Your browser does not support JavaScript!

Home    Collections    Type of Work    Post-graduate theses  

Post-graduate theses

Current Record: 4622 of 4837

Back to Results Previous page
Next page
Add to Basket
[Add to Basket]
Identifier 000364421
Title Κατανομή μακροβενθικών βιοκοινοτήτων κατά μήκος περιβαλλοντικών διαβαθμίσεων στην βαθιά ανατολική Μεσόγειο
Alternative Title Distribution of macrobenthic communities along environmental gradients in the deep eastern Mediterranean Sea
Author Παξιμαδά, Νίκη
Thesis advisor Καρακάσης, Ιωάννης
Παυλίδης, Μιχάλης
Abstract For the description of the deep water benthic ecosystem of Crete, macrofauna samples were collected along a bathymetric gradient in the oligotrophic system of Eastern Mediterranean. Samples were collected from 17 stations, which were located along 5 transects at depths from 215 m to 3600 m. The samplings took place during May 2006, south of Crete, using the HCMR research vessel “Aegaeo”, within the activities of the project HERMES (Hotspot Ecosystem Research on the Margins of European Seas). A box-corer sampler USNEL was used for the collection of samples. The aim of this study was the quantitative and qualitative assessment of the macrofauna composition at the submarine part of the Samaria Canyon, as well as at the nearby slopes, the comparison of the stations between the transects and the correlation of the species present in the sampling areas with the existing environmental parameters. The multidimensional scaling (MDS) was used for the analysis of the fauna data, the ANOSIM method was used for the similarity analysis, and the software SIMPER Analysis was used for the identification of the characteristic species. The assessment of diversity was based on the already established methods (diversity indices Shannon-Wiener, Margalef and Pielou), while for the examination of the relationship between the macrofauna data and the environmental parameters the method BIO-ENV was used. The fauna analysis was performed at a species level and indicated 100 species within a total of 2056 individuals. Although Sipuncula were the dominant taxonomic group, Polychaetes had the highest species abundance. The dominance of Sipuncula contradicts with most studies, where Polychaetes appear as the most abundant group. However, other studies have also indicated that one of the characteristics of the Cretan shelf is the relatively high abundance of Sipuncula, which can be attributed to their competitive advantage in oligotrophic conditions. Molluscs appeared down to a depth of 1086 m, while the Echinoderm group was absent from the collected samples. At a species level, most abundant was the Sipunculid Apionsoma murinae bilobatae, followed by the Polychaete Pholoides dorsipapillatus and the bivalve Kelliella abyssicola. The abundance and biomass were reduced in relation to depth, especially at depths greater than 1000 m. This is a result of the low primary productivity, and thus the reduced food availability, especially at greater depths. Abundance was higher at the most shallow sampling station, south of Agia Galini harbor. The most important factors that seem to define the macrobenthos structure were depth, organic carbon and the type of sediment, whereas stations at depths between 215 and 2500 m had similar biocommunities. At depths greater than 2500 m, the biocommunities not only presented differences in comparison to the ones of the more shallow stations, but also between them. This fact signifies the isolation conditions observed in deep basins, and therefore, the degree of specialisation regarding the organisms inhabiting them.
Language Greek
Subject Canyon
Issue date 2011-07-15
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link Bookmark and Share
Views 75

Digital Documents
No preview available

View document
Views : 23