Porto Pozzo is a NE-SW oriented “ria”, which is 4 km long and 350 m wide. It is located of river west of Liscia river mouth (NE Sardinia), between P.ta Falcone, westwards, and the peninsula of Culuccia, eastward. The southern coastal part of the bay is characterized by wide wetland settings (ponds and lagoons) communicating with the sea. Moreover, they present a particular environmental value in relation with their noterworthy floral and faunal biodiversity. Two oceanographic cruises (PALEOCLIGE 2000 and PALEOCLIGE 2001) have been realized in Porto Pozzo bay, in order to perform an interdisciplinary study concerning the geomorphological, sedimentological and palaeontological aspects of the seafloors. Through the Side Scan Sonar, Edgetech DF-1000, a geomorphological map of Porto Pozzo bay (1:10000) has been obtained, highlighting the following geomorphological units: intramatte channel, intramatte depression, muddy sand bottom, Posidonia oceanica meadow and submerged beach. The seafloors of Porto Pozzo show a shallow depth, rarely exceeding 10m . From the sedimentological point of view, sandy seafloors corresponding to delta-fronts mostly occur along the coastal platform between 0 and 5m. The deeper seafloors show sandy pelites and, then, very sands pelites. These seafloors are also characterized by Posidonia oceanica meadow. In particular, this study focuses on the distribution of selected environmental markers (ostracods) to evidence the different environmental conditions of these seafloors. In Porto Pozzo bay 49 ostracod species belonging to 24 genera have been identified. 13 of them have been maintained in open nomenclature. The ostracods species found can be included in three groups corrisponding to part of the above mentioned geomorphological units. A group characterizes intermediate conditions between the two units. The three groups are descibed below: -Group 1 (Intramatte Channel) - The.species are: Aurila convexa, Loxoconcha rhomboidea, Loxoconcha sp.1, Procythereideis senescens, Semicytherura rarecostata, Urocythereis sp.1; -Group 2 (Intramatte Channel-Submergeed beach) - The.species are: Callistocythere cf. C.badia, Loxoconcha affinis, Tenedocythere prava, Xestoleberis communis, Xestoleberis dispar; -Group 3 (Submergeed beach) - The.species are: Aurila fallax, “Barbeitina” sp., Carinocythereis whithei, Hemicytherura videns, Loxoconcha ovulata, Phlyctocythere pellucida, Semicytherura acuticostata, Urocythereis gr. favosa. Through Shannon-Weaver (SW) biotic index, which considers the specific richness and the equitability, it is also possible to highlight the environmental conditions of the sampling stations. The SW index varies from 1,39 to 2,22. It is assumed that low values correspond to bad conditions; vice versa, high values indicate good conditions. In the investigated area, two categories have been identified: -CATEGORY 1 where 1 ≤ S.W. < 2; -CATEGORY 2 where S.W>2; The best conditions occur in sampling stations characterized by Intramatte Channel; the worst conditions occur in sampling stations by Submerged Beach. Intermediate conditions occur in sampling stations characterized by geomorfological units Intramatte Channel and Submerged Beach. It is possible to recognize species which are present in only one category and others occurring in both categories. The species exclusive of only one category are: Aurila fallax, Urocythereis gr. favosa, “Barbeitina” sp., Carinocythereis whithei, Hemicytherura videns, Loxoconcha ovulata, Phlyctocythere pellucida, Semicytherura acuticostata (CATEGORY 1), Loxoconcha rhomboidea, Aurila convexa, Urocythereis sp.1, Loxoconcha sp.1, Procythereideis senescens, Semicytherura rarecostata (CATEGORY 2). The species occurring in both categories are: Loxoconcha affinis, Callistocythere cf. C.badia, Tenedocythere prava, Xestoleberis communis, Xestoleberis dispar. Thus, taking into account these categories it is also possible to evidence bad-to-good environmental conditions, which are more or less favourable for the benthic life. Species exclusive of category 1 indicate bad environmental conditions. Ostracods exclusive of category 2 may testify favourable conditions for the benthic life. Species present in both categories may indicate a wider tolerance to the environmental changes than the previously mentioned species. These data can evidence that ostracods are good tools for the environmental monitoring. Printed with INTERREG II and III funds, projects: INTERREG II “Protezione, valorizzazione e gestione dell’ambiente Sardo-Corso”, Tema 2B 3°; INTERREG III “Ambiente fisico, valorizzazione della fascia costiera Sardo-Corsa e gestione delle risorse”. Printed with Comune di Santa Teresa di Gallura funds.
ACTUOPALAEONTOLGICAL ASPECTS AND CARTOGRAPHYOF SEAFLOORS OF PORTO POZZO BAY – NE SARDINIA
DEMURO, SANDRO;
2003-01-01
Abstract
Porto Pozzo is a NE-SW oriented “ria”, which is 4 km long and 350 m wide. It is located of river west of Liscia river mouth (NE Sardinia), between P.ta Falcone, westwards, and the peninsula of Culuccia, eastward. The southern coastal part of the bay is characterized by wide wetland settings (ponds and lagoons) communicating with the sea. Moreover, they present a particular environmental value in relation with their noterworthy floral and faunal biodiversity. Two oceanographic cruises (PALEOCLIGE 2000 and PALEOCLIGE 2001) have been realized in Porto Pozzo bay, in order to perform an interdisciplinary study concerning the geomorphological, sedimentological and palaeontological aspects of the seafloors. Through the Side Scan Sonar, Edgetech DF-1000, a geomorphological map of Porto Pozzo bay (1:10000) has been obtained, highlighting the following geomorphological units: intramatte channel, intramatte depression, muddy sand bottom, Posidonia oceanica meadow and submerged beach. The seafloors of Porto Pozzo show a shallow depth, rarely exceeding 10m . From the sedimentological point of view, sandy seafloors corresponding to delta-fronts mostly occur along the coastal platform between 0 and 5m. The deeper seafloors show sandy pelites and, then, very sands pelites. These seafloors are also characterized by Posidonia oceanica meadow. In particular, this study focuses on the distribution of selected environmental markers (ostracods) to evidence the different environmental conditions of these seafloors. In Porto Pozzo bay 49 ostracod species belonging to 24 genera have been identified. 13 of them have been maintained in open nomenclature. The ostracods species found can be included in three groups corrisponding to part of the above mentioned geomorphological units. A group characterizes intermediate conditions between the two units. The three groups are descibed below: -Group 1 (Intramatte Channel) - The.species are: Aurila convexa, Loxoconcha rhomboidea, Loxoconcha sp.1, Procythereideis senescens, Semicytherura rarecostata, Urocythereis sp.1; -Group 2 (Intramatte Channel-Submergeed beach) - The.species are: Callistocythere cf. C.badia, Loxoconcha affinis, Tenedocythere prava, Xestoleberis communis, Xestoleberis dispar; -Group 3 (Submergeed beach) - The.species are: Aurila fallax, “Barbeitina” sp., Carinocythereis whithei, Hemicytherura videns, Loxoconcha ovulata, Phlyctocythere pellucida, Semicytherura acuticostata, Urocythereis gr. favosa. Through Shannon-Weaver (SW) biotic index, which considers the specific richness and the equitability, it is also possible to highlight the environmental conditions of the sampling stations. The SW index varies from 1,39 to 2,22. It is assumed that low values correspond to bad conditions; vice versa, high values indicate good conditions. In the investigated area, two categories have been identified: -CATEGORY 1 where 1 ≤ S.W. < 2; -CATEGORY 2 where S.W>2; The best conditions occur in sampling stations characterized by Intramatte Channel; the worst conditions occur in sampling stations by Submerged Beach. Intermediate conditions occur in sampling stations characterized by geomorfological units Intramatte Channel and Submerged Beach. It is possible to recognize species which are present in only one category and others occurring in both categories. The species exclusive of only one category are: Aurila fallax, Urocythereis gr. favosa, “Barbeitina” sp., Carinocythereis whithei, Hemicytherura videns, Loxoconcha ovulata, Phlyctocythere pellucida, Semicytherura acuticostata (CATEGORY 1), Loxoconcha rhomboidea, Aurila convexa, Urocythereis sp.1, Loxoconcha sp.1, Procythereideis senescens, Semicytherura rarecostata (CATEGORY 2). The species occurring in both categories are: Loxoconcha affinis, Callistocythere cf. C.badia, Tenedocythere prava, Xestoleberis communis, Xestoleberis dispar. Thus, taking into account these categories it is also possible to evidence bad-to-good environmental conditions, which are more or less favourable for the benthic life. Species exclusive of category 1 indicate bad environmental conditions. Ostracods exclusive of category 2 may testify favourable conditions for the benthic life. Species present in both categories may indicate a wider tolerance to the environmental changes than the previously mentioned species. These data can evidence that ostracods are good tools for the environmental monitoring. Printed with INTERREG II and III funds, projects: INTERREG II “Protezione, valorizzazione e gestione dell’ambiente Sardo-Corso”, Tema 2B 3°; INTERREG III “Ambiente fisico, valorizzazione della fascia costiera Sardo-Corsa e gestione delle risorse”. Printed with Comune di Santa Teresa di Gallura funds.
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