The role of feeding strategy in the tolerance of a terrestrial salamander (Plethodon cinereus) to biogeochemical changes in northern hardwood forests

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Date: Apr. 2019
From: Canadian Journal of Zoology(Vol. 97, Issue 4)
Publisher: NRC Research Press
Document Type: Report
Length: 9,012 words
Lexile Measure: 1650L

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Abstract :

We investigated whether the trophic ecology of an apex predator is influenced by ecosystem-level nutrient depletion. The feeding behavior and nutrient assimilation of a terrestrial salamander, Eastern Red-backed Salamander (Plethodon cinereus (Green, 1818)), was surveyed along a gradient of forest biogeochemistry. Recent studies have documented populations of these salamanders in forests with low-pH soils that were long thought to be fatal. One mechanism that may enable P. cinereus to tolerate acid-impaired habitats is its generalist life history. We sampled diet, invertebrate prey abundance, and tissue composition of P. cinereus from sites that range in calcium availability and soil pH in northern forests of North America. We found that P. cinereus consistently exhibited a generalist feeding strategy, having diverse diets closely representing resource availability. Prey abundances were unrelated to the biogeochemical gradient (excluding gastropods), indicating relatively intact food webs. Although P. cinereus at the two most acid-impaired sites consumed more prey, overall trophic strategies were consistent across the gradient. Salamander tissue composition was unrelated to variation in forest biogeochemistry, although manganese levels were elevated in the most acid-impaired forests. We suggest that a generalist feeding strategy, combined with diverse and compositionally stable food webs, facilitates tolerance by this abundant predator of the challenges imposed by acid-impaired habitats. Key words: calcium depletion, Eastern Red-backed Salamander, food web, Plethodon cinereus, salamander diet, trophic ecology. Nous avons verifie si l'ecologie trophique d'un predateur de niveau trophique superieur est influencee par l'appauvrissement en nutriments a l'echelle de l'ecosysteme. Le comportement d'alimentation et l'assimilation de nutriments d'une salamandre terrestre, la salamandre rayee (Plethodon cinereus (Green, 1818)), sont examines le long d'un gradient de biogeochimie de la foret. Des etudes recentes documentent des populations de ces salamandres dans des forets aux sols de faible pH longtemps soupconnes d'etre fatals. Un mecanisme qui pourrait permettre a P. cinereus de tolerer les habitats acidifies est son cycle biologique generaliste. Nous avons caracterise le regime alimentaire, l'abondance de proies invertebrees et la composition de tissus de P. cinereus de sites presentant differentes disponibilites du calcium et differents pH du sol dans des forets septentri-onales d'Amerique du Nord. Nous avons constate que P. cinereus presente uniformement une strategie d'alimentation generaliste, ses regimes alimentaires varies refletant etroitement les ressources disponibles. L'abondance de proies n'etait pas reliee au gradient biogeochimique (a l'exception des gasteropodes), ce qui indique des reseaux trophiques relativement intacts. Meme si les P. cinereus aux deux sites les plus acidifies consommaient plus de proies, il y avait une coherence dans les strategies trophiques globales le long du gradient. La composition des tissus des salamandres n'etait pas reliee aux variations biogeochimiques des forets, les concentrations de manganese etant toutefois elevees dans les forets les plus acidifiees. Nous suggerons qu'une strategie d'alimentation generaliste, combinee a des reseaux trophiques varies et de composition stable, favorise la tolerance de ce predateur abondant aux defis que posent les habitats acidifies. [Traduit par la Redaction] Mots-cles: appauvrissement du calcium, salamandre rayee, reseau trophique, Plethodon cinereus, regime alimentaire des salamandres, ecologie trophique.

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Gale Document Number: GALE|A583489821