Anthropogenic sound caused by ship traffic as well as the construction and operation of offshore windfarms have increased exponentially in the last decades. While its impact on marine life is relatively well studied for mammals and fish, the implications of anthropogenic sound on benthic invertebrates are poorly understood. Here, we tested for potential stress responses of common marine invertebrates using two widespread mesograzing crustaceans: the isopod Idotea balthica and the amphipod Gammarus locusta. All experimental animals were gathered from laboratory cultures in the facilities of the Alfred Wegener Institute in Bremerhaven, Germany, in spring 2023. Oxygen consumption rates and the activities of four key mitochondrial enzymes (cytochrome c oxidase, electron transport system complex I and III, citrate synthase and lactate dehydrogenase) were examined under the influence of added low-frequency sound (+ 25 dB SPLRMS re 1 µPa at 90 Hz, above background soundscape) to assess how basal energy demands and supplies were affected. The isopod I. balthica seemed to be robust against added sound exposure over 72 h as neither oxygen consumption rates nor enzyme activities were significantly altered. The amphipod G. locusta, however, displayed significantly lower oxygen consumption rates in response to both short-term (1–4 h; 39% reduction) and longer-term (68–72 h; 35% reduction) added sound exposure, although enzymatic activities were not significantly affected. This study underlines the need to address the potential impact of sound on the energy available for the growth and reproduction of small invertebrates. Overlooked vulnerabilities to noise pollution in key taxa could have far reaching implications for marine food webs, nutrient cycles and ecosystem functioning.