2010Impacts of the Fish Farms on the Water Column Nutrient

Environ Monit Assess (2010) 162:439451DOI 10.1007/s10661-009-0808-x

Impacts of the fish farms on the water column nutrientconcentrations and accumulation of heavy metalsin the sediments in the eastern Aegean Sea (Turkey)

Asli Kaymakci Basaran Mehmet Aksu Ozdemir Egemen

Received: 23 May 2008 / Accepted: 27 January 2009 / Published online: 26 February 2009 Springer Science + Business Media B.V. 2009

Abstract We investigated potential effects of thefish farms on water column and sediment aroundSalih Island in the Gulluk Bay (Aegean Sea,Turkey) where four seasonal samplings were per-formed from October 2001 to August 2002. Onemeasured physicochemical variables in water col-umn including dissolved oxygen, nutrients (nitrite,nitrate, ammonium, phosphate and silicate), par-ticulate organic carbon (POC) and chlorophyll a.Organic matter, total organic carbon (TOC) andheavy metals (Zn, Cu and Fe) were measured insediment samples. Although occasional increasesin ammonium and chlorophyll a concentrationswere observed at the cage stations as compared tothe control one, no statistically significant differ-ences were detected among the stations in termsof nutrients, chlorophyll a and POC. On the otherhand, significant differences were found in organicmatter, TOC and heavy metals (Zn and Fe) of thesediments among the sampling stations. Despitethese differences, our results indicate that concen-trations of physicochemical variables and heavy

Asli Kaymakci Basaran (B) Mehmet Aksu Ozdemir EgemenFaculty of Fisheries, Department of Hydrobiology,Ege University, Bornova, Izmir, Turkeye-mail: [email protected],[email protected]

metals were within the range of tolerable levels forthe marine ecosystem, and the oligotrophic natureof the water column in the study area was able toassimilate organic and inorganic loads caused bythe fish farms.

Keywords Fish farming impact Nutrients Chlorophyll a Organic carbon Heavy metals Aegean Sea

Introduction

Aquaculture is defined as the farming of aquaticorganisms, including fish, molluscs, crustaceansand aquatic plants (FAO 1990). Aquaculturalproduction has been increasing across the world.The current contribution of aquaculture to theworld aquatic production in 2004 is about 45.5 mil-lion tones, aquatic plants excluded (FAO 2006).

In the Mediterranean, there have been substan-tial increase in fish farming production over thelast decades, but there was not enough informa-tion about current and likely impacts of the ma-rine aquaculture on environment until recently.

Aquacultural processes account for releasesof metabolic waste products (faeces and excreta)and uneaten food into the marine environment.The release of soluble inorganic nutrients (nitro-gen and phosphorus) potentially cause nutrientenrichment (hypernutrification) possibly followed

440 Environ Monit Assess (2010) 162:439451

by eutrophication (increase of primary produc-tion) in the water column (FAO 1992). Accumu-lation of organic matter on sediments is likely tocause changes in physical and chemical character-istics of the benthic environment (Karakassis et al.2000).

Articles regarding environmental influences ofaquaculture on nutrients and plankton (Pittaet al. 1999; La Rosa et al. 2002; Neofitou andKlaoudatos 2008), nutrients and community struc-ture (Katavic and Antolic 1999; Mazzola et al.2000; Yucel-Gier et al. 2007), water column andsediment (Aksu and Kocatas 2007), sedimentchemistry (Porello et al. 2005), sea grass (Delgadoet al. 1999; Ruiz et al. 2001) and sediment geo-chemistry and benthic organisms (Karakassis et al.2000; La Rosa et al. 2001, 2004; Mazzola et al.1999) have been published in recent years. Re-covery of benthos after cessation of fish farmingoperation (Karakassis et al. 1999) and accumula-tion of organic matter underneath fish farm cages(Karakassis et al. 1998) were also investigated.Mesoscale changes in the water column due tofish farming zones (Pitta et al. 2005) and effectsof offshore fish farming (Maldonado et al. 2005;Kaymakci-Basaran et al. 2007) have been studiedrecently.

Inland aquaculture started in Turkey in 1970s,expanding rapidly with the contribution of ma-rine fish farms in 1980s. Sea bass (Dicentrarchuslabrax L.) and sea bream (Sparus aurata L.)production in net cages reached 37,290 and27,634 tons year1, respectively (Anonymous2005).

Uncontrolled and rapid expansion of cage fishfarming in Turkey, especially around BodrumPeninsula and in nearby coves, have led toenvironmental problems and conflicts with othercoastal area users (especially tourism and fish-eries). In order to reduce environmental im-pacts of aquaculture and overcome intersectoralconflicts, movement of fish farms to offshore isa new trend adopted by most countries in theMediterranean including Turkey. With this ap-proach, the authorities urged fish farms underoperation around the coastal areas of BodrumPeninsula to be moved offshore. Ikizadalar Is-lands and Salih Island in the Gulluk Bay werechosen for this purpose. Having been allocated

to coastal aquaculture, production around SalihIsland accounted for 4,876 tons year1 in 2002(Ozfucucu et al. 2003), reaching 24,200 tons year1in 2007 (personal communications with the fishfarm staff operating in the area).

The aim of the present study was to assess theeffects of fish farms around Salih Island, GullukBay (Aegean Sea, Turkey) on water column andsediment.

Materials and methods

Samplings were carried out at eight fish farms(one sampling station at each fish farm) aroundSalih Island and at one control station on the Eastcoast of Ikizadalar Island which is situated 1.44 km(0.78 nautical miles) Southwest of Salih Island inOctober 2001, February, May and August 2002(Fig. 1). Depths ranged from 8 to 25 m at thesampling stations (Table 1).

Salih Island is located in the Gulluk Bay(Southeast Aegean Sea). There were 17 fish farmsaround Salih Island, with a total production capac-ity of 4,876 tons year1 at the time of our study.Table 1 presents annual standing stocks at thestudied fish farms during sampling period. All thefarms used pellet and extruded feeds to producesea bream (S. aurata) and sea bass (D. labrax).

At each station, surface (1 m below surface)and bottom water (1 m above seafloor) sam-ples were collected by Nansen sampling bottle,sediment samples obtained by Van-Veen grab.Transparency was measured by Secchi disc.Temperature and dissolved oxygen measure-ments (Winkler titration method) were carriedout in situ. Pre-filtered samples were ice-cooledand taken to the laboratory. pH was measuredby Orion 420 A pH meter and nutrients (nitritenitrogen, nitratenitrogen, ammoniumnitrogen,phosphatephosphorus, silicate) determined spec-trophotometrically using HACH DR 2000(Strickland and Parsons 1972). Particulate organiccarbon (POC) analyses were carried out usingwet oxidation method and spectrophotometry(Strickland and Parsons 1972). Chlorophyll avalues were determined in vivo using TurnerDesign 10 AU Fluorometer.

Environ Monit Assess (2010) 162:439451 441

Fig. 1 Map showing the locations of the sampling stations

Surficial sediment samples for Zn, Cu andFe analyses were dried at 60C for 24 h andsieved using a 160-m mesh (Sunlu et al. 1998;Tuncer and Uysal 1983). Dried sediment sam-ples (1 g) were treated with 10 mL aqua regia(HCl/HNO3 3:1, v/v) and decomposed by the

laboratory reflux apparatus. Samples were thenfiltered through Whatman 40 filter paper and di-luted with bi-distilled water to 50 mL (Arnouxet al. 1981). Metal concentrations were deter-mined using PYE-Unicam SP9 atomic adsorptionspectrophotometer. Concentrations of the heavy

Table 1 Summary offarm (station) featuresindicating depth of seafloor below the cages,sediment type and fishbiomass

Station Depth (m) Sediment type Fish biomass (tons year1)1 8.0 Sandy with Posidonia oceanica 1502 9.5 Sandy with Posidonia oceanica 1003 9.0 Sandy with Posidonia oceanica 2004 25.0 Muddy 5505 13.0 Muddy with Posidonia oceanica 3006 20.0 Muddy with Posidonia oceanica 1007 13.0 Muddy-sandy with Posidonia 100

oceanica8 15.0 Sandy with Posidonia oceanica 609 (Control) 13.5 Sandy with Posidonia oceanica No farm


Table 2 Someenvironmentalparameters at thesampling stations(minimum, maximum andmean SE)

DO dissolved oxygen

Stations Temperature DO pH Secchi depth(C) (mg L1) (m)

1 Range 17.027.0 6.49.0 7.88.2 6.29.1Mean SE 21.8 1.3 7.5 0.34 8.07 0.06 7.6 0.62

2 Range 16.028.0 6.89.4 7.78.3 7.814.8Mean SE 21.7 1.6 7.8 0.34 8.09 0.07 10.3 1.54

3 Range 17.027.0 6.810.4 7.98.2 4.712.8Mean SE 21.9 1.4 7.9 0.47 8.11 0.04 8.2 1.77

4 Range 16.027.0 4.48.0 7.88.2 10.623.6Mean SE 21.8 1.4 6.3 0.48 8.07 0.05 14.9 3.02

5 Range 17.028.0 5.68.6 7.88.3 6.19.6Mean SE 22.5 1.5 7.2 0.34 8.09 0.06 7.6 0.74

6 Range 17.028.0 6.89.4 7.68.2 5.512.1Mean SE 22.0 1.5 7.9 0.36 8.09 0.06 8.6 1.44

7 Range 17.028.0 6.49.4 7.88.2 8.813.5Mean SE 22.0 1.5 7.7 0.39 8.07 0.07 11.4 0.99

8 Range 17.027.0 6.49.4 7.98.3 7.113.3Mean SE 22.0 1.3 7.6 0.36 8.13 0.04 9.7 1.44

9 (Control) Range 17.029.0 6.69.4 7.98.2 5.813.4Mean SE 22.1 1.6 7.6 0.35 8.10 0.04 9.3 1.72

metals in the sediment samples were measured inmicrograms per gram dry weight. Total organiccarbon (TOC) values were determined accord-ing to modified WalkleyBlack titration method(Gaudette et al. 1974). Organic matter (OM, asloss on ignition) concentrations were found as theloss of weight of the dried sample at 500C for 6 h(FAO 1983).

Normal distribution of the data was tested us-ing KolmogorovSmirnov test. Homogeneity ofthe variances was tested by Levene test. To de-tect differences among sampling stations, surface

bottom waters and seasons, KruskalWallis andMannWhitney U tests were performed. Rela-tionships between heavy metals and TOC wereestimated by the correlation coefficients.

Results

Table 2 presents the minimum, maximum, meanand standard error of some environmental para-meters at the nine stations around Salih Island andIkizadalar Islands.

Fig. 2 Averageconcentrations (samplestaken from surface andbottom) of NO2 at eightcage stations and onecontrol (station 9) stationduring four samplingcampaign


Fig. 3 Averageconcentrations (samplestaken from surface andbottom) of NO3 at ninestations during sampling

Water temperatures were found to be homoge-nous at all the sampling stations and show sea-sonal variations. pH values ranged from 7.6 to 8.3.Given annual mean values, pH variations wereobserved to be homogenous (Table 2).

Dissolved oxygen concentrations ranged from4.4 to 10.4 mg L1. Highest oxygen concentrationof 10.4 mg L1 was recorded in February 2002at station 3 due to lower temperatures. Lowestoxygen concentration was recorded at station 4(Table 2). Lowest annual mean value wasrecorded at the same station (6.3 0.48 mg L1).Secchi disc depths ranged from 4.7 to 23.6 mthroughout the sampling period. No significant

differences were found for physical parametersbetween sampling stations in the area involved.

Nutrients

Temporal variations of nitrite, nitrate, ammo-nium, phosphate and silicate concentrations (av-erage of surface and bottom waters) in the studyarea are illustrated in Figs. 2, 3, 4, 5 and 6,respectively.

Nitritenitrogen concentrations ranged fromnone detected (nd) to 1.29 M at the cage stationsaround Salih Island and from nd to 1.27 M at thecontrol station throughout the year. The highest

Fig. 4 Averageconcentrations (samplestaken from surface andbottom) of NH4 at thestations during sampling


Fig. 5 Averageconcentrations (samplestaken from surface andbottom) of PO4 at ninestations during sampling

nitritenitrogen value was recorded at the surfacewater of station 1 in February 2002.

Nitratenitrogen values varied between nd and2.28 M at the cage stations and between 0.30 and2.46 M at the control station.

Ammoniumnitrogen concentrations variedbetween nd and 3.18 M at the cage stations andbetween 0.23 and 2.15 M at the control station.Maximum value was measured at the surfacelayer of station 4 in the sampling of August 2002.

Phosphatephosphorus concentrations at thecage and control stations ranged from and to0.61 M. Maximum values were measured at the

bottom layer of stations 2 and 9 in the sampling ofOctober 2001.

Silicate levels varied between nd and 14.55 Mat the cage stations and between 3.20 and19.56 M at the control station.

No significant differences were detected be-tween seasons and between the cage stationsand the control station for nutrient (nitrite, ni-trate, ammonium, phosphate and silicate) con-centrations (KruskalWallis, p > 0.05). Surfacewater nutrient concentrations were not signifi-cantly different from those of bottom water nu-trients (KruskalWallis, p > 0.05).

Fig. 6 Averageconcentrations (samplestaken from surface andbottom) of silicate at ninestations during sampling


Fig. 7 Averageconcentrations (samplestaken from surface andbottom) of chlorophyll aat eight cage stations andone control (station 9)during three samplingcampaign

POC and chlorophyll a

Temporal variations of chlorophyll a and POCconcentrations in the study area are illustrated inFigs. 7 and 8, respectively. Unfortunately, we didnot measure chlorophyll a concentrations duringthe first sampling in October 2001.

Chlorophyll a values ranged from 0.010 to0.565 g L1 at the farm stations and from 0.010to 0.084 g L1 at the control station.

Concentrations of POC ranged from nd to1.16 mgC L1 at the cage areas and from 0.20to 0.84 mgC L1 at the control site. No consid-

erable differences were detected among surfaceand bottom waters, seasons and sampling stationsfor the concentrations of POC and chlorophyll a(KruskalWallis, p > 0.05).

Organic matter, total organic carbon, and heavymetals in sediment

Organic matter, total organic carbon, Zn, Cu andFe levels during the study period are illustrated inTable 3.

Organic matter values ranged from 3.23% to9.37% at the cage stations and from 3.65% to

Fig. 8 Averageconcentrations (samplestaken from surface andbottom) of POC at ninestations during sampling


Table 3 Minimum, maximum and mean SE values of TOC, organic matter (LOI) and heavy metals (Zn, Cu and Fe) inthe sediments of the study area

Stations TOC (%) LOI (%) Zn (g g1) Cu (g g1) Fe (g g1)1 Range 0.094.56 3.344.17 0.343.95 1.706.60 692.51879.5

Mean SE 2.07 0.94 3.82 0.19 2.4 0.88 4.39 1.01 1104.4 266.72 Range 0.345.27 3.615.80 0.353.55 5.857.9 1073.51571.0

Mean SE 2.8 1.07 4.46 0.47 2.2 0.72 7.09 0.44 1248.6 111.43 Range 0.036.74 3.364.67 4.207.3 13.421.35 2838.56175.0

Mean SE 2.38 1.49 3.78 0.31 6.2 0.68 16.29 1.80 3930.1 758.44 Range 3.8710.65 3.968.30 0.649.05 30.531.65 6150.06785.0

Mean SE 7.14 1.46 7.08 1.05 6.7 2.03 31.24 0.24 6438.7 132.95 Range 0.388.68 3.239.37 1.557.35 7.5520.65 2817.54913.0

Mean SE 4.45 1.74 5.18 1.41 3.9 1.31 12.70 2.85 3485.7 489.06 Range 0.155.9 4.997.8 4.77.7 10.4510.55 1065.52948.0

Mean SE 3.16 1.24 5.93 0.63 5.8 0.97 10.52 0.02 2139.8 407.87 Range 0.984.96 4.447.80 2.44.85 0.4011.5 1205.02151.5

Mean SE 3.08 0.96 5.93 0.63 4.0 0.79 6.46 2.29 1590.7 227.88 Range 0.586.27 4.206.83 1.35.2 3.59.3 910.02197.5

Mean SE 3.61 0.96 5.10 0.6 3.8 1.25 5.62 1.31 1427.9 277.09 (Control) Range 1.625.32 3.654.90 nd4.9 3.06.80 721.51077.0

Mean SE 2.88 0.83 4.36 0.32 2.5 1.41 4.59 0.81 880.9 89.9nd none detected

4.90% at the control station, with a highest meanvalue at station 4 (Table 3). Significant differ-ences were detected in organic matter betweensampling stations (KruskalWallis, p < 0.05). Noseasonal pattern was apparent for this variable(KruskalWallis, p > 0.05).

TOC values ranged from 0.03% to 10.65% un-der the cage stations and from 1.62% to 5.32%at the control site. Variations in the TOC valueswere similar to those observed in the organic mat-ter. Highest annual mean value was recorded atstation 4. TOC concentrations at station 4 werefound significantly different from those at the con-trol station (KruskalWallis, p < 0.05).

We have investigated the heavy metal (Zn,Fe, and Cu) concentrations in the sediments of

Table 4 Correlation coefficients for heavy metals andTOC in the sediments of sampling stations

TOC Fe Cu Zn

Zn 0.541a 0.950a 0.533a Cu 0.036 0.559a Fe 0.460a TOC aCorrelation is significant at the 0.01 level

the study area which might have accumulatedas a result of fish farm activities (uneaten feeds,faeces, antifoulants, etc.) underneath the cages.Indeed, highest heavy metal concentrations weremeasured at cage station 4 (Table 3). Significantdifferences were detected between all the sam-pling stations for Zn and Fe (KruskalWallis, p 0.05).

Relationships between heavy metals and to-tal organic carbon levels have been investigated.Pearsons correlation coefficients are shown inTable 4.

Discussion

Environmental effects of fish farms operating inclosed and semi-enclosed bays in the Mediter-ranean Sea have been investigated by many re-searchers (Katavic and Antolic 1999; Pitta et al.1999; La Rosa et al. 2002; Sanz-Lazaro and Marin2006; Neofitou and Klaoudatos 2008). However,there is limited number of studies in the easternAegean Sea (Demirak et al. 2006; Yucel-Gieret al. 2007; Kaymakci-Basaran et al. 2007).


The aim of this study was to assess the effectsof fish farms in an allocated area in the easternAegean Sea on water column and sediment.

Water temperatures changed with weatheringand showed similarities at the control and the cagestations. pH values at the study area ranged be-tween 7.80 and 8.26 during the sampling periods.pH values recorded in the surface and deep waterlayers were close to offshore pH levels.

It is well known that dissolved oxygen in thewater column is one of the most vital parame-ters for aquatic life. In summer, dissolved oxygenconsumptions are higher due to aquacultural ac-tivities and used for redox processes involved inthe degradation of organic matters. Accordingly,we found the lowest seasonal mean value of dis-solved oxygen in August 2002. Dissolved oxygenvalues found in this study were compared withthe criteria recommended by Abo and Yokoyama(2007) for the sustainable aquaculture production.Lowest value of dissolved oxygen measured atthe sampling station 4 (4.4 mg L1) was above thecritical farm value (3.7 mg L1), but below thehealthy fish farm value (5.6 mg L1) according tothis guideline (Abo and Yokoyama 2007).

Secchi disc depth fluctuated throughout thesampling period at all stations and there wereno apparent differences between cage and con-trol stations. Similarly, Nordvarg and Johansson(2002) found no measurable effects on Secchidepth in the semi-enclosed bays.

Although some increases were detected inthe nitrite and nitrate concentrations during win-ter, there were no remarkable seasonal dif-ferences. We found no significant differencesbetween control and cage stations. Maldonadoet al. (2005), studying semi-exposed cage farmsin the Mediterranean coast of Spain, found thatneither surface nor bottom waters at the fish farmsshowed abnormal concentrations of nitrite and ni-trate relative to controls, a pattern consistent withour results. Likewise, Pitta et al. (1999), investigat-ing three fish farms in the eastern Mediterranean,reported that except for a significant decreasein nitrate values at cage station compared to itscontrol station in one of the fish farms, nitrite andnitrate concentrations at cage and its respectivecontrol stations were not significantly different.

However, Demirak et al. (2006), who investigateddissolved nutrients in Gulluk Bay (Aegean Sea),observed that major differences in dissolved in-organic nitrogen (DIN) were explained by fishfarming activity. They reported that DIN con-centrations were significantly higher in summerthan in winter due to high production in summermonths.

As for ammonium concentrations, there wereincreases in the surface and bottom waters ofstations 4 and 5 in August 2002. Nevertheless,statistical analyses showed that ammonium con-centrations between cage and control stationswere not significantly different as in nitrite andnitrate. Ammonium was the abundant form ofinorganic nitrogen solute released around SalihIsland. Dosdat (2001) studied sea bass excretionand revealed that a large percentage of ingestednitrogen was excreted in a dissolved form asammonia (8590%) and urea (10%). Pitta et al.(1999) found no significant differences in ammo-nium between cages and control sites at two ofthe three farms, a pattern consistent with ourresults. However, Aksu and Kocatas (2007) de-tected significant increases in concentrations ofammonium between cage and control stations attwo of the three fish farms studied. Similarly,Yucel-Gier et al. (2007), investigating nutrientsand benthic community at a fish farm site inthe eastern Aegean Sea, found that the concen-trations of ammonium at the cage stations werehigher than those of the control stations duringspring, summer and fall.

Highest phosphorus values were recorded inMay 2002 at all sampling stations. Inorganic phos-phorus values did not display significant differ-ences between sampling stations, seasons andsurface and bottom waters (p > 0.05). On theother hand, Aksu and Kocatas (2007) reportedsignificantly increased concentrations of phos-phate at cages in comparison to the control sta-tions only in one of the farms. La Rosa et al.(2002), studying in a sheltered area, found that theconcentrations of phosphate in the fish farm sitewere up to sixfold higher than those in the control.

An increase in silicate concentrations was ob-served during August at the surface and bottomwater layers at all the stations. This increase in


silicate may be attributed to remineralisation ofbiogenic silicate accumulated at the sea bottom.Pitta et al. (2005) pointed out that there wasdecrease in silicate concentrations in the watercolumn around fish farms, which was probablyrelated to rapid uptake by diatoms, a situationsimilar to those found in the present study. Con-centrations of silicate at the control site (station9) were found higher than those of the cagestations.

No significant differences were found betweenthe cage stations and the control station inPOC and chlorophyll a concentrations (p > 0.05).Highest chlorophyll a value was recorded at sta-tion 4 in May 2002. At stations 4, 5, 6, 7 and 8,effects of fish farms were more apparent in termsof chlorophyll a (Fig. 7). However, chlorophyll avalues were within the range of other studies inthe eastern Mediterranean (0.11.8 g L1, Pittaet al. 1999; 0.041.1 g L1, Kontas et al. 2004;0.021.1 g L1, Yucel-Gier et al. 2007). In orderto avoid eutrophication in the northern Europeanwaters, maximum value of 10 g L1 in chloro-phyll a has been recommended as an environmen-tal quality standard. There is not such a standardfor the Mediterranean (Pitta et al. 1999). In thestudy area, the highest chlorophyll a value was0.57 g L1. No significant differences were de-tected between surface and bottom waters and be-tween sampling periods for POC and chlorophylla variables (p > 0.05). Consistent with the presentstudy, La Rosa et al. (2002) found no significantdifferences between cage and control stations forsuspended particulate organic matter. Similar lackof POC and chlorophyll a response to fish farmoperations has been reported by many researchers(Pitta et al. 1999, 2006; Aksu and Kocatas 2007).Pitta et al. (1999) found that location and seasonare the two major sources of variation for POCand chlorophyll a, and neither chlorophyll a norPOC seemed to be significantly affected by thenutrient release from aquaculture facilities.

Perhaps the most evident impact of marinefish farms is the sedimentation of wasted feedsand faecal material under the cages. This type ofsediment is characterised by low values of redoxpotential, high content of organic material andaccumulation of nitrogenous and phosphorous

compounds (Karakassis 1998). Total organic car-bon is an important variable to identify sedimentquality (Leong and Taner 1999; Porello et al.2005).

As a result of intensive production in thevicinity of stations 4 and 5 during the sampling(Table 1), TOC values at these stations weregenerally higher than those of other cage sta-tions and the control station. A highest valueof 10.65% was recorded at station 4 in August2002 due to increased feeding in summer months.Karakassis et al. (2000) investigated the im-pact of fish farms on the seabed in southernMediterranean and found lower TOC values thanours. The authors reported higher TOC values atthe cage stations (ranging from 0.50% to 2.80%)than the control stations (from 0.30% to 1.85%),which is consistent with our results. Likewise,Porello et al. (2005) measured the maximumTOC values beneath the cages in the westernMediterranean Sea. TOC values were between1.88% and 4.76% at the cage stations. Similarincreases of TOC concentrations to those found inthe present study were also reported by Aksu andKocatas (2007) who found TOC concentrations atthe cage stations to be significantly higher than thecontrol stations in the first and third fish farms. Itwas reported that TOC levels ranged from 0.21%to 10.54% under the cages and 0.48% to 3.50% atthe control stations.

Organic matter accumulation under the cagesvaries between farms, which is mostly influencedby local hydrological and geomorphologic fea-tures, also depending on the production capacityand feed quality. Therefore, accumulation ratesare notably different in the literature (Maldonadoet al. 2005). In the present work, organic mat-ter values ranged from 3.23% to 9.37% at thesampling site. Seasonal differences in this variablewere not evident. Highest organic matter valueswere observed at stations 4 and 5 as in TOC.Karakassis et al. (1998) discovered higher con-centrations of organic matter (ranging from 20%to 40% under the cages and around 10% at thecontrol station) than ours. On the other hand,Maldonado et al. (2005) reported exceptionallylow values (


Several studies have reported accumula-tions of heavy metals (as zinc and copper)in sediments accounted for by aquaculturalactivities (Mendigucha et al. 2006; Chou et al.2002; Sutherland et al. 2007). Fe and Zn areused in commercial sea bass and sea bream dietpellets. Copper, on the other hand, is commonlyused in antifouling chemicals for the treatmentof cage nets. Metal concentrations found in thisstudy were compared with the guideline valuesrecommended by Canadian Council of Ministersof the Environment (CCME 1995). The highestconcentration of zinc measured at the samplingstations 4 (9.05 mg kg1) was lower than therecommended value (124 mg kg1). However,the concentrations of copper determined at thesampling stations 3, 4 and 5 were above guidelinevalues (18.7 mg kg1) but below the probableeffect level (108 mg kg1). Consequently, it ispossible to say that Cu, Zn and Fe concentrationsin the sediments have yet to reach dangerouslevels for the aquatic environment in the studyarea.

Investigation of the relationship between or-ganic carbon and heavy metals revealed thatalthough the correlation coefficients were low(Table 4), there were positive correlations be-tween organic carbon, Fe and Zn (p < 0.01).However, no significant correlations between or-ganic carbon and Cu were found. Low correlationcoefficients imply that as well as the feeds used inaquaculture, natural background levels of heavymetals may also play an important part in theaccumulation process of Fe and Zn in sediments.Fe in particular has high natural background lev-els in the sediments which are thousand timesmore than the sea bass and sea bream diet levels(30 mg kg1; Hossu et al. 2001).

Benthic survey at the same stations which wasconducted at the same time with our study showedthat Capitella capitata and Neanthes caudata ofthe Polycheata and Corbula gibba of Mollusca,which are known as pollution indicators, wererepresented with one, one and six individuals,respectively. Occasional appearance of these indi-cator species throughout the year indicated thatthe impact of fish farms on the benthic organismswas not significant (Ozfucucu et al. 2003).

Conclusion

This study found no significant differences be-tween cage and control stations in dissolved nu-trients, POC and chlorophyll a. The effects of fishfarming in the area were more evident in sedi-ments rather than in the water column. Significantdifferences were found for OM and heavy metals(Fe and Zn) in sediment.

Nevertheless, our results pointed out that con-centrations of nutrients and heavy metals werein tolerable levels for the marine ecosystem. It ispossible to conclude that the oligotrophic natureof the water in the study area was able to assimi-late organic and inorganic loads produced by thefish farms. On the other hand, since this site isallocated for the fish farming, the number of thefarms will increase, with dramatic effects of thefish farms. Thus, it would be useful to monitor inthe long term both water column and sedimentenvironment in order to maintain sustainable de-velopment of the aquaculture in the area.

Acknowledgements Financial support for this work wasprovided by the Bodrum Aquaculture Research Institute,Turkish Ministry of Agriculture.

References

Abo, K., & Yokayama, H. (2007). Assimilative capacity offish farm environments as determined by the benthicoxygen uptake rate: Studies using a numerical model.Bulletin of Fisheries Research Agency, 19, 7987.

Aksu, M., & Kocatas, A. (2007). Environmental effectsof the three fish farms in Izmir Bay (Aegean SeaTurkey) on water column and sediment. Rapport du38e Congrs de la Commission Internationale PourLexploration Scientifique de la Mer Mditerrane, 38,414.

Anonymous. (2005). Aquaculture production by speciesand years. Ministry of Agriculture, General Direc-torate of Agricultural Production and Development.http://www.tugem.gov.tr/ (in Turkish).

Arnoux, A., Nienchewski, L. P. & Tatossian, J. (1981).Comparision de quelques methodes dattaque dessediments marins pour lanalyse des metaux lourds.Journal Francais dhydrologie, 12, 2948.

CCME (1995). Protocol for the derivation of Canadian sed-iment quality guidelines for the protection of aquaticlife, CCME EPC-98 E. Prepared by EnvironmentCanada, Guidelines Division, Technical Secretariat of


the CCME Task Group on water quality guidelines,Ottawa.

Chou, C. L., Haya, K., Paon, L. A., Burridge, L.,& Moffatt, J. D. (2002). Aquaculture-related tracemetals in sediments and lobsters and relevance toenvironmental monitoring program ratings for near-field effects. Marine Pollution Bulletin, 44, 12591268.doi:10.1016/S0025-326X(02)00219-9.

Delgado, O., Ruiz, J., Perez, M., Romero, J., &Ballestreros, E. (1999). Effects of fish farming on sea-grass (Posidonia oceanica) in a Mediterranean Bay:Seagrass decline after loading cessation. OceanologicaActa, 22, 109117. doi:10.1016/S0399-1784(99)80037-1.

Demirak, A., Balci, A., & Tufekci, M. (2006). Environmen-tal impact of the marine aquaculture in Gulluk Bay.Environmental Monitoring and Assessment, 123, 112.doi:10.1007/s10661-005-9063-y.

Dosdat, A. (2001). Environmental impact of aquaculturein the Mediterranean: Nutritional and feeding as-pects. In Uriarte & B. Basurco (Eds.), Environmen-tal impact assessment of Mediterranean aquaculturefarms (pp. 2336). Zaragoza, SpainCahiers OptionsMditerranennes, 55 A. INO Reproducciones, S.A.

FAO (1983). Manual of methods in aquatic environ-ments research. Part I. Fisheries Technical Report 137,pp. 201202.

FAO (1990). The definition of aquaculture and collectionof statistics. FAO Aquacult. Min. 7.

FAO (1992). Guidelines for the promotion of environmen-tal management of coastal aquaculture development.FAO Fisheries Technical Paper 328, Rome.

FAO (2006). World review of fisheries and aquaculture. Thestate of world fisheries and aquaculture. Rome, Italy:FAO Fisheries Department.

Gaudette, H. E., Flight, W. R., Toner, L., & Folger, W.(1974). An inexpensive titration method for the deter-mination of organic carbon in recent sediments. Jour-nal of Sedimentary Petrology, 44, 249253.

Hossu, B., Korkut, A. Y., & Firat, A. (2001). Fish feedingand feed technology. E.U. Faculty of Fisheries Publica-tions 50. Izmir, Turkey (in Turkish).

Karakassis, I. (1998). Aquaculture and coastal marine bio-diversity. Oceanis, 24, 271286.

Karakassis, I., Tsapakis, M., & Hatziyanni, E. (1998). Sea-sonal variability in sediment profiles beneath fish farmcages in the Mediterranean. Marine Ecology ProgressSeries, 162, 243252. doi:10.3354/meps162243.

Karakassis, I., Hatziyanni, E., Tsapakis, M., & Plaiti,W. (1999). Benthic recovery following cessation offish farming: A series of successes and catastro-phes. Marine Ecology Progress Series, 184, 205218.doi:10.3354/meps184205.

Karakassis, I., Tsapakis, M., Hatziyanni, E., Papadopolou,K.-N., & Plaiti, W. (2000). Impact of cage farmingof fish on the seabed in three Mediterranean coastalareas. ICES Journal of Marine Science, 57, 14621471.doi:10.1006/jmsc.2000.0925.

Katavic, I., & Antolic, B. (1999). On the impact of a seabass (Dicentrarchus labrax L.) cage farm on waterquality and macrobenthic communities. Acta Adriat-ica, 40, 1932.

Kaymakci-Basaran, A., Aksu, M., & Egemen, O. (2007).Monitoring the impacts of the offshore cage fish farmon water quality located in Ildir Bay (IzmirAegeanSea). A.U. The Journal of Agricultural Science, 13,2228 (in Turkish).

Kontas, A., Kucuksezgin, F., Altay, O., & Uluturhan, E.(2004). Monitoring of eutrophication and nutrientlimitation in the Izmir Bay (Turkey) beforeand after wastewater treatment plant. EnvironmentInternational, 29, 10571062. doi:10.1016/S0160-4120(03)00098-9.

La Rosa, T., Mirto, S., Mazzola, A., & Danovaro, R.(2001). Differential responses of benthic microbesand meiofauna to fish-farm disturbance in coastalsediments. Environmental Pollution, 112, 427434.doi:10.1016/S0269-7491(00)00141-X.

La Rosa, T., Mirto, S., Favaloro, E., Savona, B., Sar,G., Danavaro, R., et al. (2002). Impact on thewater column biogeochemistry of a Mediterraneanmussel and fish farm. Water Research, 36, 713721.doi:10.1016/S0043-1354(01)00274-3.

La Rosa, T., Mirto, S., Mazzola, A., & Maugeri, T. L.(2004). Benthic microbial indicators of fish farmimpact in a coastal area of the Tyrrhenian Sea.Aquaculture (Amsterdam, Netherlands), 230, 153167.doi:10.1016/S0044-8486(03)00433-2.

Leong, L. S., & Taner, P. A. (1999). Comparison ofmethods for determination of organic carbon in ma-rine sediment. Marine Pollution Bulletin, 38, 875879.doi:10.1016/S0025-326X(99)00013-2.

Maldonado, M., Carmona, M. C., Echeverra, Y., &Riesgo, A. (2005). The environmental impact ofMediterranean cage fish farms at semi-exposed lo-cations: Does it need a re-assessment? HelgolandMarine Research, 59, 121135. doi:10.1007/s10152-004-0211-5.

Mazzola, A., Mirto, S., & Danovaro, R. (1999). Ini-tial fish-farm impact on meiofaunal assemblages incoastal sediments of the western Mediterranean. Ma-rine Pollution Bulletin, 38, 11261133. doi:10.1016/S0025-326X(99)00142-3.

Mazzola, A., Mirto, S., La Rosa, T., Fabiano, M., &Danovaro, R. (2000). Fish-farming effects on benthiccommunity structure in coastal sediments: Analysis ofmeiofaunal recovery. ICES Journal of Marine Science,57, 14541461. doi:10.1006/jmsc.2000.0904.

Mendigucha, C., Moreno, C., Mnuel-Vez, M. P., &Garca-Vargas, M. (2006). Preliminary investigationon the enrichment of heavy metals in marine sedi-ments originated from intensive aquaculture effluents.Aquaculture (Amsterdam, Netherlands), 254, 317325.doi:10.1016/j.aquaculture.2005.10.049.

Neofitou, N., & Klaoudatos, S. (2008). Effects of fish farm-ing on the water column nutrient concentration in asemi-enclosed gulf of the eastern Mediterranean.Aquaculture and Research, 39, 482490. doi:10.1111/j.1365-2109.2008.01900.x.

Nordvarg, L., & Johansson, T. (2002). The effects of fishfarm effluents on the water quality in the landarchipelago, Baltic Sea. Aquacultural Engineering, 25,253279. doi:10.1016/S0144-8609(01)00088-7.


Ozfucucu, E., Katagan, T., & Egemen, O. (2003). Possibleenvironmental effects of the development of aquacul-ture in Salih Island and Ikizadalar Islands. Ministry ofAgriculture, Bodrum Aquaculture Research Institute,Publication 10. Bodrum, Turkey p. 53 (in Turkish).

Pitta, P., Karakassis, I., Tsapakis, M., & Zivanovic, S.(1999). Natural vs. mariculture induced variability innutrients and plankton in the eastern Mediterranean.Hydrobiologia, 391, 181194.

Pitta, P., Apostolaki, E. T., Giannoulaki, M., &Karakassis, I. (2005). Mesoscale changes in thewater column in response to fish farming zones inthree coastal areas in the eastern Mediterranean Sea.Estuarine, Coastal and Shelf Science, 65, 501512.doi:10.1016/j.ecss.2005.06.021.

Pitta, P., Apostolaki, E. T., Tsagaraki, T., Tsapakis, M., &Karakassis, I. (2006). Fish farming effects on chemi-cal and microbial variables of the water column: Aspatio-temporal study along the Mediterranean Sea.Hydrobiologia, 563, 99108. doi:10.1007/s10750-005-1593-3.

Porello, S., Tomasetti, P., Manzueto, L., Finoia, M. G.,Persia, E., Mercatali, I., et al. (2005). The influenceof marine cages on the sediment chemistry in theMediterranean Sea. Aquaculture (Amsterdam,Netherlands), 249, 145158. doi:10.1016/j.aquaculture.2005.02.042.

Ruiz, J. M., Perez, M., & Romero, J. (2001). Effects offish farm loadings on seagrass (Posidonia oceanica)distribution, growth and photosynthesis. Marine Pol-

lution Bulletin, 42, 749760. doi:10.1016/S0025-326X(00)00215-0.

Sanz-Lazaro, C., & Marin, A. (2006). Benthic recovery du-ring open sea fish farming abatement in westernMediterranean, Spain. Marine Environmental Re-search, 62, 374387. doi:10.1016/j.marenvres.2006.05.006.

Strickland, J. D. H., & Parsons, T. R. (1972). A practicalhandbook of sea water analysis. Ottowa: Fisheries Re-search Board of Canada.

Sunlu, U., Egemen, O., & Kaymakci, A. (1998). Trace met-als in Mediterranean mussel Mytilus galloprovincialis(L. 1758) and in surficial sediments from Urla-Iskele,Izmir-Turkey. International symposium on marine pol-lution extended synopsis, Monaco, pp. 645646.

Sutherland, T. F., Petersen, S. A., Levings, C. D., &Martin, A. J. (2007). Distinguishing between naturaland aquaculture-derived sediment concentrations ofheavy metals in the Broughton Archipelago, BritishColombia. Marine Pollution Bulletin, 54, 14511460.doi:10.1016/j.marpolbul.2007.05.010.

Tuncer, S., & Uysal, H. (1983). The distribution of totalmercury in sediment samples of Izmir Bay and itsaccumulation in soles (Solea vulgaris). UNESCO Re-ports in Marine Science, 31.

Yucel-Gier, G., Kucuksezgin, F., & Kocak, F. (2007).Effects of fish farming on nutrients and benthic com-munity structure in the eastern Aegean (Turkey).Aquaculture and Research, 38, 256267. doi:10.1111/j.1365-2109.2007.01661.x.

Impacts of the fish farms on the water column nutrient concentrations and accumulation of heavy metals in the sediments in the eastern Aegean Sea (Turkey)AbstractIntroductionMaterials and methodsResultsNutrientsPOC and chlorophyll aOrganic matter, total organic carbon, and heavy metals in sediment

DiscussionConclusionReferences

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2010Impacts of the Fish Farms on the Water Column Nutrient

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