MARINE ECOLOGY PROGRESS SERIES Published September 17 Mar Ecol Prog Ser - I P P

Accumulation of polychlorinated biphenyls by the inf aunal brittle stars filiformis and A. chiajei: effects of eutrophication and selective feeding

Jonas S. Gunnarsson*, Mattias Sköld**

Department of Marine Ecology. Göteborg University, Kristineberg Marine Research Station. 450 34 Fiskebäckskil, Sweden

ABSTRACT: Polychlonnated biphenyl (PCB) accumulation by the 2 brittle stars Amphiura filiformis and A. chjajei was studied in a laboratory experiment and in the field. In the laboratory study. the fate of '4C-2,2',4,4'-tetrachlorobiphenyl(TCB) was determined in benthic microcosn~s,with and without the addition of phytoplankton (Phaeodactylum tricornutum) Added phytoplankton was rapidly miner- alised and stimulated an increased dissolved organic carbon content in the water-column and bacterial production on the sediment surface. TCB uptake by the brittle stars was significantly higher in the microcosms enriched with phytoplankton. Differences in TCB concentrations were still significant after normalisation to lipid content, suggesting that selective feeding rather than equilibnum partitioning was the cause of the increased TCB burden. Treatment effects were more apparent in body (disk) tissue, than in the arm fraction of the bnttle stars, in agreement with the lipid content of the tissues. No difference in total organic carbon, total nitrogen or TCB concentrations of the sediment surface was detected. In the field, ophuroids and sediment cores were collected at a coastal urban estuary off the city of Göteborg, Sweden, and at an offshore station in the Kattegat Sea. Surn-PCBs of sediment and brittle stars were ca 3 times higher at the coastal station than at the offshore station. Biota sediment accumulation factors, determined from the laboratory and field exposures, ranged from 1.5 to 5.9. The results from this study suggest that eutrophication processes, such as increased phytoplankton produc- tion. may contribute to increasing the accurnulation of organic pollutants in benthic sediment-ingesting fauna. The significance of A. fjliformjs in the transfer of PCBs to higher trophic levels is also discussed based on data of sublethal by the demersal flat fish Limanda Dmanda and from production estimates of an A. filiforrnis population.

KEY WORDS: Bioaccumulation . Sediment accumulation factors . Trophic transfer . Microcosms Kattegat - Echinodermata Ophiuroidea

INTRODUCTION organic matter in the water-column and sediments (Karickhoff et al. 1979). In the water-column, the bind- Organic matter plays a fundamental role in control- ing of hydrophobic contaminants to particulate and ling the bioavailability and distribution of hydrophobic dissolved organic matter (POM, DOM) may increase organic contaminants. Due to their hydrophobic char- their apparent solubility and water retention (Chiou et acter, toxic hydrophobic organic compounds (HOCs) al. 1987), or on the contrary enhance the Sedimentation such as polychlorinated biphenyls (PCBs) and poly- rate of particle-sorbed contaminants (Millard et al. cyclic aromatic hydrocarbons (PAHs) rapidly sorb to 1993). Several studies have shown that the bioavail- ability of organic compounds via aqueous and pore 'E-rnail: j.gunnarsson@kn~f.gu.se water exposure can be decreased in the presence of "Present address: County Administration of Västra Götaland, DOM (Carlberg et al. 1986, Kukkonen et al. 1991). Nature Conservation Section, 403 40 Göteborg, Sweden Likewise, both bioaccumulation and toxicity of sedi-

O Inter-Research 1999 Resale of full article not permitted 174 Mar Ecol Prog Ser

ment-bound contaminants were reported to be in- monly found in Amphiura communities (Petersen versely proportional to the total organic carbon (TOC) 1915). A. filiformis can switch from suspension to de- content of the sediment (Rubinstein et al. 1983, posit feeding, while A. chiajei is a strict deposit feeder Nebeker et al. 1989). Inverse relationships between (Buchanan 1964).These species also provide an impor- bioavailability and DOM or TOC content are explained tant food source for many fish and invertebrate preda- by the assumption that contaminants bound to DOM tors, including dab (Limanda limanda: Duineveld & are unavailable for uptake, because the contaminant- Noort 1986), haddock (Melanogrammus aeglefinus: DOM complex is too large to pass through biomem- Mattson 1992) and Norway lobster (Nephrops norvegi- branes, and its dissociation too slow to compete with cus: Baden et al. 1990).These predators do not gener- the freely dissolved contaminant fraction (Landrum et ally consume the entire bnttle star but crop only the al. 1996). This applies to organisms for which respira- arms, which are later regenerated (Sköld et al. 1994). tion in the water-column or interstitial water is the Accumulation of PCBs by infaunal organisms has been main exposure route (Adams 1987). Sediment-ingest- shown to be the first step in their transfer to higher ing organisms, however, rnay shotv a different re- trophic levels, including human consumers (Thomann sponse, and on the contrary increase their bioaccumu- et al. 1986). Loizeau & Menesguen (1993) showed that lation of HOCs by selective feeding on TOC-nch 8 to 15% of the PCB burden in dab from the Bay of contaminated particles (Boese et al. 1990, Gunnarsson Seine could be explained by ophiuroid consumption. et al. 1996). By providing more energy to the infaunal Amphiura communities rnay therefore play an impor- organisms, an organic matter supply rnay also con- tant role in the accumulation, remobilisation and trans- tnbute to increase lipid reserves and/or increase meta- fer of PCBs and other sediment-associated contami- bolic rates which, in turn, rnay affect the bioaccumula- nants to higher trophic levels. tion and toxicity of contaminants (Niimi & Cho 1981). The objectives of the present study were: (1)' to ob- Phytoplankton constitutes an important reservoir serve the effects of phytoplankton addition, simulated for organic contaminants (Stange & Swackhamer in benthic microcosms, on the distnbution and bioac- 1994). Contaminants accumulated in phytoplankton cumulation of PCB by Amphiura fiiiformis and A. chia- will either be grazed upon and transported into other jei, (2) to determine in situ PCB concentrations of A. Eil- compartments of the pelagic food chain or carried to iformis and A. chiajei from the Kattegat Sea, (3) to the sediment by dead cells and sinking aggregates determine accumulation factors in the field and in lab- (Swackhamer & Skoglund 1993). During the last oratory exposure, and (4) to discuss the importance of decades, the , the Kattegat and the southern predation on Amphiura communities for the transfer of Skagerrak have experienced an increased anthro- PCBs to higher trophic levels. pogenic input of toxic contaminants and nutrients (Richardson & Heilmann 1995, Rosenberg et al. 1996). Reports of high concentrations of organic contaminants MATERIAL AND METHODS in sediment and biota have been presented concomi- tantly with studies revealing dramatic effects caused Experimental system and contamination. The ex- by eutrophication processes (Baden et al. 1990, Mag- penment was run in six 15 1 (22 X 29 X 24 cm) whole- nusson et al. 1996). Since the distribution and bioavail- glass aquana (microcosms), for 78 d at the Manne ability of organic contaminants are likely to be coupled Research Station Solbergstrand (MRSS), Norwegian to the production and turnover of organic matter, it is Institute for Water Research (NIVA). Each microcosm essential to evaluate hotv the cycling of contaminants (Fig. 1) received 4.8 1homogenized clay-sediment from in an aquatic system rnay be affected by changes in the the Oslofjord (60 m, total carbon [TC] = 13.5 mg g-' dry trophic Status of that system (Gunnarsson et al. 1995). weight [DW], total nitrogen [TN] = 1.2 mg g-' DW,

Eutrophication of the Kattegat and Skagerrak rnay mean grain size @ = 4.80), giving a sediment bottom have contributed to increase the abundance and bio- layer of 8 cm depth, covered by a water-column of mass of benthic macrofaunal species in areas where 15 cm. The microcosms were sealed with glass lids the water mixing is high enough to supply oxygen randomly perforated for sampling, and plugged with renewal (Pearson et al. 1985).The dominant infaunal silicone corks. Water mixing was enabled by the action bnttle Star Amphiura filiformis is one of the species of a magnetic stirrer placed upside down on the lid of which seems to have increased in number and biomass each aquanum and a Teflon coated magnet-bar on the following the increased food supply (Josefson et al. inside. Temperature was maintained between 6.5 and 1993). A. filiforrnis dominates the bottom of vast areas 8.5"C by placing the microcosms in a water-bath of the Kattegat, Skagerrak and , with densi- continuously circulated with natural seawater (from ties from about 250 to 3900 ind. m-2 (Duineveld et al. 40 m depth). During an initial 'contamination phase' of 1987). A. chiajei is another infaunal bnttle star com- 8 d all the microcosms were continuously supplied Gunnarsson & Skold: Accun~ulation of PCBs by infaunal brittle stars 175

F HT according to the technique of Veith & Comstock (1975). The column consisted of a 1.0 1 glass column, filled with 500 mg of glass beads coated with 'T-TCB. Coating was done by mixing the beads with 500 ml of hexane, containing 2.5 nlg I4C-~CB(120 pCi), and evaporating the solvent in a rotary evaporator. The column was connected to a 20 1 glass aquarium ('contamination aquarium') mixed by a magnetic WB t@ t@ stirrer Filtered seawater (0.45 pm) M was recirculated through the gener- U ator-column with a penstaltic pump, and TCB concentration of the water I was adjusted by regulating the flow BpJjmp. . .,. .: . ' .,., ...... :...... : . ..I 1::...... >.I ... . . I : .'...... , :..:: :-. :..:.,..:.~.. . . .'-. , ...... rate through the column. Before the ...... P P experiment, water was circulated 1 through the column for 7 d to allow glass surfaces and water to be - PUF - - - - saturated with eluted I4C-TCB. At the start of the experin~ent, TCB f f t t + + concentration of the contamination

Fig. 1. Expeiirnental system (I:Incoming deep 140 m] seawater; F. filters, HT: head aquarium was 15.1 ng TCB nll-l. tank; P: penstaltic pump; GC: generator-column charged with '4~-~~~;PG: pres- The TCB-contaminated water was sure gauge in equilibnum with the water level of the head tank; CA: contamination dosed to the microcosms using a aquarium with 14C-TCB-saturated seawater; PPL: batch with phytoplankton peristaltic pump arid glass tubings, [Phaeodactylum tricornuturn]; FW: batch with filtered seawater; WB. water bath with deep seawater maintaining the microcosmc at constant ternperature; M: ben- The water Of the thic microcosms with sedinlent and ophiuroids; E: enriched, i.e. with algal addition; mination aquanum was maintained C: controls, 1.e. without algal addition; PUF: polyurethane filters constant by the refilling action of a header tank, supplied with serially filtered (50 pm + 20 pm) natural with tetrachlorobiphenyl (TCB)-contaminated seawa- seawater (from 40 m depth, 34 %o).During the contam- ter. During this initial contamination phase half of the ination phase, the generator-column maintained a microcosms ('eutrophic' or 'enriched') were also con- fairly constant elution capacity until the last day of tinuously supplied with a phytoplankton culture, the exposure when TCB concentration of the contamina- other half ('oligotrophic' or 'controls') receiving an tion aquanum declined, due to a Saturation of the equivalent volume of filtered seawater (0.45 pm). TCB- column with organic matter and bacteria of the incom- contanlinated water and phytoplankton were added to ing seawater. An elution capacity of 55 % was the microcosms through separate inlets of the glass obtained, corresponding to a total addition of 0.23 mg lids. The phytoplankton addition was constituted of 8 1 I4C-TCB microcosm-' during the contamination phase. of a chemostat-culture of the marine diatom Phaeo- Following this initial contamination phase of 8 d, the dactylumtricornutum, containing 41.9 mg 1-' TOC and microcosms were left to equilibrate in a recirculating 8.1 mg 1-' DOC, and corresponding to a C enrichment mode for 38 d before the brittle stars were introduced of 5.6 g C n~-~.TCB contamination was done using in the microcosms. A more complete descnption of the radiolabelled [U-14C]-2,2',4,4'-TCB,IUPAC 47, with a experimental system and the observed partitioning of specific activity of 13.8 Ci mol-' and a punty of >98% 14C-TCB between the different pelagic fractions, i.e. (Sigma Chemicals, St. Louis, MO, USA). Owing to their TCB associated with particles and phytoplankton great stability, and hydrophobic properties, radiola- (TCBPART),associated with DOC (TCBDoc),or truly dis- belled PCB congeners are suitable model contami- solved (TCBDlss),and the Sediment dunng the initial nants for bioaccunlulation studies and for modelling phase and the equilibration phase of the expenment is the behaviour of other hydrophobic organic pollutants. given in Gunnarsson & Rosenberg (1996). The present In order to avoid the presence of an organic carner, paper focuses on the accumulation of TCB by the TCB was added to the water using a generator-column bnttle stars. 176 Mar Ecol Prog Ser 186: 173-185, 1999

Exposure of brittle stars. After 38 d of equilibra- according to Hedges & Stern (1983). DOC content of tion in a recirculating mode, O2 concentration was the culture was analysed on a Dohrman DC- increased from hypoxic (2.05 mg O2 1-') to normoxic 190 C analyser on filtered (0.45 pm) samples treated (6.86 mg O2 1-I) conditions by establishing a flow- with H3P04. Radioactivity was determined by liquid through circulation with natural (from 40 m depth), scintillation counting on a Beckman LS 5000 TD, with unfiltered seawater. A water flow of 6.4 ml min-I, correction made for quenching and background. giving a residence time of 24 h microcosm-I, was Duplicate (5 ml) samples were counted for 10 min, and used. The brittle stars Amphiura filiformis and A. chi- chemoluminescence was kept under 5%. The detec- ajei (Ophiuroidea: Echinodermata) were sampled at tion limit was 0.61 ng TCB. Extraction of TCB in the the mouth of the Guilmarsfjord, Sweden, from 35 m sediment, water and PUFs was done by solvent extrac- depth with a box corer (0.09 m2). The bnttle stars tion (acetone/hexane, 1:I), using soxhlet extraction and were removed cautiously from the sediment to pre- shaking according to Gunnarsson & Rosenberg (1996). vent arm amputations. Specimens were acclimated TCB concentrations of Pore water samples (TCBpw) for 3 d in the laboratory before initiating exposure. were below detection lirnits and instead estimated Eight A. filiformis and 7 A. chiajei were added per from the equation: TCBpw = TCB„d/(focKoc), where microcosm, corresponding to a density of 133 and TCBXd is the TCB fraction associated with sediment 116 ind. m-', respectively, and exposed to the conta- particles (pg kg-I), foc the organic C fraction of the minated sediments for 31 d. Nine sediment cores sediment (kg orgC kg-' DW sed.) and Koc the organic (height: 1 cm, diameter: 4 mm) were sampled per carbodwater partition coefficient (Di Toro et al. 1991). microcosm at the start and end of the exposure to LogKoc = 4.88 was determined from the equation: determine TOC, TC, TN content and TCB concen- logKoc = 0.007 + 0.834 logKow (Chou & Griffin 1986), trations of the sediment. Total TCB concentration of using logKow(PCB-47) = 5.85, where Kow is the octanoV the water-column and release of TCB from the sedi- water partition coefficient (Hawker & Connell 1988). ment to the tvater-column were measured by contin- Frozen ophiuroids were carefully dissected in order to uously filtering outflowing water from each micro- separate body (disk) from arms. TCB extraction from cosm through polyurethane filters (PUF). Six foam the tissues (arms and disks) tvas done with microwave- plugs, each with a height of 5 cm and a diameter of assisted extraction in 30 ml acetone/hexane (1:l) (pres- 5.5 cm, were placed in senes per filtration column. sure: 100 PSI, power: 100%, temp.: 120°C, ramp time: Activity of infaunal organisms is difficult to observe 8 min, extraction time: 20 min) with an extraction effi- since they are buried into the sediment. Infaunal ciency >90%. Duplicate 5 ml samples of the extract brittle stars feed by coiiecting food particles with 1 to were mixed with 10 ml scintillation cocktail Ultima 3 arms protruding from the sediment (Buchanan gold (Packard) and counted for 10 min. Radioisotope 1964). Daily counting of visible arms was used as a activity was expressed on a tissue dry weight basis measure of activity. Temperature (7.4 to (dpm g-I DW),normalised to lipid, TOC or TN content, 9.Z°C) and salinity (ca 34%0) of the incoming water and converted into micrograms of TCB using the spe- were registered continuously during the expenment cific activity of the compound (1 dpm = 9.45 X 10-3 ng with a data logger. Oxygen concentration of the in- TCB). Small sub-samples (2 to 5 mg) of disk and arm and outflowing water of the microcosms was re- tissues were extracted with chloroform/methanol (2:1), corded daily with an oxygen meter. The amount of and total lipid content was measured according to the resuspended particles due to activity and to micro-gravimetric technique of Gardner et al. (1985). the mechanical mixing was rneasured by collecting PCB analyses of Amphiura filiformis and A. chiajei 1 1 water samples of outflowing water at 4 different from the field. Ophiuroids and sediment sarnples occasions during the experiment. Totai particulate were collected from 2 sites of the Kattegat Sea in matter of the water-column (expressed as g DW 1-I order to get in situ PCB contamination levels. A and g AFDW 1-' [ash-free dry weight]) was deter- coastal station ('BC 64': 57"40.311N, 11°41.39' E; mined by filtration on pre-combusted GF/F filters 21 m) in the Göteborg estuary was chosen since pre- (Whatman). At the end of the experiment, the ophi- vious sediment toxicity and high contaminant concen- uroids were recovered from the microcosms by wet- trations had been reported from this site (Dave & sieving the sediment, rinsed cautiously with filtered Dennegard 1994, Magnusson et al. 1996). An offshore (0.45 pm) seawater, and frozen (-20°C) in a scintilla- station ('BC 69': 57"51.11'N, 11" 18.06'E; 70 m) on the tion vial. slope of a deep trench was chosen as a high biomass Chemical analyses. TC, TOC and TN content of of both species of ophiuroids had been reported from freeze-dried sedirnents and ophiuroids was measured it (Rosenberg 1995). Five sediment cores from each with a Carlo Erba analyser. TOC was determined after station were collected. Overlying water was carefully treating the samples with HCI to remove carbonates removed, and the upper 2 cm were scraped off into Gunnarsson & Sköld: Accumulation of PCBs by infaunal brittle stars 177

acetone-washed glass vials. Three of the sed- Table 1 Total carbon (TC), organic carbon (TOC) and nitrogen (TN) iment samples were pooled for contaminant (% of freeze-dned surface sedirnent wt) (n = 3) analyses and the remaining 2 used for TC, TOC, TN and granulometry analyses. Total Sampling Treatment TC (SD) TOC (SD) TN (SD) 7 PCBs and specific congeners of the sedi- Start (Day 46) Control 1.33 (0.02) 1.27 (0.01) 0.09 (0.01) ment were analysed and quantified by the Enriched 1.26 (0.14) 1.22 (0.14) 0.10 (0.01) Swedish Environrnental Research Institute End (Day 78) Control 1.28 (0.02) 1.25 (0.09) 0.09 (0.01) (IVL) using electron-capture gas chromato- Enriched 1.17 (0.16) 1.07 (0.16) 0.10 (0.01) graphy (GC-ECD) according to Brorström- Lunden & Mowrer (1992). Three box core samples (0.09 m2) were sieved (1 mm mesh size) and RESULTS preserved in 70% ethanol to determine macrofaunal abundance and biomass, according to Rosenberg Laboratory study (1995). PCB content of the ophiuroids was measured in 25 Amphiura filiformis from the 2 stations and in 25 Carbon, nitrogen and TCB distribution in A. chiajei from the offshore station only, since no A. sedinlent and water chiajeiwere found at the coastal station. The brittle Stars were gently removed from the sediment, nnsed C and N content of the sedirnent surface, at start and cautiously with filtered (0.45 pm) seawater and frozen end of the exposure, is presented in Table 1. Neither (-20°C) in acetone-washed glass vials. Lipid content, treatment nor time had any significant effects on C, N total PCB and 31 detectable PCB congeners were and TOC values. TCB concentrations measured in sed- measured in tnplicate pools of 5 to 10 ind. station-' iment, water and bnttle stars are presented in Table 2. by the Environmental Toxicology Laboratory at the No treatment effect, i.e. effect of the phytoplankton Norwegian College of Vetennary Medicine, Oslo, addition, was observed on TCB concentrations of the Norway, using GC-ECD according to Bernhoft & sediment surface (TCB„J (0 to 1 cm). TCBWd de- Skaare (1994). creased significantly from the start to the end of the Statistics. Data were analysed with factorial analysis experiment (F,, = 10.8, p = 0.011), indicating that a of variance (ANOVA). Pooling of nested and treatment loss of TCB from the sediment surface occurred during terms was done after the preliminary test if the nested the exposure. A substantial amount of TCB was recov- factor was not significant (p > 0.25), as recommended ered in the polyurethane filters, showing that a fraction by Underwood (1997). Data were transformed (root or of the TCB lost from the sediment surface was released log) if necessary to meet the assumptions of normality into the water-column. Average TCB concentrations of and homogeneity of variantes. Homogeneity of vari- the water-column and desorption fluxes (Table 2) were ances was evaluated using the Cochran C-test (a = calculated from the total concentrations of the poly- 0.05) (Snedecor & Cochran 1989). urethane filters divided by flow rate and exposure time.

Table 2. Tetrachlorobiphenyl (TCB) concentrations in sedirnent, water and Amphiura spp. TCB concentration in sediment (0 to 1 cm) at start and end of exposure; TCB concentration in water, collected in PUF filters; mean TCB desorption flux, measured from PUF values; TCB concentration in Pore water (Pw),predicted from logK„ = 4.88; TCB concentration in tissue fractions and total concentration per animal

TCB concentrations Control (SD) Enriched (CD)

[TCB] sed, start (Day 46) (pg kg-' DW sed) 61.4 (23.4) 61.3 (20.7) [TCB] sed, end (Day 78) (pg kg-' DW sed) 39.1 (21.0) 26.9 (12.3) [TCB] water at start (Day 46) (ng 1-I) 10.3 (1.6) 9.7 (2.7) [TCB] water at end (Day 78) (ng 1-I) 10.9 (1.0) 12.0 (1.3) TCB desorption (pg desorbed d-' m-*) 1.6 (0.1) 1.8 (0.2) [TCB] Pw, start (Day 46) (ng 1-') 63.8 - 66.1 - [TCB] Pw, end (Day 78) (ng 1.') 41.2 - 33.1 - [TCB] A. filiformis arms (pg kg-' DW arm tissue) 81.6 (15.4) 103.1 (29.1) [TCB] A. filiformis dick (pg kg-' DW disk tissue) 217.4 (71.6) 488.3 (101.9) [TCB] A. fiiiformis total (pg kg-' DW tissue) 117.1 213.0 - [TCB] A. chiajei arms (pg kg-' DW arm tissue) 74.9 (48.9) 68.3 (18.1) [TCBl A. chiajei disk (pg kg-'DW disk tissue) 324.7 (147.5) 488.4 (144 2) [TCB] A. chiajei total (pg kg-' DW tissue) 157.9 - 197.8 178 Mar Ecol Prog Ser 186: 173-185, 1999

be verified statistically since the variances of the lipid values within treatments were high and not homoge- neous. No significant treatment effect was found for total DW, TN or TOC content of the disk of A. filiformis.

Normalisation of accumulated TCB concentrations to percent lipid, TOC and TN TCB concentrations of Amphiura filiformis normal- ised to percent total lipid reduced the difference between treatments; however, lipid-normalised TCB concentrations were still significantly higher in the A. filiformis A. chiajei ennched aquana (F,, = 22.3, p = 0.0092). Normalisa- tion of disk TCB concentrations to TOC or TN content did not reduce the differences between treatments.

Resuspension, brittle star activity and temperature Resuspended particulate matter content (g DW 1-' and g AFDW 1-') of filtered water samples showed no differences between treatments. Visual observations of bnttle star activity (i.e. Counts of active arms) revealed no difference between treatments. Since no significant difference was observed between treatments, arm activity from both treatments was pooled and showed an increase with time during the expenment (Fig. 3). A. filiformis A. chiajei Water temperature was not different between treat- ments, but decreased during the experirnent (Fig. 3). Fig. 2. Amphiura spp. TCB accumulation (ng TCB g-' DW) in Increasing animal activity and absence of mortality or (A) disks and (B)arms (open bars: ennched with phytoplank- ton; filled bars: controls; error bars: standard deviation, *p sublethal Stress behaviour (e.g.arm autotomy or emer- 0.05; ns: not significant gence out of the sediment) indicated that the speci- mens were in good health dunng the entire exposure.

TCB accumulation by brittie stars Field study

TCB accumulation per gram tissue DW by the ophi- Accumulation of PCBs by Amphiura filiformis uroids is presented in Fig. 2. The phytoplankton and A. chiajei in the field ennchment induced a significantly higher TCB accu- mulation in the disks of the 2 species (Amphiura fili- Table 4A presents total PCB concentrations, sedirnent Formis, Fl,, = 288.30, p = 0.0001; A. chiajei, F,,, = 8.12, characteristics, total biomass, abundance and lipid con- p = 0.04). No treatment effect was found for the arm tent of the ophiuroids from the coastal and offshore sta- fraction (A. filiformis, F,, , = 3.66, p = 0.12; A. chiajei, tions. Total PCB concentrations of sediment and anirnals F,, , = 0.20, p = 0.64). No significant differences were higher at the coastal than at the offshore station, as between species were found.

Table 3. Arnphiura filiformjs. Dry weight (DW; g), total lipids (% g DW). total DW, lipid. TOC and TN content organic carbon (TOC; % g DW) and total nitrogen (TN; % g DW) of disk and in disks and arms arms (ND: below detection limit) Total lipids, TOC and TN content of Treatment Tissue DW (SD) Lipid (SD) TOC (CD) TN (SD) disk and arms of Amphiura filiformis are presented in Table 3. Lipid content Control Disk 0.020 (0.004) 2.9 (1.2) 20.93 (1.40) 3.31 (0.32) of the arms was below detection level. Arms 0.056 (0.017) ND - 17.02 (0.41) 2.68 (0.18) Lipid content of the disks was 2.9% in Enriched Disk 0.022 (0 004) 5.0 (4.3) 21.93 (1 39) 3.55 (0.46) controls, and 5.0% in enriched aquana. Arms 0.055 (0 012) ND - 18.08 (088) 3.05 (0 28) A treatment effect could, however, not Gunnarsson & Sköld: Accumulation of PCBs by infaunal brittle stars 179

T (OC) Table 4. PCB concentrations of sediments and Amphiura spp. in the field. -.--- Numb. Arms I30 NA: not analysed; 0.00. below detection level

Coastal station Offshore station

a.' a.' ,$o$ 49% $5' .G> @$ 8iJi\ 6 - ,." 2- P' +ab P. P. (A) General biological and chemical characteristics TOC 1%g DW) 3 24 - - 1.88 - - Md I$ (Md grain size) 22.00 - - 16.00 - - Lipid (% g DW) - 4.40 -- - 8.10 4.80 Biomass (g WW m-') - 75.45 - 340.20 84.00 Abundance (ind. m-2) - 1373 - 1917 247 Total PCB (pg kg-' DW) 30.00 80.24 8.40 27.90 25.94 Sum common PCBs" 5.62 42.73 - 2.14 13.61 13.03 (pg kg-' DW) d 46 d 78 Time (d) (B) PCB congeners (pg kg-' DW) (n = 3 pooled samples) PCB-28 0.17 1.37 - 0.27 1.39 1.55 Fig. 3. Temperature ("C) and bnttle star PCB-31 NA 3.17 - NA 1.69 2.07 activity (number of arms) (Amphiura fili- PCB-47 NA 0.10 - NA 0.00 0.00 form.~and A. chiajei, pooled data) PCB-52 0.23 NA 0.11 NA NA PCB-56 NA 0.71 NA 0.22 0.54 PCB-66 NA 1.17 NA 0.00 0.00 expected from the location of the sta- PCB-74 NA 1.13 NA 0.61 0.41 PCB-87 NA 0.00 NA 0.00 0.00 tions. The coastal station, situated at PCB-99 NA 1.49 NA 0.73 0.51 the mouth of the Göta ÄIv River, is L!clLu 0.79 3.55 0.30 3.23 4.25 exposed to anthropogenic loading PCB-105 NA 1.20 NA 0.54 0.45 from industnes along the nver and the PCB-110 NA 2.98 NA 2.15 1.13 harbour of Göteborg. Total PCB con- PCB-114 NA 0.00 NA 0.00 0.00 PCB-118 0.87 4.09 0.39 1.44 0.92 centration of the sediment at the PCB-128 NA 1.69 NA 0.42 0.33 coastal station was approximately 3.6 PCB-132 NA 2.67 NA 0.82 0.77 times higher, on a DW basis, than at PCB-136 NA 0.00 NA 0.00 0.00 the offshore station, and 2.1 times PCB-137 NA 0.26 NA 0.00 0.00 PCB-138 1.70 13.04 0.57 3.08 2.66 higher, when normalised to sediment PCB-141 NA 1.20 NA 0.31 0.29 TOC content. Total PCB accumulated PCB-149 NA 5.44 NA 1.69 1.09 by Amphiura filiformis at the coastal PCB-151 NA 1.40 NA 0.82 0.81 station was 2.7 times higher on a DW PCB-153 1.40 13.25 0.46 3.46 2.73 0.45 0.22 basis, than at the offshore station, and PCB-156 NA 1.68 NA PCB-157 NA 0.61 NA 0.30 0.20 5.3 times higher on a lipid basis. Total PCB-170 NA 3.84 NA 0.42 0.41 PCB concentrations of the 2 ophiuroids PCB-180 0.69 7.43 0.15 1.01 0.92 at the offshore station were similar on a PCB-183 NA 0.00 NA 0.00 0.00 DW basis, and 1.5 times higher in A. PCB-187 NA 3.42 NA 1.17 1.02 PCB-189 NA 0.12 NA 0.20 0.27 chiajei when normalised to lipid con- PCB-194 NA 1.95 NA 0.26 0.27 tent. No A. chiajei was found at the PCB-196 NA 0.89 NA 0.21 0.22 coastal station. A list of the analysed PCB-199 NA 0.00 NA 0.00 0.00 PCB congeners is given in Table 4B. PCB-206 NA 0.55 - NA 0.25 0.24 PCB-209 NA 0.84 NA 1.06 1.66 The sum of 6 PCB congeners analysed - in both sediments and brittle stars, aSum of 6 PCB congeners analysed both in sediments and anirnals (under- termed 'surn cornmon PCBs' (Table 4A), lined), used for the calculation of bioaccurnulation factors hCongener used in the experiment was used for the determination of bioaccumulation factors (BAFs) and biota sediment accumulation factors (BSAFs). BAFs and BSAFs calculated from the field and the coastal station and the enriched microcosms. BAFs from our experiment are given in Table 5. There was a ranged from 3.0 to 7.9, showing that ophiuroids could good correspondence between BAFs and BSAFs from accumulate between 3 and 8 times higher PCB con- the field and from the experiment, especially between centrations than bulk sediment concentrations. BSAFs 180 Mar Ecol Prog Ser

Table 5. Amphiura spp. Bioaccumulation factors in the field and Loss of TCB from the sediment surface in microcosms (n = 3). Values in parentheses are biota sediment accumulation factors (BSAFs) calculated for disk tissue only. A significant amount of TCB was lost from the sedi- Compo'unds: 'sum of common PCBs', sum of 6 PCB congeners analysed both at the coastal and at the offshore stations, 'PCB- ment surface during the expenment. Since the bio- 47',PCB congener used in the microcosms. BAF. bioaccumula- degradation of TCBs is extremely slow in natural tion factor (pg TCB g" DW tissue)/(pg TCB g-' DW sediment); benthic light and temperature conditions (Pignatello BSAP: [(pgTCB g-' DW tissue)/(g lipid g-' DW tissue)]/[(pg TCB & Chapa 1994), most of the TCB lost from the sedi- g-' DW sediment)/(g TOC g-' DW sediment)] ment surface had either been released into the water- column or been buried in the sediment and accumu- Species Station Microcosm lated in the brittle stars. Several studies have shown Coastal Offshore Control Enriched that hydrophobic contaminants can be mobilised from BAF A. filiformis 7.6 6.4 3.0 7.9 the sediment as a result of physico-chemical desorp- A. chiajei - 6.1 4.0 7.3 tion processes (Di Toro & Horzempa 1982) and mech- BSAF A. filifoormis 5.6 1.5 4 3 (2 4) 5.9 (3.9) anical or biological resuspension of contaminated par- A. chialei - 2.4 - - ticles (Kanckhoff & Morris 1985). By dividing the total amount of TCB collected by the polyurethane filters per day and Square meter, desorption of TCB from the ranged between 1.5 and 5.9. As for the BAFs, highest sediment surface can be expressed as release rates, values were found in the enriched microcosms. Slightly thus giving 1.64 pg TCB d-' m-2 and 1.80 pg TCB d-' lower values were obtained when only the disk concen- m-2 from the control and ennched sediments, respec- trations were used. tively. Comparing the total TCB loss from the sediment surface dunng the experiment to the amount collected in the PUFs, and assuming that all TCB leaving the DISCUSSION microcosms, as a truly dissolved fraction or associated with particles and colloids, was trapped by the PUFs, Phytoplankton decomposition we can estimate that ca 5 % of the total TCB pulse ini- tially deposited on the sediment surface, was remo- Phaeodactylum tricornutum is a common marine bilised into the water-column, and ca 95 % of it was diatom in coastal waters, able to form sinking aggre- buned into the sediment or accumulated by the ani- gates of algal cells (Kieirboe et al. 1990). In the present mals. The effects of brittle Star activity on the distribu- study, despite a phytoplankton pulse of 5.6 g ~rn-~,or tion and remobilisation of TCB could, however, not be 335 mg TOC, into the water-column of the eutrophic quantified per se, since no aquana without bnttle stars microcosms, no significant differences in sediment C, were used in this study. TOC or TN could be detected between treatments dur- ing the entire experiment. Manne phytoplankton con- stitute a highly attractive organic C source for micro- Accumulation of TCB by the brittle stars bial decomposers (Azam et al. 1983). Diatoms can be decomposed within days to a few weeks in the water- The phytoplankton ennchment increased the accu- column (Chen & Wangersky 1996) and even more mulation of TCB by the 2 bnttle Star species, although rapidly at the sediment surface, where they stimulate no differences in sediment C, N or TCB content could benthic bacterial production (Meyer-Reil 1983). De- be measured between the treatments. Bioaccumula- composing algal cells release substantial amounts of tion of organic contaminants may be influenced by DOC (Holmer 1996). Degradation kinetics of this DOC differences in exposure pathways and metabolic char- has been descnbed as a 2-step process, with an initial acteristics (Connel 1988). Infaunal brittle stars may rapid bacterial consumption of highly labile DOC, fol- accumulate contaminants either by direct contact with lowed by a slower mineralisation of more refractory contaminated sediment particles, or via respiration in DOC (Westnch & Berner 1984). In this expenment, interstitial and overlying water, or by ingestion of con- following the phytoplankton and TCB additions, the taminated food. Several possible mechanisms could microcosms were left for 1 mo in a recirculating mode explain the increased bioaccumulation of TCB follow- before the brittle stars were added. Hence, at the start ing the phytoplankton addition: (1) increased animal of the exposure phase, most of the phytoplankton C activity, (2) simple partitioning to a higher lipid pool, is likely to have been processed by microbial con- and (3) selective feeding on contaminated particles. sumers. This is consistent with a yellow bacterial film Greater bnttle Star activity could contnbute to in- observed on the sediment surface of the ennched crease the encounter rate of individuals with contami- microcosms. nated particles. Amphiura filiformis and A. chiajei have Gunnarsson & Skold. Accumulation of PCBs by infaunal brittle stars 181

been shown to rapidly increase their feeding activity in like A. chiajei feed on sediment-associated food items. response to added phytoplankton, and to be able to In our field study no difference between species could convert this energy into increased somatic and germi- be shown. nal growth (Sköld & Gunnarsson 1996). Even though TCB content of the brittle stars could be separated no difference in arm activity between treatments could into disk and arm fractions, and the proportions of TCB be observed in the present study, the influence of accumulated in the 2 body compartments could be increased animal activity on TCB accumulation should compared. The difference between the 2 body com- not be excluded. partments was increased in the eutrophic treatment According to the equilibrium partitioning theory, the with a shift towards dick tissue. This is in accordance bioaccumulation of hydrophobic contaminants can with our lipid analyses, which revealed that lipid con- be explained by a simple partitioning between the tent of the arms was below the detection level, and that organic C pool of the sediment and the lipid pool of the nearly all the lipid reserves were present in the disk. organisms (Lake et al. 1990). Increased TCB uptake The lipid content of the disk 1s probably related to could result from a new partitioning equilibrium with a gonad size and development and indicates that the higher lipid content of the brittle stars, caused by the disks of Amphiura species are an important target site phytoplankton ennchment. Mean lipid content was for hydrophobic contaminants. slightly higher in the eutrophic microcosms. A normal- isation of accumulated TCB concentrations to the lipid content of the ophiuroids reduced the difference in PCB accumulation in the field TCB uptake between treatments; however, the treat- inent effect remained significant. Passive equilibration PCB contamination in fish and seal has been a malor of TCB into the lipid pool of the was thus cause of concern in the seas surrounding Sweden not sufficient to explain their higher body burdens. (Olsson et al. 1994). Sediments are a main sink for Instead, the increased accumulation rnay be the result PCBs, and substantial sediment surface concentrations of an active uptake process due to selective feeding on from the Kattegat, Skagerrak, Baltic Sea and the contaminated particles. Selective feeding on TOC-rich Danish Sounds have recently been reported (Broman particles rnay explain bioaccumulation levels above et al. 1993, Magnusson et al. 1996).However, although equilibrium, because these particles are also the pref- uptake by benthic mfaunal organisms rnay be one of erential sorption site for hydrophobic organic contami- the most important vectors of sediment-associated con- nants (Boese et al. 1990). In other words, selective tarninants to demersal fish and higher trophic levels, feeding maintains a thermodynamic disequilibrium, including human consumers, there are alrnost no avail- since the animals are accumulating against a fugacity able data on the contamination of natural benthic in- gradient. vertebrate populations of the Kattegat and the Skager- The importance of sediment ingestion and selective rak. This is to our knowledge the first study which feeding for the accumulation of organic contaminants presents concentrations of PCBs in amphiurids. Brittle has been reported for other deposit feeders (Wyman & stars were sampled from a typical contaminated urban O'Connors 1980, Landrum et al. 1992, Harkey et al. estuary and from an offshore station on the slope of a 1994). Most benthic deposit feeders selectively ingest 90 m deep trench in the Kattegat. The most prominent fine, nutritious particles, such as algal cells, bacteria congeners in biota and sediments were PCB-138, PCB- and different types of DOC (Lopez & Levinton 1987). 153 and PCB-180, all 3 commonly found in marine Amphiurids rnay feed on bacteria and take up DOC mammals and humans (Safe et al. 1987, Skaare et al. (Clements et al. 1988). Both species used in our study 1990). PCB-47, the congener used in the laboratory actively select food particles with their arms and tube experiment, was found just above detection level in feet and process a mucus-coated food bolus towards Amphiura filiformis at the coastal station only. Mean their mouth below the sediment surface (Buchanan TOC and total PCB concentrations were higher at the 1964). Several studies have shown that deposit feeders coastal station, which is in accordance with the study rnay accumulate more contaminants than suspension of Dave & Dennegard (1994) and is probably caused by feeders exposed to the Same sediment (Roesijadi et al. the high anthropogenic loading from the Gota Alv 1978, Hickey et al. 1995, Meador et al. 1995). In our River and the harbour of Göteborg. Biota and sediment experiment, no difference in TCB accumulation was total PCB concentrations at the coastal station were ca found between the 2 species. The lack of difference in 3.5 times higher than at the offshore site, on a DW TCB accumulation between the species rnay be attrib- basis. Normalisations to organic carbon or lipid content uted to the mixed feeding mode of Arnphiura filiformis. are presented in the results and discussed below along A. filiformis is not a strict suspension feeder but can with the bioaccumulation factors. The bion~assand switch from suspension to deposit feeding, and thus abundance of bi-ittle stars were considerably higher at 182 Mar Ecol Prog Ser 186: 173-185, 1999

the offshore than at the coastal station. The distribution highly contributing factor to the transfer of sediment- and abundance of Amphiura populations have been associated contaminants to higher trophic levels (e.g. related to food availability, hydrodynamic processes Thomann et al. 1986, Connolly 1991). Since Amphiura such as bottom currents and lateral advection, and filiformis populations dominate the benthic macro- deposition of organic matter (Creutzberg et al. 1984, fauna of vast areas of North European seas (O'Connor Rosenberg 1995). No A. chiajei was found at the et al. 1983, Duineveld & Noort 1986), it is of pnmary coastal station. Although the 2 species are known to concern to evaluate their potential role in the transfer coexist in typical Echinocardium filiformis communi- of pollutants from contaminated sedirnents to higher ties (Petersen 1915), A. chiajei is commonly found in trophic levels. A. fjljformis populations are exposed to silty sedirnents at depths over 70 m (Buchanan 1964). extensive predation by some fish species and crusta- The shallow and sandy character of the coastal site is ceans (Baden et al. 1990).Predation on infaunal brittle the most likely explanation for the absence of A. chia- stars occurs by consumption of the whole animal, but je; from it, although toxic effects caused by the higher more commonly by cropping exposed arms. Arm loss concentrations of contaminants cannot be ruled out. and subsequent regeneration may occur on average in 50% of the population and account for a substantial Part of its secondary production (Bowmer & Keegan

Accumulati~nfactors 1983, Skiild et al. 1994). Duineveld ISINonrt (1986) reported that Amphiura spp. arms accounted on aver- In the field study, BAFs (sum common PCBs in age for about 60% of the stomach content, on a DW tissue/sum common PCBs in sediment) showed that basis, of the dab Limanda Limanda. They also esti- bnttle stars accumulated ca 7 times higher PCB con- mated that the annual food consumption of Amphiura centrations compared to the sediment. BAFs were spp. arms by an average standing stock of dab in the remarkably similar between the 2 species and the 2 North Sea was 0.84 g arms m-2 yr-'. Using the yearly stations (Table 5), and higher than the empirical arm consumption obtained by Duineveld & Noort logKoc = 4.88 value. In the laboratory study, BAFs of (1986), and data from the present study (Table 4), we the controls were closer to the empirical value; in the can estimate a possible yearly trophic transfer rate for ennched aquaria, however, BAFs were higher and PCBs, from A. filiformis to dab. By applying the PCB closer to the field values. BSAFs (sum common PCBs in concentration of A. filiformis at the coastal station lipid-normalised tissue/sum common PCBs in TOC- (80.24 pg PCB kg-'), and considering that ca 70% of normalised sediment) are based on the equilibrium the PCB concentration may be found in the arms, cal- partitioning theory and predict that if concentrations culated from Table 1 (whole animal: 117.1 pg TCB kg-' are at equilibrium between the lipid pool of the organ- DW = 100%; arm fraction: 81.6 pg TCB kg-' DW = isms and the carbon pool of the sediment a maximal 70%; dick fraction: 217.4 pg TCB kg-' DW = 186% of theoretical value of 1.7 should be reached, regardless the TCB concentration), we obtain a trophic transfer of of lipid or carbon composition (McFarland & Clarke (0.84 g arms m-2 yr-' X 80.24 ng PCB g-' X 0.70 =) 47.2 1988). In the present study BSAFs ranged from 1.5 to ng PCBs m-3 yr-' to the dab by sublethal predation on 5.9 and were within the range of values reported from A. filiformis arms. other studies (Bierman 1990, Ferraro et al. 1991). How- Aiternatively the trophic transfer of PCBs can be esti- ever, our values were often higher than the predicted mated from the available production data of Amphiura value of 1.7, especially at the coastal station and in the filiforrnis. Sköld et al. (1994) reported that A. filiformis enriched aquaria, indicating that a greater uptake of populations have a production biomass ratio of 0.46 yr-', PCBs occurred than can be explained by total lipids and that 13.3 % of the production is due to arm regen- and TOC content, and supporting this observation ac- eration. Using the PCB concentration of A. filiformis cumulation of PCBs by the bnttle stars may be strongly arms at the coastal station (70% of 80.24 ng PCB g-I), related to selective feeding on organically richer, cont- and recalculating the biomass data from this station of aminated particles. These results suggest that the 75.5 g WW (wet weight) m-2 (Table 4) into DW by a equilibnum partitioning approach may underestimate conversion factor of 0.32 according to Sköld et al. the bioaccumulation of hydrophobic contaminants by (1994), we obtain a trophic transfer of: (0.46 X 0.133 X selective benthic deposit feeders. 0.32 X 75.5 X 0.70 X 80.24 =) 83.02 ng PCBs m-3 yr-'. Both estimates of the trophic transfer rates are in the Same order of magnitude and show that between 47 Trophic transfer and 83 ng PCBs m-2 yr-' may be transferred to the dab and other predators by sublethal predation on A. fili- Several food chain models of aquatic Systems have formis populations. The present study has shown that shown that predation on benthic invertebrates is a highest PCB concentrations were found in the disks Gunnarsson & Sköld: Accumulation of PCBs by infaunal bnttle stars 183

and that their PCB burden could be significantly in- KL, Maki A\V, Brungs WA (eds) Fate and effects of sedi- creased by organic enrichment. Hence, one should ment-bound chernicals in aquatic systems. Pergamon keep in mind that these estimates are based on yearly Press, New York, p 219-244 Azarn F, Fenchel T, Field JG, Meyer-Reil LA, Thingstad F production estimates and that the actual trophic trans- (1983) The ecological role of water-column microbes in the fer will vary significantly during the year due to the sea. Mar Ecol Prog Ser 10:257-263 build up and shedding of gonads and depending on Baden SP, Loo LO, Pihl L, Rosenberg R (1990) Effects of available food resources. The redistnbution of PCB by eutrophication on benthic cornmunities including fish- Swedish West coast. Ambio 19:113-122 the shedding of gonadal products can be estimated by Bernhoft A, Skaare JU (1994) Levels of selected individual the latter approach, again using the estimates of Sköld polychlorinated biphenyls in different tissues of harbour et al. (1994) for gonad (disk) production being 68.9% of seals (Phoca vitulina) from the southern coast of Norway. total biomass production in an adult A. filiformis popu- Environ Pollut 8699-107 lation. An analogous calculation, but with the higher Bierman VJJ (1990) Equilibnum partitioning and biomagnifi- cation of organic chemicals in benthic animals. Environ PCB concentration found in the disk tissue, gives (0.46 Sci Technol 24:1407-1412 X 0.689 X 0.32 X 75.5 X 1.86 X 80.24 =) 1142.82 ng PCBs Boese BL, Lee H 11, Specht DT, Randall RC, Winsor MH (1990) m-3 yr-'. Thus in total 1225.8 ng PCBs m-3 yr-I may be Comparison of aqueous and solid-phase uptake for hexa- redistributed from the sediment due to sublethal pre- chlorobenzene in the tellinid clam Macoma nasuta (Con- rad): a mass balance approach. Environ Toxicol Chem 9: dation and shedding of gonads by an A. filiformis 221-231 population. Bowmer T, Keegan BF (1983) Field survey of the occurrence and significance of regeneration in Amphiura filiformis (Echinodermata: Ophiuroidea) from Galway Bay, west Conclusions coast of Ireland. Mar Biol 74:65-7 1 Broman D, Näf C, Zebühr Y, Bandh C, Ishaq R, Pettersen H (1993) Occurrence distribution and turnover of some toxic The accumulation of TCB by the 2 infaunal bnttle substances in the water mass and the sediments in the stars Amphiura filiformis and A. chiajei increased fol- Baltic Sea. Baltnews 4:l-10 lowing an addition of the marine diatom Phaeodacty- Brorström-Lunden E, Mowrer J (1992) Bestämning av persis- tenta organiska föreningar i sediment. Report L. 92/321. lum tricornutum, and was suggested to be caused by Swedish Environmental Research Institute, Göteborg selective feeding on TOC-nch, TCB-contarninated food Buchanan JB (1964) A comparative study of sorne features of items. PCB accumulation measured in bnttle stars col- the biology of Amphiura filiformis and Amphiura chjajei lected from 2 field sites revealed ca 3 times higher total (Ophiuroidea) considered in relation to their distribution. PCBs and individual congeners at the urban coastal J Mar Biol Assoc UK 44:565-576 Carlberg GE, Martinsen K, Kringstad A, Gjessing E, Grande estuarine site compared to the offshore site, both in M, Källqvlst T, SkAre JU (1986) lnfluence of aquatic brittle stars and sediment. The results from this study hurnus on the bioavailability of chlorinated micropollu- suggest that eutrophication processes, such as in- tants in Atlantic salmon. Arch Environ Contam Toxicol 15: creased phytoplankton production, may contribute to 543-548 Chen W, Wangersky PJ (1996) Rates of microbial degradation increase the accumulation of hydrophobic contami- of dissolved organic carbon frorn phytoplankton cultures. nants in infaunal bnttle stars and their transfer to J Plankton Res 18:1521-1533 higher trophic levels. Chiou CT, Kile DE, Brinton TI. Malcolm RL, Leenheer JA (1987) A comparison of water solubility enhancements of organic solutes by aquatic humic materials and cornrner- Acknowledgements. We thank the staff of the Marine Research cial humic acids. Environ Sci Technol 21:1231-1234 Station Solbergstrand, Odbjorn Pettersen, Einar Johannessen Chou SFJ, Griffin RA (1986) Solubility and soil mobility of and HAkon Oen for technical assistance and the Norwegian polychlonnated biphenyls. In: Waid JS (ed) PCBs and the Institute for Water Research (NIVA). We thank Vidar Berg and environrnent. CRC Press lnc. Boca Raton, FL, p 101-120 Morten Sandvik at the Norwegian College of Vetennary Clernents LAJ, Fielman KT. Stancyk SE (1988) Regeneration Medicine for PCB analyses. We thank Torsten Käiikvist for by an amphiuroid brittlestar exposed to different concen- help with algal cultures, Anders Svensson for radiochemical trations of dissolved organic material. J Exp Mar Biol Ecol analyses, Michelle Gedeon and Judith Pelletier for guidance in 122:47-61 lipid analyses, Birthe Heilman for macrofaunal measurements, Connel DW (1988) Bioaccun~ulation behaviour of persistent and the Crew of the RV 'Ancylus'. Financial Support was pro- organic chemicals with aquatic organisms. 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Editorial responsibility: John Gray (Contributing Editor), Submitted: February 9, 1998; Accepted: March 30, 1999 Oslo, Norwa y Proofs received from a uthor(s): September 14, 1999