Components of standard metabolic rate variability in three species of gammarids

Abstract

Abstract. Standard metabolic rate is a major functional trait with large inter-individual variability in many groups of aquatic species. Here we present results of an experimental study to address variation in standard metabolic rates, over different scales of organisation and environments, within a specific group of aquatic macro-invertebrates (i.e. gammarid amphipods) that represent the primary consumers in detritus food webs. The study was carried out using flow-through microrespirometric techniques on male specimens of three gammarid species from freshwater, transitional water and marine ecosystems. We examined individual metabolic rate variations at three scales: (1) at the individual level, during an 8 h period of daylight; (2) at the within-population level, along body-size and body-condition gradients; (3) at the interspecific level, across species occurring in the field in the three different categories of aquatic ecosystems, from freshwater to marine. We show that standard metabolic rates vary significantly at all three scales examined, with the highest variation observed at the within-population level. Variation in individual standard metabolic rates during the daylight hours was generally low (coefficient of variation, CV<10 %) and unrelated to time. The average within-population CV ranged between 30.0 % and 35.0 %, with body size representing a significant source of overall inter-individual variation in the three species and individual body condition exerting only a marginal influence. In all species, the allometric equations were not as steep as would be expected from the 3∕4 power law, with significant variation in mass-specific metabolic rates among populations. The population from the transitional water ecosystem had the highest mass-specific metabolic rates and the lowest within-population variation. In the gammarid species studied here, body-size-independent variations in standard individual metabolic rates were higher than those explained by allometric body size scaling, and the costs of adaptation to short-term periodic variations in water salinity in the studied ecosystems also seemed to represent a major source of variation.

CanGammarus aequicauda(Amphipoda) suppress a population ofBaeotendipes noctivagus(Chironomidae) in a hypersaline lake? A case of Lake Moynaki (Crimea)

“…This value is close to the values obtained earlier for one‐sized gammarus of other species (Krisp & Maier, 2005; Syrovatka et al., 2020). Average measured masses of G. aequicauda and chironomid larva were very close to that calculated from known equations for mass/length ratio (Alimov et al., 2013; Shadrin et al., 2019a; Shokri et al., 2019). The mass of one gammarid was about 9.4 times larger than for one chironomid.…”

“…Taking the coefficient of digestibility of 0.8, which is usual for animal food (Pechen‐Finenko, 1979; Shadrin, 2011), it was calculated that in our case, the predator can assimilate the amount of food equal to 36% of its body weight. Such a diet is enough to cover all the energy needs of metabolism, growth, and reproduction (Alimov et al., 2013; Shokri et al., 2019). Usually, eating chironomids, different species of Gammarus consume a diet equal to 30%–40% of their body weight per day (Krisp & Maier, 2005; Maier et al., 2011; Pellan et al., 2016; Syrovatka et al., 2020).…”

Biological and physical drivers of bio-mediated sediment resuspension: A flume study on Cerastoderma edule

“…(Gjoni, et al, 2017;Gjoni & Basset, 2018)] and on the individual metabolic responses to internal and external conditions [e.g. (Rosenfeld, et al, 2015;Shokri, et al, 2019)] is needed to predict the bioturbation effects on sediment resuspension.…”

Relationship between individual metabolic rate and patch departure behaviour: evidence from aquatic gastropods

“…In addition to the main drivers of individual metabolism, such as body mass and temperature, individual metabolic rates may vary in accordance with factors such as satiation, development, physiology, health, growth and reproductive state (Glazier 2005, Konarzewski and Książek 2012, Rosenfeld et al 2015, Pettersen et al 2018, Shokri et al 2019, Uiterwaal and DeLong 2019). If foragers of the same size and species operating at the same temperature have different metabolic rates, they will also have different energy demands, activity rates (Heusner 1985) and resource acquisition behaviour (Bell et al 2009, Metcalfe et al 2016).…”