Frogs of Southern Africa. A complete Guide, by Vincent Carruthers and Louis du Preez

Frogs of Southern Africa. A complete Guide, by Vincent Carruthers and Louis du Preez. Penguin Random House South Africa. Imprint: Struik Nature. 2nd edition. Cape Town, South Africa 2017. ISBN 9781775845447 / ISBN 978-1-77-584544-7

Frogs of Southern Africa. A complete Guide, by Vincent Carruthers and Louis du Preez' describes the frogs found in southern Africa south of the Zambezi, Okavango and Cunene rivers and introduces the reader to their biological and conservation significance.

Vincent Carruthers  Louis du Preez  

FROGS IN THE ENVIRONMENT

AMPHIBIANS IN DECLINE

In recent decades frogs on several continents have suffered sudden, high mortality rates, resulting in various species becoming extinct and many others undergoing massive population reductions. Globally, amphibians are now the most threatened class of vertebrate. Amphibian population fluctuations are not unusual under natural conditions, but recent declines have been excessively severe and populations have failed to recover. Because of the ecological importance of frog populations in both terrestrial and aquatic ecosystems, these losses may bring about complex and far-reaching consequences. The global decline in amphibian numbers is one of the most vexing conservation issues of recent times. A current report from the lUCN's Global Amphibian Assessment (www.globalamphibians.org) shows that as many as a third of amphibian species have suffered severe declines worldwide and more than 7% are listed as Critically Endangered, many on the brink of extinction (IUCN Red List of Threatened Species www.iucnredlist. org). Despite increased scientific awareness of the threat, recent increases in extinctions remain largely unexplained. Some instances occur in virtually undisturbed regions, far from the adverse effects of habitat destruction and pollution. A number of hypotheses have been presented to explain these enigmatic extinctions and declines, but there has been no scientific consensus on the matter. Synergy between complex factors may be obscuring the root causes of amphibian declines. Some of the environmental hazards that are known to be contributing to these declines are listed below.

Habitat destruction or modification
Annually large areas of natural wetland and vegetation are destroyed for agriculture, forestry and urban development with largescale and permanent loss of amphibian habitat.

Climate change
Meteorological events and the shifting of seasonal patterns are creating macro-climatic changes that have serious implications for amphibian reproduction and survival. Moreover, shifts in climatic conditions may provide more favourable conditions for disease.

Depletion of stratospheric ozone
The breakdown of atmospheric filters that protect against ultraviolet light and subsequent increased UV exposure affects the development of frog eggs and developing tadpoles, especially in species that breed at high elevations and where eggs are deposited near surface water.

Disease
The recent escalation of amphibian die-offs caused by the fungal pathogen Batrachochytrium dendrobatidis, or amphibian chytrid, suggests that this may be a major contributor to amphibian declines and extinctions worldwide. Sudden outbreaks of the disease may be linked to global climate change as well as to international trade in amphibians. A number of southern African species have been found to be infected with 6. dendrobatidis and sporadic die-offs have been reported, but there is currently no evidence of significant population declines. However, the large number of IUCN Red Listed species in southern Africa, many of which have very restricted distribution ranges, may be at risk in the future from chytrid fungus. (...)

This is an excerpt from Frogs of Southern Africa. A complete Guide, by Vincent Carruthers and Louis du Preez.

Title: Frogs of Southern Africa
Subtitle: A complete Guide
Author: Vincent Carruthers; Louis du Preez
Publisher: Penguin Random House South Africa
Imprint: Struik Nature
2nd edition. Cape Town, South Africa 2017
ISBN 9781775845447 / ISBN 978-1-77-584544-7
Softcover, 17 x 24 cm, 519 pages, throughout colour photographs