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

Abstract

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.

Life History of Lepidostoma hirtum in an Iberian Stream and its Role in Organic Matter Processing

“…In terms of temperature, we expected an increase in growth with temperature up to a plateau, as reported for other aquatic invertebrates such as Gammarus pulex (L.) (e.g. Sutcliffe et al, 1981). According to Iversen (1979), at temperatures higher than 13°C the increase in consumption by S. personatum does not compensate for the increase in metabolic costs, causing a decrease in growth.…”

“…Those differences influence microbial decomposition (Canhoto & Grac¸a, 1996) and invertebrate feeding and growth (Canhoto & Grac¸a, 1996;Friberg & Jacobsen, 1999;Gonza´lez & Grac¸a, 2003). Invertebrate feeding and growth are also affected by temperature, as it is an important determinant of metabolism (Sutcliffe et al, 1981;Nolen & Pearson, 1993;Gonza´lez & Grac¸a, 2003).…”

The effect of temperature on herbivory by the omnivorous ectotherm snail Lymnaea stagnalis

“…The crustacean G. pulex is one of the most important invertebrate species in temperate streams, which is widely distributed throughout Europe (Holdich & Pöckl 2007), and can reach a density of 10,000 m -2 and has a continued mortality throughout the year (Welton, 1979). G. pulex feeds on a variety of debris, such as oak and elm leaves (Sutcliffe et al, 1981). Ditches with oak trees along the banks are common in the Netherlands, and there are also plenty of macrophytes and L. stagnalis in many of these ditches.…”

PREDATION RATE AND SIZE SELECTIVITY OF THE INVASIVE AMPHIPOD GMELINOIDES FASCIATUS PREYING UPON THE NATIVE ISOPOD ASELLUS AQUATICUS

“…Similarly, the vast majority of studies have emphasized the herbivorous nature of Gammarus spp. and their shredder functional feeding group classification (Moore 1977;Sutcliffe et al 1981), others showed a far richer food base and documented the facts of their predation on planktonic crustaceans (Anderson & Raasveldt 1974;MacNeil et al 1997;Wilheim & Schindler 1999). In addition, some study confirmed the predatory nature of amphipods and the use of animal component in the diet even in the presence of abundant and diverse plant food .…”