I	ANNALES • Ser. hist. nal. • 13 • 2003 • 1 • Supplement
short scientific article	UDK 504.064:574.6(26)
received: 5.09. 2003
BIOFILTER COMMUNITY OXYGEN CONSUMPTION RATES
Ken COLLINS & Jenny MALUNSON School oi Ocean and F.anh Science, Vlniversity oi Southampton, Southampton Oceanography Centre, Southampton SOH 3ZH, UK
e-mail: kjc@soc.soton ac.uk
ABSTRACT
Biofiker communities have been incubated in-situ in UK, Israel and Slovenia. Oxygen fluxes for iight and dark experiments have been normalised using the ash free dry weight of the biota. Respiration rates for different communities, whether dominated by ascidians, hydroids, worms or sponges, show a remarkably consistent trend with temperature, over the range 6-2 7°C. It is planned to lirik respiration to rates of growth, filtering and nutrient release.
Key words: community respiration, in-situ incubation, ascidians, hydroids, tube worms
ÏASSI Di CONSUMO Dl OSSIGËNO IN COMUNITA Dl BfOFILTRI
SlNTtSI
Cli autori hanno studi a to la crescita sovrabbondante di com un i tà di biofiltri in-situ in Regno LJnito, tsraele e Slovenia. I risullati dei flussi di ossigeno in esperimenti di luce e buio sono stati normalizzati in base a I peso secco privo di cenere del biota. A prescindere dalla composizione delle comunith, dominate a turno da ascidiacei, idrozoi, policheti sedentari o spugne, i tassi respirator/ hanno evidenziato una tendenza notevolmente uniforme con temperature nell'intervallo tra i 6 ed i 27aC. Gli autori intendono correlate i risultati delle misuraz'toni della respirazione con i tassi di crescita e filtrazione degli organism/ ed il rilascio di nutrienti.
Parole chiave: respirazione di comunita, incubazione in-situ, ascidiacei, idrozoi, policheti sedentari
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I	ANNALES • Ser. hist. nal. • 13 • 2003 • 1 • Supplement
Ken COLLINS & Jenny.MALllNSON: WOTftTW COMMUNITY OXYCCN CONSUMPTION SATES. 4>46
INTRODUCTION
MATERIALS & METHODS
Ecological modelling of systems requires knowledge of the rates of energy flow. Thus, as well as the biomass in a system, its rate of growth or turnover should be de terrnined. The growth rate of reef epibiota rate could be determined by measuring change in biomass per unit area, with time. This is likely to underestimate the true growth rate since this cannot account for loss by predation or other means. For a number of benthic infauna species the annual production per unit biomass has been calculated (Schwinghamer el al., 1986). This approach has been widely adopted for determining the productivity and energy flows through benthic systems. However for many of the groups, which grow on hard substrates including artificial reefs (bryozoans, hydroids, sponges and ascidians) there is litsle or no information on their production to biomass ratios. Enclosed chamber (respirometer) experiments have a long history in examining the respiratory exchange and thus the energy utilization of animals (Collins et a/., 2002). The BIO-FAQs programme (Black ef al., 2001; plus other papers in this volume) has deployed experimental biofilters next to fish farms in order to determine the potential for the colonizing biota to remove wastes (particulate organic. carbon and nutrients) from the water column downstream of I he aquaculture facilities. This paper describes the results of in-sHu incubation chamber experiments to determine direct measurement of oxygen fluxes (and thus carbon fluxes) of biofiiter epibiota.
i't'KCI ». 2 tit C 1D 5U<taC4
3mm ID s an; pirns lube to swfir
1 sampling fun-p
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y-'	\	\
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1 \ A-	\ V
SnSHft cytwfer w«r«enlr»clips CLAM
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-siasjtmiiaa-
0 10 20 20cm
L........J__l___________J
Fig.1: Diagram ofthe biofiiter incubathn cbamber. Fig. 1: Shema biofiltrske inkubacijske posode.
The biofiiter incubation apparatus (Fig. 1} consisted of a specially constructed clear acrylic box (35 x 35 cm cross section, 65 cm high) which accommodated a whole biofiiter, (a plastic mesh cylinder 50 cm long x 25 cm diameter) transferred underwater by divers. The top lid with neoprene seal was clamped shut with over-centre clips. An internal water pump (Rule, USA, bilge pump, 12 V, 380 min"') was used to continuously mix the water in the chamber. A similar second pump was used to sample the chamber (30-40 min intervals) pumping water to the surface through 3 mm ID polythene tubing. The chamber water samples [160 ml, 3 replicates) were fixed for subsequent Winkler titration, to accurately measure the oxygen concentration. An oxygen electrode (YSl, model 5239) was used to monitor the progress of the incubation. Further Winkler titration bottles filled with water pumped from the chamber at the beginning of the experiment, were incubated in-situ under dark and light, to provide blanks, giving the magnitude of water column respiration and net photosynthesis respectively. Typically the chamber was incubated in the light for 2 hours then a further 2 hours in the dark, enclosed in a heavy-duty black polythene bag. This was considered to be a sufficiently short enough time to dis-coLint bacterial activity on the surface as of the chamber and not to cause starvation of the suspension feeders. Records of light intensity and temperature during the experiment and longer term enable extrapolation of the results of experiments over the whole year.
At the end of the incubation the biofiiter was recovered and the epibiota removed, sorted into taxonomic groups and dried in aluminum foil trays to constant weight at 80°C. The dry samples were heated in a muffle furnace to 550°C for 4 hours to determine the organic content, ash free dry weight (AFDW). AFDW was used in this study as it was considered to be a good measure of the amount of living substance (Crisp, 1984). This is especially true given the number of calcareous organisms: hydroids, bryozoans and serpulid worm tubes that were present on the biofilters.
Oxygen analysis was done by a modification of the manual Winkler titration (Strickland & Parsons, 1968). Fixed samples were acidified with concentrated sulphuric acid and titrated with sodium thiosuiphate solution in the sample bottle with an automated burette and photo-detector system to monitor the end point (Williams and jenkinson, 1982). This system gave a repeatability of measurement in the order of ±0.2%.
RESULTS AND DISCUSSION
Bio-filter cylinders were deployed in July 2000. 2001 and 2002, 3 in below a pontoon in the Southampton Oceanography Centre dock and incubated al different
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I	ANNALES • Ser. hist. nal. • 13 • 2003 • 1 • Supplement
Ken COLLINS & letiny MALIINSON: BIOriLTtft COMMUNITY OXYGEN CONSUMPTION KATES «}-4
Tab. 1: Oxygen consumption rates for certain benthic invertebrates (&molOj gAFDW' hi"1). Tab. 1: Poraba kisika (<t>mol02 gAFDW' hr') pri nekaterih bentoških nevrelenčarjih.
Taxon Taxon, Group		Oxygen consumption (<£moiO, gAFDW' hr"1)	source
			
Pyura stolonifcra	Ascidiacea	33	(Klummp, 1984}
Styeila plicate	Ascidiacea	66	(Klummp, 1984)
C iona intestina lis	Ascidiacea	47	(Klummp, 1984)
Aglaophe.nia s p.	Hydro i dea	75	(Gili & Hughes, 1995)
Eudendnum racemosum	Hydroidea	72	(Gilí & Hughes, 1995)
times of the year to determine the response to temperature. These were originally intended simply to provide material for testing oxygen incubation chambers and refining the techniques. Prolific growth of the ascidian, Asciciietla aspersa, dominated the fouling community, reaching massive densities (27 kg wet weight per biofil-ler after 9 months) (Plate li, Fig. 11). A similar pattern of ascidian dominance and mass was found on the Scottish biofilters deployed at 12 m off Oban, Scotland. In-situ incubation experiments were conducted here in September 2002. The comparability of the two sites may be explained by the fact that they are both in temperate waters and receive high levels of organic particulates, from the adjacent fish farm in Scotland and from effluent discharges into the estuary in Southampton. The fas growth of ascidians which have high filtration rates sug gests potential for significant removal of particulate ef fluents in temperate seas. In May 2003 in-situ incuba tiort experiments at 5 m were carried out off Piran, Slovenia (Plate II, Fig. 14). These biofilters were dominated by calcareous tube worms (Pomatoceros sp.}. Since all three sites were fauna dominated, only the respiration rates are reported The rate of change in incubation chamber oxygen concentration with time was determined by linear regression (typically with an r >0.95). After allowing for the water column blank, the values were related to the AI DW of the biofilter. Figure 2 shows this biofilter oxygen consumption data compared to that obtained from the Poole Bay, UK artificial reef. (Collins et al., 2002). In the latter case whole colonized concrete reef blocks (20 x 20 x 40 cm) were incubated in-situ at 12 m. These were dominated by hydroids (Haleciurn spp.), bryozoans (Bugula plumosa) and calcareous tube worms (Pomatoceros sp.). One of the Southampton biofilters (20°C) was dominated by the fan worm Sabella pavonina.
Schwingltamer ef al. (1986) demonstrate that pro-duction/biornass and other biological processes including respiration depend on size class. The biofilters and artificial reefs communities are dominated by macro fauna of sizes within 1-2 orders of magnitude, which may explain both the correspondence and variation in the data.
ip
a - Oüan a - Pir^n r - artificial tMf
6 S 10 12 M 16 IB JO 22 2* Temperature BC
Fig. 2: Oxygen consumpfion by different communities plotted against incubation temperature: experimental biofilters from Southampton, Oban and Piran and concrete artificial reef blocks from Poole Bay (Collins et al., 2002), showing a linear regression line with 95% confidence intervals.
Fig. 2: Poraba kisika pri različnih združbah v korelaciji z inkubacijsko temperaturo: poskusni hiofiltri iz South-amptna, Obana in Pirana in betonski umetni podvodni grebeni iz Poole Bay (Collins et al., 2002) so premočrtno povezani (linearna regresija z 95% intervalom zaupanja).
Knowledge of instantaneous respiration rate of the biofilter community provides direct information on carbon and indirectly nitrogen and phosphorous fluxes. Current work is determining the nutrient release associated with biofilter community respiration. This will be combined with data from the other groups within the BIOFAQs project, Part of the energy derived from is devoted to growth (production). Published produc-tion/blomass ratios (Klumpp, 1984; Schwinghamer et al., 1986; Petersen ef al., 1995) vary greatly, for the biofilter organisms values are in the range 10-40%. Comparison with known biofilter mass accumulation rates will help set limits to this. The filtration rates of biofilter organisms have been reviewed within the BIOFAQs
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I	ANNALES • Ser. hist. nal. • 13 • 2003 • 1 • Supplement
Ker» COLLINS S Jfnny MALIINSON: 3IOHLTER COMMUNITY OXYCtNCONSUMPTION KAffS. 4M6
programme. For some organisms there is published information on the relationship of filtering rate to oxygen consumption: the ascidians Pyura stolonifera (Klumpp, 1984} and Ciona intestinalis (Petersen et a!., 1995). As with production it is hoped to partition part of the energy to filtration to derive a simple model of the functioning of biofiiters for aquaculture or in a wider context the ability of hard substrate (natural or artificial! communities iri coastal waters to remove particulate matter from the water column.
ACKNOWLEDGEMENTS
This work was supported by the I:U funded BIOl AQs project. Incubation experiments were carried out at Southampton with the assistance of james Wyles, Elizabeth Vancura and Claire Lloyd. Considerable practical help with field work was given by many colleagues in Dunstaffnage Marine Laboratory, Oban and Marine Biological Station, Piran.
PORABA KISIKA NA BIOFILTRIH
Ken COLLINS & Jenny MALLINSON School of Ocean and Earth Science, University of Southampton, Southampton Oceanography Centre, Southampton SOI 4 3ZH, UK
e-mail: kjc@soc.soton.ac.uk
POVZETEK
V Veliki Britaniji, Izraelu in Sloveniji sta avtor/a spremljala proces obraščanja bioti ¡trških združb in situ. Rezultati meritev kisika v svetlih in temnih razmera/j so bili normalizirani na enoto organskega deleža biomase obrasti. Ne glede na sestavo združb in prevlado različnih skupin nevretenčarjev (kozolnjaki, trdoživnjaki, mnogoščetinci ali spužve) so rezultati respirometrije pokazali izredno enakomeren trend povezave s temperaturo v razponu med 6 in 27'C. Avtorja nameravata povezati rezultate respiracijskih meritev s stopnjo rasti filtratorjev in sproščanja hranil.
Ključne besede: respiracija združbe, inkubacija in situ, kozolnjaki, trdoživnjaki, cevkasti mnogoščetinci
REFERENCES
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Gili, j-M and Hughes, R. G. (1995): The ecology of marine benthic hydroids. Oceanography and Marine Biology: an Annula Review 33: 351-426.
Grodzittski, W., Klekowski, R. Z. and Duncan, A. (1975): Methods for Ecological Bioenergetics. IBP Handbook No. 24. Blackwell Scientific Publications, Oxford. 367pp.
Klumpp, D, W. (1984): Nutrional ecology of the as-cidian, Pyura stolonifera: influence of body size, food quantity and quality on filter feeding, respiration, assimilation efficiency arid energy balance. Marine Ecology Progress Series 19(3): 269-284. Petersen, J. K., Schou, O. and Thor, P. (199S): Growth and energetics in the ascidian Ciona intestinalis. Marine Ecology Progress Series 120(1-3): 175-184. Schwinghamer, P., Hargrave, B., Peer, D. and Hawkins, C, M. (1986): Partitioning of production and respiration among size groups of organisms in an intertidal benthic community. Marine Ecology Progress Series 31: 131142.
Williams, P. J. leB. and Jenkinson, N. (1982): A transportable microprocessor controlled precise Winkler titration suitable for field station and shipboard use. Limnology and Oceanography, 27: 576-582.
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