Abstract. Species' depth distributions and abundances were visually assessed along 24 transects in a northern Adriatic assemblage of blennioid fishes (14 species of Blenniidae, 1 species of Triptery‐giidue). Total abundance of blennioids was highest in 0.5‐1 m depth, decreasing upwards and downwards. Species diversity (Shannon‐Wiener) is highest at the shallowest depth (0‐0.5 in). The curybathic species Parablennius incognitus, Lipophrys dalmatinus, Tripterygion tripteronotus, and Parablennius tentacularis were most abundant at all depths (relative to the species investigated). All stenobathic species were most abundant at 0‐0.5 m. Depth distribution patterns and abundance ranks of species were similar at western, eastern, southern, and northern transects.
In terms of species number (47) and numerical abundance, blennioids are the most important primary resident rocky reef fishes in the Gulf of California, Mexico. We present the feeding patterns of the 34 most abundant species of blennioid fishes, 8 of which are Gulf endemics. A total of 2,144 specimens were sampled at 51 anaesthetic stations in 9 areas throughout the Gulf. Four feeding guilds were distinguished: 1) The majority (29 of 34 species) are microcarnivores exhibiting a number of different feeding strategies (ambush and stalking predators, active foragers, pickers, etc.). The more important prey categories were mobile invertebrates, and to some extent also sedentary fauna. Algae were of no importance for most of the latter species. 2) Hypsoblennius brevipinnis and H. gentilis are two omnivorous species, browsing mainly on sessile items including 52% and 13% (Vol.) algae in their diets. 3) Entomacrodus chiostictus and Ophioblennius steindachneri are herbivores, grazing on fine algae. 4) Plagiotremus azaleus specializes in cropping mucus and scales from the body surface of other fishes.Crustaceans account for 58.6% of the total volume of prey items in the 34 species investigated. Benthic amphipods were most important and made up 26% of the total volume of all prey items.Cluster analysis of percentage volumetric data using Squared Euclidian Distance and Horn's Index of Overlap produced distinct subgroups which coarsely reflected taxonomic grouping.The species are separated either by their geographic ranges, habitat and microhabitat preferences, feeding, or a combination thereof. Only rarely do sympatric species significantly overlap in diet.Trophic diversity as measured by the Shannon-index provides a tool for distinguishing: 1) specialists (6 species) from 2) low diversity feeders (18 species) and 3) high diversity generalists (10 species). Two different types of specialists can be distinguished: those which feed on the same items as the generalists but utilize only a very restricted prey spectrum (Stathmonotus sinuscalifornici and the chaenopsids Chaenopsis alepidota and Emblemaria hypacanthus). A second group of specialists (Entomacrodus chiostictus and Ophioblennius steindachneri as well as Plagiotremus azaleus) feed on items not utilized by any of the generalists.There is some evidence that high diversity generalists are numerically more abundant than the other trophic groups.In the labrisomids and blenniids a phylogenetic trend from microcarnivory towards feeding on sessile items appears to be expressed.
Abstract. The utilization of empty holes of endolithic bivalves (Gttsirocluwnu dubui by Bknnius chdmcitinus, and Litliophaga lithophaga by all other species) as shelters by egg‐guarding males of nine species of Adriatic Blenniidae is compared. A wide spectrum of entrance sizes to these “standardized” shelters is used with the most frequent utilization ranging between 1(H) and 275 mm: (11.2–18.8mm mean entrance diameters). As a trend within and between species, larger fish utilize holes with disproportionately wider entrances. There arc significant differences between species in the means of “fit” of the heads within the entrances: the heads of B. dulmaibuts, B. canaeve, B. adrialicus, and B. zvonimiri“fit” tightly into their entrances whereas the two large species, B.puvo and B. tentacularis, which only facultatively use holes of boring mussels for breeding, arc found in holes with “oversized” entrances. In most species mean shelter depth approximates mean body length. Species which tightly “fit” their entrances tend to stay longer when disturbed mechanically or chemically compared to those with only a loose “fit”. The ecological and evolutionary significance of these patterns is discussed.
The patterns ofcoiling of the gut were compared in 22 species of Eurasian Cyprinidae. In selected species, also the length of gut and mucosal surface structure were compared. Piscivorous (Aspius u.spiu.s). planktivorous (Ahramis hullerus) fishes as well as species feeding mainly on plankton and wind-borne ' drift ' (Alburnus alburnus, Pelecus cullrarus) have the relatively shortest guts, with only a single loop. The same simple arrangement of a short gut is present in many euryphagous species with more or less carnivorous tendencies (Abrumis scipa, Alhurnoides bipunctatus, Ahramis hruma. Bliccu hjoerkna. Chalcalhurnus chalcoides men to. Gohio gohio, Leuciscuy cephalus. Luuciscus Ieuciscus, Rutilirs rulilus, Scardinius erythrophthalmus. Tinca tinca. Vimhu vimba). Some benthivorous winnowers (oropharyngeal sorters) and species with herbivorous feeding tendencies have relatively long guts showing a more complex pattern of loops and coils (Barhus harhus. Cumssius carassius, Chondrostoma nasus. Ctenophuryngodon idelia, Cyprinus carpio). The goldfish, Curassius auratus, has the most complex coils. Scanning electron microscopy of the mucosal surface revealed five types of folding in the intestinal bulb which were only loosely related to feeding: I. smooth surface (Aspius aspius, Leuciscus cephalus, Vimha vintba); 2, irregularly branching folds (Alhurnus alburnus, Barbus barhus, Blicca bjoerknu, Chalcalhurnus chalcoides mento, Luuciscirs Ieuciscus, Rutilus rutilus. Scardinius erythrophthalmus); 3, curl-like folds (Tincu tinca); 4, nct-like folding pattern (Ahramis brama); 5. honeycomb-like mucosal structure (Cyprinus carpio).
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