For zebra mussels to successfully grow and reproduce, a sufficient amount of oxygen must be dissolved in the water. Karatayev et al. (1998) indicate that zebra mussels require at least 25 percent oxygen saturation. This is usually not a problem in their preferred shallow-water habitats. The quagga mussel, however, is apparently more tolerant of low oxygen conditions (Karatayev et al. 1998). Mussel oxygen consumption varies with ambient water temperature and physiological condition of an organism. Oxygen levels near the saturation values for a body of water are best for successful zebra mussel growth and reproduction. Stanczykowska (1977) found zebra mussels in European lakes with hypolimnetic oxygen levels ranging from 0.1-11.2 mg/l. Epilimnetic oxygen levels for the same lakes ranged from 4.2-13.3 mg/l (Stanczykowska 1977). These levels are common in most North American lakes. Zebra mussels (especially smaller ones) can survive for days under anaerobic (little to no oxygen) conditions, with longer survival at lower temperatures (Matthews and McMahon 1999). Although zebra mussels can survive for periods of time at very low oxygen concentrations, these conditions may not be conducive to growth or successful reproduction (Woynarovich 1961).