Your browser does not support JavaScript!

Post-graduate theses

Search command : Author="Κοτζάμπασης"  And Author="Κυριάκος"

Current Record: 3 of 679

Back to Results Previous page
Next page
Add to Basket
[Add to Basket]
Identifier 000438786
Title Συγκριτική μελέτη βένθους σκληρού υποστρώματος σε θαλάσσια σπήλαια της προστατευόμενης περιοχής Βόρειας Καρπάθου-Σαρίας
Alternative Title Comparative study of hard substrate benthos in marine caves of the protected area of Northern Karpathos-Saria
Author Διγενής, Μάρκος Κ.
Thesis advisor Γεροβασιλείου, Βασίλης
Αρβανιτίδης, Χρήστος
Reviewer Λαμπαδαρίου, Νίκος
Καρακάσης, Ιωάννης
Abstract Sea caves constitute underwater cavities of various forms mostly filled with sea water. From the first studies on marine caves in the early 1950’s, scientists recorded a rich biodiversity in their interior unveiling new information about this unique marine ecosystem. Marine caves were soon considered as a habitat of European interest (type 8330 in the EU Habitats Directive) according to European and regional legislation. In the Mediterranean Sea they have been characterized as biodiversity reservoirs because they host various endemic, rare and protected species, as well as bathyal species, living fossils and unique bioconstructions.To date, more than 3,000 marine caves have been recorded along the Mediterranean coasts, more than 600 of which are found along the Greek coasts of the Aegean Sea. However, only few caves have been systematically studied for their biodiversity. Through the present MSc thesis we aim to study both qualitatively and quantitatively the macrobenthic biodiversity of seven marine caves of the Protected Area of North Karpathos and Saria Islands (South-Eastern Aegean, Greece) through photographic frames analysis and visual census. It constitutes the first study in this area and one of the few for this marine habitat in the Eastern Mediterranean basin. The study was carried out at the Institute of Marine Biology Biotechnology and Aquaculture (IMBBC) of the Hellenic Center for Marine Research (HCMR) in Crete in the framework of the Master Studies Program “Environmental Biology” of the Biology Department, University of Crete. The studied stations included seven marine caves, five located on the coasts of Saria Island and two on Karpathos Island. Among the caves of Saria Island, four constituted semi-submerged caves (Oxonisos, Giourious, Panteleimonas and Palatia) while the fifth (Alimounda) and the two caves from Karpathos Island (Fokospilia and Troulakas) were fully submerged. The studied sea caves were divided into three ecological zones: the entrance zone, where plenty of light intrudes, the intermediate semi-dark zone, where light is steeply reduced and the inner completely dark zone. A total of 140 photographic frames were collected along the different zones of the seven caves, ten from the entrance and semidark zone of every studied cave and five from the inner dark zone of two caves. Sessile organisms were identified to the lowest possible taxonomical level and their surface coverage was calculated using the special software Photoquad for seabed image analysis. Motile taxa were recorded with visual census and photography during the dives. In total, 78 sessile taxa were identified, 47 of which to the species level, 18 to genus and 3 to family level as well as 10 categorized to higher functional and morphological groups. Sessile taxa were represented by 33 Porifera, 17 Bryozoa, 12 Macroalgae, 5 Cnidaria, 3 Ascidiacea, 3 Brachiopoda, 2 Mollusca, 1 Foraminifera, 1 Polychaeta and 1 Cirripedia. In addition, 43 motile taxa were identified to species (39), genus (2) and family (2) level represented by 23 Pisces, 9 Crustacea, 6 Echinodermata, 2 Polychaeta, 2 Mollusca and 1 Mammalia. Eleven protected species are included in the abovementioned taxa, among which is the Mediterranean seal Monachus monachus, the dusky grouper Epinephelus marginatus, the spiny lobster Palinurus elephas and the Mediterranean slipper lobster Scylarides latus. The deep-water species Anthias anthias and Neopycnodonte cochlear, the commercial shrimp Plesionika narval and several rare species alongside with species considered as characteristic for the marine cave environment were also reported in the studied caves. According to the results, different number of taxa was recorded at each of the ecological cave zones. At the entrance zone 72 taxa were recorded while 56 and 18 taxa were reported from the semidark and the dark zone respectively. Sponges presented the highest number of taxa at all ecological zones of the caves with Dedroxea lenis and Spirastrella cunctatrix presenting the highest surface coverage. Bryozoan taxa were reduced at the inner cave parts with Encrusting Bryozoa, Bryozoan turf and Ceberea boryi often being dominant. In contrast, different taxa dominated in terms of surface coverage at different ecological zones of the studied caves. Rhodophyta had the most extensive coverage at the cave entrance varying from 25% to more than 45% of total entrance zone coverage. This is due to the sufficient for their survival intensity of light that penetrates the cave entrance. Their coverage was comparatively reduced at the less lightened inner zones where only Encrusting Rhodophyta, Mesophyllum sp., Peyssonnelia sp. and Palmophyllum crissum being present. Rhodophyta coverage was also reduced as the depth increased among the caves. For example, fully submerged caves such as Fokospilia and Troulakas seemed to present less coverage of photosynthetic taxa at their less lightened entrances. The arch of Alimounda, although submerged, receives higher quantity of light due to the large dimensions of its entrances. As rhodophytes reduce their coverage at the inner semidark cave parts, space competitive sciaphilic sponges became dominant with coverage exceeding 50%. Bare substrate, polychaetes and brachiopods dominated at the cave darkest parts due to the reduced water renewal and the more oligotrophic conditions. These conditions enable more sufficient filter feeders as well as small-sized and encrusting sponges (like Spirastrella cuncatrix) to replace larger and erect sponges. Multivariate community analysis demonstrated that geomorphological and topographical factors of the studied caves are significantly associated with the observed biotic patterns. These factors were: Ecological zone, Cave, Entrance surface area, Entrance depth, Orientation and submersion level (submerged or semi-submerged). Different factors appeared to be statistically correlated with the resemblance patterns. According to one-way ANOSIM analysis pairwise tests, all caves were statistically significantly differentiated when quadrats from all cave zones were pooled together, but also when quadrats from the entrance and the semidark zone were examined separately. Regarding the factor of ecological zone, pairwise tests showed no significant differentiation between the semidark and the dark zone, possibly due to the limited number of quadrats from the darkest cave parts. Heterogeneity between the entrance and the inner sciaphilic ecological zones was in agreement with previous studies on comparative qualitative analysis of macrobenthic biocommunities of Mediterranean marine caves. Furthermore, community structure of the entrance zone was not differentiated between caves deeper than 11 meters and entrance surface area bigger than 110m2. Semi-submerged caves different significantly from fully submerged caves, probably due to the different light levels and hydrodynamic regime. Several pressures and threats were recorded in all studied caves as well, including accumulation of plastic litter and occasional necrosis of sessile taxa. Non-indigenous species were reported in all the studied caves constituting of species that had previously been recorded at different ecosystems of the same area. Such species were: the gastropod Cerithium scabridum, the long-spined sea urchin Diadema setosum and seven alien fishes (Parupeneus forsskali, Pempheris rhomboidea, Pterois miles, Sargocentron rubrum, Siganus luridus, Siganus rivulatus and Torquigener flavimaculosus). The abovementioned pressures could indicate signs of possible ecological degradation. Moreover, in order to further understand the community structure of the studied caves, additional samplings are needed to identify the species grouped at bigger functional and morphological groups. Emphasis should also be given to less known groups as well as sponges of the family Plakinidae, encrusting bryozoans and polychaetes. Future studies on the same marine caves should also focus on soft substrate macrofauna, as well as cryptobenthic species of fish and crustaceans. Building upon the findings of this work, several management and conservation actions were proposed to the Management Agency of the Protected Area, aiming at highlighting and protecting marine caves and their biota. Among the proposed actions are: a monitoring plan for the assessment of both biotic (qualitative and quantitative biodiversity assessment) and abiotic (e.g. water temperature and pH) factors every two years in order to detect potential effects of climate change. Assessment of macro- and microplastics quantity and alien species could provide valuable information about their longterm effects on both marine caves and their surrounding ecosystems. Actions for raising public awareness and training seminars for divers and local citizens as well as creation of a protected zone focusing for selected caves could ensure the future protection of this unique marine ecosystem.
Language Greek
Subject Benthic biocommunities
Βενθικές βιοκοινότητες
Issue date 2021-03-26
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/7/6/2/metadata-dlib-1617271440-502594-17612.tkl Bookmark and Share
Views 3

Digital Documents
No preview available

Download document
View document
Views : 1