Feeding and growth of the isopod <i>Asellus aquaticus</i> on actinomycetes, considered as model filamentous bacteria

Willoughby, L. G.; Marcus, J. H.

doi:10.1111/j.1365-2427.1979.tb01528.x

Cited by 26 publications

(8 citation statements)

References 17 publications

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“…Clearly, fresh Elodea, decay- ing oak leaves and Oedogonium are the only food items which result in fast growth to the animals. The mean specific growth of young animals fed on Elodea (6.40%) compared favorably with the values of 4.64 and 4.84 found by Marcus et al (1978) and Willoughby & Marcus (1979), respectively. The higher value obtained here (6.40%), is attributed to the slightly different weight and temperature used (0.3-1 mg compared to 0.8-1.3 mg and 22 C to 15 °C ), but is lower than the value of 7.19% which was found with new-born animals.…”

Section: Discussionsupporting

confidence: 60%

Utilization of grass carp faeces by the IsopodAsellus aquaticus (L.) in the laboratory

Petridis

1990

Hydrobiologia

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Grass carp (Ctenopharyngodon idella Val) faecal pellets derived from Elodea nutallii consumption were efficiently utilized by the detritivore Asellus. Immature and adult individuals of 2.1-3.2 mm and 4.9-6.0 mm respectively, exhibited a high mean specific growth (9.03 % /day and 3.33%/day) when offered faecal pellets as food during two weeks experimental trials. Individuals of the same groups, when fed on Elodea which had been mechanically fragmented to simulate the macerating action of the grass carp pharyngeal teeth, grew at rates (9.57//day and 4.06%/day) not significantly different from those fed on faecal pellets. However, the growth rates of animals fed on fresh Elodea (6.40%/day and 2.23 % /day) were significantly lower than in the above trials, indicating that the morphological destruction of the plant tissue could be responsible for the higher observed growth. The control trials, including unfed animals, showed negative growth (-0.49%/day and -0.48%/day).Grass carp herbivory makes a new food resource available to benthic invertebrates by converting fresh plant material to small plant fragments.

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Section: Discussionsupporting

confidence: 60%

Utilization of grass carp faeces by the IsopodAsellus aquaticus (L.) in the laboratory

Petridis

1990

Hydrobiologia

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“…Fungi do not seem to be especially important in the diet of G. pulex., a conclusion also reached for Asellus aquaticus (Marcus & Willoughby, 1978;Marcus « a/., 1978;Willoughby & Marcus, 1979). On a diet of leached elm leaves that carried few if any fungi, animals grew faster than on a pure diet of the fungus L. at/ualica.…”

Section: Discussionmentioning

confidence: 89%

Effects of diet, body size, age and temperature on growth rates in the amphipod Gammarus pulex

Sutcliffe¹,

Carrick²,

Willoughby³

1981

Freshwater Biology

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169

113

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Increase in body wet weight of Gammarus pulex fed on decaying elm leaves was followed to senescence and death. Growth in juveniles was approximately exponential; from birth to death it conformed to a logistic growth curve, with maximum absolute increments in weight about half-way through a life span of 350-450 days at 15''C. Some individuals lived longer, for up to 640-700 days. The instantaneous or specific growth rate was maximal near birth, at c. 5-6% wet wt day ', and declined exponentially with increasing size and age. Over the range 4.7-14.8°C there was a log-log relationship between temperature and specific growth rate. Growth was maximal at 20°C in newborn animals and at 15°C in 6-9-mg animals.The specific growth rate of young individuals was fastest on decaying leaves of elm with a well developed flora of fungi and other microorganisms. Leached elm leaves without this flora supported growth at a lower rate. The latter diet was sufficient for survival and growth of newborn individuals; detritus, faeces or other food items were not needed. Isolated specimens grew as fast as those kept in groups. Growth was generally slower on leached leaves of oak and sycamore. In newborn animals fed on the fine roots of aquatic plants {Veronica, Rorippa and Glyceria), growth was as fast as on decaying elm leaves; growth on the green living leaves of the plants was slower, as on detritus from two streams and on a pure culture of an aquatic fungus.Consumption of leached elm leaves was related to leaf thickness. In a full gut the wet weight (1.34-1.37 mg) and volume (3.8-4.1 mm^) (for 20-mg animals) was independent of leaf thickness but dependent on animal size, increasing 4-fold over the range 2-50 mg body wt. Daily consumption (dry wt) was approximately equivalent to 50% body dry wt at 5 mg and 20% at 50 mg body wet wt. Individuals fed on thick leaves ingested 50% more dry weight per day and absorbed more in the gut than when fed on thin leaves, but the relative efficiency of absorption was the same at 36-59% for 10-20-mg animals. Weight-specific absorption in the gut was highest in juveniles and decreased with increasing body weight; relative efficiency of absorption was generally lower in the larger individuals. Assuming an energy value of 5 cal mg^' dry wt for elm leaves, daily mean energy intake by absorption in thegutof G. pu/ex was2.2 calmg"' animaldry wt (9.2 Jmg"') in individuals of 0.4 mgdry wt (2 mg wet wt), decreasing to 0.3 cal mg"' (1.3 J mg~') at 10 mg dry wt (50 mg wet wt).Growth in Gammarus is briefly reviewed in the hght of work on other animals and it is emphasized that all aspects of feeding, growth and metabolism should be specifically related to size and age of the individuals, using well defined diets.

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“…In Asellus aquaticus L., high growth rates were recorded on conditioned leaves, and on a diet of a Saprolegnia species (which is not an important colonizer of leaves in streams) and considerably lower ones for an aquatic hyphomycete and several actinomycetes (Marcus, Sutcliffe & Willoughby, 1978;Willoughby & Marcus, 1979). However, the same isopod species is reported to have gained more weight on several fungal diets than on laboratory-conditioned leaves (Rossi & Fano, 1979;Rossi & Vitagliano-Tadini, 1978).…”

Section: Microbial Cells a S Foodmentioning

confidence: 99%

“…Some are toxic, some approach or surpass the nutritional qualities of well-conditioned leaves. I n experiments reported by Willoughby and colleagues (Marcus el al., 1978;Sutcliffe et al, 1981;Willoughby & Marcus, 1979;Willoughby & Sutcliffe, 1976) fungal diets were, at best, equivalent to unconditioned leaves (with one exception: Saprolegnia allowed growth similar to that on conditioned leaves). A partial explanation for the poor fungal performances in their tests may be based on their technique.…”

Section: Microbial Cells a S Foodmentioning

confidence: 99%

The role of fungi in the nutrition of stream invertebrates

Bärlocher

1985

Botanical Journal of the Linnean Society

249

154

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Dead leaves falling into streams are an important food source for many invertebrates. They are generally made more palatable and more nutritious if they are first colonized by aquatic hyphomycetes and other micro‐organisms. At least two mechanisms appear to be responsible for this conditioning effect: microbial production (addition of easily digested microbial compounds to the nutritionally poor leaf substrate), and microbial catalysis (conversion of indigestible leaf substances into digestible subunits by microbial enzymes). Different invertebrate species vary in their ability to take advantage of microbial conditioning. This appears to be influenced by their mobility, the range of their food resources and their ability to overcome defense mechanisms of leaf‐colonizing microorganisms.

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Feeding and growth of the isopod Asellus aquaticus on actinomycetes, considered as model filamentous bacteria

Cited by 26 publications

References 17 publications

Utilization of grass carp faeces by the IsopodAsellus aquaticus (L.) in the laboratory

Utilization of grass carp faeces by the IsopodAsellus aquaticus (L.) in the laboratory

Effects of diet, body size, age and temperature on growth rates in the amphipod Gammarus pulex

The role of fungi in the nutrition of stream invertebrates

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