Feeding preferences of supralittoral isopods and amphipods

Pennings, Steven C.; Carefoot, Thomas H.; Zimmer, Martin; Danko, Jean Paul; Ziegler, Andreas

doi:10.1139/cjz-78-11-1918

Cited by 13 publications

(11 citation statements)

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“…As has already been shown for shredder organisms (Kaushik & Hynes, 1971), consumption by G. roeselii increased with increasing conditioning time of leaf litter. The negative relation of consumption with polyphenols is in accordance with the observations of several authors (Rosset, Bärlocher & Oertli, 1982;Pennings et al, 2000;Abelho, 2001) who found them to be repellents of invertebrate grazers. In general, the leaf litter content of nitrogen and protein increase during decomposition, leading to an enhanced preference by shredders (Bärlocher, 1985;Suberkropp, 1992;Abelho, 2001).…”

Section: Dynamics Of Consumption and Leaf Parameters During Exposuresupporting

confidence: 91%

Consequences of the colonisation of leaves by fungi and oomycetes for leaf consumption by a gammarid shredder

et al. 2010

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1. Leaf litter breakdown by shredders in the field is affected by leaf toughness, nutritional value and the presence of secondary compounds such as polyphenols. However, experiments involving the use of single fungal strains have not supported the assumption that leaf parameters determine food selection by shredders perhaps because of a failure to test for high consumption prior to isolation of fungal strains, overrepresentation of hyphomycetes or the potential effects of accompanying bacteria. In this study, we used bacteria-free, actively growing fungi and oomycetes isolated from conditioned leaf litter for which a shredder had already shown high consumption rates. 2. Black alder (Alnus glutinosa) leaf litter was exposed to the littoral zone of Lake Constance in autumn, and subsamples were analysed for leaf parameters and consumption by Gammarus roeselii under standard conditions at regular intervals. On dates with a high consumption rate of the exposed leaves, 14 single strains of fungi and oomycetes were isolated, freed of bacteria and grown on autoclaved leaves. 3. Six of eight measured leaf parameters of exposed leaves were significantly correlated with Gammarus consumption rates, with high colinearity among leaf parameters hampering the identification of causal relations between leaf parameters and feeding activity. 4. When single strains of fungi and oomycetes were grown on autoclaved leaf litter, toughness of colonised leaves was always lower than in the control and the content of protein, N and P were increased. There were pronounced strain-specific effects on leaf parameters. Consumption rates also differed significantly, with nine of fourteen isolates consumed at higher rates than controls and none proving to be a deterrent. Protein and polyphenol content were significantly correlated with consumption rates. Oomycetecolonised leaves were consumed at similar rates but were of lower food quality than fungicolonised leaves. 5. We argue that direct strain-specific attractant or repellent effects of fungi and oomycetes on consumption by G. roeselii are not important. However, we found indirect strainspecific role operating via effects on leaf parameters.

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Section: Dynamics Of Consumption and Leaf Parameters During Exposuresupporting

confidence: 91%

Consequences of the colonisation of leaves by fungi and oomycetes for leaf consumption by a gammarid shredder

et al. 2010

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“…comm.). Amphipods feed on this beach wrack and their populations increase significantly in late summer and early fall (Pennings, Carefoot & Zimmer 2000;Lewis et al 2007), providing an abundant, high-protein and heavily utilized food source for coastal-dwelling rats (Kurle, Croll & Tershy 2008).…”

Section: The Aleutian Islandsmentioning

confidence: 99%

Measuring the realized niches of animals using stable isotopes: from rats to bears

Hopkins

Kurle

2015

Methods Ecol Evol

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Summary1. Stable isotope analysis is a powerful method for estimating the impacts animals have on their environment (resource use), revealing their ecological niches. 2. We demonstrated the use of a stable isotope mixing model for measuring the ecological niches of consumers. In particular, we used the model IsotopeR to estimate the resource use of two species with complex, omnivorous diets: invasive Norway rats from the Aleutian Islands, AK, and American black bears from Yosemite National Park, CA. Marginal posterior distributions for major food sources (for populations, groups and individuals) described the resource axes that partly define the realized niches of these omnivores. We used measures of these resource axes to inform resource management in the Aleutians and Yosemite. 3. Results from our analyses confirm that coastal rats did not rely on marine birds on rat-infested islands in the Aleutians. Instead, rats foraged primarily on terrestrial plants and preferred amphipods when they were available. We also use stable isotopes to confirm that plants and acorns are the largest contributors to black bear nutrition in Yosemite and learned that female bears foraged for acorns and pine nuts more heavily than males. 4. Although it is unclear if Norway rats can maintain viable populations in the Aleutians without access to marine-derived animal protein, results from our analyses suggest their dependence on such nutrients. In addition, sex-specific differences in foraging for high-fat acorns and pine nuts in Yosemite suggest black bear populations in the Sierra Nevada may be limited by the productivity and health of hard mast species. As demonstrated here, stable isotope analysis has wide applicability for investigating the resource use and ecological niches of animals. We anticipate and encourage its rapid development in this fundamental field of ecology.

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“…Besides removal of wrack through tidal currents and wave action, the factors contributing to this observation include mechanical breakdown of wrack via dryingrewetting cycles through solar radiation and morning dew (Newell et al 1996, Vahatalo et al 1998), flocculation and sedimentation (Harrison 1989, Opsahl andBenner 1993), microbial decomposition of detritus and its fragmentation and mass loss through feeding by detritivores (Newell and Bärlocher 1993, Zimmer et al 2002, 2004, and feeding preferences of detritivores (Pennings et al 2000). All these processes will eventually promote the marine-terrestrial transfer of nutrients and energy, since seaweeds, which are considered nutrient sinks in coastal waters, become a nutrient source when they decompose (Hanisak 1993).…”

Section: Aging Of Wrackmentioning

confidence: 99%

“…In many instances, this ''spatial subsidy'' is particularly important in that both sand and cobble beaches are physically stressful, lowproductivity environments (Kachi andHirose 1983, Houle 1997). For example, it has been shown that drift algae and seagrasses are capable of altering community structure by providing refugia (Holmquist 1997, Norkko et al 2000, serving as food to numerous intertidal invertebrates (e.g., Chown 1996, Pennings et al 2000, and releasing nutrients following bacterial decomposition and thereby altering sediment chemistry (Har- Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Wrack Deposition on Different Beach Types: Spatial and Temporal Variation in the Pattern of Subsidy

Orr

Zimmer

Jelinski

et al. 2005

Ecology

Self Cite

224

167

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The onshore deposition of macroalgal and macrophyte wrack provides a potentially significant marine subsidy to intertidal and supratidal herbivore and decomposer communities. Based on the study of daily input loads to beaches, we estimated summer wrack deposition of up to 140 Mg (dry mass)/km shoreline in Barkley Sound, British Columbia. However, input rates were highly variable depending on beach type, nearshore hydrodynamics, and buoyancy characteristics of the wrack. Cobble beaches retained ∼10 times and 30 times more wrack than did gravel and sand beaches, respectively. Cobble and gravel beaches also differed in species composition of new (fresh) wrack input, with Macrocystis integrifolia being characteristic for the former and Nereocystis luetkeana for the latter, which we attribute to buoyancy characteristics of the floating debris. On sand beaches, Phyllospadix spp. and Enteromorpha spp. were the dominant wrack species. Species composition of freshly deposited wrack also depended on wave exposure, but predictability based on the species pool within a beach's catchment was restricted. Drift lines of aging wrack differed from freshly deposited wrack in species composition, probably due to wrack decomposition that results in fluxes of nutrients and energy between the adjacent marine and terrestrial habitats. We hold that the characteristics of a given beach, e.g., substratum and wave exposure, and their effects on wrack input, will have important ecological and biogeochemical implications for the marine–terrestrial ecotone.

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Feeding preferences of supralittoral isopods and amphipods

Cited by 13 publications

References 0 publications

Consequences of the colonisation of leaves by fungi and oomycetes for leaf consumption by a gammarid shredder

Consequences of the colonisation of leaves by fungi and oomycetes for leaf consumption by a gammarid shredder

Measuring the realized niches of animals using stable isotopes: from rats to bears

Wrack Deposition on Different Beach Types: Spatial and Temporal Variation in the Pattern of Subsidy

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