Metabolic and locomotory responses to oxygen concentration changing have been studied in the Black Sea non-acclimated («pale») and acclimated to hypoxia («red», with increased hemoglobin content) epilimnetic cladocerans Moina micrura, cultured separately under laboratory conditions, and also in bathypelagic copepods Calanus euxinus from two natural ecological groups - those performing daily vertical migrations to hypoxic layers or those diapausing there.

Weight-specific respiration rate has been determined by polarograghic method, weight-specific ammonia excretion rate has been measured using the phenolhypochlorite method of Solorzano. To identify the substrates of metabolism, the atomic O:N ratio has been calculated. The characteristics of basal metabolism have been determined in narcotized specimens. The parameters of locomotory activity (frequency, duration, drag force of locomotory acts, time spent swimming) have been measured in individuals attached to a semiconductor force sensor in a hermetic chamber. Behavioral actograms have been stored on computer. Custommade software has been used for analyzing the mechanical parameters of locomotion.

It has been shown that under short-term hypoxia non-acclimated to oxygen deficiency females of M. micrura and migrating females and V copepodites of C. euxinus decrease their total, basal metabolism, scope of activity, drag force, frequency and mechanical energy of swimming appendage locomotion. Ammonia excretion rate reduces less than respiration rate in cladocerans and nearly does not change in copepods. It seems to be evident that under oxygen-deficient conditions mixed lipid-protein catabolism (being typical for planktonic crustaceans under normoxia) is limited and pure protein turns out to be the only metabolic substrate utilized mainly anaerobically.

M. micrura adapted to long-term hypoxia are able to maintain high level of total metabolism due to increased hemoglobin content in hemolymph. Additional amounts of oxygen obtained are used mainly in scope of activity which is 31 times higher in acclimated to hypoxia individuals than in non-acclimated ones. Up to 97% of scope of activity is used in filtering activity of cladocerans. Acclimation to low oxygen concentrations does not affect basal metabolism.

Diapausing under hypoxic conditions V copepodites of C. euxinus minimize their locomotory activity, respiration and excretion rates to such levels when amount of available oxygen is enough for aerobic catabolism of lipids and protein.