Dimitris Vafidis

University of Thessaly, Iolcus, Thessaly, Greece

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Publications (65)36.46 Total impact

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    K Skordas · A Lolas · A Exadactylos · D Vafidis
    11th Hellenic Symposium on Oceanography and Fisheries, HCMR, pp. 494-497, Lesvos, Hellas;; 05/2015
  • K Skordas · A Lolas · A Exadactylos · D Vafidis
    11th Hellenic Symposium on Oceanography and Fisheries, HCMR, 4p, Lesvos, Hellas; 05/2015
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    ABSTRACT: Scientific information on the biodiversity of marine caves in the eastern Mediterranean is limited, especially when considering the extensively studied caves of the north-western and central Mediterranean. Aiming to enhance current knowledge regarding cave communities, this study represents a first assessment of the marine cave biota of the eastern Mediterranean, as this has been defined by the European Union’s Marine Strategy Framework Directive (MSFD). Information retrieved from an extensive overview of relevant scientific documents was combined with original data recorded from 23 marine caves of the north-eastern Mediterranean. Our results report a total of 520 taxa recorded in eastern Mediterranean marine caves to date, the majority of which are sponges, polychaetes, rhodophytes, bivalves, fishes, and gastropods. These include several protected, endemic, and alien species. However, not all taxonomic groups have been equally studied among different areas and future studies are expected to raise the number of endemic and alien species. The overall observed trend is that the reported species number is generally related to sampling effort and scientific expertise. The most well-studied marine cave communities of the eastern Mediterranean are those of the Aegean Sea (especially its northern sector), which presented the highest number of species, followed by those of the Levantine. Furthermore, our research in Aegean caves revealed numerous new records for the marine cave fauna of the eastern basin, while several species are reported for the first time in the marine cave habitat. The critical need for further scientific research, monitoring, and conservation of this unique ecosystem was highlighted by (i) the presence of certain species endemic to the eastern Mediterranean coupled with a high proportion of alien species, especially in the Levantine, and (ii) the marine cave habitat availability in isolated insular areas of the eastern Mediterranean.
    Mediterranean Marine Science 01/2015; 16(1). DOI:10.12681/mms.1069 · 1.73 Impact Factor
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    ABSTRACT: Pinna nobilis is an endemic Mediterranean species of high economic and cultural importance. Nowadays, it is under strict protection as a dramatic decline in its populations has been recognized, assigned to the combined effect of fisheries and habitat degradation. This study attempts to evaluate, by non-destructive sampling, the current status of P. nobilis populations in the south Aegean Sea (Dodecanese island complex), where they have been affected for centuries by practically uncontrolled harvesting. Population density and total length of individuals was estimated by diving along strip transects at six islands. Two stations were randomly selected per island, and two depth zones were surveyed per station. Additionally, temporal sampling was carried out at Astypalaia Island from March 2004 to June 2006, to assess relevant trends in density of individuals and size structure of the population. In total 1372 P. nobilis individuals were measured in situ to estimate maximum shell length. The studied populations showed increased density in the shallower depth zone and sheltered sites; small-scale environmental regimes are proposed as shaping factors of P. nobilis distribution. Increased density was also detected during the cold period of the year, probably related to recruitment success. In the lower depth zone the P. nobilis population consisted of larger individuals. A significant decrease in size was detected temporally as mean length was smaller in December 2004; in the same month the presence of small-sized juveniles was depicted in a left-shift in size-frequency distribution. These observations are probably related to the reproductive biology of the species.
    Journal of the Marine Biological Association of the UK 06/2014; 94(4):787-796. DOI:10.1017/S0025315413001902 · 1.13 Impact Factor
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    Georgios Kazanidis · Alexios Lolas · Dimitris Vafidis
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    ABSTRACT: The reproductive cycle of the traditionally exploited sea cucumber Holothuria tubulosa was investigated in the Pagasitikos Gulf (39°18′457″N, 23°05′869″E) from June 2007 to July 2008. The study examined the microscopic characteristics of the gonads and was based on maturity index (MI) and oocytes’ size-frequency distribution. The reproductive cycle was found to be synchronous between sexes, following an annual pattern. The minimum MI values were recorded in December and January, marking the onset of the reproductive cycle. During the spring, MI increased due to gamete development and proliferation. Mature specimens were prominent in summer while spawning occurred between July and September. The maximum MI values were recorded in mid-autumn, when most specimens were at the postspawning stage. The oocytes’ size-frequency distribution showed analogous seasonal variability. The present findings are crucial for establishing an efficient management strategy for this commercial and ecosystem-engineering species, since its exploitation in Greek waters has not been under official control for more than a century. The authors propose a seasonal ban on the exploitation of the species from July to September and a minimum individual drained weight limit of 250 g.
    Turkish Journal of Zoology 04/2014; 38(3):306-315. DOI:10.3906/zoo-1302-31 · 0.59 Impact Factor
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    Georgios Kazanidis · Alexios Lolas · Dimitris Vafidis
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    ABSTRACT: The reproductive cycle of the traditionally exploited sea cucumber Holothuria tubulosa was investigated in the Pagasitikos Gulf (39°18′457″N, 23°05′869″E) from June 2007 to July 2008. The study examined the microscopic characteristics of the gonads and was based on maturity index (MI) and oocytes’ size-frequency distribution. The reproductive cycle was found to be synchronous between sexes, following an annual pattern. The minimum MI values were recorded in December and January, marking the onset of the reproductive cycle. During the spring, MI increased due to gamete development and proliferation. Mature specimens were prominent in summer while spawning occurred between July and September. The maximum MI values were recorded in mid-autumn, when most specimens were at the postspawning stage. The oocytes’ size-frequency distribution showed analogous seasonal variability. The present findings are crucial for establishing an efficient management strategy for this commercial and ecosystem-engineering species, since its exploitation in Greek waters has not been under official control for more than a century. The authors propose a seasonal ban on the exploitation of the species from July to September and a minimum individual drained weight limit of 250 g.
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    1st Pan-Hellenic Scientific Conference on Natural Resources Environmental Economics: Climate Change, Volos, Hellas, Abstract; 03/2014
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    ABSTRACT: Despite their scientific interest and high conservation value, marine caves of the eastern Mediterranean are poorly explored. Herein, a submerged cave from the Aegean Sea was surveyed through SCUBA diving and photoquadrats. A rich fauna of 65 taxa and 4 distinct benthic assemblages were identified. The biotic spatial heterogeneity observed was associated with the unique topography of the different cave sectors.
    40th CIESM Congress, Marseille, France; 11/2013
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    ABSTRACT: The impact of shellfish farming on the water column nutrient concentration and the benthic community structure was investigated seasonally at a mussel farm (Mytilus galloprovincialis L.) of Maliakos Gulf (Eastern Mediterranean). In most cases concentration of nutrients and chl a at the farm site was lower than those observed at the control sites. Statistical analysis in concentration of all nutrients and chl a indicated significant interactions between sites and seasons, which in all cases were temporal. Furthermore, no significant interactions were found between sites and seasons for all sediment and benthic community parameters, except for Shannon–Wiener diversity index and species richness. The significant interactions detected in the biotic data were temporal. Analysis of similarity and similarity percentages analysis revealed a certain fluctuation of benthic macrofaunal community during the overall sampling year mainly due to temporal rather than spatial effects. Cluster analysis and multidimensional scaling ordination plot indicated the clearly separation of the farm site and the control sites in most of the seasons. K-dominance curves showed small difference in elevation and overlap indicating minimal difference in biological stress between the farm site and the control sites. All the above indicates that probably the farming of mussels was beneficial for the trophic status of Maliakos Gulf and that there was a minimal environmental stress caused by the shellfish farming for the surrounding benthic environment.
    Aquaculture International 10/2013; DOI:10.1007/s10499-013-9712-z · 0.96 Impact Factor
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    The Mediterranean Science Commission, 40th CIESM Congress, Marseille, France, Rapp. Comm. Int. Mer. Médit. 40, p809; 10/2013
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    ABSTRACT: Twenty-one hcxacoral species belonging Lo the orders Actiniaria (3), Corallirnorpharia (1), and Scleractinia (17) were collected in the North Aegean Sea. Three of these (Amphianthus dohrnii, Cladopsammia rolandi, and Monomyces pygmaea ) are new records for the Eastern Mediterranean and two ( Lophelia pertusa and Madrepora oculata) are new records for the Aegean Sea. It was estimated that 56 species belonging to these three orders have been found in the Eastern Mediterranean and Black Sea and are presented here for the first time in a checklist. Zoogeographical consideration of the Eastern Mediterranean hexacoral fauna shows that the bulk of the species can be characterized as Atlanta-Mediterranean, fo llowed by the Mediterranean endemic and cosmopolitan species. In the Aegean, Atlanta-Mediterranean species dominate both in the order Acti niaria (78.5%) and in Scleractinia (70%). However, cosmopolitan species are more numerous among Scleractinia (25%) than among Actiniaria (3.6%); in the latter, endemic species appear with a greater percentage (14.3%). The number of species belonging to these three taxa known from the Mediterranean is estimated to be 88 species, 64 of which are characterized as Atlanto-Mediierranean, 15 as endemic, 8 as cosmopolitan and 1 as lndo-Mediterranean. The species numbers of all the above categories, except the last, seem to decrease generally from the Western to the Eastern Mediterranean and to the Black Sea, from which only a few species are known.
    Israel Journal of Zoology 07/2013; 43(1):55-70. DOI:10.1080/00212210.1997.10739780 · 0.61 Impact Factor
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    ABSTRACT: 350 «έγκυρα» ερωτηματολόγια. Για την εξαγωγή των παραγόντων που επηρέασαν τους ερωτώμενους, ώστε να αποδώσουν χρησιμότητα στην υδρόβια γενετική ποικιλότητα εφαρμόστηκε Ανάλυση Κυρίων Συνιστωσών (PCA), με τη βοήθεια μιας πολυθεματική ερώτησης με 20 θέματα. Οι ερωτώμενοι κλήθηκαν να απαντήσουν σε πεντάβαθμη κλίμακα Likert για κάθε θέμα. Η ανάλυση σε κύριες συνιστώσες έδωσε 5 παράγοντες, που εξηγούν το 62,615 % της συνολικής μεταβλητότητας. Ο έλεγχος σφαιρικότητας του Bartlett ήταν ίσος με 1376,441 (β.ε=190, ρ=0,000). Ο δείκτης των Kaiser – Mayer – Olkin έχει τιμή 0,821. Η συνολική αξιοπιστία της κλίμακας είναι 0,873. Τα αποτελέσματα της PCA δείχνουν ότι οι πολίτες αντιλαμβάνονται και ιεραρχούν υψηλά τη συμβολή της υδρόβιας γενετικής ποικιλότητας στην προσαρμοστικότητα των ειδών στις διάφορες μεταβολές (κλιματολογικές αλλαγές κ.λπ.). Στη συνέχεια, με τη βοήθεια των κριτηρίων Mann-Whitney και Krustal-Wallis, εξετάστηκε αν τα κοινωνικοοικονομικά χαρακτηριστικά και οι απόψεις των ερωτώμενων σχετικά με την υδρόβια γενετική ποικιλότητα, έχουν στατιστικά σημαντική διαφορά ως προς τους παράγοντες που προέκυψαν από την PCA. Σύμφωνα με τα αποτελέσματα, τα κοινωνικοοικονομικά χαρακτηριστικά των ατόμων (επίπεδο μόρφωσης, επαγγελματική δραστηριότητα κ.λπ.) επιδρούν στον τρόπο που αντιλαμβάνονται οι πολίτες τη χρησιμότητα της υδρόβιας γενετικής ποικιλότητας και αποδίδουν αξία σε αυτή. Χαρακτηριστικά, τα άτομα που διαθέτουν μεταπτυχιακές σπουδές αντιλαμβάνονται καλύτερα τη χρησιμότητα της υδρόβιας γενετικής ποικιλότητας, ως προς τον πρώτο παράγοντα της PCA (προσαρμοστικότητα ειδών). 112 Πρακτικά 35ου Επιστημονικού Συνεδρίου της Ελληνικής Εταιρείας Βιολογικών Επιστημών Ναύπλιο, 23-25 Μαΐου 2013 In the present study attempted to identify factors that influence people to identify utility (and economic value) of aquatic genetic resources beyond that is associated with real use and their value in real markets. For this reason a face-to-face survey of 350 respondents randomly selected residents of Volos city was carried out. Principal Components Analysis was used as a tool for measuring different public perceptions and preferences with regard to importance of aquatic genetic resources. Specifically, for this reason respondents were asked to indicate on a five-point Likert scale (Not at all, Not Much, Fairly, Much, Very Much) for each topic their opinion for the importance of 20 reasons -utility of aquatic genetic resources. Reliability analysis of the question revealed that Cronbach-a was 0.873. The Kaiser-Meyer-Olkin (KMO) criterion for sampling adequacy was equal to 0.821 and the Bartlett's test of sphericity was equal to 1376.44 (with a P-value of 0.000). 0.873 The results of PCA indicate that the populations' ability to resistance, tolerance of climatic change and population productivity and fitness is the most important service provided by aquatic genetic diversity.Mann-Whitney and Krustal-Wallis criteria were used to compare differences between socioeconomic characteristic of respondents (education level, occupation etc) and their opinion about utility of aquatic genetic resources. For examples, the results of Mann-Whitney test indicate that the highly educated people are more able to distinguish impacts of aquatic genetic resources to population ability of resistance, tolerance in climatic change and its productivity. 113
    35th Scientific Conference of Hellenic Association for Biological Sciences, Nafplio, May 23-25, 2013; 05/2013
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    35th Scientific Conference of the Hellenic Society of Biological Sciences, Nauplium, Hellas, Poster; 05/2013
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    ABSTRACT: The population structure of marine fishes is often cryptic, due to limited knowledge about life history and ecological habitats. Understanding environmental stability is a challenge to retrieve possible structuring patterns responsible for dispersal and demographic habits. In the present study, a combination of genetic and phenotypic assessments was applied in order to investigate population structure of the saddled seabream, Oblada melanura in the Aegean Sea, eastern Mediterranean basin. Analyses of 6 microsatellite loci and 15 morphometric characters revealed that saddled seabream individuals differ among northern, southern and central Aegean populations. These observed boundaries may be related to the differentiated seascape of the Aegean Sea, suggesting that oceanographic factors are a significant stressor for population subdivision of the saddled seabream. Individual-based landscape genetic approaches and multivariate analysis of the morphometric characters suggest the presence of habitat-related limitations of saddled seabream dispersal potential. Molecular genetics and phenotypic analyses along with life history traits provide useful informative data for the management and conservation schemes applied for this species in the Aegean Sea. KEYWORDS: Oblada melanura • Microsatellite • Morphometrics • Aegean Sea • Population structure
    Aquatic Biology 03/2013; 18:69-80. DOI:10.3354/ab00490 · 1.12 Impact Factor
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    Kotsiri Z. · Hatziioannou M. · Vafidis D.
    35th Scientific Conference of Hellenic Association for Biological Sciences, Nafplio, May 23-25; 01/2013
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    ABSTRACT: Five colonies of the rare pennatulacean Crassophyllum thessalonicae were recently collected from Thermaikos Gulf (north-east Mediterranean), which allowed a study of their biometry; accordingly, new features are added to the original description of the species. Based on these data the morphological characters that distinguish C. thessalonicae from its congeners are reviewed.
    Marine Biodiversity Records 12/2011; 4. DOI:10.1017/S1755267210001181
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    4th International Symposium “Hydrobiology – Fisheries”., Volos, Greece; 06/2011
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    4rd International symposium on hydrobiology and fisheries, Volos Greece; 06/2011
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    4rd International symposium on hydrobiology and fisheries, Volos, Greece; 06/2011
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    4rd International symposium on hydrobiology and fisheries, Volos, Greece; 06/2011

Publication Stats

395 Citations
36.46 Total Impact Points

Institutions

  • 2007–2015
    • University of Thessaly
      • Department of Icthyology and Aquatic Environment
      Iolcus, Thessaly, Greece
  • 2013
    • Fisheries Research Institute
      Neapolis, East Macedonia and Thrace, Greece
  • 2004–2008
    • Aristotle University of Thessaloniki
      • Department of Zoology
      Thessaloníki, Kentriki Makedonia, Greece
    • Fisheries Research Institute, Kavala
      Neapolis, East Macedonia and Thrace, Greece
  • 2005
    • National Centre for Social Research, Greece
      Athínai, Attica, Greece
  • 2000
    • N.AG.RE.F. - NATIONAL AGRICULTURAL RESEARCH FOUNDATION
      • Fisheries Research Institute
      Megalokastro, Crete, Greece