximum density on both among months (Table 1). Maximum density on both macroalgal species occurred in June 1983; density macroalgal species occurred in July 1983; density declined by 3 orders of magnitude during the fall and declined during the fall and remained low throughout remained low throughout the winter (Fig. 6). the winter. One species, Notoplana atomata, and a Halacarid mites represented about 3 to 35 O/O of the multispecies grouping were identified. Density of N. epifauna on both macroalgal species (Fig. 5). Density atomata reached a maximum in September 1983 on of halacaridae varied significantly among months but both macroalgal species (N. atomata accounted < 18 not between macroalgal species with a significant and < 9 % of all turbellarians present on A. nodosum interaction between month and macroalgal species and F. vesiculosus respectively in any month). (Table 1). Density was maximum around June and July Chironomid larvae and pupae represented from 0 to 1983 on both macroalgal species respectively, and 7 % of the epifauna on Ascophyllum nodosum and 0 to Mar. Ecol. Prog. Ser. 37: 209-227. 1987

Table 1. Ascophyllum nodosum and Fucus vesicdosus. Two- this time. Chironomids were rare or absent throughout way ANOVA of the density of major epifaunal taxa between 2 the winter and spring. macroalgal species and among 14 mo. Data are F-values with Other less abundant taxa included Foraminifera, corresponding probability levels: 'p < 0.05, 'p < 0.01, ' ' 'p < 0.001, ns, not significant Nemertinea, Annelida, Gastropoda, Bivalvia, Ostracoda, Calanoida, Isopoda, and Arnphipoda (Fig. 8; Appendices 1 & 2). With the exception of Taxon Month Algal Interaction species Ostracoda, the density of these minor taxa varied significantly among months (Table 1). Seasonal fluctua- Foraminifera 7.17"' 0.01 ns 2.91. ' tions in density were similar among all these taxa with Turbellaria 25.33 .' 36.80" ' 1.82 ns the exception of Foraminifera on Ascophyllum Nemertinea 18.06- ' 4.00' 1.58 ns nodosum, and Ostracoda and Calanoida on both ma- Nematoda 39.72' 16.92 ' 4.36"' Annelida 31.38' " 12.52' ' ' 3.27' " croalgal species. Densities generally increased during Gastropods 19.47 ' 1.05 ns 0.47 ns the spring reaching maxima between June and August Bivalvia 15.65. ' 5.74' 2.04' 1983. Densities generally declined rapidly throughout Halacaridae 37.61 ' 0.88 ns 2.38' the summer and early fall, although some taxa (e.g. Ostracoda 0.89 ns 1.56 ns 0.83 ns Isopoda) had a more protracted period of maximal Harpacticoida 27.93 ' 15.09. ' 2.15' (adults and density. Nemertinea, Gastropoda, Isopoda and copepodites) Amphipoda were rare or absent throughout the winter, Harpacticoida 33.28 ' 3.84 ns 3.18. while other minor taxa occurred at low densities. The (nauplii) densities of Nemertinea, Annelida, and Bivalvia varied Calanoida 37.34"' 1.78 ns 1.07 ns Isopoda 11.60"' 1.17ns 0.71ns significantly between macroalgal species (Table l). Amphipoda 29.19"' 0.09 ns 1.39 ns The interaction between month and macroalgal Diptera 48.86 ' 20.42 ' ' 2.80" species was significant for Annelida and Bivalvia. The density of most major harpacticoid species, total harpacticoid density (including nauplii) and the total Table 2. Ascophyllum nodosum and Fucus vesiculosus. Two- wav ANOVA of the densitv of maior har~acticold s~ecies density of most other major (nematodes, halacand between 2 macroalgal species and among 14 rno. Data are F- mites, tubellarians and chironomids) and minor taxa values with corresponding probability levels: 'p < 0.05, were positively correlated with epiphyte biomass on "p < 0.01, ' "p < 0.001, ns, not significant both macroalgal species (Tables 3 & 4).

Species Month Algal Interaction species Classification and ordination

Harpacticus sp. 2 8.80' 3.58 ns 0.60 ns ' ' Bray-Curtis similarity coefficients were calculated Tisbe spp. 4.82- " 4.44' 0.63 ns Thalestris purpurea 5.36' ' ' 10.14" 2.44' between macroalgal samples for both Ascophyllum Parastenheliaspinosa 5.54"' 1.55 ns 3.12" nodosum and Fucus vesicdosus. Dendrograms pro- Amphiascopsis sp. 10.09' ' ' 9.53' ' 3.14" duced by group average clustering of these values Nitocra typica 10.40' ' 18.21. ' ' 2.27 show 2 distinct clusters separating at approximately 42 Mesochra sp. 1 4.82"' 44.62' ' ' 1.29 ns Mesochra sp. 2 28.49" ' 41.81" ' 2.94" and 35 % similarity for A. nodosum (Fig. 9) and F. Heterolaphon te 16.65' ' ' 3.98 ns 1.53 ns vesiculosus (Fig. 10) respectively. These clusters discophora (adults) correspond closely to the periods May through Heterolaophonte spp. 50.85- ' 16.46 ' 2.69. October, and November through April. For A. (adults) Heterolaophonte spp. 52.27. ' ' 8.84 3.86' nodosum, these clusters subdivide into 4 clusters at Ijuveniles) approximately 60 % sirmlarity, generally corresponding to the periods: (A) June through October; (B) May; (C) November, March, Apnl; (D) December through 4 % of the epifauna on Fucus vesiculosus (Fig. 5). February. For F. vesiculosus 4 clusters at approxi- Chironomid density varied significantly among mately 52 O/O similarity corresponded closely to the months and between macroalgal species with a signifi- periods: (A) September, May, June, October; (B) June cant interaction between month and macroalgal through August; (C) October, November, March, April; species (Table 1). Densities increased markedly from (D) December through February. Samples collected May 1983 to a maximum in June 1983 on both macro- within months were generally most similar to each algal species (Fig. 6), then declined rapidly during the other. summer and fall. The marked decline in density is in Ordination by multidimensional scahng (MDS) of part due to the emergence of adults from pupae over macroalgal samples yielded results similar to those of a 3. -g 2 oa . g G F 3% m C 0 .W 0A-c z nw g;, a .zmovl %$,"z'aJ2 c% 22; U "5" .5 2 2; ri) aJS g 2.;; E g 9 .-ri)mcn E 3 U W 2 Os'Kg "7 C ri) '3 q$aJ 0 bgm 6" ' i;: :S Mar. Ecol. Prog. Ser. 37: 209-227, 1987

Foraminifera R

Bivalvia - v. Gastropoda rCOO 9 1000 v 100 CrJ l00 E r\] 10 10

E 1 1 -cC . 0 1 - 0 1

lsopoda Amphipoda

MJJ ASONDIJF MAMJ

Fig. 8. Density of minor taxa on Ascophyllum nodosum and Fucus vesiculosus collected at Lower Prospect, Nova Scotia. See Fig. 3 for explanation of shading. Sample size is 3 for each macroalgal species. (*) Months with statistically significant differences between macroalgal species (t-test, p < 0.05) Table 3. Ascophyllum nodosum and Fucus vesiculosus. Rela- Table 4. Ascophyllum nodosurn and Fucus vesiculosus. Rela- tionship of density of major epifaunal taxa and epiphyte tionship of density of harpacticoid copepods and epiphyte biomass for months where macroscopic epiphytic algae were biomass for months where macroscopic epiphytic algae were present. Data are Spearman rank correlation coefficients and present. Data are Spearman rank correlation coefficients and corresponding probability levels: 'p < 0.05, 'p < 0.01, corresponding probability levels: 'p < 0.05, "p < 0.01, " 'p < 0.001, ns, not significant. Sample size is 36 for A. " 'p < 0.001, ns, not significant. Sample size is 36 for A. nodosum and 30 for F. vesiculosus. nodosum and 30 for F. vesiculosus

Taxon A. nodosum F. vesicu1osus Species A. nodosum F. vesiculosus

Turbellaria 0.308 ns 0.561 ' Harpacticus sp. 2 0.357' 0.471 Nematoda 0.842 0.853 . ' ' ' Tisbe spp. 0.125 ns 0.413' Annelida 0.541 0.538 ' Thalestns purpurea 0.062 ns 0.113 ns Gastropoda 0.409' 0.491" Parastenhelid spinosa 0.128 ns 0.507' Bivalvia 0.177 ns 0.449' ' Amphiascopsis sp. 0.290 ns 0.281 ns 0.630 0.824 Halacaridae ' ' Nitocra typica 0.042 ns 0.302 ns Harpacticoida 0.723 0.774" ' ' ' Mesochra sp. 1 0.193 ns 0.284 ns (adult and Mesochra sp. 2 0.760- 0.826. copepodites) ' ' He terolaophon te 0.757' .' 0.711'" Harpacticoida 0.767 * m 0.756' ' ' ' djscophora (nauplii) Heterolaophonte spp. 0.734' 0.775. Isopoda 0.276 ns 0.171 ns ' ' .' (adult) Amphipoda 0.576- ' 0.769 ' ' Heterolaophonte spp. 0.654 ' ' ' 0.813. m ' Diptera 0.688 m m 0.799 ' ' (juvenile) Total fauna 0.809' m 0.789 m ' Johnson & Scheibling: Epifaunal assemblages on macroalgae 217

Sept 183 IS - Sept 183 13 1JuIyl83Auq/83 l?7 ----vh

May184 39 tlay/84 38 B May184 37 May183 2 May183 I ApnlI84 36 Apnll84 35 Apm1184 34 March18432 C March18433

March1843 1 Nov 183 21 Nov183 20 Nov183 19 Feb184 30 Dec 183 22 - Jan184 26 . Dec183 23 D ~an/84 25 - - Feb/84 29 Febl84 28 -- Decl83 24 Fig. 9. Ascophyllum nodosum. Dendro- LJan184 27 gram of percentage similarity (Bray-Curtis measure) of faunal composition among l I 1 1 I I 1 1 42 samples collected over 14 mo at Lower 0 Prospect, Nova Scotia. Four main clusters 100 90 8 0 7 0 6 0 5 40 30 (A, B, C, D) are delineated at approxi- SIMILARITY % ma:c!y thc 6C ?L s+Arrity !eve1 cluster analysis for both Ascophyllum nodosum (Fig. results (Fig. 9 & 10). Samples from May through 11) and Fucus vesicu1osus (Fig. 12). Clusters of samples October separate at 56 % similarity into 2 major clus- from the corresponding classification dendrograms ters (Fig. 13). These clusters show no clear trends with have been delineated on these plots. Samples wittun respect to month or macroalgal species. Both macroal- months generally show the closest proximity (similar- gal species and all months except July, August, and ity). The distribution of samples shows a clear relatlon October are common to both clusters (Fig. 13). (Sam- with epiphytic algal biomass. For both A. nodosum and ples from October occur only in Cluster A; samples F. vesiculosus, epiphyte density generally decreases from July and August occur only in Cluster B.) Ordina- from the lower left to the upper right of these figures. In tion by multidimensional scaling of these samples for general, where samples within months did not group both macroalgal species supports these results (Fig. well, between-sample variability in epiphyhc algal 14). Clusters of samples from the corresponding biomass is high. Stress values (relating to the effective- dendrogram are delineated on this plot. Epiphyte bio- ness of MDS in representing actual similarities mass decreases from the lower left to upper right of this between samples) for the 2-dimensional solutions are plot. Samples in Cluster A have lowest epiphyte bio- 0.102 and 0.087 for A. nodosum and F. vesiculosus mass (Fig. 14). The stress of this 2-dimensional solution respectively, indicating a satisfactory representation of is 0.132, indicating a satisfactory representation of similarities between samples (Kruskal 1964a). similarities between samples (Kruskal 1964a). The program ORDANA is limited to < 51 samples. Samples from November through April separate at To enable comparisons of faunal similarity between 57 % similarity into 2 clusters closely corresponding to macroalgal species, the samples were split into 2 the periods: (A) November, March, April; (B) groups: May through October, and November through December through February (Fig. 15). The 2 macroal- April based on the above clustering and ordination gal species tend to cluster separately at approximately Mar. Ecol. Prog. Ser. 37: 20S227, 1987

Aug183 10 July183 8 July183 7 May183 2 nay 183 I May184 38 Oct183 16 Oct183 I8 May184 37 March184 32 Nov183 21 Nov183 20 Apn1184 3b Apn1/84 35 March184 33 March/84 31 April/84 34 Feb/84 30 Feb/84 29 Feb/84 28 Dec/83 22

Fig. 10. Fucus vesiculosus. Den- Dec183 24 drogram of percentage sirnilari- Dec/83 23 ty (Bray-Curtis measure) of Nov/83 19 fauna1 composition among 42 samples collected over 14 mo at 1 I I Lower Prospect, Nova Scotia. 100 90 80 70 60 5 0 4 0 30 Four main clusters (A, B, C, D) are delineated at approximately SIMILARITY % the 52 % similarity level

58 and 62 % similarity within Clusters A and B respec- constitute the 'typical' phytal fauna (see reviews by tively. Separation of samples by macroalgal species is Coull et al. 1983, Hicks 1985). The composition of the particularly apparent in samples from December harpacticoid epifauna corresponds closely to that pre- through February (Cluster B). Ordination by mul- viously reported for macroalgae (Colman 1940, Ohm tidimensional scaling supports these results (Fig. 16). 1964, Hagerman 1966, Hicks 1980, 1985) or macroalgal The stress of this representation is 0.200 indicating a debris (Marcotte 1977). The harpacticoid families Har- poor representation of actual similarities between pacticidae, Tisbidae, and Diosaccidae are typically samples (Kruskal 1964a). phytal dwelling (Hicks 197713). The families Laophon- tidae and Canthocamptidae are more characteristic of sediment biotopes (Hicks 1977b), although several DISCUSSION species of these families are also abundant on A. nodosum, F. vesiculosus, and F;.serratus (Colman 1940, The composition of the epifaunal assemblages of Ohm 1964, Hagerman 1966, Hicks 1980). Ascophyllum nodosum and Fucus vesiculosus in this Pronounced seasonal changes in density and species study is similar to that reported for intertidal A. composition are evident for most components of the nodosum and F, vesiculosus in England (Colman epifaunal assemblage of both Ascophyllum nodosum 1940), subtidal F, vesiculosus and F. serratus in Ger- and Fucus vesiculosus in this study. Seasonal variation many (Ohm 1964), and subtidal F. serratus in Denmark in epifauna has been documented previously for inter- (Hagerman 1966). These assemblages are dominated tidal macroalgae (Gunnlll 1983) and subtidal macroal- by harpacticod copepods and their nauplii, and contain gae (Ohm 1964, Hagerman 1966, Mukai 1971, Haage many of the meiofaunal families and genera which 1975, Edgar 1983). Variations in density reflect popula- Johnson & Scheibling: Epifau nal assemblages on macroalgae 219

subtidal F. serratus in the Oresund have been related to low water temperatures (Hagerman 1966).However, most seasonal studies of macroalgal epifauna have been limited to more temperate regions where water temperatures do not fall below 7.0°C. Epiphytic algae appear to have a pronounced effect on the abundance and species composition of the epifauna of Ascophyllum nodosum and Fucus vesi- OX) culosus. The density of most major taxa was positively 019 - correlated with epiphyte biomass, and cluster analysis and multidimensional scaling indicated that sample groupings were strongly related to epiphytic algal biomass. A similar relation has been reported previously for various macroalgal species (Colman 1940, Hager- man 1966, Zavodnick 1967, Nagel 1968, Kangas 1978, .l02 Stress = Gunnill 1982, 1983, Edgar 1983). Epiphytic algae and associated microflora (bacteria, diatoms, fungi) repre- sent abundant and diverse food resources. Amphipods Fig. 11. Ascophyllum nodosum. Ordination by multidimen- (Hagerman 1966, McBane & Croker 1983, Pederson & sional scaling of 42 samples collected over 14 rno at Lower Capuzzo 1984, D'Antonio 1985), gastropods (Hager- Prospect, Nova Scotia. Four clusters (A, B, C, D) of samples man 1966, D'Antonio 1985) and chironomid larvae are deheated visually based on the dendrogram in Fig. 9. (Hagerman 1966, Morley & Rng 1972) are known to Symbols indicate different levels of epiphytic algal biomass graze epiphyhc algae. Harpacticoid copepods and (g dry weight m-2 macroalgal surface) in samples: no symbol, Og m-2; (0) ~0.1g m-'; (e) 20.1, <1.0 gm-'; (A) 21.0, nematodes consume microbial films and may exhibit < 10.0 g m-'; (A) P 10.0, < 100.0 g very specific food preferences (Lee et al. 1976, Hicks 1977a, Trotter & Webster 1984). Highly selective feeding by members of the epifaunal community may allow for the coexistence of a wide variety of morphologi- cdy similar species. The presence of epiphytic algae increases microhabitat ccmp!e~jty providing spatial refu~eswhich may reduce predation on the epifauna (Coull & Wells 1983). Conversely, the presence of epiphytic algae may enhance predation rates on some species by attracting predators. Pederson & Capuzzo (1984) showed that the amphipod Calliopius laeviusculus is attracted to the epiphytes of Fucus which it consumes along with assodated harpacticoid copepods. Increased structural complexity afforded by epiphytic algae also increases opportunities for attachment, enabling species to become established or to maintain their position on macroalgae when subjected to wave action or currents. Fig. 12. Fucus vesiculosus. Ordination by multidimensional Microhabitat structure is especially important for those scaling of 42 samples collected over 14 mo at Lower Prospect, Nova Scotia. Four clusters (A, B, C, D) of samples are deline- species or life history stages which are poor swimmers. ated visually based on the dendrogram in Fig. 10. Symbols Populations may spread from refuge areas (e.g. the indicate different levels of epiphytic algal biomass (g dry subtidal or areas of low wave exposure) to take advan- weight macroalgal surface) in samples: no symbol, 0 g tage of seasonal increases in epiphyte abundance m-2;(0) ~0.1g m-'; (e)20.1, <1.0 g m-2; (a) 2 1.0, < 10.0 (Edgar 1983). g m-'; (A) 2 10.0. < 100.0 g m-2 Dessication is another important factor controhng tion dynamics, which are controlled by a complex the distribution and abundance of epifaunal species on interplay of physical and biological factors. Fluctua- intertidal macroalgae (Gunnill 1983). Due to the thick- tions in the density of epifaunal taxa in this study ness of the macroalgal mat at Lower Prospect, only the generally exceed those previously reported. This may surface layer dried at low tide while the inner fronds be due in part to the relatively harsh physical environ- remained wet. The algal mat also provides some ther- ment at Lower Prospect. Low epifaunal densities on mal buffering: temperatures within the mat were up to Mar. Ecol. Prog. Ser. 37: 209-227, 1987

F -164 48 T hete4 47 A .Met84 25 A Cne184 : 3 f OCLi83 41 F Sept183 37 A Octt83 I8 ACM1183 17 A %?p1 fl3 l4 A Oct /83 I6 F Mq/83 27 A My183 I A n~/aj 2 A my184 21 A n~la4m A W184 IQ F W184 44 F Ocll83 40 F Sept183 39 F kDll83 M F &l 183 42 F June184 46 A Junl84 22 F JIMIU3 30 F Are183 IP A Ant183 5 F JIM183 28 F -W3 36

Fig. 13. Ascophyllum nodosum and Fucus vesiculosus. Dendrogram of percentage sirmlarity (Bray-Curtis measure) of fauna1 composition among 48 samples collected from May through Oct 1983, and May through Jun 1984 at Lower Prospect. Nova r I I I I I Scotia. Total number of samples for each 100 90 80 70 60 50 40 30 macroalgal species is 24. Two main clusters (A, B) are delineated at approximately the SIMILARITY Oh 56 O/O similarity level

3.0 C" cooler in the summer and up to 2.0 C" warmer in cell layers by Ascophyllum nodosum may limit or the winter than air temperatures. Epifaunal species reduce certain microflora (Filion-MyMebust & Norton such as the amphipod Hyale nilssoni may migrate into 1981). Increased mucus secretion during reproductive the mat when exposed at low tide (McBane & Croker periods may affect phytal epifauna by trapping sedi- 1983). Smaller, less motile taxa generally are associ- ments or rendering the surface uninhabitable (Hager- ated with epiphytic algae which retain large amounts man 1966). Abundance and species composition of the of water when exposed at low tide. epifauna on the subtidal macroalga Sargassum Retention of sediments by macroalgae may also seratifolium in the Sea of Japan was related to growth influence species composition and abundance of and annual senesence of the plant fronds (Mukai 1971, epifauna in some areas (Dahl 1948, Wieser 1959, Hicks Kito 1977). Gunnill (1983) reports that epifapna are in 1977b, Warwick 1977). Epiphytic algae and surface low abundance on Pelvetia fastigiata during the winter mucus secretions of macroalgae may trap sediment reproductive period of the alga, although this may be and detritus (Dahl 1948, Hicks 1980). However, sedi- due to environmental factors rather than algal phy- ment retention on plants in this study was low, presum- siological state. In Nova Scotia, epifaunal abundance ably because of the low turbidity of the embayment increases during the reproductive period of A. and the coarseness of its sediments (pers. obs.). Small nodosum (Apr to Jun) but decreases during the repro- quantities of coarse grain sediments occasionally were ductive period of Fucus vesiculosus (Sep). Changes in present on Ascophyllum nodosum and Fucus vesi- the reproductive condition of macroalgae may affect culosus after storms. only those epifauna which dwell on the surfaces of the Seasonal changes in the physiological state of the macroalgae. macroalgae may influence the epifaunal assemblage Comparisons of Bray-Cubs similarities between directly or indirectly by affecting the microbial surface samples of Ascophyllum nodosurn and Fucus vesi- film. Increased phenolic release or sloughing of outer culosus indicate a stronger tendency for samples to Johnson & Scheibling: Epifaunal assemblages on macroalgae 22 1

2' Stress =.l32

Stress = .200

Fig. 14. Ascophyllum nodosum and Fucus vesiculosus. Ordi- Fig. 16. Ascophyllum nodosum and Fucus vesiculosus. Ordi- nation by multidimensional scaling of 48 samples collected nation by multidimensional scaling of 36 samples collected from May through Oct 1983, and May through Jun 1984 at from Nov 1983 to Apr 1984 at Lower Prospect, Nova Scotia. Lower Prospect, Nova Scotia. Total number of samples for Total number of samples for each macroalgal species is 18. each macroalgal species is 24. Two clusters (A, B) of samples Two clusters (A, B) of samples are delineated visually based are delineated visually based on the dendrogram in Fig. 13. on the dendrogram in Fig. 14. Symbols inlcate different Symbols inlcate different levels of epiphytic algal biomass levels of epiphytic algal biomass (g dry weight m-' macroal- (g dry weight m-2 macroalgal surface) in samples: no symbol, gal surface) in samples: no symbol, 0 g m-?; (0) <0.1 g m-*; 0 g m-2; (0) tO.l g m-2; (0) 20.1, <1.0 g m-'; (A) 21.0, (m) 20.1, c1.0 g m-2; (A) 2 1.0, <10.0 g m-2; (A) 210.0. < 10.0 g m-2; (A) 2 10.0. < 100.0 g m-' < 100.0 g m-2

F Apn1/84 36 F Apn1/84 35 F March184 33 i :arch184 3: F Apn1184 34 F March184 32 A Apn1184 18 A Apnl184 17 iA Apn1184 16 A March184 I S A March184 13 F Nov/83 21 F Nov183 20 A Dec183 4 A Nov183 3 A Nov183 2 A Novl83 l F Feb184 30 F Feb184 29 F Feb/84 28 F Dec183 22 F JanI84 27 F Jan184 26 F Jan184 25 F Dec183 24

A Feb184 10 A Dec183 6 A Jan 184 9 F Dec183 23 Fig. 15. Ascophyllum nodosum and A Feb 184 12 Fucus vesicu~osus. Dendrogram of per- A Jar1184 8 centage similarity (Bray-Curtis mea- A Dec183 S A Jan.184 7 sure) of fauna1 composition among 36 F Nov183 19 samples collected from Nov 1983 to Apr 1984 at Lower Prospect, Nova Scotia. I i I I I I I Total number of samples for each mac- 100 90 8 0 70 6 0 5 0 40 30 roalgal species is 18. TWO main clusters (A, B) are delineated at approximately SIMILARITY% the 57 O/O similarity level Mar. Ecol. Prog. Ser. 37: 209-227. 1987

Appendix 1. Ascophyllum nodosum. Mean density and standard error (in parentheses) of epifauna (individuals m-2 of macroalgal surface) at Lower Prospect, Nova Scotia. Sample size is 3

June July ~ugust September October November

Foraminifera 69 (57) Tubellaria 1325 (724) Unidentif~ed 1311 (727) Notoplana atomata 14 (4) Nemertinea 1 (1) Nematoda 62 465 (36 674) Annelida 366 (283) Lurnbridllus Lineatus 296 (245) Fa brida sabella 71 (43) Spuorbis borealis 0 Streplosyllis vanans 0 Umdenfified polychaete 0 Gastropoda 164 (120) Skeneopsis planorbis 103 (103) Lacuna vincta 2 (1) Littorina htlorea 0 Liltorina obtusata 59 (25) Misc. gastropod 0 Bivalvia 87 (82) Mytilus edulis 87 (82) Unidenlified spat 0 Halacaridae 12540 (9484) Rhombognathides seahami 11 461 (8474) HalacareUus spp. 1079 (1014) Ostracoda 0 Harpacticoida 55 173 (34 969) Family Ectinosomatidae 77 (54) Microselella norvegica 77 (54) Family Harpactiadae 837 (824) Harpacticus sp. 1 0 Harpacticus sp. 2 837 (824) Harpacticus sp. 3 0 Zaus abbreviatus 0 Family Tisbidae 25 (25) Tisbe spp. 25 (25) Fady Thalestridae 1081 (705) Thalestns purpurea 202 (202) Thalestris gibba 0 Parathaleslns sp. 0 Diarihrodes major 879 (503) Family Parastenheliidae 485 (485) Parastenhelia spinosa 485 (485) Family Diosaccidae l051 (1020) Arnphjascopsis sp. l051 (1020) Family Ameiridae 416 (277) N~tocramica 416 (277) Fady Canthocamptidae 5448 (2771) Mesochra sp. 1 0 Mesochra sp. 2 5448 (2771) Family Laophontidae 45710 (28974) Pseudonychocamptus koreni 0 Heterolaophonte discophora 3755 (1713) (adults only) Heterolaophonte spp. (adults only) Heterolaophonte spp. (juveniles only) Other harpacticoids Harpactlcold nauph Cenlropages typicus lsopoda Jaera marina Idotea balt~ca ldotea phosphorea Amphipoda Amphjloe rubncata Calliopius laeviusculus Chaetogammarus finmarchlcus GammareUus angulosus Gammarus oceanicus Hyale dssoni Jassa falcata D~ptera(larvae) Total Johnson & Scheibling: Epifaunal assemblages on macroalgae

Appendix l (continued)

Taxa December January February March April May June

Foramlmfera 36 (16) 506 (139) 624 (778) TurbeUaria 35 (12) 45 (31) 850 (423) Un~denLlf~ed 35 (12) 42 (32) 833 (427) Notoplana atornata 1 (1) 3 (2) 17 (9) Nemert~nea 0 o 16 (3) Nematoda 46 (20) 23925 (5775) 17 117 (12069) Annelida 7 (5) 34 (19) 658 (525) LumbriuUus Imeatus 0 34 (19) 226 (131) Fabricia sabeUa 0 418 (407) Spirorbis borealis 0 1 (1) Streptosylhs vanans 0 0 Unidentified polychaele 0 0 Gastropoda 4 (1) 76 (62) Skeneopsis planorbis 0 1 (1) Lacuna nncta 1 (1) 0 kttorina httorea 0 0 Lttorina obtusata 2 (1) 74 (61) MSC.gastropod 0 0 Bivalvla 0 58 (36) Myths eduhs 0 Unidentified spat 0 Halacandae 1107 (603) RhombognaUudes seahami 1090 (592) HalacareUus spp. 17 (12) Ostracoda 7 (7) Harpacticoida 3502 (539) Family EcLlnosomatidae 29 (IS) Microsetella norvegica 29 (15) Fam~lyHarpachc~dae 502 (408) Harpacllcus sp. 1 0 Harpacllcus sp. 2 494 (401) Harpacllcus sp. 3 Zaus abbrenatus Family Tisbidae Tisbe spp. Family Thalestridae Thalestris purpurea Thalestriis gibba Para thalestris sp. D~arthrodesmajor Farmly Parastenheludae Parastenheha spinosa Farmly D~osaccidae Amphascops~ssp. Famlly Ameu~dae Nitocra tpica Family Canthocamphdae Mesochra sp. 1 Mesochra sp. 2 Family Laophontidae Pseudonychocamptus koreni Heterolaophon te discophora (adults only) Heterolaophonte spp. (adults only) Heterolaophonle spp. (Juveniles only) Other harpactlcoids Harpactlcoid nauplii Centropages typicus Isopoda Jaera manna Idotea baltica Idotea phosphorea Amphipoda Amphitoe rubncata CaUlopius laeviusculus Chaetogammarus finmarchicus GammareUus angulosus Gammarus oceanicus Hyale nilssoni Jassa lalcata D~plera(larvae) Total Mar. Ecol. Prog. Ser. 37: 209-227, 1987

Appendix 2. Fucusvesiculosus. Mean density and standard error (in parentheses) of epifauna (individuals m -2 of macroalgal surface) at Lower Prospect, Nova Scotia.Sample size is 3

Taxa May June J~Y August September October November - - i Foraminifera 257 (179) 159 (27) 262 (122) 635 (491) 12 (2) 34 (12) TurbeUaria 1250 (1111) 4177 (741) 6381 (2432) 3954 (2815) 232 (81) 85 (45) Unidentified 1248 (1110) 4176 (742) 6380 (2433) 3943 (2815) 211 (68) 79 (45) Notoplana atomata 3 (2) 1 (1) 2 (2) 11 (4) 20 (16) 6 (3) Nemertinea 2 (2) 2 (2) 4 (4) 30 (17) 19 (17) 1 (1) Nernatoda 50624 (22875) 280672 (73785) 25 198 (13048) 8794 (1565) 504 (299) 284 (125) Annelida 212 (73) 1205 (245) 428 (207) 157 (50) 91 (43) 18 (81 Lumbriduslineatus 144 (38) 861 (347) 404 (209) 126 (20) 76 (48) 5 (2) Fabricia sabella 62 (50) 343 (133) 24 (3) 30 (30) 0 3 (21 Spirorbis borealis 4 (2) 0 0 0 15 (11) 10 (8) Streptosyllis varians 0 0 0 0 0 0 Unidentified polychaele 2 (21 0 0 0 0 0 Gaslropoda 48 (16) 123 (39) 124 (67) 239 (144) 49 (8) 43 (11) Skeneopsis planorbls 12 (12) 52 (45) 2 (2) 7 (4) 4 (2) 1 (1) Lacuna vincta 7 (51 0 2 (7-1 71 (58) 0 14 (9) Littorina iittorea 0 4 (2) 3 (2) 0 1 (1) 0 tittorina obtusata 27 (2) 67 (39) 116 (70) 162 (87) 45 (8) 27 (11) Misc. gastropod 0 0 0 0 0 0 Bivalvia 25 (14) 26 (18) 572 (193) 549 (480) 10 (2) 2 (1) Mytilus edufjs 25 (14) 26 (18) 572 (193) 549 (480) 10 (2) 2 (1) Unidentified spat 0 0 0 0 0 1 (1) Halacaridae 6601 (1336) 44681 (9376) 18258 (2752) 9071 (1547) 2206 (314) 1440 (370) RhombognaUlldes seahami 6135 (1066) 41 127 (8947) 17993 (2748) 8969 (1492) 2200 (313) 1438 (368) HalacareUus spp. 463 (297) 3554 (585) 267 (45) 102 (62) 6 (2) 2 (2) Ostracoda 80 (74) 53 (53) 0 0 2 (1) 5 (5) Harpacticoida 12032 (6597) 244402 (37502) 25392 (8749) 10726 (4340) 1129 (612) l199 (892) Family Ectinosomatidae 471 (225) 37 (37) 0 0 39 (12) 12 (7) MicroseteUa norvegica 471 (225) 37 (37) 0 0 39 (19) 12 (7) Family Harpacticidae 669 (323) 715 (212) l08 (941 256 (138) 2 (1) 51 (24) Harpacticus sp. 1 0 54 (52) 0 0 0 2 (2) Harpacticus sp 2 610 (330) 662 (237) l0 (10) 256 (138) 2 (1) 44 (28) Harpacticus sp. 3 52 (47) 0 98 (98) 0 0 0 Zaus abbrevlalus 7 (4) 0 0 0 0 4 (3) Farmly Tisbidae 69 (69) 0 128 (79) 73 (73) 87 (74) 99 (44) 7isbe spp. 69 (69) 0 128 (79) 73 (73) 87 (74) 99 (44) Family Thalestridae 1278 (1250) 26066 (7149) 1558 (1084) 31 (31) 517 (362) 711 (694) Thaleslris purpurea 73 (67) 165 (76) l509 (1100) 31 (31) 517 (362) 710 (694) Thalestris gibba 0 3 (3) 0 0 0 0 Parathalestris sp 38 (33) 0 0 0 0 0 Diarthrodes major 167 (1150) 25897 (7181) 49 (49) 0 0 1 (1) Farnlly Parastenhehidae l05 (61) 1458 (940) 0 288 (209) 6 (4) 18 (9) Parastenhelia spmosa 105 (61) 1458 (940) 0 288 (209) 6 (4) 18 (9) Fanuly Diosaccidae 0 3106 (351) 0 138 (108) 0 6 (6) Amphiascopsis sp. 0 3106 (351) 0 138 (108) 0 6 (6) Family Ameiridae 35 (35) 2325 (579) 79 (43) 223 (74) 268 (192) 148 (81) Nitocra typica 35 (35) 2325 (579) 79 (43) 223 (74) 268 (192) 148 (81) Family Canthocamptidae 1642 (778) 23737 (7949) 5454 (3019) 1696 (875) l19 (72) 76 (58) Mesochra sp. 1 35 (35) 0 0 72 (41) 107 (79) 44 (41) Mesochra sp. 2 1607 (775) 23737 (7949) 5454 (3019) 1624 (840) 12 (9) 32 (17) Family Laophonl~dae 7484 (4110) 186959 (31785) 18065 (8223) 8010 (3170) 82 (43) 74 (46) Pseudonychocamptuskorenj 189 (139) 0 0 0 0 21 (21) Helerolaophonte dscophora 1143 (560) 25553 (2809) 627 (572) 0 0 0 (adults only) Helerolaophonte spp. 558 (252) 38226 (7576) 6857 (3069) 2384 (508) 65 (32) 18 (9) (adults only) Heterolaophontespp. 5594 (3460) 123180 (25290) 10580 (5980) 5626 (2663) 18 (13) 36 (19) (~uvenilesonly) Other harpacticoids 279 (151) 53 (53) 0 l0 (10) 10 (9) 4 (31 Harpacticoid nauplu 125146 (77434) 205587 (60013) 10375 (2974) 27172 (9821) 1983 (869) 2650 (1608) Centropages lyp~cus 0 0 0 0 23 (91 1 (11 Isopoda 2 (2) 20 17) 18 (81 12 (51 16 (8) 27 (19) Jaera marina 0 2 (2) 9 (3) 3 (2) 11 17) 22 (18) Idotea baltica 2 (2) 6 (3) 9 (91 9 (4) 6 (6) 5 (2) ldotea phosphorea 0 12 (7) 0 0 0 0 Amphipoda I00 (48) 1174 (469) 479 (283) 341 (272) 4 (3) 7 (1) Amphjtoe mbricata 47 (24) 109 (80) 32 (19) 10 (4) 2 (1) 0 Calhopius laevlusculus 0 0 0 56 (30) 0 0 Chaelogammarusfinrnarch~cus 2 (2) 0 0 0 0 0 Gammarus oceanlcus 1 (1) 0 4 (4) 2 12) 0 0 Hyale nilssoni 49 (26) l055 (489) 443 (260) 272 (263) 2 (2) 4 (2) Jassa lalcata 3 (2) 10 (7) 0 1 (1) 0 3 (2) Diptera (larvae) 1064 (485) 35473 (16180) 1703 (585) 565 (212) 21 (7) 5 (5) Total 197386 (107762) 817753 (190676) 89195 (25315) 62246 (20028) 6302 (2091) 5799 (2981) - - - ,- 6 -.- - -m 6 - m W-- -?-F - m UP W ----v - - m-N -mm- &i S m - -0K------t---mmm-z2-~ 5 -2 zz ~r-.m--mwr--o -3 --?-m-mwmmwo mm a wnmmm--mooomm m me -- -m -m m F- =~.c?~DIscIz=~~,LO= N_C?=OICOIE(DIO=N EFS ZZZSY C=:SZCZZ.P-~=CN_N = ;EZ! %'P N,C %C?. CZ

- -- - - m m (? - m - P.P.-- a NN -- - -- I. - 9. P. ----p. - - 000 mm mm - - m--- -- u)LYCC'P - NI 9 ZZCC2CCZ=Z=C C ""Cd C%!!?.!E%CC?2C!2.~ d N, g 9 C?. C. = -- NI mm~--~oooooo~~~omo~m-~)~)~w---w~w~~~~~-~~-~.~.wwmmmm~)o-m ooo~~~~~ooooo--m (?W- V) -3 9. m0 --V) 9.m --39. W N N d m - V)"-, (? V) m d --- - # W

- 6 - 66 ------N B ------N -mm-- - --oo----m- -9. - m d ------p,-- - *--- W ro, NI=% "'CCCC"" c ZC~C?.~ CCC"""C~~~"z = CC "C?. r OI ~)~N-OOOOOOOO~~N-~OOOO~V)--~~~~O~O~P.P.V)N~~~~~~NN--~~~-~V)~,a -~ONNOO-ooooo-oV) V) ~f: W mm N- - a 9. 0 --3 -3- - - V) 2

------6 m------Ss -C---- mm- V)------W ?m_? NOCCr. =. - YY CC! ClOCdCC ""E C?. !%!E22L"%"C.CC - c ON, L- N~-?OO~-~---OO-OOO-O~~OWWONN----OOO~~~-OO~-O~~~~~NNWN~NOO- - N~OOOOOOOOOOOOO W m- - am 5 o o mm- W (? El - -3 Mar. Ecol. Prog. Ser. 37: 209-227, 1987

separate according to macroalgal species from Haage. P. (1975). Quantitative investigations of the Baltic November to April, when epiphyhc biomass was low, Fucus belt macrofauna. 2. Quantitative seasonal fluctua- than from May to October, when epiphytic algal bio- tions. Contr. Asko Lab. Univ. Stockholm 9: 1-88 Hagerman. L. (1966). The macro- and microfauna associated mass was high. A. nodosum and F. vesiculosus have with Fucus serratus L., with some ecological remarks. different phenologies (A. nodosum consists of numer- Ophelia 3: 1-43 ous slender elliptical stalks, while F, vesiculosus has Hicks, G. R. F. (1977a). Obsewahons on substrate preference numerous broad thin thalli). These differences may be of marine phytal harpacticoids (Copepoda). Hy- drobioloqa 56: 7-9 obscured by epiphytic algae when they are abundant. Hicks, G. R. F. (1977b). Species composition and zoogeogra- Since A. nodosum and F. vesiculosus have a similar phy of marine phytal harpacticoid copepods from Cook epiphyhc flora (Sieburth & Tootle 1981), differences in Strait, and their contribution to total phytal meiofauna. the composition of epifauna between A, nodosum and N. Z. J1 mar. Freshwat. Res. 11: 441-469 H~cks,G. R. F. (1977~).Species associations and seasonal F. vesiculosus may only become apparent when populahon densities of marine phytal harpacticoid epiphyhc algae are sparse or absent. copepods from Cook Strat. N. Z. J1 mar. Freshwat. Res. 11: 621-643 Acknowledgements. This research was funded by a Natural Hicks, G. R. F. (1980). Structure of phytal harpacticoid Sciences and Engmeering Research Council Operating Grant copepod assemblages and the influence of habitat com- to RES. SCJ was supported by a Natural Sciences and plexity and turbidity. J. exp. mar. Biol. 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This article was presented by Dr. R. J. Conover; it was accepted for printing on February 16, 1987