Gut characteristics and assimilation efficiencies in two species of herbivorous damselfishes (Pomacentridae: Stegastes dorsopunicans and S. planifrons)

• Published in: Marine biology Vol. 142; no. 1; pp. 35 - 44
• Main Authors: CLEVELAND, A, MONTGOMERY, W. L
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 2003; Berlin Springer Nature B.V
• Subjects: Absorption; Agnatha. Pisces; Algae; Animal and plant ecology; Animal populations; Animal, plant and microbial ecology; Animals; Archipelagoes; Autoecology; Biological and medical sciences; Energy; Feeding. Feeding behavior; Fish; Food resources; Fundamental and applied biological sciences. Psychology; Herbivores; Herbivorous fish; Marine biology; Nutrients; Physiology; Reefs; Retention; Retention time; Trophic levels; Vertebrata; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Central America; Caribbean Sea; Panama; America; Assimilation; Nutrition; Herbivorous; Digestive system; Interspecific comparison; Gut; Retention time; Coastal zone; Feeding; Trophic group; Marine environment; Vertebrata; Diet; Functional morphology; Pisces; Reef animal
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-002-0916-4

The morphological and physiological mechanisms by which marine herbivores assimilate energy and nutrients from primary producers and transfer them to higher trophic levels of reef ecosystems are poorly understood. Two wide-ranging Caribbean fishes, the dusky damselfish, Stegastes dorsopunicans, and the threespot damselfish, S. planifrons, defend territories on patch reefs in the Archipelago de San Blas, Republic of Panama. We examined how relative intestine length and retention time influence digestion and absorption of energy and nutrients in these fishes. The dusky damselfish has a relative intestine length (RIL=intestine length/standard length) of 1.2 and a Zihler index {ZI=intestine length (mm)/10[mass(g)1/3]} of 3.4. These values are significantly lower (PRIL=PZI<0.0001) than those for the threespot damselfish (3.0 and 8.2, respectively). Both RIL and ZI for both species fall well below previously published values for other herbivorous pomacentrids, and may reflect their primary food resource at San Blas (diatoms). Energy-rich diatoms may be easier to digest than refractory macroalgae characteristic of diets of many herbivorous fishes (RIL range: 2-20). Despite differences in RIL and ZI between these two species, gut retention time is the same (P>0.05) for both dusky (6.6 h) and threespot damselfish (6.5 h). Thus, food travels the length of the threespot damselfish intestine ~2.5 times faster than it does in the dusky damselfish intestine. Levels of protein, carbohydrate, and lipid are significantly (0.003The morphological and physiological mechanisms by which marine herbivores assimilate energy and nutrients from primary producers and transfer them to higher trophic levels of reef ecosystems are poorly understood. Two wide-ranging Caribbean fishes, the dusky damselfish, Stegastes dorsopunicans, and the threespot damselfish, S. planifrons, defend territories on patch reefs in the Archipelago de San Blas, Republic of Panama. We examined how relative intestine length and retention time influence digestion and absorption of energy and nutrients in these fishes. The dusky damselfish has a relative intestine length (RIL=intestine length/standard length) of 1.2 and a Zihler index {ZI=intestine length (mm)/10[mass(g)1/3]} of 3.4. These values are significantly lower (PRIL=PZI<0.0001) than those for the threespot damselfish (3.0 and 8.2, respectively). Both RIL and ZI for both species fall well below previously published values for other herbivorous pomacentrids, and may reflect their primary food resource at San Blas (diatoms). Energy-rich diatoms may be easier to digest than refractory macroalgae characteristic of diets of many herbivorous fishes (RIL range: 2-20). Despite differences in RIL and ZI between these two species, gut retention time is the same (P>0.05) for both dusky (6.6 h) and threespot damselfish (6.5 h). Thus, food travels the length of the threespot damselfish intestine ~2.5 times faster than it does in the dusky damselfish intestine. Levels of protein, carbohydrate, and lipid are significantly (0.003 [PUBLICATION ABSTRACT]