Diversity and community structure of the snail fauna (Mollusca,_Gastropoda) in the source area of the Cetina River

Abstract

Glavni cilj ovog rada bio je odrediti sastav i strukturu zajednice slatkovodnih puževa izvorišnog područja rijeke Cetine. Odabrane su dvije postaje: Preočki most i Crveni most. Prva istraživana postaja nalazi se 1,5 km, a druga 2,5 km nizvodno od izvora Glavaš. Sakupljanje uzoraka makrozoobentosa obavljano je svaki drugi mjesec od listopada 2004. do kolovoza 2005. godine. Na svakoj postaji odabrane su tri različite podloge (mikrostaništa): valutice, makrovegetacija i sitni sediment. Nakon izdvajanja iz bentosa puževi su u laboratoriju determinirani do razine vrste. Iz dobivenih podataka o brojnosti jedinki za svaku vrstu utvrđena je abundancija, a na osnovu morfometrijskih mjerenja kućice prikazana je uzrasna struktura. Tijekom istraživanja ukupno su pronađene 3 vrsta puževa. Dominantna vrsta na obje postaje je Radomaniola curta germari, druga vrsta po zastupljenosti je Horatia klecakiana. Vrsta Ancylus fluviatilis pojavljuje se u malom broju primjeraka na postaji Preočki most, dok na postaji Crveni most nije zabilježena. Provedena analiza funkcionalnih hranidbenih grupa pokazala je da na istraživanim postajama podjednak udio strugača i detritivora. Najviše vrijednosti Shannonovog i Simpsonovog indeksa raznolikosti zabilježene su na makrovegetaciji postaje Preočki most, dok su najniže vrijednosti ovog indeksa utvrđene na sitnom sedimentu iste postaje. Klaster analiza sličnosti, koja je provedena prema tipu mikrostaništa, pokazala je najveću sličnost između mikrostaništa sa valuticama obaju postaja, dok je najmanja sličnost utvrđena između mikrostaništa karakteriziranih sitnim sedimentom. Dobiveni podaci značajan su doprinos boljem poznavanju faune slatkovodnih puževa rijeke Cetine.The main objective of this study was to determine the composition and structure of recommunities of freshwater snails in the source area of the Cetina River. Two locations were chosen: Preočki most and Crveni most. The first research location is located 1,5 km and the second one 2,5 km downstream from the source Glavas. Collection of macroinvertebrates samples took place every other month from October 2004 to August 2005. At each location three various substrates (microhabitats) were selected: pebbles, macrovegetation and sediment. Snails were separated from the benthos in the laboratory and were determined to the species level. Abundance of each species was determined based on the number of individuals, and age structure was based on morphometric measurements of their shells. During this study, a total of three snail species was found. The dominant species at both locations is Radomaniola curta germari. Horatia klecakiana is the second dominant species. Species Ancylus fluviatilis occurs in a small number of samples at the location Preočki most while at the location Crveni most was not recorded. The analysis of functional feeding guilds at researched sites showed equal share of the grazers and detritivora. Highest values of the Shannon and Simpson diversity indices were recorded at macrovegetation of Preočki most, while the lowest values of the indices were determined on the sediment of the same stations. Cluster analysis of similarity, which was carried out according to the type of habitat, showed the greatest similarity between microhabitats with pebbles of both stations, while the lowest similarity was found between microhabitats characterized by sediment. The obtained data are significant contribution to better understanding of the freshwater snail’s fauna of the Cetina River