No abstract

Humans have drastically altered nocturnal environments with electric lighting. Animals depend on natural night light conditions and are now being inundated with artificial lighting. There are numerous artificial light sources that differ in spectral composition that should affect the perception of these light sources and due to differences in animal visual systems, the differences in color perception of these anthropogenic light sources should vary significantly. The ecological and evolutionary ramifications of these perceptual differences of light sources remain understudied. Here, we quantify the radiance of nine different street lights comprised of four different light sources: Metal Halide, Mercury Vapor, Light Emitting Diodes, and High‐Pressure Sodium and model how five animal visual systems will be stimulated by these light sources. We calculated the number of photons that photoreceptors in different visual systems would detect. We selected five visual systems: avian UV/VIS, avian V/VIS, human, wolf and hawk moth. We included non‐visual photoreceptors of vertebrates known for controlling circadian rhythms and other physiological traits. The nine light types stimulated visual systems and the photoreceptors within the visual systems differently. Furthermore, we modelled the chromatic contrast (Just Noticeable Differences [JNDs]) and color space overlap for each light type comparison for each visual system to see if organisms would perceive the lights as different colors. The JNDs of most light type comparisons were very high, indicating most visual systems would detect all light types as different colors, however mammalian visual systems would perceive many lights as the same color. We discuss the importance of understanding not only the brightness of artificial light types, but also the spectral composition of light types, as most organisms have different visual systems from humans. Thus, for researchers to understand how artificial light sources affect the visual environment of specific organisms and thus mitigate the effects, spectral information is crucial.

The 2009-2010 El Niño was accompanied by a severe drought strongly impacting Mexico as well as Central America, the Caribbean, and the southern USA. The present work aims at assessing how such a major climatic event impacted the hydrological typology of transitional waters in Terminos Lagoon, one of the largest shallow tropical lagoons fringing the Gulf of Mexico. Spatiotemporal inter-comparison of hydrological conditions was conducted by pairing a reference multiparametric dataset (14 hydrological parameters versus 34 sampling stations) averaged over the October 2008 to July 2010 period with each sampling occurrence dataset and running Principal Component Analyses (PCA), setting the reference-survey dataset as active variables and each sampling occurrence dataset as non-active (supplementary) variables. It revealed that the exceptional deficit in freshwater supply to the lagoon during the 2009-2010 El Niño drastically reduced hydrological diversity and lowered the trophic status of the lagoon. Short-term shifts in environmental status are common in transitional waters and responsible for temporary shifts in community structure but climate change projections show a significant long-term decrease in the freshwater discharge at the regional scale that will impact Terminos Lagoon as well as other coastal lagoons of Mexico and Central America. When combined with sea level rise, such a decrease will result in a long-term shift in hydrological conditions with a subsequent increase in salinity and a decrease in the diversity of environmental conditions affecting trophic status, will have a long-term impact on the biota.

Anthropogenic noise is a complex disturbance known to elicit a variety of responses in wild animals. Most studies examining the effects of noise on wildlife focus on vocal species, although theory suggests that the acoustic environment influences non‐vocal species as well. Common mammalian prey species, like mule deer and hares and rabbits (members of the family Leporidae), rely on acoustic cues for information regarding predation, but the impacts of noise on their behaviour has received little attention. We paired acoustic recorders with camera traps to explore how average daily levels of anthropogenic noise from natural gas activity impacted occupancy and detection of mammalian herbivores in an energy field in the production phase of development. We consider the effects of noise in the context of several physical landscape variables associated with natural gas infrastructure that are known to influence habitat use patterns in mule deer. Our results suggest that mule deer detection probability was influenced by the interaction between physical landscape features and anthropogenic noise, with noise strongly reducing habitat use. In contrast, leporid habitat use was not related to noise but was influenced by landscape features. Notably, mule deer showed a stronger predicted negative response to roads with high noise exposure. This study highlights the complex interactions of anthropogenic disturbance and wildlife distribution and presents important evidence that the effects of anthropogenic noise should be considered in research focused on non‐vocal specialist species and management plans for mule deer and other large ungulates.

No abstract