ANNALES - Ser. hist. nat. • 13 • 2003 • 1 • Supplement
short scientific article	DDK 639,32:504.064(262-11)
received: 2003-09 02
EFFECT OF TIME OF FIRST DEPLOYMENT AND DURATION ON THE SUCCESSION OF BENTHIC ORGANISMS ON BIOFILTERS USED TO MITIGATE IMPACT OF FISH FARMS ON WATER QUALITY IN CRETE
Eugenia APOSTOLAKI, Mano!is TSAPAKIS, Tat/ana TSACARAKl, Kostantla PAPADOPOULOU
& ioannis KARAKAS5IS
Institute of Marine Biology of Crete, GR-71003 Harakiton, POB 22 i 4 E-mail: jkiirak@itnbc.gr
ABSTRACT
A total of 18 biofiiters were deployed in an open coastal bay of Crete, in order to study the efficiency of bio filter:; using the locally available fouling communities for mitigation of pollution effects by fish farms. Wet biomass, abundance and species diversity of fouling organisms increased with increasing deployment time during all seasons and for ail the filters deployed. Shannon diversity index and average taxonomic distinctness found to be quite stable after the first two months of deployment. Multidimensional scaling (MDS) of wet biomass and species abundance revealed biofiiters clustering in relation to deployment period, regardless of deployment season.
Key words: biofiiters, succession, fish farming, Eastern Mediterranean, Crete
EFFETTO PI PERIODO DEL PRIMO POSIZIONAMENTO E DURATA SU SUCCESSION! Di ORCANISMI BENTONICI SU BIOFILTRI IJSATI PER RÍDURRE L'IMPATTO 01 ALLEVAMENTl Dt PESCI SULLA QUALITÁ DELL'ACQUA A CRETA
SINTESI
Oiciotto biofiltri sono staff posizionati in una baia aparta di Creta, alio scopo di stud ia re I'efficienza dei biofiltri nell'uso di comunica di fouling disponibili per ridurre gli eftetti dell'inquinamento provocato da allevsmenti di pesci. La biomassa umida, il numero di specie ed individui degli organism: del fouling sono aumentad con /'aumentare del período di imp/ego dei filtri in tutte le stagioni e per turn i filtri posizionati. L'indice di divers its di Shannon e la precisions media tassonomica sono risultati abbastanzn stabili dopo due mesi di posizionamento- II método "multidimensional scaling" (MDS) applicato alb biomassa umida e all'abbondanza di specie ha rívelato un raggruppamento di biofiltri in relazione al periodo di posizionamento, a prescindere dalla stagione di posizionamento.
Parole chiave: biofiltri, successione, allevamento di pesci, Mediterráneo oriéntale, Creta
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ANNALES - Ser. hist. nat. • 13 • 2003 • 1 • Supplement
[:iit(Hii.i APOSTOl. AKt ef a/.™CFF£CT Of TlMt Of NRSÏ DFPIQVMÏNT ANO DURAI ION ON 1HI suCCfSStON Of BENTMIC ORGANISA«;.... 29-J2
INTRODUCTION
Fish farms release a substantial amount of wastes in both paniculate and solute forms reaching more than 70% of the nitrogen and phosphorus supplied through fish feed (Holby & Hall, ¡991; Hall ef al., ¡992). The most severe environmental problems affecting other users of the coastal zone could arise from the solute and fine particulate wastes that may by transported at large distance from the farming sites, thus affecting water quality and marine resources over large areas {Pitta et al., 1999). The use of filtering systems based on marine organisms as a means for minimizing these effects has been suggested by various authors in different contexts (Kautsky & F'oike, 1989; Neori et al., 2000: Chopin ei al., 2001). It has been recently suggested (Angel & Spanler, 2002) that the deployment of biofilters using the locally available fouling communities could provide a mean for mitigation of pollution effects by fish farms. In the present paper, we have investigated the performance of in situ biofilters deployed during the warm season of the year (May to November), when most of the wastes are discharged into the marine environment. This paper addresses the issue of colonization of these substrates depending on the time and duration of deployment.
MATERIALS AND METHODS
The area selected for the deployment of biofilters is an exposed coastal bay at eastern part of Crete, characterized by fairly rough weather, ensuring adequate water flushing, and low background concentrations of nutrients and particulate matter. The fish farm operating there has a mean annual production of 1000-1200 tons of European seabass (Morone labrax) and gifthead se-abream (Spams auratus). Biofilters were constructed of hard plastic net and rolled to a total surface area of 0.5 nr. A total of 18 biofilters (BF) were deployed at 6 m distance from the fish cages and 5 m depth from the sea surface (Plate II: Fig. 10). Nine biofilters were deployed in May 2002, three of which were retrieved two months later (July 2002) [code number 2(M-j)- number refers to total duration of deployment in months, and the two letters to deployment and retrieval month respectively]. In July 2002, six new biofilters were deployed. In September 2002, 3 biofilters deployed in May [4<M-S)i and 3 deployed in July |2(J-S)I were retrieved, whereas 3 new biofilters were deployed. In November 2002, all standing biofilters were collected |3 BF 6(M-Ni, 3 BF 4(J-N) and 3 BF 2(S-N)]. Sampling was made by means of scuba diving. Biofilters were enclosed in plastic bags, to prevent loss of epifauna, arid transferred to the laboratory and photographed. Fouling organisms were sorted
and weighed and animals were identified to species level where possible. Differences in community structure were assessed by means of both uni- and multivariate analysis using the PRIMER software package (Clarke & Warwick, 1994). Species abundance and biomass were transformed with log(x+1) and square root respectively, prior to performing multidimensional scaling (MDS).
RESULTS AND DISCUSSION
Wet biomass of fouling organisms increased with increasing deployment time (Fig. 1). The largest, increase in biomass was observed on the filters deployed in May between the 4lh and 6lh month of deployment. Multidimensional scaling (MDS) of wet biomass (Fig. 3a) showed a weak clustering reflecting time of deployment. The number of species showed a monotonie increase during all seasons and for all the filters (Fig. 2a). During the first two months of deployment, 19 to 29 species had colonized the filters (Plate II: Fig. 10).
Macrofaunal abundance also increased with time of deployment (Fig. 2b), showing very similar patterns for all three series of biofilters deployed during different months of the year. Shannon diversity was found t:o be quite stable after the first two months of deployment (Fig. 2c) and this was also the case with average taxo-nomic distinctness (Fig. 2d). Multidimensional scaling (MDS) of species abundance revealed biofilters clustering in relation to deployment period, regardless of deployment season (Fig. 3b).
The results of the present paper indicate that there is little change in fouling community attributes regarding the time of first deployment whereas the effect of duration of deployment is the major factor affecting the community structure.
Deployment period
fig. 1: Wef biomass of fouling organisms with deploy-men t period.
SI. 1: Biomasa organizmov obrasti v času postavitve biofiltrov.
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ANNALES • Ser. hist. nat. 1.3 • 2003 • 1 • Supplement
Eugcnci ATOSTOLAKI cTr.7 MirfcT OF TIME OF FIRST DEPLOYMENT ANpTxj RATION ON THE SUCCESSION OF BENTTiicORGANISMS '.'.'., 29-32
Deployment period
Fig. 2: (a) Species number; (b) macrofaunal abundance; (c) Shannon-Wiener diversity index; (d) average taxonomic distinctness with deployment period.
SI. 2: (a) število vrst; (b) abundanca makrofavne; (c) Shannoti-Wienerjev indeks diverzitete; (d) povprečna takso-nomska različnost glede na obdobje postavitve.
20(300
E 10000
5000
c o
C C PJ
n V)
nov
july	Sfept	rov
(a)	4(M-S)	Stress: 0,01	(b) 6(M-N)	Stress: 0,08 2(M-J)
6(M-N)			4(M-S)	
		2(M-ji	4(J-N)	2(S-N)
			2{J-S)	
Fig. 3: (a) MDS ot'biotllters biomass; (b) MDS of species abundance at the biofilters. SI. 3: (a) MDS biomase biofiltrov; (h) MDS abundance vrst na biofiltrih.
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ANNALES • Ser. hist. nat. • 13 • 2003 • 1 • Supplement
Eugenia AFOSIOLAKI a »I.: EFffCl OF TIME OF flRSl DEPLOYMENT AND OUR/VfJON ON THE SUCCESSION OF BLN7I «C ORGANISMS .. 29-32
UČINEK ČASA PRVE POSTAVITVE IN TRAJANJA NA SUKCESIJO BENTOŠKIH ORGANIZMOV NA BIOFITR1H, UPORABLJENIH ZA ZMANJŠEVANJE UČINKOV RIBOGOJNIC NA KAKOVOST VODE NA KRETI
Eugenia APOSTOLAKt, Manolis TSAPAKIS, Tatiana TSACARAKI, Kostaiitia PAPADOPOULOU
& loannis KARAKASSI5 Institute of Marine Biology of Crete, GR-71003 HerakNon, POB 2214 E-mail: jkaiak@imbc.gr
POVZETEK
V enem izmed zaprtih zalivov na Kreti so avtorji postavili 18 biofiltrov', da bi lahko preučevali njihovo učinkovitost ob uporabi lokalno razpoložljive združbe oblasti za zmanjšane učinke onesnaževanja, ki ga povzročajo lokalne ribogojnice. Biomasa, gostota in diverziteta vrst med organizmi obrasti so se povečevale s podaljševanjem časa uporabe, biofiltrov v vseh letnih časih in za vse razvrščene biofiltre. Po prvih dveh mesecih je bilo ugotovljeno, da sta Shannonov diverzitetni indeks in povprečna taksonomska različnost precej stabilna. Mu It id i m enzlona i na primerjava biomase in gostote vrst je razkrilo kopičenje na biofiltrih glede na čas njihove postavitve in ne glede na letni čas njihove postavitve.
Ključne besede: biofiltri, sukcesija, marikultura, vzhodni Mediteran, Kreta
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