Freshwater species have declined 88 percent since 1970 — twice the decline of animals on the land or ocean, according to recent research, yet large gaps remain in monitoring and conservation efforts. The two main threats, they found, are overexploitation and the loss of free-flowing rivers. “The results are alarming and confirm the fears of scientists involved in studying and protecting freshwater biodiversity,” said Sonja Jähnig, of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries. Jähnig was the senior author of the study, which was published in Global Change Biology. Researchers complied data for 126 freshwater megafauna species worldwide, including river dolphins, crocodiles, giant turtles and sturgeons. Large fish species and reptiles were particularly affected, they found. Success stories include the American beaver (Castor canadensis), a species that is increasing in North America.