Dietary DNA metabarcoding reveals a trophic niche partitioning among sympatric Iberian sandgrouses and bustards.

The study of trophic niche partitioning is of great importance for understanding community structure and species coexistence, particularly if these are threatened. Here DNA metabarcoding was used to assess the diet of four threatened steppe bird species (two bustards and two sandgrouses), with the aim of better understanding their dietary requirements, trophic interactions, and potential threats. The results showed seasonal and interspecific differences in their plant diet, with greater importance of cultivated plants during autumn and winter (around 50 % of their diet) than spring.

Density effects on ammonium nitrate toxicity on amphibians. Survival, growth and cannibalism.

Temporary ponds where many amphibians breed experience a gradual desiccation that leads to growing larval densities, which can reduce tadpole survival rates and increase cannibalistic interactions among carnivorous salamander larvae. Concentrations of many agrochemicals, including nitrogenous fertilizers, can also increase as the water volume decreases. We analyzed the effects of ammonium nitrate fertilizer at two larval densities on growth and survival of Rana dalmatina tadpoles, and on cannibalistic behaviors of Salamandra salamandra larvae.

Ambient ultraviolet B radiation and prevalence of infection by Batrachochytrium dendrobatidis in two amphibian species.

Chytridiomycosis, the emerging disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd) is responsible for declines and extirpations of amphibian populations worldwide. Environmental covariates modify the host-Bd interaction and thus affect the ongoing spread of the pathogen. One such covariate may be the intensity of ultraviolet B (UV-B) radiation.

Responses of toad tadpoles to ammonium nitrate fertilizer and predatory stress: differences between populations on a local scale.

Agriculture-related pollution is among the major causes of global amphibian population declines. The multiple stressors to which amphibians are exposed in the field, such as predation pressure, can make agrochemicals far more deadly than when they act in isolation. Even within a small area, diffuse agricultural pollution does not affect all aquatic environments equally, which could account for local differences in amphibian sensitivity to agrochemicals.

Differences in susceptibility to Saprolegnia infections among embryonic stages of two anuran species.

Many amphibians are known to suffer embryonic die-offs as a consequence of Saprolegnia infections; however, little is known about the action mechanisms of Saprolegnia and the host-pathogen relationships. In this study, we have isolated and characterized the species of Saprolegnia responsible for infections of embryos of natterjack toad (Bufo calamita) and Western spadefoot toad (Pelobates cultripes) in mountainous areas of Central Spain. We also assessed the influence of the developmental stage within the embryonic period on the susceptibility to the Saprolegnia species identified.

Influence of ammonium nitrate on larval anti-predatory responses of two amphibian species.

Sublethal effects of toxicants can upset normal behavioural responses to predators, leading to increased predation. For example, sensory capabilities can be impaired by toxicants, leading to difficulty in detecting predators or other threats. Alteration of locomotor abilities by pollutants can also explain the difficulty of tadpoles to escape from predators.

Adaptation to osmotic stress provides protection against ammonium nitrate in Pelophylax perezi embryos.

The negative effects of pollution on amphibians are especially high when animals are additionally stressed by other environmental factors such as water salinity. However, the stress provoked by salinity may vary among populations because of adaptation processes. We tested the combined effect of a common fertilizer, ammonium nitrate (0-90.

Alteration of courtship behavior because of water acidification and minor effect of ammonium nitrate in the Iberian newt (Lissotriton boscai).

Although many studies have assessed the effects of water pollution on amphibians, few have focused on the alteration of vital behaviors. Newt species usually display complex courtship behavior that may be altered by sublethal levels of contaminants. We analyzed the effects of ammonium nitrate and water acidification on courtship behavior of the Iberian newt (Lissotriton boscai).

Saprolegnia diclina: another species responsible for the emergent disease 'Saprolegnia infections' in amphibians.

Many amphibians are known to suffer embryonic die-offs as a consequence of an emergent disease known as 'Saprolegnia infections'. Thus far, the only species of Saprolegnia shown to be involved in natural infections is Saprolegnia ferax. In this study, we have isolated and characterized another Saprolegnia species responsible for 'Saprolegnia infections' on embryos of Bufo calamita in mountainous areas of central Spain.

Effects of ammonium nitrate exposure and water acidification on the dwarf newt: the protective effect of oviposition behaviour on embryonic survival.

Embryonic mortality in many aquatic animals, including most amphibian species, is usually very high. In addition to mechanical and chemical defences, some species have developed behavioural patterns that can increase egg survival. For example, females of some newt species protect their eggs by wrapping them in leaves of aquatic plants.