Manuel E. Ortiz-Santaliestra, Adolfo Marco. Archives of Environmental Contamination and Toxicology. January 2015. Temporary ponds, where many amphibians from temperate regions breed, show an annual cycle with a maximum water volume in spring followed by a progressive desiccation throughout late spring and summer. This desiccation leads to a decrease in dissolved oxygen and an increase in nitrogen levels, which can additionally increase because of anthropogenic sources such as chemical fertilizers. Leer más.