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NaslovThe influence of depth on the Mediterranean reef fish assemblage revealed by the new video on underwater scooter method / Igor Glavičić, Marcelo Kovačić, Dejan Paliska, Dani Laslo.
Materijalni opisIlustr., graf. prikazi.
Način izrade datotekeizvorno digitalna građa
Vrstačlanak
OpisThe new video on underwater scooter method in combination with rebreather diving techniques was introduced and applied for visual census of fish assemblages. The presently applied method facilitates deeper visual census studies below 40 m, where they have rarely been done before due to the increasing research challenges with depth. The video on underwater scooter method is also expected to be less disturbing and faster compared to swimming divers. The method was applied in visual census study of fish assemblages from 8 to 50 m depth conducted at two locations in the east Adriatic using 102 video transects. The environmental variables contributing to the variation of the reef fish community in the depth range of the infralittoral and upper circalittoral bottoms were also recorded. Thirty-one fish species were recorded on transects and 10.3% of all individuals were not identified to the species level. The average density on transects was 0.8 individuals/m², with C. chromis, C. julis and G. auratus being both the most abundant and the most frequent species. Three environmental variables, depth, bottom with zoocover and eastern orientation of the coast, were identified as highly significant for species occurrence. Abundance and species richness of fish assemblages showed no significant variation with depths, inclinations, orientations and sites. A significant difference in the fish assemblage structure was found among orientations, depths and inclinations with the gradient change of species composition with increasing depth and with increasing inclination.Nova metoda videa sa podvodnog skutera uz rebreather ronilačku tehniku uvedena je i primjenjena za vizualni census zajednica riba. Ova metoda omogućuje istraživanja vizualnim cenzusom na dubinama većim od 40 m, na kojima se, zbog teškoća u ronjenju na većim dubinama, vizualni cenzus rijetko izvodi. Metoda videa sa podvodnog skutera uz rebreather ronilačku tehniku također bi trebala biti manje uznemirujuća i brža u odnosu na plivajuće ronioce. Metoda je primjenjena u istraživanju vizualnim cenzusom na dubinama 8 do 50 m na dvije postaje na istočnom Jadranu sa 102 video transekta. Zabilježene su također varijable okoliša koje utječu na varijaciju u sastavu zajednice riba stjenovitog dna infralitorala i cirkalitorala.Trideset i jedna vrsta riba je zabilježena, uz 10,3% primjerka koji nisu određeni do razine vrste. Prosječna gustoća riba po transektu bila je 0,8 primjeraka/m², a najčešće i najbrojnije vrste bile su C. chromis, C. julis i G. auratus. Tri varijable okoliša: dubina, dno sa životinjskim obraštajem i istočna orjentacija dna, bile su izrazito značajne za prisutnost vrsta. Brojnost primjeraka i bogatstvo vrsta nisu pokazale značajnu promjenjivost sa promjenama dubine, nagiba, orjentacije i postaja. Utvrđena je značajna promjena u sastavu zajednice riba sa promjenom orjentacije obale, dubine i nagiba dna na transektima. Sastav vrsta postepeno se mijenjao sa porastom dubine dna i s povećanjem nagiba dna.
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