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2. Length relationships of cyprinig prey in diet analysis of Eurasian otter Lutra lutra in Mediterranean habitats
- Creator:
- Miranda, Rafael, Díez-León, Maria, and Escala, Maria Carmen
- Type:
- article and TEXT
- Subject:
- dietary preferences, Ebro River basin, Barbus graellsii, Chondrostoma miegii, and Leuciscus cephalus
- Language:
- English
- Description:
- Relationships between bone size and body length are reported for common Iberian barbel Barbus graellsii, Iberian nase Chondrostoma miegii and chub Leuciscus cephalus from the Ebro River basin. Linear regression was used to analyse possible relationships between bone and fish length and multiplicative regression to investigate relationships between bone size and body weight. All generated regressions were highly significant and displayed high coefficients of determination (> 0.89). No differences were found between the generated regressions and other relationships reported for similar species. Therefore, we suggest that our regressions might be used for other Mediterranean species belonging to these genera.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/
3. Morphometrical comparison of cleithra, opercular and pharyngeal bones of autochthonous Leuciscinae (Cyprinidae) of Spain
- Creator:
- Miranda, Rafael and Escala, Maria Carmen
- Type:
- article and TEXT
- Subject:
- cleithra, opercular bone, pharyngeal bone, Principal Component Analysis, Leuciscinae, and Spain
- Language:
- English
- Description:
- There are fifteen autochthonous species within the subfamily Leuciscinae (Cyprinidae) in Spain, all of them endemic except for two. The diversity, peculiarity and complex taxonomic position of most of these species make them an interesting group to study. In the present work, 456 specimens of 11 species were studied. Cleithra, opercular and pharyngeal bones were extracted from each specimen. These bones were compared and measured morphologically to obtain biometric indices. The biometric differences for each bone and for the three bones together were analysed using these indices by means of Principal Component Analyses. The results show a direct relationship between morphological and biometrical differences and similarities. Besides, this osteological comparison partially agrees with the present taxonomic position of these species, contributing to the difficult systematics and phylogeny of this group.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/
4. Summer feeding relationships of the co-occuring Phoxinus phoxinus and Gobio lozanoi (Cyprinidae) in an Iberian river
- Creator:
- Oscoz, Javier, Leunda, Pedro M., Miranda, Rafael, and Escala, Maria C.
- Type:
- article and TEXT
- Subject:
- Gobio lozanoi, Phonixus phonixus, diet composition, diet overlap, feeding strategy, ontogenetic diet shift, and river Larraun
- Language:
- English
- Description:
- The alimentary tract content composition of 106 European minnow (Phoxinus phoxinus, 25-75 mm TL) and 49 gudgeon (Gobio lozanoi, 31-123 mm TL) captured in August 1996 in the river Larraun (Northern Spain) was investigated in order to analyse their diet composition and interspecific diet overlap. Both species fed mainly on Chironomidae larvae, Trichoptera larvae and terrestrial invertebrates, although trophic diversity was significantly higher for European minnows. The diet composition and the feeding strategy plots revealed a similar ontogenetic shift of the relative contribution or these prey items to a more pronounced generalist feeding strategy as fish of both species grew larger. Additionally, comparisons between diet composition and the benthic macroinvertebrate community revealed that P. phoxinus and G. lozanoi refused Caenidae, showing a preference for Chironomidae and Psychomyidae. The simplified Morisita index proved that the diet overlap between the two species was indeed very high and significant. We discuss how morphological constraints - i.e. mouth size - , prey handling costs and habitat partioning could be responsible for the observed inter- and intra-specific (size-related) changes in diet preferences. However, we suggest that the combination of differential microhabitat use, diel feeding rhythms and diet plasticity could minimize the interspecific competition, allowing co-occurrence of these Cyprinidae species in relatively high densities in this reach of the river Larraun.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/