Arsenic’s occurrence in the environment could be due to human activities as well as to natural sources. In this study, Posidonia oceanica and Cymodocea nodosa are collected in 84 sites around the Mediterranean basin. In addition, both seagrass are collected monthly, in two sites (Calvi in Corsica and Salammbô in Tunisia). Arsenic concentrations in C. nodosa present seasonal variations in relation with spring phytoplankton blooms. For both species arsenic concentration is higher in the vicinity of geological sources (mining), lagoon outlets and industrial activities. Moreover, Mediterranean islands (Balearic, Sardinia, Corsica, Malta, Crete and Cyprus) and the Southern basin coastline exhibit lower concentrations in Arsenic than the rest of the Mediterranean basin. The wide spread distribution of these two species would encourage their use in a global monitoring network devoted to Arsenic contamination.peer-reviewe

5th Mediterranean Symposium on Marine Vegetation

Akcali, Baris

Alvarez-Perez, E.

Apostolaki, Eugenia

Bakran-Petricioli, Tatjana

Belbacha, Said

Borg, Joseph A.

Buia, Cristina Maria

Casalta, Buia

Celebi, Billur

Fernandez-Torquemade, Y.

Hadjichristoforou, M.

Langar, H.

Lipej, Lovrenc

Llagostera, I.

Lopez Y Royo, C.

Marcou, M.

Mavrič, Borut

Panzalis, P.

Pergent, Gerard

Pergent-Martini, Christine

Romero, Javier

Salivas-Decaux, M.

Semroud, Rachid

Skoufas, George

Turk, R.

Weitzmann, B.

Zapata-Salgado, F. J.

OAR@UM

Christine PERGENT-MARTINI, SALIVAS-DECAUX M., LANGAR H., PERGENT G., AKÇALI B., ALVAREZ-PÉREZ E., APOSTOLAKI E., BAKRAN-PETRICIOLI T., BELBACHA S., BORG J., BUIA C., CASALTA B., CELEBI B., FERNANDEZ-TORQUEMADE Y., HADJICHRISTOFOROU M., LLAGOSTERA I., LIPEJ L., LOPEZ Y ROYO C., MARCOU M., MAVRIC B., PANZALIS P., ROMERO J., SEMROUD R., SKOUFAS G., TURK R., WEITZMANN B., ZAPATA-SALGADO F.J. FRES 3041, University of Corsica, 20250 Corte, France E-mail: pmartini@univ-corse.fr ARSENIC CONCENTRATIONS IN SEAGRASS AROUND THE MEDITERRANEAN COAST AND SEASONAL VARIATIONS Abstract Arsenic’s occurrence in the environment could be due to human activities as well as to natural sources. In this study, Posidonia oceanica and Cymodocea nodosa are collected in 84 sites around the Mediterranean basin. In addition, both seagrass are collected monthly, in two sites (Calvi in Corsica and Salammbô in Tunisia). Arsenic concentrations in C. nodosa present seasonal variations in relation with spring phytoplankton blooms. For both species arsenic concentration is higher in the vicinity of geological sources (mining), lagoon outlets and industrial activities. Moreover, Mediterranean islands (Balearic, Sardinia, Corsica, Malta, Crete and Cyprus) and the Southern basin coastline exhibit lower concentrations in Arsenic than the rest of the Mediterranean basin. The wide spread distribution of these two species would encourage their use in a global monitoring network devoted to Arsenic contamination. Key-words: Coastal contamination, Posidonia oceanica, Cymodocea nodosa, Arsenic, Human-induced pressure.  Introduction Seagrasses are often used to monitor trace metals, and in the Mediterranean Sea most of these studies focused on Posidonia oceanica (L.) Delile meadows, due to their widespread distribution around the Mediterranean Sea and of their ability to accumulate the trace metals (see for instance: Augier et al., 1978; Costantini et al., 1991; Pergent-Martini & Pergent, 2000; Lafabrie et al., 2008; Luy et al., 2012). Metals and metalloids are regarded as serious pollutants of the aquatic environment because of their toxicity, persistence, difficulties in biodegrading and their tendency to concentrate in aquatic organisms (Ikem & Egiebor, 2005 in Luy et al., 2012). Among these metalloids, Arsenic (As) is widely distributed in the biosphere. Its occurrence in the environment could be due to human activities (mining, pesticides, burning of fossil fuel etc.) as well as to natural (geogenic) sources (Kim et al., 2002). As contamination of the environment from both anthropogenic and natural sources has occurred in many parts of the world and is recognized as a global problem (Storelli & Marcotrigiano, 2000). Only few studies deal with the potential use of the main Mediterranean seagrasses as bio-integrator for As (Grauby et al., 1991; Luy et al., 2012). However these two seagrasses constitute a continuous belt all around the Mediterranean coastlines. Thus, in order to increase the interest in using seagrass in Mediterranean monitoring programs, it would be interesting to confirm their capacities of bio-integrator for this element. 5th Mediterranean Symposium on Marine Vegetation (Portorož, Slovenia, 27-28 October 2014)137The aim of this study is (i) to assess the potential of P. oceanica and of Cymodocea nodosa (U.) Aschers. as As bio-integrators, (ii) to determine seasonal variations of As concentrations and (iii) to evaluate the level of As concentration along the Mediterranean coasts. Material and methods P. oceanica and C. nodosa leaves were collected monthly in two sites (Fig. 1) during the vegetative period; i.e. between March and October in Calvi and between January and December 2007 in Salammbô). Other 82 sites were sampled (between May 2007 and July 2008), 15 sites concerned C. nodosa and 68 P. oceanica (Tab. 1).  Tab. 1: Coordinates of sampling sites in decimal degrees (WGS 84). Site number is indicated for Posidonia oceanica and followed by c and in bold for Cymodocea nodosa. N° Station North East N° Station North East ALGERIA 1 Annaba 36.893456 7.779814     CROATIA 2 Brbinjscica 44.055117 14.991983 5 Seget Donji 43.511983 16.213789 3 Island Vlasnik 42.753353 16.796739 6 Zadar 44.103583 15.235861 4 Lavdara 43.948000 15.198533     CYPRUS 7 Cape Greco 35.152778 34.173889 8 Larnaca 34.870117 33.655133 EGYPT 9 Alexandria 31.094064 29.692653     FRANCE 10 Arinella 42.666667 9.450000 16 La Parata 41.883333 8.616667 11 Canari 42.783333 9.333333 17 Macinaggio 42.983333 9.483333 12 Cavalaire 43.178500 6.540380 18 Porto 42.250000 8.650000 13 Diane 42.116667 9.566667 19 Porto-Pollo 41.733333 8.766667 14 Ile Rousse 42.633333 8.933333 20 Sagone 42.083333 8.666667 15 La Chiappa 41.583333 9.366667 21 Toga 42.700000 9.450000 GREECE 22 Crete 35.399658 25.027119 24 Ligaria  35.401069 25.028414 23 Kalogria 40.129519 23.760458     ITALY 25 Agropoli 40.375783 15.001250 34 Porto Ercole  42.436717 11.206133 26 Alghero 40.580044 8.309533 35 Porto Torres  40.838728 8.417222 1c Bari 41.096733 16.964767 36 Santa Marinella  42.040267 11.894617 27 Bosa 40.284808 8.474883 37 Scarrupata 40.697056 13.916522 28 Cagliari 1 39.222444 9.239306 38 Talamone 42.559624 11.157310 29 Cagliari 2 39.207083 9.302083 39 Tavolara 40.849633 9.692300 2c Civitavecchia 42.141716 11.743600 4c Torre Canne 40.840417 17.469800 30 Gallipoli 40.057417 17.976183 5c Torre Lapillo 40.282667 17.842183 31 Lacco Ameno 40.753817 13.891842 40 Torre Mozza 42.946567 10.694533 32 Olbia 41.000444 9.621306 6c Torre Salinas 39.351722 9.593583 33 Oristano 39.833042 8.553292 41 Torre San Giovanni 39.897350 18.097500 3c Porto Cesaro 40.257967 17.890850     LIBYA 42 Garabouilli 32.814530 13.705220 43 Tajura 32.897528 13.355822 MALTA 44 Bahar ic-Caghaq iCaghaq 35.953650 14.448467 47 Qalet Marku Bay 35.949267 14.453017 45 Dahlet ix-Xmajjar 35.998983 14.366783 48 Rdum il-Kbir 36.065017 14.296233 46 Marsaxlokk Bay 35.828633 14.547200 49 St Paul’s Bay 35.954783 14.392733 SLOVENIA 50 Gulf of Trieste 45.548683 13.696233     SPAIN 51 Alicante 38.251947 0.512400 54 Medes 42.048889 3.219167 52 Chafarinas 35.180006 0.569414 11c Salines 40.599906 0.711792 7c Depuradora 40.621092 0.636822 12c Tancada 40.635772 0.737244 8c Galatxo 40.587508 0.646989 13c Torre Sant Joan 40.630797 0.740547 9c Irta 40.625719 0.665625 55 Torredembarra 41.146983 1.426717 53 Mallorca 39.760083 3.406533 14c Trabucador 40.618517 0.729028 10c Mari 40.583769 0.608322     5ème Symposium Méditerranéen sur la Végétation Marine (Portorož, Slovénie, 27-28 octobre 2014)138Tab. 1 (continued): Coordinates of sampling sites in decimal degrees (WGS 84). Site number is indicated for Posidonia oceanica and followed by c and in bold for Cymodocea nodosa. N° Station North East N° Station North East TUNISIA 56 Kerkenah 34.681514 11.113286 61 Sidi Ali el Mekki 37.172792 10.262000 57 La Galite 37.536801 8.938876 62 Sidi Mechreg 37.164717 9.122424 58 La Goulette 36.813900 10.307603 63 Tabarka 36.954744 8.767150 59 Monastir 35.775128 10.843294 64 Zembra 37.136125 10.808897 60 Rades 36.767925 10.301869     TURKEY 65 Gokceada  40.224400 25.867894 67 Turgutlar bay 36.154100 33.445267 66 Mersin 36.790522 34.637447 68-15c Urla 38.360847 26.794650  The P. oceanica and C. nodosa leaf blades were cleaned (epiphytes scraped off), rinsed (ultrapure water) and either lyophilised (Heto® FD4-85 freeze dryer, HetoHolten A/S) or dried at 30°C to constant weight, before they were manually reduced to powder. Analyses were run with quality assurance procedures at the Laboratory of Rouen / ETSA (Rouen, France). They were performed using the hydride generation and atomic absorption spectrometry method.   Fig. 1: Sampling sites of Calvi (Corsica) and Salammbô (Tunisia). Results Arsenic concentrations in C. nodosa were higher than in P. oceanica all year round (respectively a mean of 10.0 ± 1.3 and 0.9 ± 0.1 µg.g-1 DW in Calvi, and a mean of 0.6  ±  0.1 and 0.4 ± 0.0 µg.g-1 DW in Salammbô), with an important difference between the both species, observed in Calvi. Seasonal variations were observed for C. nodosa in the two sites, with a maximum concentration in spring (27.8 ± 3.44 µg.g-1 DW) in Calvi, and at the end of winter (1.3 ± 0.1 µg.g-1 DW) in Salammbô. Two concentration peaks emerge during the sampling period: the first in April and the second in July in Calvi and the first in February and the second in September in Salammbô. A significant correlation (Pearson’s correlation test, p<0.05) was observed between Calvi and Salammbô, with a lag of two months (probably due to seasonal gaps between the northern and southern Mediterranean coast). For P. oceanica, As concentrations were similar all year round (repeated measures ANOVA, p<0.05 and Tukey HSD Test) even a maximum is observed in summer in Calvi (1.9 ± 0.1 µg.g-1 DW).  Highest As concentrations were reported in Trabuccador (Spain) for C. nodosa (Fig. 2A) and in Brbjinscica (Croatia) for P. oceanica (Fig. 2B). For both seagrass, the highest values are significantly different from the lowest values of arsenic concentrations (Nested design ANOVA, p<0.05). Discussion Very few studies concern As concentrations in seagrasses and their seasonal variations (Fourqurean et al., 2007, Malea & Krevekidis, 2013). Nutrients such as phosphorus (P) 5th Mediterranean Symposium on Marine Vegetation (Portorož, Slovenia, 27-28 October 2014)139are required for growth of phytoplankton and seagrasses (Romero et al., 2006). The chemical similarities between As and P can explain substitutions of these elements. Thus, it has been suggested that indiscriminate uptake of As by marine biota can occur when P concentrations in the water column are depleted (Apte et al., 1986; Michel et al., 1998). In this study, peaks in As occur just after phytoplankton blooms, identified at the end of March and at the beginning of June by Goffart et al., (2002) in Corsica while arsenic concentration peaks occurred in April and July. The uptake of P by phytoplankton, which results in a depletion of this nutrient in the water column, could explain high As concentrations in seagrass during the following months (Howard et al., 1995). This phenomenon appears more visible in C. nodosa, perhaps due to the first’s higher leaf growth rate (Cancemi et al., 2002) which induces a higher uptake of nutrients.    Fig. 2: Arsenic concentrations (µg.g-1 DW), in C. nodosa (A) and in P. oceanica (B) in Mediterranean sites. (Mean ± SE). Sites with * are significantly different from those with **.  The average concentrations in Calvi (more than 15 times higher than in Salammbô) could be explained by the presence, in proximity of Calvi, of a geological restricted zone rich in As and of a mine containing arsenopyrite (BRGM, 1994).  Concentrations of As, in P. oceanica around the western Mediterranean basin, exhibit a significant difference (Kruskal-wallis, p< 0.05) between Northern and Southern coasts. The significant higher concentrations observed on northern coast are probably linked to urbanization (UNEP, 2005). Indeed, metal contamination in coastal environments is often associated with impacts induced by human activities. Significant difference was also identified between continental sites and islands (Kruskal-wallis, p< 0.05), due to reduced human activities in the Mediterranean islands studied (Biggi, 2001). The highest value, recorded in Brbinjscica (Croatia), confirms high As contamination yet observed in Adriatic Sea (Fattorini et al., 2008).   5ème Symposium Méditerranéen sur la Végétation Marine (Portorož, Slovénie, 27-28 octobre 2014)140The highest concentrations of As, in C. nodosa (> 2.0 µg.g-1 DW; Fig. 2A), were observed at the outlets of rivers and lagoons. The presence of As in estuaries has already been pointed out due to the accumulation of pollutants, released by upstream industries, and to specific mechanisms of desorption in estuaries (Michel et al., 1998). Conversely, the two sites with lowest values (less than 0.6 µg.g-1 DW) were located in open sea (Bari and Civitavecchia).   Conclusion Concentrations of As, found in P. oceanica do not show important seasonal variations, conversely to C. nodosa where these variations seem linked to the availability of nutrients (P in water column); indeed similarities between As and P could induce an increased uptake of this metalloid after phytoplankton blooms.  For both seagrass species concentrations are higher in the vicinity of geological sources, lagoon outlets and in the vicinity of industrial activities. Moreover, Mediterranean islands (Balearic, Sardinia, Corsica, Malta, Crete and Cyprus), as well as the Southern basin coastline, exhibit lower concentrations in As.  The potential of seagrasses as contaminant bio-indicator is confirmed and the widely spread distribution of these two species in the Mediterranean basin would encourage their use in a global monitoring network devoted to As contamination, especially for P. oceanica where concentrations are few affected by seasonal variations. Aknowledgements This work was supported by a grant from the “Collectivité Territoriale de Corse” and the collaboration of several Mediterranean laboratories. References APTE S.C., HOWARD A.G., MORRIS R.J., MCCARTNEY M.J. (1986) - Arsenic, Antimony and Selenium speciation during a spring phytoplankton bloom in a closed experimental ecosystem. Mar. Chem. 20: 119-130. AUGIER H., GILLES G., RAMONDA G. (1978) - Research on mercury pollution of marine medium in Marseille region (Mediterranean, France) .1. Degree of Mercury contamination of marine phanerogam Posidonia oceanica in vicinity of harbor complex and outflow area of main sewer of Marseille. Environ. Pollut. 17: 269-285. BIGGI M. (2001) - La coopération interrégionale et les îles de la Méditerranée. Confl. Medit. 36: 125-134. BRGM (1994) - Risque de pollution par métaux lourds, arsenic, des eaux destinées à la consommation humaine. Identification des zones susceptibles d'être contaminées en liaison avec les indices et travaux miniers en Haute-Corse. P 05201402: 1-21. CANCEMI G., BUIA M.C., MAZZELLA L. (2002) - Structure and growth dynamics of Cymodocea nodosa meadows. Sci. Mar. 66: 365-373. COSTANTINI S., GIORDANO R., CIARALLI L., BECCALONI E. (1991) - Mercury, Cadmium and Lead evaluation in Posidonia oceanica and Codium tomentosum. Mar. Pollut. Bull. 22: 362-363. FATTORINI D., NOTTI A., DI MENTO R., CICERO A.M., GABELLINI M., RUSSO A., REGOLI F. (2008) - Seasonal, spatial and inter-annual variations of trace metals in mussels from the Adriatic sea: A regional gradient for arsenic and implications for monitoring the impact of off-shore activities. Chemosphere 72: 1524-1533. FOURQUREAN J.W., MARBA N., DUARTE C.M., DIAZ-ALMELA, RUIZ-HALPERN S. (2007) - Spatial and temporal variation in the elemental and stable isotopic content of the seagrasses Posidonia oceanica and Cymodocea nodosa from the Illes Balears, Spain. 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(2000) - Marine phanerogams as a tool in the evaluation of marine trace-metal contamination: an example from the Mediterranean. Int. J. Environ. Pollut. 13: 126-147. ROMERO J., LEE K.S., PEREZ M., MATEO M.A., ALCOVERRO T. (2006) - Nutrients and seagrasses. In: A.W.D. Larkum, R.J.Orth and C.M. Duarte (Eds.). Seagrasses: Biology, Ecology and Conservation. Springer: 227-254. STORELLI M.M., MARCOTRIGIANO G.O. (2000) - Total organic and inorganic arsenic from marine turtles (Caretta caretta) beached along the Italian coast (South Adriatic Sea). Bull. Environ. Contam. Toxicol. 65: 732-739. UNEP (2005) - A Sustainable Future for the Mediterranean: The Blue Plan's Environment and Development Outlook. 1-464.  5ème Symposium Méditerranéen sur la Végétation Marine (Portorož, Slovénie, 27-28 octobre 2014)142View publication stats

Arsenic concentrations in seagrass around the Mediterranean coast and seasonal variations

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Arsenic concentrations in seagrass around the Mediterranean coast and seasonal variations

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