Hábitos alimentarios y selectividad de habitat de la guitarra chica, Zapteryx brevirostris (Chondrichthyes, Rhinobatidae), en el ecosistema costero bonaerense y uruguayo
The diet composition and feeding habits of Zapteryx brevirostris were studied through stomach contents analysis. 158 specimens were collected from 7 research cruises carried out by Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP, Argentina)between 2001 to 2004, in the Buenos Aires Province (Argentina) and Uruguay coasts (34°-41° S), until 50 m depth. Of the total stomach analysis, 81percentage contained food. According to the alimentary index expressed as a percentage (IA percentage ), indicated that polychaetes, decapods and lancelets were more consumed prey, representing 44.37percentage , 19.94 percentage and 17.36 percentage of the diet, respectively. The amphipods (8.74 percentage ), cumaceans (4.11percentage ) and isopods (3.29 percentage)were little represented, while teleost fishes, tanaidaceas, bivalves and ascidaceas were very little preyed. The consumption of polychaetes and lancelets may be due that Z. brevirostris has capacity to dig into the substratum, and captured inafaunal prey. The diet significantly varied with Z. brevirostris size. The individuals =500 mm of total length (TL)consuming more cumaceans than major individuals, due possibly to morphological limitations (less size of the mouth). The individuals =600 mm TL preyed more heavily on lancelets than small individuals, caused possibly by habitat use different. However, highest dietary overlap among size classes were found, that may be caused by high consumption of polychaetes and decapods. The feeding strategy was characterized by medium specialization on polychaetes, with variation in the importance and specialization of the others prey depending size classes. The trophic breadth was low, indicating little variability in the diet. Habitat selectivity of Z. brevirostris was assessed, in the northem region (34°-38°S). Z. brevirostris selected sandy bottoms in a high proportion to the other bottom types. This pattern explained partly the high consumption of lancelets, since this prey live in sandy bottoms
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| Format: | Theses and Dissertations biblioteca |
| Language: | Spanish / Castilian |
| Published: |
2006
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| Subjects: | Feeding behaviour, Food consumption, Habitat selection, Stomach content, |
| Online Access: | http://hdl.handle.net/1834/3133 |
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