Digestive enzyme and gut surfactant activity of detritivorous gizzard shad (Dorosoma cepedianum)

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 57; no. 6; pp. 1113 - 1119
• Main Authors: Smoot, James C, Findlay, Robert H
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.06.2000; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Biological and medical sciences; Digestive system; Enzymatic activity; Enzymes; Feeding. Feeding behavior; Fish; Fundamental and applied biological sciences. Psychology; Shad; Studies; Surface active substances; Surfactants; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Clupeidae; Digestive system; Enzyme; Intestinal juice; Saprophagous; Digestion; Freshwater environment; Peptidases; Vertebrata; Enzymatic activity; Pisces; Interindividual comparison; Hydrolases; Age
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f00-036

Measuring digestive enzyme and surfactant activities tested specialization of gizzard shad (Dorosoma cepedianum) digestive physiology to a detritivorous feeding strategy. Digestive enzyme activity was measured in adult and larval gizzard shad using fluorescently labeled artificial substrates. Surfactant activity in gizzard shad was measured by comparing gut juice drop diameters over a range of dilutions. Enzyme activity in the ceca region of adult gizzard shad was high for esterase, beta-glucosidase, lipase, and protease. Enzyme activity was lower in posterior intestine sections than in anterior intestine sections, although protease activity remained high for the greatest distance in the intestine. Micelles were detected in adult gizzard shad gut juice, and surfactant activity was greatest in the ceca region. Larval gizzard shad protease activity was similar to that of adult fish, and surfactants were below their critical micelle concentration. Gizzard shad coupled digestive physiology with gut anatomy to obtain nutrients from detritus, and these adaptations may explain elevated growth rates observed in these fish when they are planktivorous.