Volume 13 – No.11a – 2004 REPRINT pp. 1122 - 1128 STRUCTURE OF THE “AMPHIOXUS SAND” COMMUNITY IN THERMAIKOS BAY (EASTERN MEDITERRANEAN) Chryssanthi Antoniadou - Yiannis Krestenitis - Chariton Chintiroglou Angerstr. 12 85354 Freising - Germany Phone: ++49 – (0) 8161-48420 Fax: ++49 - (0) 8161-484248 Email: [email protected] www.psp-parlar.de © by PSP Volume 13 – No 11a. 2004 Fresenius Environmental Bulletin STRUCTURE OF THE “AMPHIOXUS SAND” COMMUNITY IN THERMAIKOS BAY (EASTERN MEDITERRANEAN) Chryssanthi Antoniadou1, Yiannis Krestenitis2 and Chariton Chintiroglou1 1Aristotle University, School of Biology, Department of Zoology, P.O. Box 134, 540 06 Thessaloniki, Greece 2Aristotle University, School of Mechanics, Department of Hydraulics and Environmental Engineering, 540 06 Thessaloniki, Greece SUMMARY The structure of the “Amphioxus sand” community in expanded during the last decade as a result of increasing Thermaikos Bay was studied over a two-year period. The eutrophication and organic pollution, causing a consider- examination of the collected 4,767 specimens revealed the able decrease in B. lanceolatum’s population density and presence of 141 species. Gastropoda and Polychaeta were also a change on its community structure. Thus, this com- the dominant taxa. Multivariate analyses showed high simi- munity type seems to be threatened worldwide [19, 20]. In larity, whereas samples discriminated according to sediment the 70’s, the “Amphioxus sand” community was common granulometry. The degradation of this community was in Thermaikos Gulf, but today its presence is limited. evident in its structure as most of the recorded macrobenthic This study took place at the NE side of Thermaikos species characterizes the organically enriched sediments. Bay, where a large fishing area of the common seashell Venus verrucosa is heavily exploited [21]. The main aim was to detect the ‘Amphioxus sand’ community, and elabo- rate its structural variability in both spatial and temporal KEYWORDS: biodiversity, soft substrate, sublittoral, Thermaikos, scales. Furthermore, the most critical factors that influence organic pollution. its distributional range were identified. MATERIALS AND METHODS INTRODUCTION Study area Ecological studies of zoobenthos have proved to be ex- Thermaikos Gulf is a shallow-water embayment in tremely useful for biomonitoring [1-3]. Many authors have the NW Aegean (Figure 1). Its northern part, named as showed that the structure of benthic communities reflects Thessaloniki Gulf, is divided at three distinct areas: (1) the integrated conditions over a period of time [4-6]. Con- the inner bay, which is a very closed area as regards water sequently, this kind of data is helpful for pollution impact renewal, (2) the central gulf and (3) the outer gulf. Ther- studies due to anthropogenic interference [7-9]. In order to maikos receives discharges from large river systems (Ax- detect and deal with such cases, as defined by many inter- ios, Loudias, Aliakmonas) and also sewage and industrial national directives and conventions (e.g. Rio 1992, Water effluents from the city of Thessaloniki [22, 23]. The study Framework Directive, Directive 2000/60/EC), it is neces- was conducted at the NE side of the central gulf, which sary to create a database concerning the composition of covers a surface of 136 km2 with a mean depth of 25 m. natural communities [10, 11]. After preliminary sampling the “Amphioxus sand” com- Besides the intense quantitative research on soft sub- munity was found at two sites. The first site (St.1) had a strate communities, little is known about the Branchiostoma depth ranging from 3 to 5 m, whereas the second one lanceolatum facies, often called as “Amphioxus sand” [12]. (St.2), located northern, had a depth ranging from 7 to 10 m Most of the relevant information derives from studies in the (Figure 1). Western Mediterranean and the Adriatic [13-17], as there is only one reference from the Eastern basin [18] and the Black Sampling techniques Sea [19]. The“Amphioxus sand” community normally ex- Abiotic Factors: The main abiotic factors, e.g. tempera- tends on gravel and coarse sand with shell fragments, often ture, salinity, dissolved O2 and pH, were measured in the accompanied by certain Polychaeta species (e.g. Stauro- water column with a CTD on a monthly basis. Currents were cephalus keffersteini) and venerupid bivalves (e.g. Venerupis recorded with an autographic current-meter (AANDERAA aurea, Venus verrucosa) [12]. However, muddy areas have RCM9) placed five meters beyond see level. A sediment 1122 © by PSP Volume 13 – No 11a. 2004 Fresenius Environmental Bulletin FIGURE 1 - Map of the study area indicating sampling sites. analysis (granulometric composition and amount of organic The data obtained per sampling site were analyzed material contained in sediment) was carried out at each with multidimensional scaling techniques, based on the sampling site on a seasonal basis. Two substrate samples Bray-Curtis similarity and log transformed numerical were collected with a core sampler of 1 lt volume, at each abundances, using PRIMER package [30]. The signifi- period with SCUBA diving. The organic material was cance of the multivariate results was assessed with measured with the H2O2 method and the identification of ANOSIM test. SIMPER analysis was applied to identify the granulometric composition was based on Folks system the contribution of each species to the overall similarity of sediment classification [24, 25]. within a group of samples and the dissimilarity among groups [30]. Finally, the BIOENV procedure was used to Macrofauna examine which environmental parameters are related to Sampling was carried out in August and January for the observed biotic pattern (MDS plot) and the degree of two consecutive years (summer 2001 to winter 2003). Mac- this relation [30]. rofaunal samples were collected from each site and period by SCUBA diving with the use of an 18 x 25 cm core sam- pler (3 replicates from the shallow-depth site and 5 repli- RESULTS cates from the deeper one) [26, 27]. Overall, 32 samples were obtained, sieved (mesh opening 0.5 mm) and fixed Community structure in 9% formaldehyde. After sorted, all living specimens A total of 4,767 individuals were counted, belonging to were identified at species level and counted. 142 species. From these species 55 were dominant (15 Poly- chaeta, 36 Mollusca, 4 Crustacea), according to population Data analysis density values and frequency (> 60%) (Table 1). Data was analyzed by standard biocoenotic methods. Gastropods dominate in the first year and polychaetes Thus, the population density, the mean dominance, the in the second. MANOVA results showed that from the frequency, and also Margalef’s richness, Shannon-Wiener four dominant taxa only Gastropoda had unequal disper- and Pielou’s evenness indices, were calculated [27, 28]. sion of abundance in time and Bivalvia in both time and Numerical abundance data were analyzed by mANOVA, space (Table 2). in order to examine the effect of three different factors: a) The values of diversity indices were high (Figure 2). site, b) season and c) year of sampling. A logarithmic trans- Richness values (d) ranged from 7.47 to 9.77, H’ values formation (logx+1) was used to normalize the variance of from 3.42 to 4.43 and J’ values from 0.72 to 0.95, indicat- numerical abundances [29]. ing the evenly dispersion of numerical abundance among species. 1123 © by PSP Volume 13 – No 11a. 2004 Fresenius Environmental Bulletin TABLE 1 - Taxonomic list of the recorded species. Taxa - Species Cnidaria Bittium reticulatum (DaCosta, 1778) Lucinella divaricata (Linnaeus, 1758) Cereus pedunculatus (Pennant, 1777) Bolinus brandaris (Linnaeus, 1758) Macoma cumana (Costa O.G., 1829) Polychaeta Caecum trachea (Montagu, 1803) Mactra corallina (Linnaeus, 1758) Abarenicola claparedei (Levinsen, 1883) Cerithiopsis horrida (Monterosato, 1874) Modiolus barbatus (Linnaeus, 1758) Aonides oxycephala (Sars, 1862) Cerithium vulgatum Bruguiere, 1792 Mysia undata (Pennant, 1777) Aphelochaeta marioni Saint-Josephl, 1894 Chrysallida doliolum (Philippi, 1844) Mytilus galloprovincialis Lamarck, 1819 Aponuphis bilineata (Baird, 1870) Clanculus jussieui (Payraudeau, 1826) Nucula nitidosa Winckworth, 1930 Aricidea fragilis mediterranea Laubier & Ramos, Conus mediterraneus Hwass, in Bruguiere, 1792 Nucula sulcata Bronn, 1831 1974 Branchiomma bombyx (Dalyell, 1853) Cytharella coarctata (Forbes, 1840) Nuculana pella (Linnaeus, 1767) Capitella capitata (Fabricius, 1780) Epitonium sp. Paphia aurea (Gmelin, 1791) Caulleriella bioculata (Keferstein, 1862) Eulimella scillae (Scacchi, 1835) Parvicardium exiguum (Gmelin, 1791) Ceratonereis costae (Grube, 1840) Euspira catena (DaCosta, 1778) Pita rudis (Poli, 1795) Chone filicaudata Southern, 1914 Folinella excavata (Philippi, 1836) Psammobia depressa (Pennant, 1777) Cirriformia tentaculata (Montagu, 1808) Fusinus rudis (Philippi, 1844) Scrobicularia plana (DaCosta, 1778) Diopatra neapolitana DelleChiaje, 1841 Fusinus syracusanus (Linnaeus, 1758) Tellina donacina (Linnaeus, 1758) Eteone picta Quatrefages, 1865 Gibbula adansonii (Payraudeau, 1826) Tellina planata (Linnaeus, 1758) Eunice vittata (DelleChiaje, 1829) Hadriana oretea (Brocchi, 1814) Tellina pulchella Lamarck, 1818 Euclymene oerstedi (Claparede, 1863) Haminaea navicula (DaCosta, 1778) Venus verrucosa (Linnaeus, 1758) Exogone naidina Oersted, 1845 Hexaplex trunculus (Linnaeus, 1758) Cirripedia Glycera tridactyla Schmarda, 1861 Jujubinus striatus (Linnaeus, 1758)