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Mazariegos-Villarreal A.,Institute Polytechnic Nacional 195 | Pinon-Gimate A.,Institute Polytechnic Nacional 195 | Aguilar-Mora F.,Institute Polytechnic Nacional 195 | Aguilar-Mora F.,Universidad Michoacana de San Nicolas de Hidalgo | And 2 more authors.
Journal of Shellfish Research | Year: 2013

The diet of the keyhole limpet Megathura crenulata was determined from stomach contents of 119 specimens collected from 3 rocky reefs on the west coast of the Baja California Peninsula, Mexico, in July and November 2006 and March 2007. Limpet stomachs contained 78 taxa, including filamentous cyanobacteria, diatoms, brown and red algae, marine seagrass, foraminifera, hydrozoans, bryozoans, nematodes, bivalves, gastropods, crustaceans, and tunicates. The main food items (>10% index of relative importance) consumed by the limpet were a tunicate; red algae of the genera Callophyllis, Coralina, Cryptopleura, Nienburgia, Pterosiphonia, and Rhodymenia; the brown algae Cystoseira osmundacea; the hydrozoan Eudendrium; and the bryozoan Crisia. Despite the differences in composition and abundance of the main items among sites and dates, the food groups of tunicates and algae account for more than 80% index of relative importance of the diet. The trophic niche breadth (Levin's index) was 0.52 ± 0.20. Our findings show that M. crenulata is an omnivorous gastropod that feeds primarily on tunicates and red algae, although it consumes other algae and invertebrates associated with their main food source.

Guzman-Villanueva L.T.,Institute Polytechnic Nacional 195 | Ascencio-Valle F.,Institute Polytechnic Nacional 195 | Macias-Rodriguez M.E.,University of Guadalajara | Tovar-Ramirez D.,Institute Polytechnic Nacional 195
Fish Physiology and Biochemistry | Year: 2014

The effect of β-1,3/1,6-glucan, derived from yeast, on growth, antioxidant, and digestive enzyme performance of Pacific red snapper Lutjanus peru before and after exposure to lipopolysaccharides (LPS) was investigated. The β-1,3/1,6-glucan was added to the basal diet at two concentrations (0.1 and 0.2 %). The treatment lasted 6 weeks, with sampling at regular intervals (0, 2, 4, and 6 weeks). At the end of this period, the remaining fish from either control or β-glucan-fed fish were injected intraperitoneally with LPS (3 mg kg-1) or with sterile physiological saline solution (SS) and then sampled at 0, 24, and 72 h. The results showed a significant increase (P < 0.05) in growth performance after 6 weeks of feeding with β-glucan. Superoxide dismutase (SOD) activity in liver was significantly higher in diets containing 0.1 % β-glucan in weeks 4 and 6, compared to the control group. β-Glucan supplementation at 0.1 and 0.2 % significantly increased aminopeptidase, trypsin, and chymotrypsin activity. At 72 h after injection of LPS, we observed a significant increase in catalase activity in liver from fish fed diets supplemented with 0.1 and 0.2 % β-glucan; SOD activity increased in fish fed with 0.1 % β-glucan in relation to those injected with SS. Feed supplemented with β-1,3/1,6-glucan increased growth, antioxidant activity, and digestive enzyme activity in Pacific red snapper. © 2013 Springer Science+Business Media Dordrecht.

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