Experiments on feeding and growth of the amphipod Gammarus pulex (L.) related to its distribution in the River Duddon

Abstract

Individuals of Gammarus pulex were kept at 15°Cfor periods of 23-70 days on diets comprised of elm or oak leaves, Tricladium and Clavariopsis {Hypho-mycete fungi), Molinia (grass), Zygogonium (alga), Nardia (liverwort). Both the mean interval between moults (mt), and daily increments in body wet weight, were related to diet. The lowest value for mi was 14-6 days on a diet of naturally decaying elm and oak leaves. The largest weight gains also occurred on this diet; the average daily gain in weight (Dw) = 130'8 ixglday, the mean specific gain in weight (Gw) = 1 -69 fxg yjday. On green Molinia and fungi diets Dw ranged from nil to 60-7 tig I day, and mi = 17-4-18-4 days was significantly (P<001) longer than mi on leaf diets. Survival and growth were poor on brown Molinia. Nardia did not support growth or survival. A mixed diet of Tricladium, Zygogonium, Nardia and decaying grasses was not sufficient to promote an increase in body weight, and mi = 21-8 days. This diet represents the commonly available food materials in Mosedale Beck, an acid stream in the upper Duddon catchment. Survival and growth of G. pulex on fungi and leaf diets in media containing low concentrations of potassium ions are also described and discussed briefly in relation to the distribution of G. pulex in the upper catchment of the R. Duddon.

Molecular insight into lignocellulose digestion by a marine isopod in the absence of gut microbes

“…G. pulex is a detrivore whose diet includes lignocellulose. Although this species prefers partially decayed material, it is able to survive on diets of undecayed or "inactivated" leaf litter (40,41). The hepatopancreas of G. pulex has been shown to contain endogenous cellulase (and phenoloxidase) activities that are not due to bacterial endosymbionts (41).…”

Dietary Preference ofGammarus pulexandAsellus aquaticusduring a Laboratory Breeding Programme for Ecotoxicological Studies

“…However, workers such as Nilsson [11] found that, at 15 • C, an average of 1928.7 calories were produced from alder leaves g −1 day −1 , which is considerably greater than other leaves, for example, beech (197.6 calories were produced from beech leaves g −1 day −1 ). The growth rate for Nilsson's smaller G. pulex specimens, which were fed on alder leaves was similar to the rate of 130.8 µg day −1 at 15 • C obtained by Willoughby and Sutcliffe [1] with a diet of oak and elm.…”

“…Bacteria and fungi are important components of the detritivore diet [1], G. pulex and A. aquaticus both discriminated between fungal mycelia and either fungally colonized or uncolonized leaf material [9], which was illustrated by this study. The results clearly demonstrate that both species of macroinvertebrates preferred a diet of conditioned leaf material over unconditioned leaves, with natural conditioning being the favoured conditioning option.…”

“…In contrast, Willoughby and Sutcliffe [1] found that the best diet for G. pulex was a mixture of conditioned elm and oak leaves. On this diet, the animals had a growth rate of approximately 150 µg day −1 at 10 • C in specimens of less than 16 mg body weight.…”

“…Over the years, scientists have used a variety of nutritional supplements to feed macroinvertebrates during breeding programmes and experiments, including dog food [1], baby, and fish food [2]. If the macroinvertebrates were being bred for ecotoxicological studies (or as test subjects within bioassays) they need to be representative of wild specimens, and it is well documented that a test, animals response could be affected by their past history, diet, life stage, disease and so forth [3,4].…”